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  • maize  (202)
  • Springer  (202)
  • 1990-1994  (201)
  • 1970-1974  (1)
  • 1950-1954
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  • 1
    Electronic Resource
    Electronic Resource
    Whole-cell and single-channel currents across the plasmalemma of corn shoot suspension cells (1991)
    Springer
    The journal of membrane biology 121 (1991), S. 11-22 
    Details
    ISSN: 1432-1424
    Keywords: channel ; protoplast ; K+ current ; patch clamp ; corn ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Whole-cell sealed-on pipettes have been used to measure electrical properties of the plasmalemma surrounding protoplasts isolated from Black Mexican sweet corn shoot cells from suspension culture. In these protoplasts the membrane resting potential (V m ) was found to be −59±23 mV (n=23) in 1mm K o − . The meanV m became more negative as [K−] o decreased, but was more positive than the K+ equilibrium potential. There was no evidence of electrogenic pump activity. We describe four features of the current-voltage characteristic of the plasmalemma of these protoplasts which show voltagegated channel activity. Depolarization of the whole-cell membrane from the resting potential activates time- and voltage-dependent outward current through K+-selective channels. A local minimum in the outward current-voltage curve nearV m =150 mV suggests that these currents are mediated by two populations of K+-selective channels. The absence of this minimum in the presence of verapamil suggests that the activation of one channel population depends on the influx of Ca2+ into the cytoplasm. We identify unitary currents from two K+-selective channel populations (40 and 125 pS) which open when the membrane is depolarized; it is possible that these mediate the outward whole-cell current. Hyperpolarization of the membrane from the resting potential produces time- and voltage-dependent inward whole-cell current. Current activation is fast and follows an exponential time course. The current saturates and in some cases decreases at membrane potentials more negative than −175 mV. This current is conducted by poorly selective K+ channels, whereP Cl/P K=0.43±0.15. We describe a low conductance (20 pS) channel population of unknown selectivity which opens when the membrane is hyperpolarized. It is possible that these channels mediate inward whole-cell current. When the membrane is hyperpolarized to potentials more negative than −250 mV large, irregular inward current is activated. A third type of inward whole-cell current is briefly described. This activates slowly and with a U-shaped current-voltage curve over the range of membrane potentials −90〈V m 〈0 mV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870647
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  • 2
    Electronic Resource
    Electronic Resource
    Allelic mutations in acetyl-coenzyme A carboxylase confer herbicide tolerance in maize (1992)
    Springer
    Theoretical and applied genetics 83 (1992), S. 435-442 
    Details
    ISSN: 1432-2242
    Keywords: Tissue culture mutant selection ; Herbicide tolerance ; Fatty acid biosynthesis ; Acetyl-CoA carboxylase ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The genetic relationship between acetyl-coenzyme A carboxylase (ACCase; EC 6.4.1.2.) activity and herbicide tolerance was determined for five maize (Zea mays L.) mutants regenerated from tissue cultures selected for tolerance to the ACCase-inhibiting herbicides, sethoxydim and haloxyfop. Herbicide tolerance in each mutant was inherited as a partially dominant, nuclear mutation. Allelism tests indicated that the five mutations were allelic. Three distinguishable herbicide tolerance phenotypes were differentiated among the five mutants. Seedling tolerance to herbicide treatments cosegregated with reduced inhibition of seedling leaf ACCase activity by sethoxydim and haloxyfop demonstrating that alterations of ACCase conferred herbicide tolerance. Therefore, we propose that at least three, and possible five, new alleles of the maize ACCase structural gene (Acc1) were identified based on their differential response to sethoxydim and haloxyfop. The group represented by Acc1-S1, Acc1-S2 and Acc1-S3 alleles, which had similar phenotypes, exhibited tolerance to high rates of sethoxydim and haloxyfop. The Acc1-H1 allele lacked sethoxydim tolerance but was tolerant to haloxyfop, whereas the Acc1-H2 allele had intermediate tolerance to sethoxydim but was tolerant to haloxyfop. Differences in tolerance to the two herbicides among mutants homozygous for different Acc1 alleles suggested that sites on ACCase that interact with the different herbicides do not completely overlap. These mutations in maize ACCase should prove useful in characterization of the regulatory role of ACCase in fatty acid biosynthesis and in development of herbicide-tolerant maize germplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226531
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  • 3
    Electronic Resource
    Electronic Resource
    Distribution of second generation European corn borer,Ostrinia nubilalis, egg masses in field corn and relationship to subsequent tunneling damage (1993)
    Springer
    Entomologia experimentalis et applicata 68 (1993), S. 15-23 
    Details
    ISSN: 1570-7458
    Keywords: insecta ; Ostrinia nubilalis ; egg distribution ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between second generation European corn borer (Ostrinia nubilalis Hübner) egg mass numbers and subsequent field corn damage, as measured by stalk cavity numbers, was studied in 79 fields in northeastern North Carolina over three years. A mean of 0.028 egg masses per plant (645 egg masses/23400 plants) was found over the course of the study. Significant differences in oviposition rate were detected between fields and years. Ca. 85% of egg masses were deposited in a five leaf zone surrounding the primary ear; of these, 89% were found on the lower four leaves in this zone. Egg masses appeared to be distributed randomly within fields but at low rates of incidence, and oviposition was relatively uniform between sampling areas within individual fields. Under moderate to high oviposition pressure (mean number of egg masses per plant over the duration of the oviposition period 〉ca. 0.02), eggs laid during the early phases of the oviposition period account for more subsequent stalk damage than eggs laid during the later phases of the oviposition period. Variations in second generation egg mass numbers accounted for ca. 70% of variation in stalk cavity numbers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02380577
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  • 4
    Electronic Resource
    Electronic Resource
    Geographical variation in pheromone response of the European corn borer, Ostrinia nubilalis, in North Carolina (1992)
    Springer
    Entomologia experimentalis et applicata 64 (1992), S. 177-185 
    Details
    ISSN: 1570-7458
    Keywords: Insecta ; Ostrina nubilalis ; pheromone trapping ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The response of male European corn borer, Ostrinia nubilalis (Hübner) to synthetic pheromone lures containing various isomeric blends of the sex pheromone 11-tetradecenyl acetate was measured in 13 counties in North Carolina. The blends consisted of either 3% Z (‘E strain’), 97% Z (‘Z strain’), or 35% Z (‘hybrid’) 11-tetradecenyl acetate. Response to E strain lures predominated in those counties located in the Coastal Plain (east) of the state, while response to the Z strain pheromone was dominant in the west. A zone of overlap of these broad strain distributions appears to occur in the eastern Piedmont. Within this zone there was substantial response to both E and Z blends. The proportion of these responses changed considerably between generations within years as well as between years. Significantly higher capture rates in hybrid baited traps in parts of the overlap zone may be indicative of increased rates of hybridization between the E and Z strains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00162990
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  • 5
    Electronic Resource
    Electronic Resource
    Irrigation effects on European corn borer — maize water relations (1992)
    Springer
    Entomologia experimentalis et applicata 64 (1992), S. 11-21 
    Details
    ISSN: 1570-7458
    Keywords: European corn borer ; Ostrinia nubilalis ; maize ; water ; drought ; stress ; development ; models ; microenvironment ; irrigation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study examined the impact of irrigation water on certain aspects of an insect-plant relationship in the field including the assessment of plant-mediated water effects on an herbivore's development, survival, and behavior, and plant damage parameters and host tissue water status. Maize (Zea mays L.) plants were arranged in a randomized complete block design in the field over two years in North Carolina (NC). Four blocks were subjected to three different irrigation treatments initiated ca. one week before anthesis: optimal, intermediate, deficit water supply. Each plant was infested with one (1986) or two (1987) black head stage, E-race European corn borer [Ostrinia nubilalis (Hübn.)] (ECB) egg masses at tasselling. ECB development, tunnelling site, and survival as well as plant tissue water status (tissue % water contents [θ] & leaf water potentials [Ψ]) were recorded through July. The irrigation effect on ECB parameters was slight and variable. Internal stalk temperatures of optimal plants were consistently cooler than their deficit counterparts (1 day-degree/day). With degree-days included as an explanatory variable in the analyses, there were no significant irrigation effects on the ECB parameters, except for total proportion of ECB's bored into maize plant parts. More ECB's bored into drier plants than in optimal plants; however, this trend was not significant in 1987. Plant water indices showed that though Ψ responded to irrigation, there were only minor changes in tissue θ, particularly in view of the larger diurnal tissue changes observed and the relatively high, sustained stalk θ levels seen over all treatments. Examination of ECB pupal θ confirmed that dietary water changes were minor or non-limiting to the insects' developmental physiology, because pupal θ was not sensitive to the irrigation treatments. Though water supply changes have drastic developmental and agronomic consequences for the maize plant, little or no changes were seen in the ECB feeding environment. Furthermore, a plant damage model was developed whereby the total % of ECB's tunnelled into maize was related to the mean larval age. The implications of this model on the understanding of ECB tunnelling behavior, damage potential, and pest management is noted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688989
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  • 6
    Electronic Resource
    Electronic Resource
    Toxicity and anticholinesterase activity of the fungal metabolites territrems to the corn earworm, Helicoverpa zea (1992)
    Springer
    Entomologia experimentalis et applicata 65 (1992), S. 57-64 
    Details
    ISSN: 1570-7458
    Keywords: Heliothis ; corn ; maize ; insecticide ; Aspergillus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The toxicity and anticholinesterase activity of tremorgenic fungal metabolites, territrems, to the corn earworm, Helioverpa zea (Boddie) (Lepidoptera, Noctuidae) were examined. In oral toxicity studies, territrem A significantly inhibited growth by 40% at 25 ppm and by 89% at 250 ppm. Territrem B and an epoxy-derivative significantly inhibited growth by ca. 45% at 250 ppm. Piperonyl butoxide administered orally synergized the toxicity of the territrems tested. In topical toxicity studies, the epoxy-derivative caused 26% mortality and 25% growth retardation at 10 mg/gm insects. Territrem A and B were not significantly lethal, but did reduce growth by 15–20% at 10 mg/gm insect. Paraoxon tested in the same way caused 100% mortality at 25 ppm orally and 10 mg/gm topically. However, all territrems tested in vitro as inhibitors of H. zea head acetylcholinesterase were at least comparable to or were more active than paraoxon. Topically administered epoxy-territrem B also inhibited H. zea head acetylcholinesterase. The potential for development of new insecticides from a territrem lead structure is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00189717
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of temperature and host plant on the development of the blackfaced leafhopper (1990)
    Springer
    Entomologia experimentalis et applicata 55 (1990), S. 285-294 
    Details
    ISSN: 1570-7458
    Keywords: Graminella nigrifrons ; maize ; oats ; johnsongrass ; development ; fecundity ; host suitability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé La dynamique des populations (durée de développement de l'œuf à l'adulte, poids et taille des adultes, fécondité) de G. nigrifrons Forbes (Homop. Cicadellidae) a été étudiée au laboratoire à 5 températures sur plantules de maïs (Zea mays L.), avoine (Avena sativa L.) et sorgho vivace (Shorgum halepense (L.) Pers.). Sur les 3 plantes, les mâles se développent en moyenne 1,2 j plus vite que les femelles. Les relations entre vitesse de développement et température ont été déterminées en utilisant à la fois un modèle linéaire et le modèle biophysique à 2 paramètres de Sharpe & DeMichele (1977). Les températures plus basses donnent des adultes des 2 sexes plus gros et plus lourds. Moins de G. nigrifrons se sont développés sur la graminée vivace que sur les 2 graminées annuelles à la température la plus élevée (30°C), tandis qu'à la température la plus basse (18°C) moins de cicadelles se sont développées sur les graminées annuelles. La température semble jouer un rôle significatif en déterminant l'adéquation des plantes comme hôtes convenant au développement de G. nigrifrons. Le potentiel de ponte de cette cicadelle avait été sous-estimé par les étudies précédentes.
    Notes: Abstract Population dynamics of the blackfaced leafhopper, Graminella nigrifrons (Forbes) (Homoptera: Cicadellidae), was studied at five temperatures (18, 21, 24, 27, & 30°C) in the laboratory on seedling maize (Zea mays L.), oats (Avena sativa L.), and the perennial johnsongrass (Sorghum halepense (L.) Pers.). Effects of temperature and host plant on egg to adult mean development time, adult size and weight, and fecundity were determined. Leafhoppers on all three hosts developed fastest at the highest temperature tested (21.3 days), and slowest at the lowest temperature tested (73.2 days). The duration from first to last adult eclosion was shortest at 30°C, (11.5 days) and longest at 18°C (43 days). The sex ratio of males to females did not differ from 1:1, but males developed an average of 1.2 days faster than females on all three hosts. Mean percent development/day ranged from 1.4% at 18°C to 4.7% at 30°C. The relationship of this development rate and temperature was determined using both a linear model and a variable parameter biophysical model. Based on these models, the developmental threshold is estimated at 12–15°C. The lowest temperature yielded larger and heavier adults (312 μg, dry weight) than did the highest temperature (225 μg). Fewer leafhoppers developed on the perennial than the annuals at 30°C and fewer on the annuals than the perennial at 18°C. Our results suggest that early in the season johnsongrass and perhaps other perennials are the superior developmental hosts for this leafhopper, whereas in midsummer when temperatures are highest, annuals are the better hosts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00190668
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  • 8
    Electronic Resource
    Electronic Resource
    Oviposition by the African migratory locust, Locusta migratoria migratorioides, in a crop environment in South Africa (1991)
    Springer
    Entomologia experimentalis et applicata 61 (1991), S. 169-177 
    Details
    ISSN: 1570-7458
    Keywords: African migratory locust ; crop environment ; oviposition behaviour ; oviposition sites ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Oviposition by the African migratory locust, Locusta migratoria migratorioides (Orthoptera: Acrididae), was studied in maize and wheat crops on the Orange Free State Highveld. Maize was shown to be the most important oviposition habitat with peak laying taking place in autumn and early winter when highest pod densities were recorded. Laying was mainly concentrated along the middle of the crop interrows in maize and within clearings in the wheat crop. Despite the uniform layout of these crops, the distribution of egg pods was found to be aggregated. Non-reproductive behaviour, such as locust aggregation, basking and feeding, as well as environmental factors appeared to influence the distribution of egg pods in these crops. Secondary selection for optinum soil moisture and compaction on the laying site enhanced the aggregation of pods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00191747
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  • 9
    Electronic Resource
    Electronic Resource
    Diel flight periodicity of Chilo partellus (1992)
    Springer
    Entomologia experimentalis et applicata 65 (1992), S. 165-170 
    Details
    ISSN: 1570-7458
    Keywords: Lepidoptera ; Pyralidae ; stem borer ; suction trap ; behaviour ; maize ; dispersal ; pheromones ; activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The diel flight periodicity of the nocturnal moth Chilo partellus (Swinhoe) (Lepidoptera;Pyralidae) was measured in the laboratory using an actograph and in the field with suction traps. Females showed almost no flight activity on the night of eclosion. Flight activity of mated females peaked before midnight, the period of peak oviposition activity. Male peak activity occurred after midnight coinciding with female eclosion. Presence or absence of females did not affect when or how long males were active. Data on flight activity and reproductive behaviour are discussed in relation to the use of pheromones to protect maize.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221367
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  • 10
    Electronic Resource
    Electronic Resource
    The ethnoecology of maize variety management: A case study from Mexico (1991)
    Springer
    Human ecology 19 (1991), S. 389-418 
    Details
    ISSN: 1572-9915
    Keywords: maize ; indigenous knowledge ; technological change ; Mexico
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Ethnic Sciences
    Notes: Abstract This paper presents a case study of the relationship between farmers' knowledge of maize varieties and their selection and management of these varieties under conditions of technological change. Research for this paper was done among Spanish-speaking small farmers in an ejidoof central Chiapas, Mexico. This ejido is well integrated into the market, and the use of modem technologies is widespread. This research demonstrates that farmers have an extensive and widely shared knowledge of their maize varieties. This knowledge reflects objective maize characteristics. Variation occurs in the farmers' selection and management of maize varieties, but on average the variation deviates from a random pattern in the direction predicted by the farmers' knowledge base. They have incorporated the technological changes brought about by development into their knowledge base. Farmers maintain maize varieties with contrasting traits, and their knowledge base provides important information about which traits and constraints are important to them.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00888984
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  • 11
    Electronic Resource
    Electronic Resource
    Intercropping Acacia albida with maize (Zea mays) and green gram (Phaseolus aureus) at Mtwapa, Coast Province, Kenya (1991)
    Springer
    Agroforestry systems 14 (1991), S. 193-205 
    Details
    ISSN: 1572-9680
