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  • maize  (98)
  • Springer  (98)
  • American Chemical Society
  • Annual Reviews
  • 2005-2009
  • 1990-1994  (98)
  • 1980-1984
  • 1950-1954
  • 2009
  • 1993  (48)
  • 1992  (50)
Collection
Keywords
Publisher
Years
  • 2005-2009
  • 1990-1994  (98)
  • 1980-1984
  • 1950-1954
Year
  • 1
    Electronic Resource
    Electronic Resource
    Production ofNosema marucae for biological control of cereal stem borers (1993)
    Springer
    Entomologia experimentalis et applicata 67 (1993), S. 143-148 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02386519
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  • 2
    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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  • 3
    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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  • 4
    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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  • 5
    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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  • 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
    Foliar urea fertilization of cereals: A review (1992)
    Springer
    Nutrient cycling in agroecosystems 32 (1992), S. 209-222 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01048783
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of nitrification inhibitors and time and rate of slurry and fertilizer N application on silage maize yield and losses to the environment (1993)
    Springer
    Nutrient cycling in agroecosystems 34 (1993), S. 267-277 
    Details
    ISSN: 1573-0867
    Keywords: animal manure ; leaching ; maize ; nitrification inhibitor ; nitrogen recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Field experiments with silage maize during eight years on a sandy soil in The Netherlands, showed that dicyandiamide (DCD) addition to autumn-applied cattle slurry retarded nitrification, thus reducing nitrate losses during winter. Spring-applied slurry without DCD, however, was on average associated with even lower losses and higher maize dry matter yields. Economically optimum supplies of mineral N in the upper 0.6 m soil layer in spring (EOSMN), amounted to 130–220 kg ha−1. Year to year variation of EOSMN could not be attributed to crop demand only. According to balance sheet calculations on control plots, apparent N mineralization between years varied from 0.36 to 0.94 kg ha−1 d−1. On average, forty percent of the soil mineral N (SMN) supply in spring, was lost during the growing season. Hence, the amounts of residual soil mineral N (RSMN) were lower than expected. Multiple regression with SMN in spring, N crop uptake and cumulative rainfall as explanatory variables, could account for 79 percent of the variation in RSMN. Postponement of slurry applications to spring and limiting N inputs to economically optimum rates, were insufficient measures to keep the nitrate concentration in groundwater below the EC level for drinking water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750573
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  • 9
    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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  • 10
    Electronic Resource
    Electronic Resource
    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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00705243
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  • 11
    Electronic Resource
    Electronic Resource
    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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  • 12
    Electronic Resource
    Electronic Resource
    Construction and characterisation of a yeast artificial chromosome library containing three haploid maize genome equivalents (1992)
    Springer
    Plant molecular biology 19 (1992), S. 299-308 
    Details
    ISSN: 1573-5028
    Keywords: cloning in YACs ; genome mapping ; maize ; PCR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have constructed a yeast artificial chromosome (YAC) library using high-molecular-weight DNA prepared from agarose-embedded leaf protoplasts of the maize inbred line UE95. This library contains 79 000 clones with an average insert size of 145 kb and should therefore represent approximately three haploid genome equivalents. The library is organised as an ordered array in duplicate microtitre plates. Forty-one pools of DNA from 1920 individual clones have been prepared for rapid screening of the library by the polymerase chain reaction (PCR). Using this approach, together with conventional colony hybridisation, we have been able to identify between one and eight positive clones for every probe used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027351
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  • 13
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00026781
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  • 14
    Electronic Resource
    Electronic Resource
    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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  • 15
    Electronic Resource
    Electronic Resource
    The heat shock response of pollen and other tissues of maize (1992)
    Springer
    Plant molecular biology 19 (1992), S. 623-630 
    Details
    ISSN: 1573-5028
    Keywords: gene expression ; heat shock ; intron ; maize ; pollen ; RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract While a heat shock treatment of 40 °C or 45 °C induced the vegetative tissues of maize to produce the typical heat shock proteins (HSPs), germinating maize pollen exposed to the same temperatures did not synthesize these characteristic HSPs. Comparison of RNA accumulation in shoot and tassel tissue showed that mRNAs for HSP70 and HSP18 increased several-fold, reaching high levels within 1 or 2 hours. At the higher temperature of 45 °C these vegetative tissues were blocked in removal of an intron from the HSP70 mRNA precursor, which accumulated to a high level in tassel tissue. In germinating pollen exposed to heat shock, mRNAs for these HSPs were induced but accumulated only to low levels. The stressed pollen maintained high levels of RNA for α-tubulin, a representative normal transcript. It is likely that the defective heat shock response of maize pollen is due to inefficient induction of heat shock gene transcription.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00026788
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  • 16
    Electronic Resource
    Electronic Resource
    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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  • 17
    Electronic Resource
    Electronic Resource
    Nucleotide sequence and expression of two cDNA coding for two histone H2B variants of maize (1992)
    Springer
    Plant molecular biology 20 (1992), S. 581-588 
    Details
    ISSN: 1573-5028
    Keywords: histone variants ; cDNA ; expression ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The complete amino acid sequences of two variants of histone H2B of maize were deduced from the cDNAs isolated from a maize cDNA library. The two encoded proteins are 150 (H2B(1)) and 149 (H2B(2)) amino acids long and shows the classical organization of H2B histones. The hydrophobic C-terminal region is highly conserved as compared to that of the animal counterparts with only 21 changes (13 conservative) among the 90 residues. Between the N-terminal part and the C-terminal region we note the presence of a basic cluster (9 residues) characteristic of histones H2B. The N-terminal third is extended as compared to the animal consensus H2B and has the same size as the H2B histone of wheat. Up to 9 acidic residues and a five time repeated pentapeptide PA/KXE/KK are present in this region. Southern-blot hybrization showed that the H2B histones are encoded by a multigenic family like the other core histones (H3 and H4) of plants. The general expression pattern of these genes was not significantly different from that of the H3 and H4 genes neither in germinating seeds nor in different tissues of adult maize.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00046443
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  • 18
    Electronic Resource
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    Structure and expression of the lignin O-methyltransferase gene from Zea mays L. (1992)
    Springer
    Plant molecular biology 20 (1992), S. 857-867 
    Details
    ISSN: 1573-5028
    Keywords: cDNA ; differential screening ; genomic cloning ; lignin ; maize ; O-methyltransferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The isolation and characterization of cDNA and homologous genomic clones encoding the lignin O-methyltransferase (OMT) from maize is reported. The cDNA clone has been isolated by differential screening of maize root cDNA library. Southern analysis indicates that a single gene codes