    Keywords: Acacia albida ; intercropping ; maize ; green gram ; coastal lowlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Long-term agroforestry demonstrations/trials using Acacia albida and other nitrogen fixing multipurpose trees/shrubs were initiated in mid-1982 to assess soil and crop productivity at a coastal lowland site characterized by low soil fertility, weed problems and consequent poor crop yields. Growth performance (height and diameter at breast height, dbh) of Acacia albida under eight densities rotationally intercropped with maize (Zea mays) and green gram (Phaseolus aureus), crop grain yields, soil fertility changes and weed control were assessed for a 5-year period (May 1982 to March 1987). A parallel-row systematic spacing field layout was used. Intercropped Acacia albida mean hight and dbh were 140 and 24% respectively higher than tree-only controls by the fifth year. Growth rate was low during the first year but increased in subsequent years to mean height and dbh of 9 m and 10 cm respectively by March 1987. While differences in dbh were significant, those between stand heights were not. Crop yields, especially under higher tree densities, declined considerably due to unexpected shade which also caused significant reductions in weed biomass. Soil fertility levels remained unchanged during the experimental period relative to the initial status, and differences between the intercropped Acacia albida plots and the tree — or crop — only control appeared not to be significant. We conclude that an understanding of the mechanism regulating leaf fall/retention phenomena of Acacia albida is crucial towards determining the intercropping potentials of the species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00115735
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  • 12
    Electronic Resource
    Electronic Resource
    The potential of alley cropping im improvement of cultivation systems in the high rainfall areas of Zambia II. Maize production (1992)
    Springer
    Agroforestry systems 17 (1992), S. 241-261 
    Details
    ISSN: 1572-9680
    Keywords: alley cropping ; maize ; soybean ; soil fertility ; Leucaena leucocephala ; Sesbania sesban ; Albizia falcataria ; Flemingia congesta ; Gliricidia sepium ; Cassia spectabilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Theee trials to evaluat the potential of alley cropping in maize production on the low fertility, acidic soils in Northern Zambia are described. Leucaena leucocephala, Gliricidia sepium, Sesbania sesban, Albizia falcataria, Fleminga congesta, and Cassia spectabilis, were grown in alley crops with hybrid maize and soybean. All trials received recommended rates of P and K fertiliser; N fertiliser was applied at three rates as a subplot treatment. One trial received lime before establishment. Only in the limed trial was there a significant improvement in maize yields through alley cropping; when no N fertiliser was applied, incorporation of Leucaena leucocephala prunings resulted in an increase of up to 95% in yields, with a smaller improvement being produced by Flemingia congesta. There was a significant correlation between the quantity of prunings biomass applied and the proportional increase in maize yields over the control treatment. It is suggested that the lack of effect of most of the tree species on crop yields was due to low biomass production. An economic analysis showed that alley cropping with limed Leucaena was only profitable when fertiliser costs were high in relation to maize prices. However, lime is both expensive and difficult to obtain and transport for most small scale farmers in the region, and is therefore not a practical recommendation. It is suggested that future alley cropping research should focus on screening a wider range of tree species, including other species of Leucaena, for acid tolerance and higher biomass production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00054150
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  • 13
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    The potential of alley cropping in improvement of cultivation systems in the high rainfall areas of Zambia. III. Effects on soil chemical and physical properties (1993)
    Springer
    Agroforestry systems 21 (1993), S. 117-132 
    Details
    ISSN: 1572-9680
    Keywords: alley cropping ; maize ; nitrogen ; organic matter ; soil fertility ; Leucaena leucocephala ; Flemingia congesta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A detailed study of the soil chemical and physical properties in seven-year-old alley cropping trial containingLeucaena leucocephala andFlemingia congesta in Northern Zambia is described. There was a strong correlation between the maize yield and the total amount of nitrogen applied, both from prunings and fertiliser, suggesting that a major reason for the observed benefit from alley cropping, particularly withLeucaena, was due to an improvement in nitrogen supply.Leucaena produced significantly more biomass, and its leaves had higher concentrations of nitrogen, phosphorous and potassium and lower C/N and C/P ratios than did those ofFlemingia. There was also evidence that the trees had a beneficial effect on other soil chemical properties; under the hedgerows, particularly those ofLeucaena, there were higher levels of organic carbon, Mg, K and ECEC, and pH values were also highest. It is suggested that higher levels of organic carbon in the alley crop treatments were responsible for the improvements observed in soil physical properties. Lower bulk density, lower penetration resistance, and a higher infiltration rate and pore volume fraction were measured in the alley crops, although there was no significant change in the soil water release parameters. A deteriorating effect of constant applications of nitrogen fertiliser on soil fertility was observed; as the level of urea application increased, there were significant decreases in Mg, K and pH, increases in Al and soil acidity, and higher penetrometer resistance. These results highlight the urgent need for further research on biological methods of maintaining soil fertility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00705224
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  • 14
    Electronic Resource
    Electronic Resource
    The effect of feeding maize husk and leucaena mixed or separately on the voluntary intake of the husk (1993)
    Springer
    Agroforestry systems 24 (1993), S. 271-276 
    Details
    ISSN: 1572-9680
    Keywords: intake ; maize ; husk ; leucaena ; goats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of feeding maize (Zea mays L.) husk and leucaena (Leucaena leucocephala) as a mixture or separately on the voluntary intake of maize husk was studied over a 40-day period. Ten male goats with an average weight of 15 kg were used. The maize husk intake and total dry matter intake for the two feeding methods was about the same. Thus, total dry matter intake was not affected (P〈0.05) by the feeding method. There was also no significant difference (P〈0.05) between the two feeding methods in the digestibility values. The data were considered to indicate that there were no significant differences in the intake of maize husk when fed in a mixture with leucaena or when offered separately but at the same time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00705626
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  • 15
    Electronic Resource
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    Niacin, thiamin, and pantothenic acid bioavailability to humans from maize bran as affected by milling and particle size (1993)
    Springer
    Plant foods for human nutrition 43 (1993), S. 87-95 
    Details
    ISSN: 1573-9104
    Keywords: maize ; bran ; niacin ; thiamin ; pantothenic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of the project was to determine the bioavailability of selected B vitamins (niacin, pantothenic acid and thiamin) to humans from wet and dry milled maize brans which were coarsely or finely ground. Using a double cross-over design, the nine subjects were fed laboratory controlled diets containing unsupplemented bread or bread supplemented with finely ground, wet milled maize bran; coarsely ground, wet milled maize bran; finely ground, dry milled corn bran; or coarsely ground, dry milled maize bran. Subjects made complete collections of urine throughout the study which were analyzed for contents of the test vitamins. Although varying somewhat among vitamins, in general, better apparent bioavailability was achieved with the finely ground, dry milled maize bran than with the other test brans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01088100
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  • 16
    Electronic Resource
    Electronic Resource
    Dryinid (Hym.: Dryinidae) parasitoids ofDalbulus leafhopper (Hom.: Cicadellidae) in Mexico (1993)
    Springer
    BioControl 38 (1993), S. 41-49 
    Details
    ISSN: 1573-8248
    Keywords: Insect parasitoids ; Dryinidae ; Dalbulus ; maize ; teosintes ; Tripsacum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Les connaissances relatives aux ennemis naturels des Cicadelles du genre Dalbulus [Hom.: Cicadellidae] sont encore limitées. Dans l'état du Jalisco, au Mexique, a été réalisée une étude sur les dryinides (petites guêpes), parasitoïdes de ces cicadelles. L'état du Jalisco abrite le plus grand nombre d'espèces deDalbulus et se trouve localisé dans la région d'origine deDalbulus ainsi que de ses plantes hôtes: maïs, téosinte (Zea) etTripsacum. Le dryinideGonatopus bartletti a été rencontré parasitantDalbulus maidis sur des plantes de maïs ainsi que sur le téosinte annuelZea mays spp.parviglumis: G. flavipes a été identifié parasitantD. elimatus sur le téosinte pérenne,Zea perennis; de plus, une nouvelle espèce,G. moyaraygozai, ainsi queAnteon ciudadi ont été observés en tant que parasites deD. quinquenotatus surTripsacum pilosum et surTripsacum dactyloides. Le parasitisme par des dryinides a été observé à des altitudes comprises entre 680 et 2 000 m s.n.m..Dalbulus maidis, espèce qui cause les pertes de rendement les plus importantes en Amérique latine, est parasité entre 680 m s.n.m. et 1 760 m s.n.m.. Les espèces deDalbulus associées à des plantes hôtes annuelles (maïs etZ. mays spp.parviglumis) ont été parasitées par des dryinides pendant la saison des pluies alors que les espèces deDalbulus associées à des plantes hôtes pérennes (Z. perennis etTripsacum) ont été parasitées par des dryinides pendant la saison des pluies et la saison sèche. La plus grande diversité d'espèces parasitantDalbulus spp. ainsi que la plus grande fréquence de parasitisme ont été rencontrées sur ces espèces pérennes, suggérant que ces plantes sont des réservoirs d'ennemis naturels deDalbulus spp.
    Notes: Abstract Little is known about the natural enemies of the leafhopperDalbulus spp. (Homoptera: Cicadellidae). Searches for its dryinid (wasps) parasitoids were made in Jalisco, Mexico. Jalisco contains the greatest number ofDalbulus species, and is considered to be near to the center of origin of this leafhopper genus and its host plants: maize, teosintes (Zea spp.) and gamagrasses (Tripsacum spp.). The dryinidGonatopus bartletti was found parasitizingD. maidis on maize and on annual teosinteZea mays spp.parviglumis. G. flavipes was found parasitizingD. elimatus on perennial teosinteZ. perennis; and a new speciesG. moyaraygozai andAnteon ciudadi parasitizingD. quinquenotatus onTripsacum pilosum andT. dactyloides. Parasitism by dryinids was found at altitudes of 680–2,000 m.Dalbulus maidis, the leafhopper species which causes the greatest losses in maize in Latin America, was found to be parasitized from 680–1,760 m. TheDalbulus species associated with annual host plants (maize andZ. mays spp.parviglumis) were parasitized by dryinids during the rainy season, while theDalbulus species associated with perennial host plants (Z. perennis andTripsacum) were parasitized by dryinids during both the rainy and dry season. The greatest diversity of dryinid parasitoids ofDalbulus spp. and the highest levels of parasitism were recorded from perennial plants, indicating that such species are reservoirs of natural enemies ofDalbulus spp.
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    Host-size preference of the parasitoidAnisopteromalus calandrae [Hym: Pteromalidae] onSitophilus zeamais (Col.: Curculionidae) larvae with a uniform age distribution (1993)
    Springer
    BioControl 38 (1993), S. 225-233 
    Details
    ISSN: 1573-8248
    Keywords: host size preference ; parasitoid ; stored product ; maize ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé La première génération d'Anisopteromalus calandrae (Howard) récoltée dans du maïs stocké commercialement en Caroline du Sud fut exposée, dans du maïs écossé, à un mélange de jeunesSitophilus zeamais Motschulsky, de toutes tailles représentant une distribution d'âge uniforme. On a observé 87% de parasitisme sur les larves comportant un tunnel de 0,9 à 1,8 mm et 6% sur les prépupes et pupes pour cette distribution d'âge. Le taux de préférence était le plus élevé pour les grosses larves-hôte (1,6 mm de diamètre), moyen pour les autres larves de 0,9 à 1,8 mm, et le plus bas pour les pupes et les petites larves. On a discuté de la sélectivité des hôtes en utilisant les paramètres de Chesson (1983): préférence, αi, probabilité de parasitisme, Pi, et index d'électivité ɛi.
    Notes: Abstract First generationAnisopteromalus calandrae (Howard) collected from commercial stored maize in South Carolina were exposed to a mixture of all sizes of immatureSitophilus zeamais Motschulsky, representative of a uniform age distribution, in shelled maize. Eighty-seven percent of parasitism is expected on larvae with tunnel diameters of 0.9 to 1.8 mm and 6% on prepupae and pupae, given this host-size distribution. Preference was greatest for large host larvae (1.6 mm diameter), intermediate for other larvae in the range 0.9 to 1.8 mm, and least for pupae and small larvae. Host-stage preference is discussed with respect to Chesson's (1983) parameters for preference, αi, probability of parasitism, Pi, and electivity index, ɛi.
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    Influence of the egg parasitoidPlatytelenomus busseolae [Hym.: Scelionidae] on the population ofSesamia nonagrioides [Lep.: Noctuidae] in central greece (1990)
    Springer
    BioControl 35 (1990), S. 61-70 
    Details
    ISSN: 1573-8248
    Keywords: Sesamid ; Platytelenomus ; egg parasitoid ; maize ; sex ratio ; parasitism ; Sesamia ; Platytelenomus ; maïs ; parasitoides oophages ; sex ratio ; parasitisme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Le parasitoïde scelionid,Platytelenomus busseolae, a été recueilli des ooplaques de la sésamie dans la région d'Istiaea, en Grèce Centrale. Le parasitisme naturel a été étudié pendant les années 1986 et 1987. Un nombre de 3 382 ooplaques avec un total de 205 227 œufs ont été recueillis. Les premiers œufs parasitisés ont été récoltés fin-juillet, début-août et les derniers à la mi-octobre. En 1986, 76,2% des ooplaques et 42,8% des œufs étaient parasitisés, mais en 1987 les valeurs respectives étaient 27,6% et 12,9%. L'activité moindre du parasitoïde en 1987 serait due aux conditions climatiques hivernales et estivales. En 1987, la sex ratio, femalle: mâle, a été 1,5: 1 et 26,2% des ooplaques seulement ont donné naissance à des ♂♂. Les ♀♀ fécondées ont produit 3 fois plus de ♀♀ que de ♂♂. Dans des conditions climatiques favorables, le parasitoïde peut jouer un rôle important dans la lutte biologique contre la sésamie.
    Notes: Abstract The egg parasitoid,Platytelenomus busseolae (Gahan) (Hymenoptera: Scelionidae) was recorded from egg masses of the corn stalk borer,Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae) on maize in the area of Istiaea, Central Greece. Natural parasitism was studied during the years 1986, 1987. A total of 3,382 egg masses, containing 205,227 eggs, was collected from corn fields. Parasitized eggs were found from end July to mid-October. In 1986. 76.2% of the egg masses and 42.8% of all eggs were parasitized, while in 1987, respective values were 27.6% and 12.9%. The inferior performance of the parasitoid in 1987 may be due to the unfavorable winter and summer conditions. Parasitism decreased when the host population was at its peak, but it increased again within 1 to 3 weeks. A small percentage of egg masses was completely parasitized (9.5% and 4.7% for the 2 years respectively). In 1987, the sex ratio, ♀♀/♂♂ was 1.5: 1 and 26.2% of the egg masses produced only ♂♂. Mated ♀♀ produced 3 times more ♀♀ than ♂♂. It seems that the parasitoid, under favorable weather conditions, can play a significant role in the control of the corn stalk borer.
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    Survey for parasites ofSesamia calamistis (Lep.: Noctuidae) andEldana saccharina (Lep.: Pyralidae) in southwestern Nigeria (1994)
    Springer
    BioControl 39 (1994), S. 367-376 
    Details
    ISSN: 1573-8248
    Keywords: Insect parasitoid ; parasitic nematode ; stem borer ; maize ; West Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Des enquêtes sur le terrain ont été effectuées entre 1990 et 1992 en vue d'étudier les espèces présentes et l'abondance relative des parasites des lépidoptères foreurs des tigesSesamia calamistis Hampson etEldana saccharina Walker dans des champs de maïs du sud-ouest du Nigéria. Parmi les espèces de parasitoïdes découvertes sur les deux foreurs de tiges figuraient les parasitoïdes des larves et pupes,Sturmiopsis parasitica Curran (Diptera: Tachinidae) etBrachymeria feae Masi (Hymenoptera: Chalcididae), ainsi que le parasitoïde des larves,Dolichogenidea polaszeki Walker (Hymenoptera: Braconidae). Des attaques du braconidéCotesia sesamiae (Cameron) ont été observées surS. calamistis. L'hyperparasitoïdeExoristobia dipterae (Risbec) (Hymenoptera: Encyrtidae) a été observé sur une pupe deS. parasitica. Des nématodes parasites appartenant àMermis sp. et/ouHexamermis sp. ont été observés sur des larves des deux foreurs des tiges. Dans l'ensemble, le parasitisme larvaire était faible avec des valeurs comprises entre 4.2 et 22.8% pourS. calamistis, et 1.2 et 13% pourE. saccharina. Parmi les parasitoïdes observés, l'espèce la plus courante étaitS. parasitica. Des attaques de quatre hyménoptères parasitoïdes des oeufs ont été observées surS. calamistis: Telenomus busseolae Gahan,T. isis Polaszek (Scelionidae),Lathromeris ovicida Risbec, etTrichrogrammatoidea eldanae Viggiani (Trichogrammatidae). Les oeufs étaient parasités à des valeurs comprises entre 0 et 33%. L'unique parasitoïde des oeufs observé surE. saccharina étaitT. applanatus Bin et Johnson (Scelionidae) qui ne provoquait qu'un parasitisme de 5%.
    Notes: Abstract Field surveys were conducted during 1990–92 to document the relative abundance of different species of parasites of the lepidopterous stem borersSesamia calamistis Hampson andEldana saccharina Walker in maize fields in southwestern Nigeria. Species of parasitoids detected on both stem borers included the larvalpupal parasitoidsSturmiopsis parasitica Curran (Diptera: Tachinidae) andBrachymeria feae Masi (Hymenoptera: Chalcididae), and the larval parasitoidDolichogenidea polaszeki Walker (Hymenoptera: Braconidae). The braconidCotesia sesamiae (Cameron) was found attackingS. calamistis. The hyperparasitoidExoristobia dipterae (Risbec) (Hymenoptera: Encyrtidae) was detected on a pupa ofS. parasitica. Parasitic nematodes belonging toMermis sp. and/orHexamermis sp. were found infesting larvae of both stem borers. Overall, larval/pupal parasitization levels at Ibadan were low and ranged from 4.2 to 22.8% forS. calamistis and 1.2 to 13% forE. saccharina. Of the parasites found,S. parasitica was the most common, followed by nematodes. Four hymenopteran egg parasitoids were found attackingS. calamistis: Telenomus busseolae Gahan,T. isis Polaszek (Scelionidae),Lathromeris ovicida Risbec, andTrichogrammatoidea eldanae Viggiani (Trichogrammatidae). Egg parasitization ranged from 13.4 to 41.5%. The only egg parasitoid detected onE. saccharina wasTelenomus applanatus Bin and Johnson, which inflicted only 5% parasitization.
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    Maturation of stamens and ovaries on cultured ear inflorescences of maize (Zea mays L.) (1990)
    Springer
    Plant cell, tissue and organ culture 23 (1990), S. 59-66 
    Details
    ISSN: 1573-5044
    Keywords: development ; ears ; maize ; maturation ; ovaries ; stamens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Observations were made on the maturation of stamens and ovaries from cultured maize (Zea mays L.) ear inflorescences. Immature ears (5.1–10.0 mm long) of maize were cultured in kinetin medium to study microsporogenesis and pollen maturation in developing stamens. Male spikelets developed on ears cultured in kinetin medium. Meiosis-I began by 7 days of culture in the developing anthers and the mature tri-nucleate pollen grains were developed by 20 days of culture. Further, kinetin was required in the culture medium for at least initial 5 days to obtain the microspores in differentiated stamens. To observe the embryosac formation in developed ovaries, ears were cultured in control, kinetin (10.1–15.0 mm long ears) medium, and kinetin + gibberellic acid (5.1–10.0 mm long ears) medium. Formation of embryosacs was noticed in the developed ovaries which were sampled after 20 days of culture. This differential flower development using two growth regulators provides an opportunity to uncover the biochemistry and physiology of micro- and mega-gametophyte development in maize.
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    URL: http://dx.doi.org/10.1007/BF00116090
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    The effect of insertion of the maize transposable elementMutator is dependent on genetic background (1990)
    Springer
    Biochemical genetics 28 (1990), S. 9-20 
    Details
    ISSN: 1573-4927
    Keywords: mutator ; transposable element ; alcohol dehydrogenase ; maize ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A secondary mutant, derived from an allele of maize alcohol dehydrogenase 1 (Adh1) carrying a Mutator transposable element (Mu1) in its first intron, was reported to exhibit a threefold decrease in ADH enzymatic activity and steady-state RNA levels compared to the original mutant. The original mutant,Adh1-S3034 (abbreviatedS3034), was previously characterized at the molecular level. The derivative, abbreviatedS3034b, has now been cloned; at the DNA sequence level the insertion and surroundingAdh1 sequences are indistinguishable fromS3034. Furthermore, in our lines there is no difference in relative ADH activities between products of the two putative alleles. A comparison of gene expression in heterozygotes obtained by crossing to different tester lines reveals a correlation between the measured decrease in levels of ADH polypeptide produced by the mutant allele and the background in which it is measured; this effect is distinct from any background-related variation in the expression of the progenitor allele. It does not appear to be attributable to alternative patterns of DNA modification. It appears to reflect a background-associated difference in the level of normalAdh1-RNA produced. Thus the previously reported distinction betweenS3034 andS3034b may be due to differences in the extent to which the mutant allele and a given genetic background interact to produce functionalAdh1-RNA.
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    Comparative isozyme polymorphisms of north American eastern gamagrass,Tripsacum dactyloides var.dactyloides and maize,Zea mays L. (1994)
    Springer
    Genetica 94 (1994), S. 77-83 
    Details
    ISSN: 1573-6857
    Keywords: isozymes ; Tripsacum ; maize ; wide hybridizations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Random samples, consisting of at least 100 individual seedlings, were taken from the diploid (2n=2x=36) eastern gamagrass (Tripsacum dactyloides var.dactyloides) and assayed to determine which of 12 enzyme marker loci and isozyme systems would be most informative in providing satisfactory resolution of both maize andTripsacum isozyme systems. For comparison, eight maize inbreds were included in the study to aid evaluation and comparison of the various isozyme systems. In addition, evaluations were conducted to identify if the identified optimum isozyme system could be used to detectTripsacum introgression in maize following a maize ×Tripsacum backcrossing scheme. Using the established isozyme techniques for maize (Zea mays L.), theAdh, Pgd, Cat, Est, B-Glu, Got, Idh, Tpi isozyme systems detected no polymorphism among theTripsacum individuals assayed. TheEst andB-Glu systems forTripsacum were unscorable due to poor staining and resolution. TheAcp, Mdh, Pgm, andPhi isozyme systems were found to be satisfactory markers for differentiating between eastern gamagrass individuals as well as detectingTripsacum introgression in maize. The availability of useful isozyme systems which can simultaneously provide significant isozyme resolution of maize,Tripsacum and maize-Tripsacum backcross hybrids, on a single gel system, will be useful for the detection of marker assistedTripsacum introgression into maize. In addition, the identification of a set of variable biochemical markers should also assist breeding, selection and genetic manipulations in eastern gamagrass.
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    A study of alley-cropping data from Northern Brazil. I. Distributional properties (1993)
    Springer
    Agroforestry systems 22 (1993), S. 241-258 
    Details
    ISSN: 1572-9680
    Keywords: agroforestry ; Inga edulis ; maize ; beans ; statistical analysis ; distributions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Measurements from trees and plants of a BrazilianInga/maize/beans alleycrop experiment were assessed for their distributional properties for three years of the study. Results for the tree data were similar to those found in an earlier study. Results for the crop data demonstrated similarities between the distributions for alleycrops and solecrops, nonnormality shown by positive skewness and peaked distributions. Changes in the distributional shapes were demonstrated from year to year as soil nutrient depletion increased and as climatic variables fluctuated. Variation across the rows in the alley was often of a similar size to variation from plant to plant within the rows. Initial recommendations for analysis of such data are given on the basis of these results.
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    URL: http://dx.doi.org/10.1007/BF00705237
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    Alley cropping Sesbania sesban (L) Merill with food crops in the highland region of Rwanda (1990)
    Springer
    Agroforestry systems 10 (1990), S. 169-181 
    Details
    ISSN: 1572-9680
    Keywords: Alley cropping ; highland agroforestry ; maize ; pole bean ; Sesbania
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Food production in the densely populated Rwandan highlands is impeded by soil erosion and loss in fertility. Alley cropping leguminous shrubs with food crops on contours is purported to minimize the problem and to provide wood and forage. This study reports the effect of Sesbania prunings plus moderate levels of N and P on bean (Phaseolus sp) and maize (Zea mays) yields in alley cropping. Experimental design was a randomized complete block with split-split plots. Main plots were alley width: 2, 4, 6 and 8 m. Phosphorus (P) at 0, 30 and 60 kg P2O5/ha occupied the subplot and nitrogen (N) at 0, 30 and 60 kg/ha were assigned at the sub-sub plot level. No P was applied to maize during the second cropping season. Crop yield in kg/ha included the land space taken by hedgerows. Bean yield in 6 m alleys (1100 kg/ha) was about twice that in 2 m alleys (500 kg/ha). Bean responded to N and P. Optimum alley width and N for bean yield were 6 m and 30 kg/ha, respectively. Cuttings from alley hedgerows provided stakes for climbing beans. Maize responded to N but not to residual P. The highest maize yield came from 8 m alleys with 40 kg/ha, but yields from 8 and 6 m alleys with the same N treatment were not significantly different. Maize plants in middle rows were significantly taller than plants in rows adjacent to hedgerows. Maize rust development showed significant alley width and row position effect. There were significantly fewer uredinia in the Sebania alleys relative to the control plots without shrub hedgerows. Rust development on maize in middle rows was significantly greater than development in border rows.
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    Effect on maize growth of the interaction between increased nitrogen availability and competition with trees in alley cropping (1993)
    Springer
    Agroforestry systems 21 (1993), S. 239-249 
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    ISSN: 1572-9680
    Keywords: Erythrina ; Gliricidia ; alley cropping ; maize ; competition ; nitrogen availability ; Costa Rica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize growing next toErythrina hedgerows had 44% lower biomass (p〈0.01) and 35% lower N content (p〈0.1) than maize growing in the middle of the alleys. Maize growing next toGliricidia hedgerows had the same biomass but 56% higher N content (p〈0.1) than maize growing in the middle of the alleys. However these differences did not develop until 2 months after sowing of the maize. Spatial variability in soil nitrogen mineralization and mulch nitrogen release did not explain any of the differences in growth or N uptake of the maize with respect to distance from the trees. It is hypothesized that the slower growth of the maize next to theErythrina trees after 2 months is due to increasing light and/or nutrient competition from the trees as the trees recover from pollarding. The apparent lack of competition fromGlirigidia may be due to different rates of regrowth or different shoot and root architecture. A theoretical model is described demonstrating that if a crop is to take advantage of the higher nutrient availability under alley cropping it must complete the major part of its growth before the trees recover significantly from pollarding, and start competing strongly with the crop.
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    Soil fertility changes and response of maize and beans to green manures of leucaena, sesbania and pigeonpea (1990)
    Springer
    Agroforestry systems 12 (1990), S. 197-215 
    Details
    ISSN: 1572-9680
    Keywords: Agroforestry ; green manure ; leucaena ; sesbania ; pigeonpea ; soil fertility ; maize ; beans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three multipurpose tree species (MPTS)-leucaena (Leucaena leucocephala), sesbania (Sesbania sesban var. nubica) and pigeonpea (Cajanus cajan) were pruned at a height of 60 cm above the ground every two months, and resulting plant biomass was incorporated into the soil as green manure. For comparison, maize (Zea mays) stover was also incorporated into some plots, while some other plots were left fallow. Varying quantities of plant biomass which were incorporated into the soil over a period of 12 months caused large changes in major soil plant nutrients, and it substantially improved soil fertility. To test for improved soil fertility, test crops of maize and beans (Phaseolus vulgaris) were grown on the plots after six biomass incorporations of 4806, 13603, 16659 and 7793 kg. ha−1yr−1 for pigeonpea, sesbania leucaena and maize, respectively. Responses of the test crops indicated that sesbania and leucaena green manures improved maize stover, cobs and grain yields; and bean haulms and grain yields by 77.6% when compared to fallow plots. Residual effects of green manures still resulted in significant (P 〈 0.05) yield differences in the test cropin the third testing season. Economic significance of green manures in increasing food crop yields to small scale farmers is discussed.
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    Alley cropping of maize with nine leguminous trees (1992)
    Springer
    Agroforestry systems 17 (1992), S. 159-168 
    Details
    ISSN: 1572-9680
    Keywords: alley cropping ; maize ; nitrogen fixing trees ; soil degradation ; traditional farming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A maize-leguminous tree alley cropping system was studied on N-deficient soils in Hawaii to determine mulch effects on maize yields. Calliandra calothyrsus, Cajanus cajan, Cassia siamea, Gliciridia sepium, KX1 — Leucaena hybrid (L. pallida X L. diversifolia), L. leucocephala, L. pallida, L. salvadorensis, and Sesbania sesban were evaluated for green manure and yield of intercropped maize. S. sesban, G. sepium, L. pallida, and KX1 produced between 5 and 12 dry t/ha/yr green manure with nitrogen yields between 140 and 275 kg N/ha in 4 prunings. Maize yields responded linearly to nitrogen applied as green manure. Maize yield increased 12 kg for each kg of nitrogen applied. Additions of prunings from hedge rows were able to support maize grain yields at about 1800 kg/ha for two consecutive cropping seasons, while control plot yields averaged less than 600 kg/ha. Maize yields reflected the amount of nitrogen applied as green manure, regardless of tree species from which the nitrogen was derived. In March, maize yields decreased 34% in the row spaced 40 cm from the hedge, relative to the one spaced 110 cm away. In July, increasing the distance away from the hedge to 60 cm and coppicing the hedge earlier in maize growth, significantly improved grain yield. Grain yields decreased only 10% in the row closest to the trees.
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    URL: http://dx.doi.org/10.1007/BF00053120
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    Use of the SCUAF model to simulate natural miombo woodland and maize monoculture ecosystems in Zimbabwe (1993)
    Springer
    Agroforestry systems 22 (1993), S. 259-271 
    Details
    ISSN: 1572-9680
    Keywords: SCUAF ; computer model ; soil carbon ; soil nitrogen ; miombo ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract ‘Soil Changes Under Agroforestry’ (SCUAF), a computer model designed to predict changes in erosion, soil carbon and soil nitrogen over time within various agroforestry systems and climatic regimes, was assessed using input data from an undisturbed miombo woodland and an adjacent maize field in Zimbabwe. Predicted changes in soil carbon were in a realistic range for both miombo and maize treatments. However, the accuracy of the model may be a reflection of the detail required in its initialisation. Several problematic relationships were found within the model, in particular inconsistent patterns between nitrogen uptake and plant productivity under complex fertilisation simulations and a lack of attenuation of productivity in the simulation of miombo woodland as it approached maturity.
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    Alley cropping and mulching withErythrina poeppigiana (Walp.) O. F. Cook andGliricidia sepium (Jacq.) Walp.: effects on maize/weed competition (1994)
    Springer
    Agroforestry systems 25 (1994), S. 119-134 
    Details
    ISSN: 1572-9680
    Keywords: alley cropping ; Erythrina poeppigiana ; Gliricidia sepium ; weeds ; maize ; mulch ; weed competition ; weed reduction potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The potential of allye cropping systems to sustain a high productivity with low external inputs and the reduction of maize/weed competition through weed suppression in different alley cropping and sole-cropped mulched systems was studied in Costa Rica at CATIE. Data were recorded eight years after establishment of the experiment. Plant residues ofErythrina poeppigiana trees (10 t/ha dry matter) planted at 6 by 3 m reduced weed biomass by 52%, whileGliricidia sepium trees (12 t/ha dry matter) planted at 6 by 0.5 m reduced weed biomass by 28%, in comparison to controls.Erythrina had a considerable impact on grass weeds, whileGliricidia reduced the incidence of some dicot weeds. Weed competition significantly reduced maize yield in all systems. Nevertheless weed suppression contributed to the higher maize grain yield underErythrina andGliricidia alley cropping of 3.8 t per hectare as opposed to the unmulched control yield of 2.0 t per hectare.
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    Evaluation of phytotoxic effects ofGliricidia sepium (Jacq.) Walp prunings on maize and cowpea seedlings (1994)
    Springer
    Agroforestry systems 26 (1994), S. 249-254 
    Details
    ISSN: 1572-9680
    Keywords: phytotoxicity ; cowpea ; Gliricidia sepium prunings ; maize ; seedlings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phytotoxic effects ofGliricidia prunings were tested on maize seedlings in the laboratory and on maize and cowpea seedlings in the field. In the laboratory test, growth of maize seedlings was significantly depressed by addition of leachate ofGliricidia prunings. In the field, leaf, chlorosis of maize and cowpea seedlings occurred when mulched withGliricidia prunings; number of affected leaves increased with increasing mulch rate. Maize was more susceptible than cowpea. This phytotoxic effect, however, did not reduce growth of maize and cowpea seedlings in the field. ApplyingGliricidia mulch one week before planting eliminated the phytotoxic effects on maize.
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    URL: http://dx.doi.org/10.1007/BF00711214
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    The effects of alley cropping withLeucaena leucocephala and of different management practices on the productivity of maize and soil chemical properties in lowland coastal Kenya (1994)
    Springer
    Agroforestry systems 27 (1994), S. 31-51 
    Details
    ISSN: 1572-9680
    Keywords: alley cropping ; leucaena mulch ; dairy cattle slurry ; maize ; cowpea ; lowland coastal tropics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of leucaena hedgerows, mulching with leucaena foliage (0,50 and 100% of harvested foliage), cowpea intercropping and adition of dairy cattle slurry (55 t ha−1 per maize crop) on the yield of maize from a sandy soil were assessed. The four-year results from five maize crops are reported. Except in the first year, yields of maize grain and stover were significantly reduced by 30% in the presence of leucaena hedgerows. Use of leucaena mulch eliminated this effect; application of all the harvested leucaena mulch (100%) increased the total maize grain yield of the five crops by 44% over sole maize. Hedgerow and mulching management required an additional 36 mandays labour ha−1 which was more than compensated by the increased maize yields. Furthermore leucaena hedgerows substantially depressed the growth of weeds between cropping seasons. Intercropping with cowpea significantly depressed yields of maize grain and stover when both crops were sown together, but not in later seasons when cowpea was sown four weeks after the maize. Application of slurry increased the total yields of maize grain and stover by 35 and 37%, respectively. The grain yield of maize in leucaena hedgerow treatments fertilized with slurry did not respond to application of more than 50% of leucaena foliage, which suggested that half of the foliage could be spared for feeding to livestock. The cumulative yield of maize grain from the highest yielding organic system was 85% of the yield from the fertilizer treatment. The study, which is continuing, demonstrates that large increases in agricultural productivity are possible through the intercropping of maize with woody forage and grain legumes and the integration of dairy cattle production into the system. It thus shows the importance of exploiting crop/livestock interactions.
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    Interaction between visual and olfactory stimuli during host-finding by leafhopper,Dalbulus maidis (Homoptera: Cicadellidae) (1990)
    Springer
    Journal of chemical ecology 16 (1990), S. 2121-2133 
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    ISSN: 1573-1561
    Keywords: Leafhopper ; Dalbulus maidis ; Homoptera ; Cicadellidae ; hostfinding ; maize ; visual ; olfactory ; synergism ; pest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Virtually nothing is known about the role plant volatiles play in host-finding by Homoptera in the Suborder Auchenorrhyncha. In laboratory bioassays, we examined the influence of plant volatiles on orientation and postcontact behaviors of the leafhopper,Dalbulus maidis, and determined the relationship between visual and olfactory stimuli during host-finding. When compared to the number of contacts made with reflected green light in the presence of a hexane control,D. maidis made more contacts when exposed to volatile extracts from its preferred host, maize; a similar number of contacts when exposed to volatiles from a marginal host, gamagrass; and fewer contacts when exposed to volatiles from a nonhost, sorghum. There was no difference between males and females in the number of contacts made with green light when exposed to maize volatiles compared to hexane alone. More contacts were made with green light than with white light of similar intensity, both in the presence and in the absence of olfactory stimuli; however, maize volatiles acted as a Synergist by increasing the number of contacts leafhoppers made with green light. After contacting the green light, exposure of maize volatiles significantly increased, relative to hexane, the amount of stationary time, but did not influence the amount of time spent moving, the distance traveled, or the speed while moving when within the boundaries of the green light. This study provides the first evidence for an interaction between visual and olfactory stimuli during host-finding for a leafhopper and also for olfactory mediation of postcontact behaviors not associated with feeding.
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    Correlation of phenolic acid content of maize to resistance toSitophilus zeamais, the maize weevil, in CIMMYT'S collections (1990)
    Springer
    Journal of chemical ecology 16 (1990), S. 301-315 
    Details
    ISSN: 1573-1561
    Keywords: Phenolic acids ; resistance ; susceptibility ; maize ; maize weevil ; Sitophilus zeamais ; Coleoptera ; Curculionidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The (E)-ferulic acid content of the grain of nine populations of land races of maize derived from CIMMYT's collections was found to be negatively correlated to susceptibility characteristics towards the maize weevilSitophilus zeamais. Correlation coefficients for six susceptibility parameters and (E)-ferulic acid content were significant and ranged from −0.58 to −0.79. A multiple regression analysis by the SAS forward procedure using the primary seed characteristics associated with susceptibility indicated that the ferulic acid content was the only significant factor in explaining variation in at least two susceptibility parameters: the Dobie index and adult preference. In 15 CIMMYT pools, correlations between four susceptibility parameters and (E)-ferulic acid content were also significant (−0.76 to −0.81). The results suggest that phenolic acid content is a leading indicator of grain resistance or susceptibility to insects and may represent a newly identified mechanism of resistance.
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    Hydroxamic acid glucosides in honeydew of aphids feeding on wheat (1992)
    Springer
    Journal of chemical ecology 18 (1992), S. 841-846 
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    ISSN: 1573-1561
    Keywords: Rhopalosiphum padi ; Homoptera ; Aphididae ; wheat ; maize ; DIMBOA ; hydroxamic acids ; aphid honeydew
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract DIMBOA glucoside (2-O-/gb-D-glucopyranosyl-4-hydroxy-7-meth-oxy-1,4-benzoxazin-3-one), the main hydroxamic acid (Hx) in intact wheat plants, was detected in the honey dew ofRhopalosiphum padi feeding on seedlings of six wheat cultivars that differed in their concentration of Hx, suggesting that the chemical circulates in the phloem. Neither the aglucone (DIMBOA) nor its main breakdown product were found in any of the honeydew samples. Honey dew production by aphids caged on seedlings of the wheat cultivars and DIMBOA glucoside concentrations in the honeydew followed biphasic curves when plotted against Hx concentration, suggesting passive ingestion of the chemical from the phloem at low Hx concentrations and limited ingestion due to feeding deterrency by Hx in mesophyll cells at high Hx concentrations. The presence of plant toxins such as Hx glucosides in the phloem sap, the main ingesta of aphids, and in the mesophyll cells, has major implications for plant defense, through a feeding deterrent effect during stylet penetration, and deterrency (antixenosis) along with antibiosis during feeding.
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    Production ofNosema marucae for biological control of cereal stem borers (1993)
    Springer
    Entomologia experimentalis et applicata 67 (1993), S. 143-148 
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    ISSN: 1570-7458
    Keywords: Nosema marucae ; microsporidium ; production ; biological control ; cereal stem borer ; Chilo partellus ; maize ; sorghum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a study covering 3 years, experiments were carried out in order to determine the feasibility of producing a microsporidian pathogenNosema marucae in the spotted stalkborerChilo partellus. A maximum yield of 4.9×108 spores/larva (equivalent to 3.1×1010 spores/g fresh larval body weight) was obtained in 3rd instar larvae. It is considered that the production is inexpensive and can be readily adapted for small scale pathogen propagation systems in the tropics.
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    Mycotoxin production by Fusarium species isolated from New Zealand maize fields (1991)
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    Mycopathologia 113 (1991), S. 35-40 
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    ISSN: 1573-0832
    Keywords: Fusarium ; maize ; moniliformin ; mycotoxins ; trichothecenes ; zearalenone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Forty Fusarium isolates obtained from maize fields were screened for moniliformin production on maize kernels. Twelve isolates, including seven of F. subglutinans, were found to produce moniliformin at levels ranging from 0.4 to 64 ppm. Twenty six isolates were also screened for production of deoxynivalenol, diacetoxyscirpenol, T-2 toxin and zearalenone. Of these, 22, including all 11 isolates of F. graminearum, produced zearalenone at levels ranging from 0.1 to 96.0 ppm, while 13 produced T-2 toxin at low levels, (〈1.1 ppm). Deoxynivalenol and diacetoxyscirpenol were each produced by six isolates, also at low levels (〈1.0 ppm). Three isolates of F. graminearum and one of F. sambucinum produced four toxins simultaneously.
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    Improving fertilizer recommendations for subsistance farmers in West Africa: The use of agro-economic analysis of on-farm trials (1992)
    Springer
    Nutrient cycling in agroecosystems 32 (1992), S. 333-342 
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    ISSN: 1573-0867
    Keywords: Fertilizer ; on-farm trials ; rice ; maize ; groundnuts ; Senegal ; West Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A large number of zero, half and full rate fertilizer trials were conducted on-farm in Southern Senegal with rainfed lowland rice (n = 24), maize (n = 48), and groundnuts (n = 18). Trial sites were located according to farmer selected criteria: soil texture in the case of rice; compound garden versus outer field in the case of maize; and, previous cropping history in the case of groundnuts. Quadratic fertilizer response curves using all the cases explained only 16–29% of the variance. Subsequent stratification of the fields by soil organic matter, texture, and pH permitted the identification of fertilizer responsive and non-responsive fields. Response curves using only the tests conducted on soils without a limiting constraint explained 36 to 47% of the variance. At half rate fertilization levels VCR's of 3.8 (maize), 5.8 (rice) and 6.9 (groundnuts) resulted. Within productive fields, level of weed control, percent barrenness and final stand at harvest explained much of the remaining variation in yields for rice (82%), maize (61%) and groundnuts (76%) respectively. Response curves were then used in an economic analysis to address on-farm fertilizer allocation issues. Based on survey results and field trial data, partial budgets for small and medium-sized farms were developed. This analysis showed marginal rates of return of 400 and 165 percent to half and full rate fertilization, respectively. This type of fertilizer validation program, conducted on farmer-selected sites, improved targeting of recommendations, and helped to identify agronomic practices that should result in reduced economic risk and increased fertilizer adoption by farmers.
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    Foliar urea fertilization of cereals: A review (1992)
    Springer
    Nutrient cycling in agroecosystems 32 (1992), S. 209-222 
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    ISSN: 1573-0867
    Keywords: Wheat ; maize ; barley ; rice ; foliar urea ; grain yield ; breadmaking quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract It has been suggested that there are several potential benefits of providing nitrogen to cereals via the foliage as urea solution. These include: reduced nitrogen losses through denitrification and leaching compared with nitrogen fertilizer applications to the soil; the ability to provide nitrogen when root activity is impaired e.g., in saline or dry conditions, and uptake late in the season to increase grain nitrogen concentration. Factors that influence the degree of foliar absorption in field conditions have not, however, been clearly defined and losses to the atmosphere and soil can occur. Foliar urea applications may also hinder crop productivity although the explanations for this vary, and include desiccation of leaf cells, aqueous ammonia and urea toxicity, biuret contamination and the disruption of carbohydrate metabolism. It has not yet been determined which one, or combinations, of these mechanisms are most important in field situations. When damage has not been severe, foliar urea applications have increased grain yield, particularly when applied before flag leaf emergence and when nitrogen availability is limiting. Increases in grain nitrogen content are often larger when applications of nitrogen fertilizers to the soil are reduced, and when the urea solution is sprayed either at anthesis or during the following two weeks. It is during this period that foliar urea sprays can be of greater benefit than soil applications with regard to nitrogen utilization by the crop. Increases in wheat grain nitrogen concentration following urea application can improve breadmaking quality. Responses in loaf quality may, however, be variable particularly when increases in grain nitrogen content have been large, and/or when the nitrogen: sulphur ratio in the grain is increased. These circumstances have lead to alterations in the proportions of the different protein fractions which influence breadmaking potential. To exploit the full potential benefits of foliar urea application to cereals, more needs to be known about the mechanisms, and thus how to prevent losses of nitrogen from the foliage, and to reduce the phytotoxic influences of sprays. More information is also required to exploit the reported effects that urea may have on limiting the development of cereal diseases.
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    Microbiological changes in mawè during natural fermentation (1994)
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    World journal of microbiology and biotechnology 10 (1994), S. 410-413 
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    ISSN: 1573-0972
    Keywords: Enterobacteriaceae ; fermentation ; lactic acid bacteria ; maize ; mawè ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Lactic acid bacteria increased from 3.2 × 106 and 1.6 × 107 c.f.u./g (wet wt) to 2 × 109 and 1.6 × 109 c.f.u./g after 12 to 24 h of fermentation of home-produced mawè (a dough produced from dehulled maize) and commercial mawè, respectively. In commercial mawè, the yeast count increased from 1.3 × 105 to 2.5 × 107 c.f.u./g after 48 h of fermentation before decreasing, whereas in the home-produced mawè it increased from 2.5 × 104 to 3.2 × 107 c.f.u./g after 72 h of fermentation; the dominant yeasts were mainly Candida krusei, although C. kefyr, C. glabrata and Saccharomyces cerevisiae were also present. Enterobacteriaceae counts increased slightly during the initial stage ofthe fermentation, but decreased below the detection level after 24 to 48 h. Enterobacter cloacae was mostly found in commercial mawè and Escherichia coli mostly in homeproduced mawè.
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    Cyclopiazonic acid production byPenicillium griseofulvum in relation to different cultivars of maize (1992)
    Springer
    World journal of microbiology and biotechnology 8 (1992), S. 208-209 
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    ISSN: 1573-0972
    Keywords: Cyclopiazonic acid ; Penicillium ; phytopathogen ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The reaction of 15 varieties of maize to the growth and cyclopiazonic acid (CPA) production ofPenicillium griseofulvum was examined as a means of identifying varieties which would be resistant to this infestation. Only one variety, MMEH-25, was resistant to the fungus, seeds containing little CPA 30 days after infestation. This variety and Ganga-5, which was only moderately resistant, are popular commercial cultivars.
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    Sources of microorganisms in pozol, a traditional Mexican fermented maize dough (1993)
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    World journal of microbiology and biotechnology 9 (1993), S. 269-274 
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    ISSN: 1573-0972
    Keywords: Enterobacteriaceae ; fermentation ; lactic acid bacteria ; maize ; nixtamal ; pozol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Freshly prepared pozol, a traditional Mexican fermented maize dough, contained (c.f.u./g wet wt): lactic acid bacteria, 104 to 106; aerobic mesophiles, 104 to 105; Enterobacteriaceae, 102 to 103; yeasts, 102 to 104; and mould propagules, 〈103. After 30 h at 28°C the numbers were, respectively: 109, 7×106, 5×105, 106 and 104. Soaking alkali-treated grains overnight allowed lactic acid bacteria, aerobic mesophiles and Enterobacteriaceae to grow and these then constituted the primary microbial flora of the pozol dough. Grinding in a commercial mill inoculated the dough with lactic acid bacteria, aerobic mesophiles, Enterobacteriaceae and yeasts. Other processing stages, including the nature of the surface upon which the balls were made, handling of the dough, and air, contributed only minor numbers of microbes compared with the two major sources, soaking and grinding. The pH of pozol fell from an initial value of 7.3 to 4.6 after 30 h incubation at 28°C. The numbers of Enterobacteriaceae and other aerobic mesophilic bacteria remained constant between 11 and 30 h incubation and there was no evidence of the acidic conditions having any lethal effects on these organisms.
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    Effect of sub-optimal root zone temperatures at varied nutrient supply and shoot meristem temperature on growth and nutrient concentrations in maize seedlings (Zea mays L.) (1990)
    Springer
    Plant and soil 126 (1990), S. 215-225 
    Details
    ISSN: 1573-5036
    Keywords: maize ; nutrient concentration ; nutrient availability ; root growth ; root zone temperature ; shoot growth ; shoot meristem temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize seedlings were grown for 10 to 20 days in either nutrient solution or in soils with or without fertilizer supply. Air temperature was kept uniform for all treatments, while root zone temperature (RZT) was varied between 12 and 24°C. In some treatments the basal part of the shoot (with apical shoot meristem and zone of leaf elongation) was lifted up to separate the indirect effects of root zone temperature on shoot growth from the direct effects of temperature on the shoot meristem. Shoot and root growth were decreased by low RZT to a similar extent irrespective of the growth medium (i.e. nutrient solution, fertilized or unfertilized soil). In all culture media Ca concentration was similar or even higher in plants grown at 12 as compared to 24°. At lower RZT concentrations of N, P and K in the shoot dry matter decreased in unfertilized soil, whereas in nutrient solution and fertilized soil only the K concentration decreased. When direct temperature effects on the shoot meristem were reduced by lifting the basal part of the shoot above the temperature-controlled root zone, shoot growth at low RZT was significantly increased in nutrient solution and fertilized soil, but not in unfertilized soil. In fertilized soil and nutrient solution at low RZT the uptake of K increased to a similar extent as plant growth, and thus shoot K concentration was not reduced by increasing shoot growth rates. In contrast, uptake of N and P was not increased, resulting in significantly decreased shoot concentrations. It is concluded that shoot growth at suboptimal RZT was limited both by a direct temperature effect on shoot activity and by a reduced nutrient supply through the roots. Nutrient concentrations in the shoot tissue at low RZT were not only influenced by availability in the substrate and dilution by growth, but also by the internal demand for growth.
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    Field evaluation of several chemical indexes of soil nitrogen availability (1990)
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    Plant and soil 123 (1990), S. 83-88 
    Details
    ISSN: 1573-5036
    Keywords: maize ; nitrogen availability tests ; soil nitrate ; UV absorbance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The ability of several chemical soil N availability indexes to predict the N supplying capability (NSC) of soils to maize in the field was evaluated in 49 field experiments over 3 years in Pennsylvania. Two recently proposed indexes based on the amount of NH4 + released by treating soil with 2 M KCl at 100°C for 4 hr or with a pH 11.2 phosphate-borate buffer for 8 min were not good predictors of NSC (r=0.484 and 0.254, respectively). The absorbance of a 0.01 M NaHCO3 extract at 260 nm was also poorly correlated with field-measured NSC (r=0.412). The pre-sidedress soil NO3 − test (PSNT), the soil NO3 − concertration in the surface 20 cm of soil at planting, and the UV absorbance at 200 nm of a 0.01 M NaHCO3 extract of at planting soils were all moderately well correlated with NSC (r=0.672, 0.750, and 0.737, respectively). The latter two indexes are very simple, rapid, and inexpensive to perform and offer the possibility of improving the prediction of NSC in heavily manured fields.
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    Genotypical differences among graminaceous species in release of phytosiderophores and uptake of iron phytosiderophores (1990)
    Springer
    Plant and soil 123 (1990), S. 147-153 
    Details
    ISSN: 1573-5036
    Keywords: barley ; chlorosis resistance ; cucumber ; genotypical differences ; grasses ; iron mobilization ; iron uptake ; maize ; microorganisms ; oat ; phytosiderophores ; rice ; root exudates ; root growth ; rye ; sorghum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Graminaceous species can enhance iron (Fe) acquisition from sparingly soluble inorganic Fe(III) compounds by release of phytosiderophores (PS) which mobilize Fe(III) by chelation. In most graminaceous species Fe deficiency increases the rate of PS release from roots by a factor of 10–20, but in some species, for example sorghum, this increase is much less. The chemical nature of PS can differ between species and even cultivars. The various PS are similarly effective as the microbial siderophore Desferal (ferrioxamine B methane sulfonate) in mobilizing Fe(III) from a calcareous soil. Under the same conditions the synthetic chelator DTPA (diaethylenetriamine pentaacetic acid) is ineffective. The rate of Fe(III)PS uptake by roots of graminaceous species increases by a factor of about 5 under Fe deficiency. In contrast, uptake of Fe from both synthetic and microbial Fe(III) chelates is much lower and not affected by the Fe nutritional status of the plants. This indicates that in graminaceous species under Fe deficiency a specific uptake system for FePS is activated. In contrast, the specific uptake system for FePS is absent in dicots. In a given graminaceous species the uptake rates of the various FePS are similar, but vary between species by a factor of upto 3. In sorghum, despite the low rate of PS release, the rate of FePS uptake is particularly high. The results indicate that release of PS and subsequent uptake of FePS are under different genetic control. The high susceptibility of sorghum to Fe deficiency (‘lime-chlorosis’) is most probably caused by low rates of PS release in the early seedling stage. Therefore in sorghum, and presumably other graminaceous species also, an increase in resistance to ‘lime chlorosis’ could be best achieved by breeding for cultivars with high rates of PS release. In corresponding screening procedures attention should be paid to the effects of iron nutritional status and daytime on PS release as well as on rapid microbial degradation of PS.
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    Sterol content and efficiency of ion uptake by roots of maize genotypes (1990)
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    Plant and soil 123 (1990), S. 181-183 
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    ISSN: 1573-5036
    Keywords: maize ; sterols ; sulphate uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Data of compartmental analysis of sulphate were compared with the sterol content of roots of differently yielding maize genotypes. In conditions of steady state nutrient supply, sterol content was significantly correlated only with sulphate efflux (ϕco). This increased at increasing concentration of sterols in the roots. Influx to cytoplasm (ϕoc) was evaluated after sulphate deprivation leading to an induced rate of sulphate uptake. This was negatively correlated with sterol content, which was lower in the high than in the low yielding genotypes. When the highest yield genotype was grown at different sulphate concentrations, influx, efflux, root content of sulphate and sterols were positively correlated with the concentration of sulphate in the nutrient medium. Sterol content in roots appears to be controlled by both the genetic settlement and the nutritional status in maize. Low sterol content is connected with a high efficiency of sulphate utilization.
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    Nitrogen transfer from nodulating soybean to maize or to nonnodulating soybean in intercrops: the 15N dilution method (1991)
    Springer
    Plant and soil 132 (1991), S. 53-63 
    Details
    ISSN: 1573-5036
    Keywords: Glycine max (L.) Merr. ; intercropping ; maize ; N-depleted soil ; 15N dilution method ; N transfer ; soybean ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In 1985, 1986 and 1988, maize (Zea mays L.) was monocropped or intercropped with nodulating or nonnodulating soybean (Glycine max [L.] Merr.). In addition, nodulating soybean and nonnodulating soybean were each monocropped and grown as a mixture. In 1985 and 1986, treatments were grown at 0 and 60 kg N ha−1 and in 1988, the treatments were grown without N fertilizer, on N-depeted soil and on non-N-depleted soil. 15N enriched N was applied to soil in all the aforementioned treatments to test for N transfer from nodulating soybean to non-N2-fixing crops by the 15N dilution method. The 15N dilution method did not show the occurrence of N transfer in 1985 and 1986, but the N sparing effect was evident from the total N uptake of nonnodulating soybean, dwarf maize and tall maize, in 1986. In 1988, maize and nonnodulating soybean seed yields and seed N yields were higher on non-N-depleted soil than on N-depleted soil. On N-depleted soil, the 15N dilution method indicated N transfer from nodulating soybean to maize and to nonndulating soybean. At a population ratio of 67% nodulating soybean to 33% nonnodulating soybean, N transfer was also seen on non-N-depleted soil in 1988.
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    Phosphate stress response in hydroponically grown maize (1991)
    Springer
    Plant and soil 132 (1991), S. 85-90 
    Details
    ISSN: 1573-5036
    Keywords: maize ; phosphate ; phosphatase ; roots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The long-term response of hydroponically grown maize plants to variations in the phosphate concentration in the growth medium was studied. There was a 5-week lag period before any differences between experimental and control groups could be seen. After this period, the plants grown without phosphate devoted a higher percentage of their total mass to roots than did the controls. The roots of the phosphate-free plants were longer and less bushy than those of the control plants. Plants grown without phosphate showed an increase in the amount of acid phosphatase extractable from the external surfaces of the roots by a high salt solution. These phosphate stress responses were induced by 5 μM phosphate but not by 25 μM phosphate.
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    Xylem exudate yield from detopped maize plants as an estimator of root pruning (1991)
    Springer
    Plant and soil 134 (1991), S. 277-280 
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    ISSN: 1573-5036
    Keywords: bleeding rate ; maize ; root pruning ; root-study methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Current methods of studying roots are either labour intensive or require expensive equipment. In 1986 and 1987 root pruning treatments were given to maize plants grown indoors. In both years the amount of xylem exudate collected from plant stumps shortly after root pruning increased with the dry weight of roots attached to the plant. The measurement of xylem exudation is presented as an alternative for conventional laborious root-study methods.
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    Manganese deficiency in maize affects pollen viability (1991)
    Springer
    Plant and soil 138 (1991), S. 139-142 
    Details
    ISSN: 1573-5036
    Keywords: maize ; manganese deficiency ; pollen viability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize (Zea mays L. cv. G2) was grown with 0.55 mg L−1 (sufficient), or 0.0055 mg L−1 (deficient) manganese in sand. Manganese-deficient plants developed visible deficiency symptoms and showed poor tasseling and delayed anther development. Compared to Mn-sufficient plants, Mn-deficient plants produced fewer and smaller pollen grains with reduced cytoplasmic contents. Manganese deficiency reduced in vitro germination of pollen grains significantly. Ovule fertility was not significantly affected by Mn. But in Mn-deficient plants seed-setting and development was reduced significantly.
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    URL: http://dx.doi.org/10.1007/BF00011816
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    The effect of soil aggregate size on early growth and shoot-root ratio of maize (Zea mays L.) (1991)
    Springer
    Plant and soil 138 (1991), S. 189-194 
    Details
    ISSN: 1573-5036
    Keywords: aggregate size ; carbon allocation ; maize ; shoot-root ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Shoot dry mass and leaf area of 16-d old maize plants decreased as soil aggregate size in greenhouse pots increased in diameter from 0.075–0.5 to 4–8 mm. Root length was also much greater on the finer aggregate beds, due primarily to increased growth of second-order laterals. In a subsequent experiment in which shoot dry matter again decreased with increasing aggregate size, it was found that a similar change in root morphology as noted in experiment I resulted in increased root dry mass as aggregate size increased. The associated change in shoot-root ratio was significant eight days after emergence. This change was due to a change in allocation of fixed carbon rather than allocation of seed reserves. Neither transpiration rate per unit leaf area, nor net assimilation rate were affected by aggregate size. Likewise nutrition could not account for the differences in shoot or root growth.
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    Root-soil contact of maize, as measured by a thin-section technique (1992)
    Springer
    Plant and soil 139 (1992), S. 119-129 
    Details
    ISSN: 1573-5036
    Keywords: image analysis ; maize ; nearest-neighbour distance ; root-soil contact ; soil compaction ; soil porosity ; thin-section technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The degree of root-soil contact was evaluated from thin sections for maize grown in pots with soil aggregates packed at three bulk densities. Root-soil contact was found to increase with bulk density of the soil. For soils with a porosity of 60, 51 and 44% (v/v), the average fraction of root-soil contact was 60, 72 and 87%, respectively. The frequency distribution of nearest-neighbour distances from points in a void to the nearest point of the soil matrix was measured. This was then used for a statistical test of a null hypothesis of random positioning of roots in voids. Where roots grew in larger pores or voids the degree of root-soil contact was greater than expected for random positioning of roots. Possible mechanisms of the observed preference of roots for proximity to the soil, and higher root-soil contact are discussed.
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    URL: http://dx.doi.org/10.1007/BF00012849
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    Root-soil contact of maize, as measured by a thin-section technique (1992)
    Springer
    Plant and soil 139 (1992), S. 109-118 
    Details
    ISSN: 1573-5036
    Keywords: freeze-drying ; maize ; root-soil contact ; soil compaction ; soil porosity ; thin-section technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In models of oxygen, water and nutrient uptake by plant roots, the degree of root-soil contact is an important parameter. An observation technique is required to evaluate to what extent root-soil contact depends on plant species, soil texture and structure. Thin sections for studying soil structure may be used for this purpose, provided that roots do not shrink during section preparation, and that all root cross sections are recognized. Maize was grown in pots with soil aggregates obtained by sieving and compacting to three bulk densities. Thin sections were made by freeze-drying samples before impregnating the soil with resin. Two checks were made on the validity of the method. Firstly, visual appearance of roots with intact epidermis, cortex and other tissues did not show signs of shrinkage. Secondly, the agreement was checked between root lengths obtained by washing duplicate soil samples and the number of root cross sections counted on horizonal and vertical thin sections. For the latter, the angle at which roots intersected the thin-section plane was determined from the shape of the cross sections. The frequency distribution of calculated angles was in agreement with the frequency distribution expected for a randomly oriented set of cylinders when an error term was included in the simulated measurements. Some results are presented for a field test of the thin-section method with barley on a calcareous marine sandy loam. Root hairs, apparently undamaged by sample preparation, are important for bridging the gap between roots and soil in this situation. According to the experience presented, the thin-section technique is suitable to derive the degree of root-soil contact, as influenced by species, soil texture and structure, in samples obtained from pot or field experiments.
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    Root-soil contact of maize, as measured by a thin-section technique (1992)
    Springer
    Plant and soil 139 (1992), S. 131-138 
    Details
    ISSN: 1573-5036
    Keywords: maize ; nitrate uptake ; root-soil contact ; soil compaction ; soil porosity ; thin-section technique ; water uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Whilst adverse effects of soil compaction on plant growth are well known, experimental evidence also suggests that a very loose soil can adversely affect crop growth. We tested the hypothesis that poor root-soil contact in a loose soil is partly responsible for the existence of an optimum in the response curve of crops to soil compaction. In a pot experiment with maize at restricted nitrogen supply, five levels of soil compaction were compared and the percentage root-soil contact was measured in three of these. At the highest soil porosity tested, shoot growth was slightly slower than that at intermediate soil porosity. In the more compacted soil, shoot growth clearly lagged behind. Shoot fresh weight per unit root length decreased with increasing soil porosity over the whole range tested. In the most compacted soil, roots were mainly restricted to the upper zones of the pot and total root length was smaller than in less compacted soil. Water and nitrate uptake were highest at the intermediate pore volume and slightly lower at the highest soil porosity. Water absorption and nitrate uptake per unit root length decreased from compacted to loose soil with decreasing root-soil contact. This effect was more than proportional with the percentage root-soil contact and was in line with a correction value based on a transport model.
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    Effect of VAM inoculum carry-over on the successive cropping of maize and mungbean (1992)
    Springer
    Plant and soil 140 (1992), S. 303-309 
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    ISSN: 1573-5036
    Keywords: cropping pattern ; Glomus mosseae ; inoculum ; maize ; mungbean ; VAM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field study to determine the endomycorrhizal inoculum carry-over effect of the first crop [maize inoculated with Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe] on the succeeding crop (mungbean) was carried out in fumigated and nonfumigated acidic soil (pH 5.3) with moderate extractable P (Olsen 23 ppm). G. mosseae inoculation increased maize dry matter and grain yield over the uninoculated control in the nonfumigated soil. The maize inoculation failed to carry the effective inoculum over to the mungbean crop planted immediately after maize harvest and thus did not increase root colonization and grain yield of the succeeding crop. Fresh inoculation of the mungbean with G. mosseae increased grain yield over the uninoculated control.
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    Role of cytokinin in enhanced productivity of maize supplied with NH4 + and NO3 − (1992)
    Springer
    Plant and soil 142 (1992), S. 307-313 
    Details
    ISSN: 1573-5036
    Keywords: cytokinin ; field ; greenhouse ; maize ; nitrogen form
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Supplying both N forms (NH4 ++NO3 −) to the maize (Zea mays L.) plant can optimize productivity by enhancing reproductive development. However, the physiological factors responsible for this enhancement have not been elucidated, and may include the supply of cytokinin, a growth-regulating substance. Therefore, field and gravel hydroponic studies were conducted to examine the effect of N form (NH4 ++NO3 − versus predominantly NO3 −) and exogenous cytokinin treatment (six foliar applications of 22 μM 6-benzylaminopurine (BAP) during vegetative growth versus untreated) on productivity and yield of maize. For untreated plants, NH4 ++NO3 − nutrition increased grain yield by 11% and whole shoot N content by 6% compared with predominantly NO3 −. Cytokinin application to NO3 −-grown field plants increased grain yield to that of NH4 ++NO3 −-grown plants, which was the result of enhanced dry matter partitioning to the grain and decreased kernel abortion. Likewise, hydroponically grown maize supplied with NH4 ++NO3 − doubled anthesis earshoot weight, and enhanced the partitioning of dry matter to the shoot. NH4 ++NO3 − nutrition also increased earshoot N content by 200%, and whole shoot N accumulation by 25%. During vegetative growth, NH4 ++NO3 − plants had higher concentrations of endogenous cytokinins zeatin and zeatin riboside in root tips than NO3 −-grown plants. Based on these data, we suggest that the enhanced earshoot and grain production of plants supplied with NH4 ++NO3 − may be partly associated with an increased endogenous cytokinin supply.
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    Soil phosphorus levels needed for equal P uptake from four soils with different water contents at the same water potential (1992)
    Springer
    Plant and soil 143 (1992), S. 93-98 
    Details
    ISSN: 1573-5036
    Keywords: anion exchangeable P ; buffer power ; diffusion coefficient ; growth chamber experiment ; maize ; mechanistic uptake model, P ; rates ; root length ; soil texture ; solution P
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soil volumetric water contents, φ, at −33 kPa potential may vary with soil from 0.06 to 0.70. Because P diffusion depends on φ, most economic P fertilizer rates required for different soils may require adjusting according to their soil-water relationships. The objective of this study was, after experimentally verifying a mechanistic nutrient uptake model on a series of soils varying in θ at −33 kPa potential, to use the model to predict labile P levels needed for each of these soils to achieve equal P uptake by maize (Zae mays L.) and verify these predictions. Maize was grown in a pot experiment using four soils having θ of 0.13, 0.20, 0.26, and 0.40 at −33 kPa each at 0, 200, and 400 mg kg-1 of added P. When root parameters obtained experimentally were used, predicted P uptake with the uptake model agreed with observed P uptake, y=0.99x+9.08 (r2=0.98). When P uptake was plotted vs. soil solution P, Cli, the relation varied with soil. The higher the θ the lower the Cli needed for equal P uptake. A similar relation was found between P uptake and diffusible soil P, Csi. Differences between the two plots occurred because of differences among soils in buffer power, ΔCsi/ΔCli. The Csi vs. P added relation was used to calculate differences among soils in the Csi needed to obtain equal P uptake. The Csi values ranged from 1.3 to 4.0 mmol kg−1. The calculated values were used in a second pot experiments to verify the predictions. No significant difference (α=0.05) in P uptake occurred. The results of this research indicate that the mechanistic nutrient uptake model can be used to predict the degree of adjustments in Csi needed to obtain the most economic P fertilizer rates among soils varying in θ.
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    Potential errors caused by roots in analyses of rhizosphere soil (1992)
    Springer
    Plant and soil 143 (1992), S. 223-231 
    Details
    ISSN: 1573-5036
    Keywords: exchangeable cations ; macronutrients ; maize ; micronutrients ; rhizosphere ; root composition ; soluble ions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Roots contain high concentrations of many elements, and have the potential to interfere with measurements of chemical change in rhizosphere soil. To assess potential interferences, maize (Zea mays L.) roots (free of soil) and soil (free of roots) were extracted separately with several extractants commonly used to assess the status of soil nutrients. The maize roots were grown within filter envelopes which prevented direct contact with soil, but permitted passage of mineral nutrients and water from the adjacent soil. Water, ammonium acetate (pH 7), DTPA (pH 7.3), Morgan's solution (pH 4.8), and dilute HCl were used as extractants. Most elements were released readily into soluble forms from roots killed by freezing to lyse the cells. Significantly lower amounts were extracted from fresh roots, with the greatest differences between fresh and killed roots for the extractants H2O and DTPA, which were the mildest in terms of acidity and salt concentration. Extraction of P from the fresh roots by H2O and HCL was particularly low. Contamination of rhizosphere samples with root materials would almost certainly prevent the accurate measurement of water-soluble P, K, Mn, Zn, Cu, and Na in the slightly alkaline soil used in this experiment. Large errors would be likely also for P, Mn, and Cu extracted by ammonium acetate. The DTPA extractant is normally used only for micronutrient metals or heavy metals, and the small amounts of these elements released by roots should not contribute to significant error. With Morgan's solution, errors would likely be large only for P. Dilute HCl is a reasonably strong extractant for many elements in soil, and major errors from roots contained in rhizosphere samples are unlikely. The relatively high probability of errors in extractions of soluble elements from rhizosphere soil is unfortunate, because these elements are among the most readily available to plants and the most likely to be altered by the normal activities of roots.
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    Re-sorption of organic components by roots of Zea mays L. and its consequences in the rhizosphere (1992)
    Springer
    Plant and soil 143 (1992), S. 259-266 
    Details
    ISSN: 1573-5036
    Keywords: maize ; organic components ; re-sorption ; rhizosphere ; root
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The re-sorption of carbon compounds from the rhizosphere was investigated using 14C-labelled glucose, mannose and citric acid. Uptake in roots of 5-day-old, intact Zea mays plants in sterile solution culture was determined over a period of 48 hours. Under optimal growth conditions significant re-absorption of glucose and mannose occurred with the uptake rates being 70.5 and 40.2 μg compound g-1 root DW h-1, respectively. For glucose and mannose approximately 25% of the 14C label taken up by the root was recovered inside the plant as low-MW compounds and 33% polymerized into high MW compounds. 42% was respired as 14C-CO2. Citric acid by comparison showed little accumulation within plant tissues (11.4%) with most being respired and recovered as 14C-CO2 in KOH traps (88%). The uptake rate for citric acid was 34.8 μg g-1 root DW h-1. Over the 48-hour period a net efflux (i.e. exudation) of labelled plus unlabelled C was observed at a rate of 608 μg C g-1 root DW h-1 (equivalent to 1520 μg glucose/mannose). Of the C released as root exudates, a minimum estimate of the amount of C taken back into the plant was therefore 9.5%. The two main C fluxes within the rhizosphere, namely release of C by the root and uptake by the microorganisms, have been well documented in recent years. It is now apparent however that a third flux term, re-sorption of C by roots, can also be identified. This may play an important but previously overlooked role within the rhizosphere, and further work is needed to determine its significance. A comparison between exudate release in static (permitting accumulation of C) and flowing culture (C removed as it is released) was also made with the respective rates being 15.36 and 45.18 mg C g-1 root DW in 2 days. The relative important of re-sorption in natural environments and laboratory experiments is discussed.
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    Gas-filled root porosity in response to temporary low oxygen supply in different growth stages (1993)
    Springer
    Plant and soil 152 (1993), S. 187-199 
    Details
    ISSN: 1573-5036
    Keywords: aeration ; aerenchyma ; carnation ; cucumber ; gerbera ; maize ; oxygen stress ; oxygen transport ; redox dye ; rice ; rose ; sugar beet ; sweet pepper ; tomato ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The development of gas-filled root porosity in response to temporary low oxygen supply was tested for a range of edible and ornamental crops: rice, maize, wheat, sugar beet, tomato, cucumber, sweet pepper, carnation, gerbera and rose. In a first experiment, the roots of tomato, maize and gerbera had a higher gas-filled root porosity, Ep (% v/v), when grown permanently in a non-aerated instead of aerated solution. The Ep of roots increased during two weeks when half the root system of a young plant was transferred to a non-aerated solution; in older plants this response was not seen. Carnation had a negligible gas-filled porosity in all treatments. In a second experiment, a comparison was made between high (20 kPa) and low (about 2 kPa) O2 partial pressure in a recirculating nutrient solution. Half of the root system was transferred to low O2 at various growth stages. In most species older plants did not increase Ep on exposure to low O2. For tomato, sweet pepper and rose, Ep was normally in the range 3–8% (v/v). Young plants of cucumber, wheat and sugar beet also had an Ep in that range, but in older plants values ranged from 1 to 3%. Transverse root sections examined by light microscopy showed, on average, 60% more intercellular spaces in the root cortex than the measurements of gas-filled porosity, probably because some gaps and spaces in the cortex were not gas-filled. This effect was most pronounced in tomato. A negative pressure in the cortex may be needed for gaps to be gas-filled. An exodermis may increase the effectiveness of gas spaces in the cortex by closing the gas channels and, by offering some resistance to water uptake, allowing a negative pressure head in the cortex which keeps gaps gas-filled. A redox dye method was developed to study the length of root which is effectively supplied with oxygen, as a function of Ep. Results indicated that for every percent Ep the root can remain aerated over at least 1 cm in a non-aerated medium under the conditions of the test.
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    Influx and efflux of amino acids from Zea mays L. roots and their implications for N nutrition and the rhizosphere (1993)
    Springer
    Plant and soil 155-156 (1993), S. 87-90 
    Details
    ISSN: 1573-5036
    Keywords: amino acids ; maize ; rhizosphere ; root exudates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The aim of the study was to investigate the ability of Zea mays L. roots to regulate the amount of free amino acids present in the rhizosphere. The active uptake of amino acids was shown to conform to Michaelis-Menten kinetics. Comparison of amino acid-N and NO3-N kinetic parameters and soil solution concentrations showed that root uptake of free amino acids from soil may contribute significantly to a plant's N budget. The influx of amino acids also helps to minimize net C/N losses to the soil, and is therefore important in regulating the size of the rhizosphere microbial population. Experimental data and a computer simulation model of amino acid influx/efflux in a sterile solution culture, showed that roots were capable of re-sorping over 90% of the amino acids previously lost into solution as a result of passive diffusion.
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    Response of vesicular-arbuscular mycorrhizas of maize to various rates of P addition to different rooting zones (1994)
    Springer
    Plant and soil 158 (1994), S. 119-128 
    Details
    ISSN: 1573-5036
    Keywords: maize ; P placement ; P supply ; rooting zone ; VAM colonization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Colonization of plant roots by vesicular-arbuscular mycorrhizal fungi is known to be reduced as the phosphorus nutrition of the plant is increased. It is generally accepted that the concentration of P in the plant rather than the soil regulates VAM colonization. Whether it is the shoot P concentration, the mean P concentration in the root system or the P concentration in the specific root being colonized is not known, but is of agronomic significance because fertilizer P is frequently applied in concentrated zones which would be expected to result in higher P concentration in roots growing in the fertilized zone than in the remainder of the root system. Growth chamber and field experiments were conducted to determine the effect on colonization of supplying varying amounts of P to different portions of the rooting zone. In growth chamber studies using a split-pot technique, the proportion of maize (Zea mays L.) root length containing arbuscules in a high-P zone was lower than that of roots of the same plant growing in a low- or medium-P zone. Root P concentration was higher in the high-P zone. In a field experiment conducted over a two-year period, VAM colonization of roots of young maize plants growing in fertilized soil was affected differently than that of roots growing outside the fertilized zone. A small addition of fertilizer P increased colonization of roots in the fertilized soil, but further additions resulted in an abrupt decline followed by a slower further decline, although colonization was not eliminated even by rates of 1600 μg P g-1 soil. Colonization of roots growing outside the fertilized zone declined gradually with increasing P addition but the overall decline was less than for roots in the fertilized zone. The data support the hypothesis that it is P concentration in the portion of the root system being colonized rather than the general P status of the plant which regulates VAM colonization. The agronomic implication of this is that, although a fertilizer band may reduce VAM colonization of roots in the band volume, roots growing outside this volume may be well colonized so the mycorrhizal symbiosis may be an important contributor to P nutrition.
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    Can maize cultivars with low mineral nutrient concentrations in the grains help to reduce the need for fertilizers in third world countries? (1992)
    Springer
    Plant and soil 146 (1992), S. 227-231 
    Details
    ISSN: 1573-5036
    Keywords: cultivars ; grains ; maize ; nitrogen ; phosphorus ; potassium ; tropical climate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An earlier study revealed considerable genotypic variation in grain N, P and K concentrations (GNC, GPC and GKC, respectively) in tropical maize. The expression of varietal differences in GNC, GPC and GKC, however, may depend on environmental conditions such as the N status of the soil. Two tropical maize hybrids (Suwan 2301 and CP 1) with comparable yielding capacity, but contrasting GNCs, GPCs and GKCs, were therefore grown at four levels of N in a field experiment at Farm Suwan (Thailand, latitude 14.5°N). Suwan 2301 exhibited a higher GNC than did CP 1 at all rates of N, but large differences in GPC and GKC were found only at high N fertilization. This was obviously due to individual grain yield responses of the cultivars to increasing rates of N fertilizer, demonstrating that grain nutrient concentrations are, at least in part, functions of the amount of grain carbohydrates which dilute a genetically and environmentally fixed amount of grain P and K. As compared to Suwan 2301, CP 1 accumulated less N, P and K in the grains at almost all levels of N fertilization, confirming our hypothesis that the cultivation of maize genotypes with low grain mineral nutrient concentrations may help third-world cash-crop farmers to reduce the need for scarce and costly mineral fertilizers. This finding has to be verified at reduced availability of soil −P, −K, and water.
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    A comparison between minirhizotron and monolith sampling methods for measuring root growth of maize (Zea mays L.) (1992)
    Springer
    Plant and soil 147 (1992), S. 127-134 
    Details
    ISSN: 1573-5036
    Keywords: image processing ; methods ; maize ; minirhizotron ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Transparent plastic minirhizotron tubes have been used to evaluate spatial and temporal growth activities of plant root systems. Root number was estimated from video recordings of roots intersecting minirhizotron tubes and of washed roots extracted from monoliths of the same soil profiles at the physiological maturity stage of a maize (Zea mays L.) crop. Root length was measured by the line intercept (LI) and computer image processing (CIP) methods from the monolith samples. There was a slight significant correlation (r=0.28, p〈0.005) between the number of roots measured by minirhizotron and root lengths measured by the LI method, however, no correlation was found with the CIP method. Using a single regression line, root number was underestimated by the minirhizotron method at depths between 0–7.6 cm. A correlation was found between root length estimated by LI and CIP. The slope of estimated RLD was significant with depth for these two methods. Root length density (RLD) measured by CIP showed a more erratic decline with distance from the plant row and soil surface than the LI method.
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    URL: http://dx.doi.org/10.1007/BF00009378
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    Inhibition of nitrate uptake by aluminium in maize (1993)
    Springer
    Plant and soil 151 (1993), S. 97-104 
    Details
    ISSN: 1573-5036
    Keywords: aluminium ; ammonium ; induction ; maize ; nitrate ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments with two maize (Zea mays L.) hybrids were conducted to determine (a) if the inhibition of nitrate uptake by aluminium involved a restriction in the induction (synthesis/assemblage) of nitrate transporters, and (b) if the magnitude of the inhibition was affected by the concurrent presence of ambient ammonium. At pH 4.5, the rate of nitrate uptake from 240 μM NH4NO3 was maximally inhibited by 100 μM aluminium, but there was little measurable effect on the rate of ammonium uptake. Presence of ambient aluminium did not eliminate the characteristic induction pattern of nitrate uptake upon first exposure of nitrogen-depleted seedlings to that ion. Removal of ambient aluminium after six hours of induction resulted in recovery within 30 minutes to rates of nitrate uptake that were similar to those of plants induced in absence of aluminium. Addition of aluminium to plants that had been induced in absence of aluminium rapidly restricted the rate of nitrate uptake to the level of plants that had been induced in the presence of aluminium. The data are interpreted as indicating that aluminium inhibited the activity of nitrate transporters to a greater extent than the induction of those transporters. When aluminium was added at initiation of induction, the effect of ambient ammonium on development of the inhibition by aluminium differed between the two hybrids. The responses indicate a complex interaction between the aluminium and ammonium components of high acidity soils in their influence on nitrate uptake. ei]{gnA C}{fnBorstlap}
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    Re-sorption of organic compounds by roots of Zea mays L. and its consequences in the rhizosphere (1993)
    Springer
    Plant and soil 153 (1993), S. 47-59 
    Details
    ISSN: 1573-5036
    Keywords: maize ; mathematical model ; re-sorption ; rhizosphere ; root exudates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The exudation of soluble carbon compounds from Zea mays roots was investigated over a 10 day growth period under sterile and non-sterile solution culture conditions. The results showed that plants grown in sterile static solution culture, where C was allowed to accumulate, released 8 times less C than plants grown under culture conditions in which the solutions were replaced daily. The increased C loss from plant cultures in which exudates were removed daily was attributable to, (a) the reduced potential for root re-sorption of previously lost C, and (b), increasing diffusion gradients between the root and the surrounding bathing solution increasing passive leakage of exudates from the roots. In treatments where C was removed daily from the root-bathing solution, 86% of the total C lost was of a soluble low molecular weight nature, whereas, in sterile and non-sterile static cultures, allowing the accumulation of C over 10 days, this was reduced to 67.5 and 48% respectively. The main C fluxes operating in a solution culture system (efflux and influx of C by both roots and microorganisms) were examined using a computer simulation model to describe movement of soluble sugar-C in both sterile and non-sterile conditions. In sterile static cultures where C was allowed to accumulate in solution over a 10 day growth period, 98% of the C exuded was re-absorbed by the plant. Where C was removed daily from the root-bathing solution this was reduced to 86%. The predicted patterns of C accumulation were similar to those found in the experiments. Simulations showed that the pattern of accumulation and final equilibrium concentrations were dependent on the rate of exudation, the spatial characteristics of exudation, solution volume, root growth rate and the presence of a microbial population. Simulations under non-sterile conditions showed that roots can compete with microorganisms for exudates in solution indicating the possible importance of re-sorption in a soil environment. The results clearly indicate that roots are capable of regulating the net amount of C released into a solution culture with the amount of C collected being highly dependent on the experimental conditions employed. The possible implications of soluble C influx on processes operating within the rhizosphere and in experimental systems is discussed.
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    URL: http://dx.doi.org/10.1007/BF00010543
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    Light differentially regulates lateral and longitudinal auxin transport in the mesocotyl of etiolated maize seedlings (1994)
    Springer
    Plant growth regulation 14 (1994), S. 167-171 
    Details
    ISSN: 1573-5087
    Keywords: auxin-transport ; indoleacetic acid ; maize ; photoinhibition ; transport ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The uptake of IAA into excised mesocotyls of non-irradiated maize seedlings was linear up to a concentration of about 4×M and in this range there was a tight coupling between the IAA in the stele and the cortex. Prior irradiation with white light of intact seedlings unbalanced this coupling. Lateral and longitudinal transport were affected differently. In the stele, the effect of prior irradiation on longitudinal transport was multiphasic, with an initial stimulatory effect followed by a negative effect at longer prior irradiation times. The lateral transport from the stele to the cortex showed no stimulatory effect and appeared to be inhibited within at least 15 min. The effect of the prior irradiation on longitudinal transport in the stele appeared to be a high intensity effect. In contrast, the effect of the prior irradiation on the lateral transport from the stele to the cortex was saturated at much lower intensities. The data suggest that the light induced change in the lateral transport of IAA between the two tissues may be due to changes either in the number of open lateral transport channels/carriers or in the conductivity of these channels/carriers.
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    URL: http://dx.doi.org/10.1007/BF00025219
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    Genetic and environmental effects on abscisic acid accumulation in leaves of field-grown maize (1994)
    Springer
    Euphytica 78 (1994), S. 81-89 
    Details
    ISSN: 1573-5060
    Keywords: abscisic acid ; inheritance ; drought stress ; Zea mays ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This study analyzes the components of phenotypic variation for abscisic acid (ABA) content in maize (Zea mays L.) leaves and the correlations with drought sensitivity index (DSI) and silk delay (SD), involved in the reaction to water deficit. Eight early- and seven medium-maturity inbreds were examined in field trials: in 1990 with low irrigation volume and in 1991 with low and high irrigation volumes. ABA concentration and DSI were investigated at growth stages (S) corresponding to stem elongation (S3), appearance of the first husks (S4), and mid-end of silking (S5). The ABA concentration was significantly higher in conditions of water deficit and in the later growth stage. The genetic component for ABA concentration attained higher relative values than those shown by DSI in the same growth stages and by SD; moreover, it increased from growth stage 3 to stage 5. The genotype × year and genotype × irrigation volume interactions were smaller for ABA concentration than for DSI and SD. The broad sense heritability on a plant basis, estimated in drought conditions, for ABA concentration ranged from 21.4 to 55.1% according to maturity group and growth stage. A wide variation was observed among lines for ABA concentration: the medium-maturity group showed a three-fold range (from 219 to 605 ng ABA g−1 dry weight). No clear relationships between ABA concentration, DSI and SD were found. These results indicate the feasibility of a selection for ABA concentration within segregating populations derived from crosses between the inbred lines herein tested.
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    URL: http://dx.doi.org/10.1007/BF00021401
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    Variation and inheritance of response to acetochlor among maize inbred lines and hybrids (1990)
    Springer
    Euphytica 45 (1990), S. 131-137 
    Details
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; acetochlor ; heterosis ; susceptibility ; tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The variation of response to acetochlor was studied in a two-year experiment carried out by subjecting 18 maize (Zea mays L.) inbred lines to three herbicide rates (0, 2.5 and 5 l a.i./ha). In both years some inbred lines consistently exhibited an evident susceptibility, with symptoms consisting of the seedling curling up below the soil surface and causing impaired field emergence. The results were poor plant density and lower grain yield in comparison to control. In contrast, other lines showed a satisfactory level of tolerance. Then, to gather data on the inheritance of response to acetochlor, four tolerant inbreds (T) and four susceptible inbreds (S) were crossed to obtain four T×T, four S×S, four S×T and the corresponding four T×S two-way hybrids. These hybrids were studied together with parental lines by applying the same herbicide rates used in the previous trial. The S×S hybrids showed susceptibility to the herbicide and the T×T were tolerant, whereas the S×T and the T× S hybrids showed a tolerance very close to that of the T×T hybrids. No difference was found between S×T and the corresponding T×S hybrids as to herbicide response. On average, the 16 hybrids exhibited greater tolerance than the eight parental lines, with each hybrid group being more tolerant than its parental line group. These results indicate that tolerance to acetochlor is prevailingly dominant, that action of extranuclear genes should be ruled out, and that the level of plant vigour can affect herbicide reactiveness.
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    URL: http://dx.doi.org/10.1007/BF00033280
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    Genetic variation of the rate of leaf appearance in maize: Possible yield prediction at the early stage (1990)
    Springer
    Euphytica 46 (1990), S. 237-247 
    Details
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; genetic variation ; prediction ; dry matter yield ; early vigour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Evidence of genetic variation for early vigour is presented using maize line × tester crosses. The leaf appearance rate and associated variance components are affected by a physiological stress attributable to the transition to autotrophic nutrition by the plant. At this stage, specific combining ability plays an important role in the total genetic variation. It is concluded that differing genetic controls exist in early and late material, and that this difference is also manifested in leaf initiation and elongation rates. The ground coverage rate, as a component of plant development, is genetically correlated to total dry matter yield. The genetic correlations vary according to the growth stage.
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    URL: http://dx.doi.org/10.1007/BF00027223
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    Dosage effects of y gene on grain yield and other agronomic traits in maize (1990)
    Springer
    Euphytica 48 (1990), S. 63-72 
    Details
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; corn ; yield ; kernel weight ; shelling percentage ; plant height ; ear height ; husk weight ; cob weight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary White-endosperm (y y y) maize (Zea mays L.) is vital to the maize dry-milling industry. However, a substantially greater acreage in the U.S.A. is planted to yellow (Y Y Y) than white maize. Data on comparative performance of yellow and white maize is scanty, and results are inconclusive. This field study was conducted to provide information on dosage effects of y gene on grain yield, 500-kernel (K) weight, shelling percentage, plant and ear height, and cob weight. Yellow x yellow, yellow x white, and white x white endosperm crosses were made among five yellow and five white endosperm lines of Mo14W × Oh7B parentage. In the material studied, the genetic complement of the white-endosperm parent Mo14W varied from 12.50% to 87.50% across 15 treatments. The effect of Mo14W dosages among treatments was removed through analysis of covariance. If differences among treatment means existed, they were attributed to the y gene. A test of parallelism among regression coefficients (Ho. β1=β2=---β15=βc) indicated that these regressions coefficients for plant height, ear height, 500-K weight, and husk weight showed parallelism across yellow x yellow, yellow x white, and white x white crosses. Differences in plant height were significant in 3 out of 5 comparisons each between Y Y vs. y y, Y y vs. y y, and Y Y vs. Y y. Differences in ear height were significant in 1 of 5 Y Y vs. y y comparisons, in 3 of 5 Y y vs. y y comparisons, and in 1 of 5 Y Y vs. Y y comparisons. Differences in 500-K weight were significant in 4 of 5 Y Y vs. y y, in 2 of 5 Y Y vs. Y y and in 1 of 5 Y y vs. y y comparisons. Differences in husk weight were significant in all the Y Y vs. y y comparisons, in 4 of 5 Y y vs. y y comparisons, and in 1 of 5 Y Y vs. Y y comparisons. An increase in the y gene dosage caused, in general, a significant decrease in grain yield, 500-K weight, plant height, ear height, and husk weight. Shelling percentage was decreased but not appreciably. The Y y combination had a heterotic effect on plant height, ear height, and cob weight. An implication of the findings of this study is that it would be difficult to breed for high-yielding white maize if one used this y gene source. At this time, this is the only source (chromosome 6) available for white-endosperm maize. Non-parrallelism among regression coefficients was noted for shelling percentage, grain yield, and cob weight. Non-parallelism was observed in shelling percentage of the yellow x yellow crosses, cob weight of the yellow x white crosses and in grain yield of both yellow x yellow and yellow x white crosses. In general, an increase in mean Mo14W dosage resulted in increased grain yield. Mo14W dosages generally reduced cob weight in the yellow x white crosses. Shelling percentage increased as the mean Mo14W dosages increased for the yellow x yellow crosses. An increase in Mo14W dosages resulted in an increase in 500-K weight.
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    Changes in the photosynthetic light response curve during leaf development of field grown maize with implications for modelling canopy photosynthesis (1994)
    Springer
    Photosynthesis research 42 (1994), S. 217-225 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; leaf age ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in the photosynthetic light-response curve during leaf development were determined for the fourth leaf of maize crops sown on 23 April and 10 June. Temperatures were unusually mild during late spring/early summer and neither crop experienced chilling damage. The concept of thermal time was used to take into account the effects of different temperature regimes on developmental stage, thereby enabling photosynthetic light-response data to be combined for both crops to describe the general response. Large variations in the upper asymptote (Asat) and convexity (Θ) of the light-response curve occurred during leaf development, but the maximum quantum yield of CO2 assimilation remained relatively constant throughout. Dark respiration rates showed a small but significant decrease with leaf age and generally ranged between 5 and 10% of Asat. A simple mathematical model was developed to assess the sensitivity of daily leaf photosynthesis (AL) to reductions in the Asat, Θ and the initial slope (Φ) of the light-response curve at different stages of leaf development. On bright sunny days, and at all developmental stages, AL was ca. twice as sensitive to reductions in Asat than to reductions in Φ and Θ. In overcast conditions, however, all three parameters contributed significantly to reductions in leaf photosynthesis, although the contribution of Φ was greatest during early leaf growth, while older leaves were most sensitive to depressions in Asat. The implications of these results for modelling the sensitivity of canopy photosynthesis to chill-induced photoinhibition of the light-response curve are discussed.
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    Expression and distribution of cytosolic 6-phosphogluconate dehydrogenase isozymes in maize (1992)
    Springer
    Biochemical genetics 30 (1992), S. 233-246 
    Details
    ISSN: 1573-4927
    Keywords: phosphogluconate dehydrogenase ; isozymes ; maize ; gene dosage ; tissue-specific expression ; null alleles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Maize (Zea mays L.) cytosolic 6-phosphogluconate dehydrogenase isozymes (EC 1.1.1.44; 6-PGD) are encoded by unlinked lociPgd1 andPgd2. Two families from a Robertson's Mutator line were isolated which have no detectable expression ofPgd2. ThesePgd2-null mutants and aPgd1-null line were used to generate plants homozygous for null alleles at both cytosolic 6-PGD loci. The specific activity of 6-PGD in the double-null mutant was between 20 and 30% of wild-type levels in root extracts. The double-null mutant was reproductively viable in a moderate environment, suggesting that wild-type levels of cytosolic 6-PGD activity are not essential for growth. Isozyme dimer ratios in roots, leaves, and scutellum were binomial and reflected the wild-type gene copy number. 6-PGD isozymes showed tissue- and cell type-specific expression.
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    Analysis ofl-alanine:2-oxoglutarate aminotransferase isozymes in maize (1992)
    Springer
    Biochemical genetics 30 (1992), S. 371-383 
    Details
    ISSN: 1573-4927
    Keywords: alanine aminotransferase ; maize ; isozymes ; allozymes ; glutamate dehydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Isozyme analysis ofl-alanine:2-oxoglutarate aminotransferase (ALT) in maize indicates that there are three genes encoding this enzyme activity. Two of the gene products interact with each other to form heterodimers, while the third gene product does not interact with the other two. Another isozyme that appears after gel electrophoresis and ALT staining is shown to be glutamate dehydrogenase-1. Anaerobic treatment does not result in increased ALT levels, indicating that the previously reported increase in alanine levels caused by this treatment may be due to increases in the level of pyruvate, a substrate of ALT.
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    Characterization of mutation-induced changes in the maize (Zea mays L.) ADH1-1S1108 alcohol dehydrogenase (1993)
    Springer
    Biochemical genetics 31 (1993), S. 497-506 
    Details
    ISSN: 1573-4927
    Keywords: alcohol dehydrogenase ; maize ; Zea mays ; mutation ; cDNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The homodimeric alcohol dehydrogenase gene product of maize (Zea mays L.)Adh1-1S1108 mutation was purified and compared with the parentalAdh1-1S enzyme. The mutant alcohol dehydrogenase activity had pH optima and substrate specificity similar to those of the parental enzyme, but exhibited somewhat increased and decreasedK mvalues for acetaldehyde and NADH, respectively. The mutant enzyme was also markedly less stable than the enzyme from parental tissues to temperatures as low as 50°C. Sequence analysis of a polymerase chain reaction (PCR)-generated cDNA clone revealed a G-to-C mutation at position 406 and a C-to-T mutation at position 974. These would result in residue 103 of each protein subunit being changed from an alanine to a proline and residue 292 being changed from an alanine to a valine. Whether one or both of these changes in primary sequence is responsible for the altered substrate affinities and stability is not yet understood.
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    Expression and distribution of cytosolic 6-phosphogluconate dehydrogenase isozymes in maize (1992)
    Springer
    Biochemical genetics 30 (1992), S. 233-246 
    Details
    ISSN: 1573-4927
    Keywords: phosphogluconate dehydrogenase ; isozymes ; maize ; gene dosage ; tissue-specific expression ; null alleles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Maize (Zea mays L.) cytosolic 6-phosphogluconate dehydrogenase isozymes (EC 1.1.1.44; 6-PGD) are encoded by unlinked lociPgd1 andPgd2. Two families from a Robertson's Mutator line were isolated which have no detectable expression ofPgd2. ThesePgd2-null mutants and aPgd1-null line were used to generate plants homozygous for null alleles at both cytosolic 6-PGD loci. The specific activity of 6-PGD in the double-null mutant was between 20 and 30% of wild-type levels in root extracts. The double-null mutant was reproductively viable in a moderate environment, suggesting that wild-type levels of cytosolic 6-PGD activity are not essential for growth. Isozyme dimer ratios in roots, leaves, and scutellum were binomial and reflected the wild-type gene copy number. 6-PGD isozymes showed tissue- and cell type-specific expression.
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    Characterization of mutation-induced changes in the maize (Zea mays L.) ADH1-1S1108 alcohol dehydrogenase (1993)
    Springer
    Biochemical genetics 31 (1993), S. 497-506 
    Details
    ISSN: 1573-4927
    Keywords: alcohol dehydrogenase ; maize ; Zea mays ; mutation ; cDNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The homodimeric alcohol dehydrogenase gene product of maize (Zea mays L.)Adh1-1S1108 mutation was purified and compared with the parentalAdh1-1S enzyme. The mutant alcohol dehydrogenase activity had pH optima and substrate specificity similar to those of the parental enzyme, but exhibited somewhat increased and decreasedK mvalues for acetaldehyde and NADH, respectively. The mutant enzyme was also markedly less stable than the enzyme from parental tissues to temperatures as low as 50°C. Sequence analysis of a polymerase chain reaction (PCR)-generated cDNA clone revealed a G-to-C mutation at position 406 and a C-to-T mutation at position 974. These would result in residue 103 of each protein subunit being changed from an alanine to a proline and residue 292 being changed from an alanine to a valine. Whether one or both of these changes in primary sequence is responsible for the altered substrate affinities and stability is not yet understood.
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    URL: http://dx.doi.org/10.1007/BF02426881
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    Glycine-rich RNA-binding proteins from Sorghum vulgare (1990)
    Springer
    Plant molecular biology 15 (1990), S. 783-785 
    Details
    ISSN: 1573-5028
    Keywords: sorghum ; maize ; glycine-rich proteins ; RNA-binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00016128
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    Chemical detection of Z-DNA within the maize Adh1 promoter (1992)
    Springer
    Plant molecular biology 18 (1992), S. 1181-1184 
    Details
    ISSN: 1573-5028
    Keywords: alcohol dehydrogenase-1 ; maize ; plant ; promoter ; Z-DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Z-DNA is a left-handed helix which can form within tracts of alternating purines and pyrimidines. Tracts of potential Z-DNA identified by sequence inspection are often noted within regulatory portions of genes, but evidence that these tracts of sequence actually exist as Z-DNA is very limited, and not available for any plant gene. In this study, the chemical probes osmium tetroxide, diethylpyrocarbonate and hydroxylamine were used to show that a tract of alternating purines and pyrimidines in the Adh1 promoter (from -311 to -325) actually assumes a Z-DNA conformation under superhelical stress in vitro.
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    URL: http://dx.doi.org/10.1007/BF00047722
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    DNaseI-sensitive and undermethylated rDNA is preferentially expressed in a maize hybrid (1993)
    Springer
    Plant molecular biology 21 (1993), S. 805-821 
    Details
    ISSN: 1573-5028
    Keywords: DNaseI sensitivity ; maize ; methylation ; nucleolar dominance ; rDNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An Eco RI polymorphism, present in the 26S ribosomal RNA gene (rDNA) of the maize hybrid Sx19 (B73×Mo17), was utilized to correlate DNaseI sensitivity, undermethylation and expression in rDNA. We had previously shown that in double digest experiments with methylation-sensitive restriction enzymes and Eco RI, Sx19 rDNA fragments originating from repeat units with two Eco RI sites (8.0 kb) are undermethylated, whereas the fragments originating from repeat units with a single Eco RI site (9.1 kb) are completely methylated. In the present study, Sx19 rDNA chromatin structure was examined by purifying intact nuclei and digesting them briefly with increasing amounts of DNaseI. Analysis of this DNA with Eco RI showed that the 8.0 kb rDNA fragments are extremely sensitive to DNaseI digestion, while the 9.1 kb rDNA fragments are relatively resistant to digestion even at high levels of DNasel. Specific sites hypersensitive to DNaseI cleavage were mapped to a region in the intergenic spacer (IGS) near the major undermethylated site. Analysis of polymerase chain reaction (PCR) products synthesized using Sx19, B73, and Mo17 DNAs as templates indicated that the Eco RI polymorphism is due to a base change in the recognition site. Direct rRNA sequencing identified a single-base change in Mo17 rRNA relative to B73 rRNA. Allele-specific oligonucleotide probes containing the region surrounding and including the Eco RI polymorphic site were utilized to detect a nucleolar dominance effect by quantitating levels of rRNA transcripts in Sx19 and the reciprocal cross. Results from these single-base-pair mismatch hybridization experiments indicate that the majority of the rRNA transcripts in Sx19 orginate from the DNaseI-sensitive, undermethylated, Eco RI-polymorphic rDNA repeat units.
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    URL: http://dx.doi.org/10.1007/BF00027113
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    Transcriptional characterization of an α-zein gene cluster in maize (1993)
    Springer
    Plant molecular biology 22 (1993), S. 323-336 
    Details
    ISSN: 1573-5028
    Keywords: gene cluster ; maize ; multigene family ; transcriptional regulation ; zein ; early in-frame stop codon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cluster of five α-zein subfamily 4 (α-zein SF4) genes are present in a 56 kb region of the maize W22 genome. Two types of α-zein SF4 genes are in the cluster. One of the genes, termed a type 1 (T1) α-zein SF4 gene, contains no early in-frame stop codons. Four of the genes, termed type 2 (T2) α-zein SF4 genes, contain one or two early in-frame stop codons. The base sequence of the T1 α-zein SF4 gene is similar (〉90%) to the sequences of any of the four T2 α-zein SF4 genes. However, their sequences differ markedly at distances greater than -875 bp upstream from the translation initiation codon of the α-zein coding region. This region of dissimilarity is well inside the functional 5′-flanking region for the genes since a 1.8 kb transcript is initiated in this region and the sequences of the T2 α-zein SF4 genes are similar in this region. Two sizes of mRNA transcripts, 1.8 kb and 0.9 kb, were detected in a gene specific manner for 4 of the 5 genes in this α-zein SF4 gene cluster. One of the T2 α-zein SF4 genes had only the 0.9 kb transcript. The RNA level for the 0.9 kb transcript of the T1 α-zein SF4 gene was 5- to 10-fold higher than the transcript levels of any of the T2 α-zein SF4 genes. In each case, the amount of the 0.9 kb transcript detected was at least 5-fold higher than the amount of the 1.8 kb transcript. A cDNA clone with a sequence identical to a T2 α-zein SF4 gene was isolated, providing the first direct evidence for the transcription of T2 α-zein genes containing early in-frame stop codon(s) in maize endosperm.
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    URL: http://dx.doi.org/10.1007/BF00014939
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    MNF1, a leaf tissue-specific DNA-binding protein of maize, interacts with the cauliflower mosaic virus 35S promoter as well as the C4 photosynthetic phosphoenolpyruvate carboxylase gene promoter (1992)
    Springer
    Plant molecular biology 19 (1992), S. 545-553 
    Details
    ISSN: 1573-5028
    Keywords: CaMV 35S promoter ; leaf-specific DNA-binding protein ; maize ; PEP carboxylase gene promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When gel shift assays were performed with maize nuclear extract and a DNA fragment containing the cauliflower mosaic virus (CaMV) 35S promoter, three DNA-protein complexes were observed. Analyses with nuclear extracts prepared from green leaves, etiolated leaves, stems and roots showed that the complexes resulted from the existence of at least two nuclear factors. One of them is presumably a constitutive nuclear factor found in all tissues tested, and another is a leaf-specific factor present both in green and etiolated leaves. This leaf-specific nuclear factor seemed to be identical to MNF1, previously identified as a factor interacting with the promoter of the maize gene for phosphoenolpyruvate carboxylase involved in the C4 photosynthesis. Deletion analysis revealed that MNF1 binds to the sequence from −281 to −235 relative to the transcription start site of the CaMV 35S promoter. MNF1-like nuclear protein was also found in tobacco nuclear extracts. The possibility that MNF1 participates as a positive trans-acting factor in the expression of genes in maize leaves is discussed.
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    URL: http://dx.doi.org/10.1007/BF00026781
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    Iron induces ferritin synthesis in maize plantlets (1992)
    Springer
    Plant molecular biology 19 (1992), S. 563-575 
    Details
    ISSN: 1573-5028
    Keywords: maize ; ferritin ; iron stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The iron-storage protein ferritin has been purified to homogeneity from maize seeds, allowing to determine the sequence of the first 29 NH2-terminal amino acids of its subunit and to raise specific rabbit polyclonal antibodies. Addition of 500 μM Fe-EDTA/75 μM Fe-citrate to hydroponic culture solutions of maize plantlets, previously starved for iron, led to a significant increase of the iron concentration of roots and leaves, albeit root iron was mainly found associated with the apoplast. Immunodetection of ferritin by western blots indicated that this iron treatment induced ferritin protein accumulation in roots and leaves over a period of 3 days. In order to investigate this induction at the ferritin mRNA level, various ferritin cDNA clones were isolated from a cDNA library prepared from poly(A)+ mRNA isolated from roots 48 h after iron treatment. These cDNAs were classified into two groups called FM1 and FM2. Upstream of the sequence encoding the mature ferritin subunit, both of these cDNAs contained an in-frame coding sequence with the characteristics of a transit peptide for plastid targeting. Two members of the FM1 subfamily, both partial at their 5′ extremity, were characterized. They are identical, except in their 3′ untranslated region: FM1A extends 162 nucleotides beyond the 3′ terminus of FM1B. These two mRNAs could arise from the use of two different polyadenylation signals. FM2 is 96% identical to FM1 and contains 45 nucleotides of 5′ untranslated region. Northern analyses of root and leaf RNAs, at different times after iron treatment, revealed ferritin mRNA accumulation in response to iron. Ferritin mRNA accumulation was transient and particularly abundant in leaves, reaching a maximum at 24 h. The level of ferritin mRNA in roots was affected to a lesser extent than in leaves.
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    URL: http://dx.doi.org/10.1007/BF00026783
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    Sequence analysis of three members of the maize polygalacturonase gene family expressed during pollen development (1992)
    Springer
    Plant molecular biology 20 (1992), S. 343-345 
    Details
    ISSN: 1573-5028
    Keywords: maize ; microsporogenesis ; pollen ; polygalacturonase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014505
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    Differential transcription of plastome-encoded genes in the mesophyll and bundle-sheath chloroplasts of the monocotyledonous NADP-malic enzyme-type C4 plants maize and Sorghum (1994)
    Springer
    Plant molecular biology 25 (1994), S. 669-679 
    Details
    ISSN: 1573-5028
    Keywords: C4 photosynthesis ; maize ; plastid gene expression ; Sorghum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The transcription of plastome-encoded genes in mesophyll and bundle-sheath chloroplasts of the monocotyledonous NADP-malic enzyme-type C4 species Zea mays L. (maize) and Sorghum bicolor (L.) Moench. was investigated. RNA accumulation and transcription were assayed starting from isolated mesophyll and bundle-sheath chloroplasts and using quantitative northern and run-on transcription analysis. Determination of the mesophyll to bundle-sheath ratios of transcript abundance in maize and Sorghum chloroplasts showed that the mRNAs of the plastome-encoded photosystem II genes analysed (psbA, psbB, psbD, psbH and psbE/F) varied from 2.5- to 4.0-fold (maize) and 3.1- to 5.2-fold (Sorghum), respectively. The rbcL transcript, in contrast, was more abundant in bundle-sheath chloroplasts of both species, about 3-fold in maize and more than 10-fold in Sorghum. On the other hand, transcripts of genes encoding the 16S ribosomal RNA (r16) and subunits of photosystem I (psaA) and the cytochrome b/f complex (petB, petA) accumulated to similar levels in both types of chloroplasts. Determination of absolute transcript levels for rbcL and psbA in chloroplasts from maize and Sorghum demonstrated that for both genes, the mesophyll to bundle-sheath differences in transcript abundance were more pronounced in Sorghum. Measurements of the transcriptional activities of rbcL and psbA showed that the transcription rate of rbcL is higher in bundle-sheath chloroplasts while psbA is more actively transcribed in mesophyll chloroplasts. The differences in the transcription rates between the two chloroplast types were again more pronounced in Sorghum, thus reflecting the differences between maize and Sorghum in the relative levels of the rbcL and psbA transcripts. However, although transcription rate and mRNA abundance are correlated, they did not exactly match one another. This indicates additional regulation of transcript abundance at the level of RNA stability.
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    URL: http://dx.doi.org/10.1007/BF00029605
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    Regulation of the maize HRGP gene expression by ethylene and wounding. mRNA accumulation and qualitative expression analysis of the promoter by microprojectile bombardment (1992)
    Springer
    Plant molecular biology 20 (1992), S. 529-538 
    Details
    ISSN: 1573-5028
    Keywords: cell wall ; ethylene ; genetic transformation ; HRGP ; maize ; wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of the maize gene coding for a hydroxyproline-rich glycoprotein (HRGP) has been studied by measuring the mRNA accumulation after wounding or ethylene treatment. RNA blot and in situ hybridization techniques have been used. The temporal and tissue-specific expression has been observed: the cells related to the vascular system show the more intense HRGP mRNA accumulation. Transcriptional constructions of the maize HRGP promoter have been tested on different maize tissues by microbombarding. A 582 bp promoter is able to direct the expression of the gus gene on calli and young leaves. Constructions having shorter promoter sequences lose this ability. The 582 bp construction retains the general specificity of expression observed for the HRGP gene.
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    URL: http://dx.doi.org/10.1007/BF00040611
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    Organic matter contributed to soil by plant roots during the growth and decomposition of maize (1990)
    Springer
    Plant and soil 121 (1990), S. 107-114 
    Details
    ISSN: 1573-5036
    Keywords: aseptic ; 14C-labelled ; carbohydrate ; decomposition ; root exudate ; maize ; monosaccharides ; root lysate ; sandy loam sonication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize (Zea mays var. Caldera) plants were grown under sterile and not sterile conditions in soil in an atmosphere continuously enriched with 14CO2 for 36 days. At harvest the above ground parts of the maize were cut off and the roots were separated from the soil by washing with water. The soil was dispersed using ultrasonics and separated into soluble clay silt and sand fraction. Roots were included in the coarse sand fraction. 25% of the total label present in the soil ≡ 5.5% of that in the soil-plant system, was water soluble. Very little label was present in the clay and silt fractions (5% in each) and most (65%) was in the sand fraction as root material. Rapid extraction of soil after the removal of roots without ultrasonic treatment released soluble matter which amounted to 〈0.5% of the total activity in the soil-plant system. Isolated roots steeped in water released about 18% of their activity. Much of the soluble fraction may therefore be root lysate. The soil and roots accounted for 22% of the total activity in the soil-plant system. Glucose accounted for 89% of the sugars in the soluble fraction of the soil. 78% or more of the 14C present in glucose, arabinose and xylose constituents of the root-soil mixture occurred in the coarse and fine sand fractions, which also included root material. For mannose and galactose the value was 70% and for rhamnose, 50%. After reinoculation of the soil-root mixture and decomposition for 56 weeks, the water soluble material obtained on fractionation of the soil decreased to less than 1% of the total activity. A much greater proportion, 25%, was present in the clay fraction as a result of decomposition.
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    URL: http://dx.doi.org/10.1007/BF00013103
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    Organic matter contributed to soil by plant roots during the growth and decomposition of maize (1990)
    Springer
    Plant and soil 122 (1990), S. 107-114 
    Details
    ISSN: 1573-5036
    Keywords: aseptic ; 14C-labelled ; carbohydrate ; decomposition ; root exudate ; maize ; monosaccharides ; root lysate ; sandy loam sonication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize (Zea mays var. Caldera) plants were grown under sterile and not sterile conditions in soil in an atmosphere continuously enriched with14CO2 for 36 days. At harvest the above ground parts of the maize were cut off and the roots were separated from the soil by washing with water. The soil was dispersed using ultrasonics and separated into soluble clay silt and sand fraction. Roots were included in the coarse sand fraction. 25% of the total label present in the soil ≡ 5.5% of that in the soil-plant system, was water soluble. Very little label was present in the clay and silt fractions (5% in each) and most (65%) was in the sand fraction as root material. Rapid extraction of soil after the removal of roots without ultrasonic treatment released soluble matter which amounted to 〈0.5% of the total activity in the soil-plant system. Isolated roots steeped in water released about 18% of their activity. Much of the soluble fraction may therefore be root lysate. The soil and roots accounted for 22% of the total activity in the soil-plant system. Glucose accounted for 89% of the sugars in the soluble fraction of the soil. 78% or more of the14C present in glucose, arabinose and xylose constituents of the root-soil mixture occurred in the coarse and fine sand fractions, which also included root material. For mannose and galactose the value was 70% and for rhamnose, 50%. After reinoculation of the soil-root mixture and decomposition for 56 weeks, the water soluble material obtained on fractionation of the soil decreased to less than 1% of the total activity. A much greater proportion, 25%, was present in the clay fraction as a result of decomposition.
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    URL: http://dx.doi.org/10.1007/BF02444110
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    Penetrometer resistance, root penetration resistance and root elongation rate in two sandy loam soils (1991)
    Springer
    Plant and soil 131 (1991), S. 59-66 
    Details
    ISSN: 1573-5036
    Keywords: maize ; mechanical stress ; penetrometer ; root growth ; sandy loam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Root penetration resistance and elongation of maize seedling roots were measured directly in undisturbed cores of two sandy loam soils. Root elongation rate was negatively correlated with root penetration resistance, and was reduced to about 50 to 60% of that of unimpeded controls by a resistance of between 0.26 and 0.47 MPa. Resistance to a 30° semiangle, 1 mm diameter penetrometer was between about 4.5 and 7.5 times greater than the measured root penetration resistance. However, resistance to a 5° semiangle, 1 mm diameter probe was approximately the same as the resistnace to root penetration after subtracting the frictional component of resistance. The diameter of roots grown in the undisturbed cores was greater than that of roots grown in loose soil, probably as a direct result of the larger mechanical impedance in the cores.
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    Screening legume green manures as nitrogen sources to succeeding non-legume crops (1990)
    Springer
    Plant and soil 128 (1990), S. 275-282 
    Details
    ISSN: 1573-5036
    Keywords: buried bag incubation ; leguminous green manures ; maize ; N mineralization ; N supplying potential ; N uptake ; Oxisol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A buried bag incubation technique was proposed to monitor N release from soil and decomposing green manure. The technique would facilitate not only the screening of legumes as sources of N but also measurement of the N supplying capacity of soils. Several tropical legumes were incorporated into field plots followed either by maize (Zea mays L.) or by bare fallow. Soil samples from the plow layer containing the incorporated green manure were placed in low density polyethylene bags and buried within the plow layer under the maize crop for in situ incubation. Periodic withdrawal of the bags was accompanied by fallow soil profile sampling. Above ground N accumulation by maize was equally well correlated to N release measured by either method although the bag technique required much less labor. Supplemental experiments suggested that N accumulation in the bags was reduced due to inadequate O2 diffusion but only when O2 demand was high and soil water potential was high. The results show that in situ bag incubation alone or together with fallow soil sampling can be used to estimate the N supplying potential of soil and leguminous residues.
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    URL: http://dx.doi.org/10.1007/BF00011119
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    Mobilization of cadmium and other metals from two soils by root exudates of Zea mays L., Nicotiana tabacum L. and Nicotiana rustica L. (1991)
    Springer
    Plant and soil 132 (1991), S. 187-196 
    Details
    ISSN: 1573-5036
    Keywords: cadmium ; copper ; extraction method ; iron ; maize ; manganese ; nickel ; root exudate ; tobacco ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soluble root exudates were collected from three plants (Nicotiana tabacum L., Nicotiana rustica L. and Zea mays L.), grown under axenic and hydroponic conditions, in order to study their metal-solubilizing ability for Cd and other cations (Cu, Fe, Mn, Ni, Zn). Nicotiana spp. and Zea mays L. root exudates differed markedly in C/N ratio, sugars vs. amino acids ratio and organic acids content. Metals from two soils were extracted with either root exudate solutions, containing equal amounts of organic carbon, or distilled water as control. In the presence or absence of root exudates, the solubility of Fe and Mn was much higher than of the four other metals tested. Root exudates increased the solubilities of Mn and Cu, whereas those of Ni and Zn were not affected. Root exudates of Nicotiana spp. enhanced the solubility of Cd. The extent of Cd extraction by root exudates (N. tabacum L. N. rustica L. Zea mays L.) was similar to the order of Cd bioavailability to these three plants when grown on soil. An increase in Cd solubility in the rhizosphere of apical root zones due to root exudates is likely to be an important cause of the relatively high Cd accumulation in Nicotiana spp.
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    Old tree root channels in acid soils in the humid tropics: Important for crop root penetration, water infiltration and nitrogen management (1991)
    Springer
    Plant and soil 134 (1991), S. 37-44 
    Details
    ISSN: 1573-5036
    Keywords: cassava ; Guelph permeameter ; leaching ; maize ; methylene blue ; rice ; rooting depth ; soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Under high rainfall conditions on acid soils with shallow crop root systems the rate of N leaching is high. A simple model predicts nitrogen uptake efficiency as a function of the amount of rainfall in excess of evapotranspiration, rooting depth and degree to which N leaching is retarded in comparison with water transport. Field observations on acid soils in S.E. Nigeria and S. Sumatera (Indonesia) showed that this model should be amended to include the role of old tree root channels. Crop roots can follow these channels, which are coated with partly decayed organic matter, into the acid subsoil. Measurements of water infiltration with a Guelph permeameter and a methylene blue dye showed that such channels form the major infiltration sites during rainstorms. Implications for nitrogen use efficiency and cropping pattern are discussed.
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    URL: http://dx.doi.org/10.1007/BF00010715
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    Indexes of assessing N availability in sewage sludges (1992)
    Springer
    Plant and soil 139 (1992), S. 15-21 
    Details
    ISSN: 1573-5036
    Keywords: incubation ; maize ; N availability indexes ; N mineralization ; N uptake ; sewage sludges
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Biological and chemical methods were used in an attempt to estimate N availability in sewage sludges. The two biological methods, i.e. maize plants grown in pots, and soil-sludge mixtures incubated at 2, 4, 6, 8, 12 and 16 weeks, and the four chemical methods, i.e. autoclave, 0.5 M KMnO4, pepsin and 0.6 M HCl, were compared to determine N availability in twelve sewage sludges in a given soil. In the mineralization test, the aerobically treated sewage sludges gave higher mineralization rates than the anaerobically treated wastes. The simple correlation between available N, estimated from the plant N uptake during 6 weeks and N extracted by chemical methods showed that HCl and pepsin appeared to be the better single indexes. Prediction of availability of N in sewage sludges to plants in the growth chamber improved if N mineralized during the incubation period and extracted by several chemical methods were combined in a multiple regression analysis.
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    URL: http://dx.doi.org/10.1007/BF00012837
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    Phosphorus availability under alley cropping and mulched and unmulched sole cropping systems in Costa Rica (1991)
    Springer
    Plant and soil 137 (1991), S. 275-283 
    Details
    ISSN: 1573-5036
    Keywords: alley cropping ; beans ; Erythrina ; Gliricidia ; humid tropics ; isotopically exchangeable P ; maize ; mulching ; phosphorus cycle ; P desorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus availability was measured in soils under five cropping systems: alley cropping with Erythrina poeppigiana, alley cropping with Gliricidia sepium, sole cropping with Erythrina poeppigiana mulch applied, sole cropping with Gliricidia sepium mulch applied, sole cropping with no mulch. The following parameters were measured: 1) plant-available soil P assessed by P uptake of maize and bean bioassay plants; 2) phosphate desorbable by anion exchange resin; 3) adsorption of added P into isotopically exchangeable and non-exchangeable pools. In the bioassay, P uptake of beans declined in the order: mulched sole-cropped〉unmulched sole-cropped〉alley-cropped soils. For maize the relative uptake was: mulched sole-cropped〉unmulched sole-cropped = alley-cropped soils. These results suggest trees had not incorporated a significant quantity of P into the system after seven years and, probably, there was a decrease in available soil P due to the sequestration of P in the tree biomass. Potentially resin-desorbable P was higher in alley-cropped and mulched sole-cropped soils than in unmulched sole-cropped soils. The adsorption and desorption of added P into and from exchangeable and non-exchangeable pools did not differ between alley-cropped and unmulched sole-cropped soils. Crop yield and crop N, P and K uptake were all higher in the alley crops than in the unmulched sole crop. The supply of P to the crop under alley cropping seems to be dependent on P cycled and released from the mulch. The P cycle in alley cropping appears to be self-sustaining at least under conditions of moderate P fertiliser input.
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    A statistical analysis of the influence of Striga hermonthica on maize yields in fertilizer trials in Southwestern Kenya (1991)
    Springer
    Plant and soil 138 (1991), S. 1-8 
    Details
    ISSN: 1573-5036
    Keywords: fertilizer trials ; Kenya ; maize ; Striga hermonthica ; sunflower
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The adverse effect of the parasitic weed Striga hermonthica on yield of maize was studied in a fertilizer trial in Southwestern Kenya. In two years of experimentation (1987 and 1988), the weed had a highly significant, negative impact on maize yields. The spotty incidence of Striga disturbed the fertilizer trials. Inclusion of the degree of Striga infestation in a regression model caused an increase in the fraction of experimental variation that could be explained by the model. Several methods were tested to combat Striga. Hand-pulling reduced Striga incidence and increased grain yields during the following growing season. No clear effect was obtained from the trap crop sunflower, although such an effect may have been concealed by the success of hand-pulling. Application of mineral fertilizers or farmyard manure did not significantly reduce Striga infestation.
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    URL: http://dx.doi.org/10.1007/BF00011801
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    Root-microbial effects on plant iron uptake from siderophores and phytosiderophores (1992)
    Springer
    Plant and soil 142 (1992), S. 1-7 
    Details
    ISSN: 1573-5036
    Keywords: chelate ; iron ; maize ; nutrition ; oat ; phytosiderophores ; siderophores ; trace metal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Collaborative experiments were conducted to determine whether microbial populations associated with plant roots may artifactually affect the rates of Fe uptake and translocation from microbial siderophores and phytosiderophores. Results showed nonaxenic maize to have 2 to 34-fold higher Fe-uptake rates than axenically grown plants when supplied with 1 μM Fe as either the microbial siderophore, ferrioxamine B (FOB), or the barley phytosiderophore, epi-hydroxymugineic acid (HMA). In experiments with nonsterile plants, inoculation of maize or oat seedlings with soil microorganisms and amendment of the hydroponic nutrient solutions with sucrose resulted in an 8-fold increase in FOB-mediated Fe-uptake rates by Fe-stressed maize and a 150-fold increase in FOB iron uptake rates by Fe-stressed oat, but had no effect on iron uptake by Fe-sufficient plants. Conversely, Fe-stressed maize and oat plants supplied with HMA showed decreased uptake and translocation in response to microbial inoculation and sucrose amendment. The ability of root-associated microorganisms to affect Fe-uptake rates from siderophores and phytosiderophores, even in short-term uptake experiments, indicates that microorganisms can be an unpredictable confounding factor in experiments examining mechanisms for utilization of microbial siderophores or phytosiderophores under nonsterile conditions.
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    URL: http://dx.doi.org/10.1007/BF00010169
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    Rapid methods for quantifying VAM fungal infections in maize roots (1992)
    Springer
    Plant and soil 147 (1992), S. 317-319 
    Details
    ISSN: 1573-5036
    Keywords: bioassay ; maize ; root pigmentation ; vesicular arbuscular mycorrhiza
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Roots of maize (Zea mays cv W64A × W182E) infected by vesicular arbuscular mycorrhizal (VAM) fungi (Glomus versiforme (Karst) Berch or a Glomus species isolated from an alfalfa soil) exhibit a bright yellow pigmentation. The percentage of pigmented roots can be quantified by a rapid visual estimate or by a grid intersect method. Both methods gave similar estimates of VAM infection to those obtained using a grid intersect count on cleared roots stained with chlorazol black E. Thus for experimental or field evaluation where speed and quantity are important, the rapid visual estimate (less than one minute for each washed root system) yields reliable results. The yellow root intersect method takes longer (5–15 minutes per root system) but gives more reproducible results. The yellow root pigmentation is light sensitive However, root systems can be reliably assayed after 1 week when stored at 5°C in the dark or after 1 year if dried.
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    Nutrient fluxes in the shifting cultivation system of south-west Côte d'Ivoire (1993)
    Springer
    Plant and soil 154 (1993), S. 179-188 
    Details
    ISSN: 1573-5036
    Keywords: ash ; burning ; Côte d'Ivoire ; efficiency of utilization of nutrients ; maize ; nutrient uptake ; residual effects ; shifting cultivation ; Taï National Park ; upland rice ; weed growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract At two sites, one with a 4-year-old (4-Y) secondary vegetation and the other with a 20-year-old (20-Y) vegetation, the influence of burning slashed vegetation on crop performance was studied during three seasons. In the first season after clearing, also the influence on weed growth was studied. At both sites, burning significantly decreased the number of weed seedlings. The lowest number of seedlings was found on the burnt plots of the 20-Y site. Burning increased yield and nutrient uptake significantly in the first and second season after clearing. In the third season after burning, only at the 4-Y site a significantly higher yield and nutrient uptake were found. At the 20-Y site the effect had disappeared. Calculations of efficiency of utilization of absorbed N, P and K indicated that P was the least available nutrient, also after burning. At both sites three consecutive crops absorbed approximately 40% of P applied in ash, while the cumulative recovery of K was at least 36% at the 4-Y site and at least 59% at the 20-Y site. On non-burnt plots, yields were not lower in the third season than in the first season after clearing, thus indicating that the inherent soil fertility did not decrease. Hence, yield decline on the burnt plots could be ascribed to ash depletion. It was concluded that in the local shifting cultivation system, the combination of ash depletion and infestation of weeds are the main reasons for abandoning the fields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00012523
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  • 98
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    Variability in nitrogen fixation of common bean (Phaseolus vulgaris L.) intercropped with maize (1993)
    Springer
    Plant and soil 152 (1993), S. 93-101 
    Details
    ISSN: 1573-5036
    Keywords: common bean ; maize ; intercropping ; nitrogen fixation ; 15N isotope ; 15N natural variation ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Thirty one selected bean lines were evaluated in the field for ability to support N2 fixation when intercropped with maize which received 0, 30 and 60 kg N ha−1 as ammonium sulphate. The amount of fixed N2 was estimated using the natural variation of 15N and wheat as the standard non-fixing crop. Nitrogen as low as 15 kg N ha−1 at sowing suppressed nodule weight and activity (acetylene reduction activity) but not nodule number, suggesting that the main effect of mineral N was on nodule development and function. 15N data revealed a high potential of the bean genotypes to fix N2, with the most promising ones averaging between 50–60% of seed N coming from fixation. Bean lines CNF-480, Puebla-152, Mexico-309, Negro Argel, CNF-178, Venezuela-350 and WBR22-3, WBR22-50 and WBR22-55 were ranked as good fixers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00016337
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  • 99
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    Electronic Resource
    Nuclear magnetic resonance studies of the location and function of plant nutrients in vivo (1993)
    Springer
    Plant and soil 155-156 (1993), S. 45-55 
    Details
    ISSN: 1573-5036
    Keywords: compartmentation ; cytoplasm ; 39K NMR ; maize ; nitrogen ; 14N NMR ; 15N NMR ; pea ; phosphorus ; potassium ; 31P NMR ; vacuole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The cytoplasmic and vacuolar pools of ammonium, inorganic phosphate and potassium can be studied non-invasively in plant tissues using high resolution nuclear magnetic resonance spectroscopy. The techniques that allow these pools to be discriminated in vivo are described and their application to plants is reviewed with reference to the phosphorus, nitrogen and potassium nutrition of root tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024983
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  • 100
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    Electronic Resource
    Differences between maize and wheat in growth-related nutrient demand and uptake of potassium and phosphorus at suboptimal root zone temperatures (1993)
    Springer
    Plant and soil 150 (1993), S. 129-138 
    Details
    ISSN: 1573-5036
    Keywords: adaptation ; maize ; nutrient uptake ; root growth ; root temperature ; shoot base temperature ; shoot growth ; shoot demand per unit of roots ; spring wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of low root zone temperatures (RZT) on nutrient demand for growth and the capacity for nutrient acquisition were compared in maize and wheat growing in nutrient solution. To differentiate between direct temperature effects on nutrient uptake and indirect effects via an altered ratio of shoot to root growth, the plants were grown with their shoot base including apical shoot meristem either within the root zone (low SB), i.e. at RZT (12°, 16°, or 20°C) or, above the root zone (high SB), i.e. at uniformly high air temperature (20°/16° day/night). At low SB, suboptimal RZT reduced shoot growth more than root growth in wheat, whereas the opposite was true in maize. However, in both species the shoot growth rate per unit weight of roots, which was taken as parameter for the shoot demand for mineral nutrients per unit of roots, decreased at low RZT. Accordingly, the concentrations of potassium (K) and phosphorus (P) remained constant or even increased at low RZT despite reduced uptake rates. At high SB, shoot growth at low RZT in both species was higher than at low SB, whereas root growth was not increased. At high SB, the shoot demand per unit of roots was similar for all RZT in wheat, but increased with decreasing RZT in maize. Uptake rates of K at high SB and low RZT adapted to shoot demand within four days, and were even higher in maize than in wheat. Uptake rates of P adapted more slowly to shoot demand in both species, resulting in reduced concentrations of P in the shoot, particularly in maize. In conclusion, the two species did not markedly differ in their physiological capacity for uptake of K and P at low RZT. However, maize had a lower ability than wheat to adapt morphologically to suboptimal RZT by increasing biomass allocation towards the roots. This may cause a greater susceptibility of maize to nutrient deficiency, particularly if the temperatures around the shoot base are high and uptake is limited by nutrient transport processes in the soil towards the roots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00779183
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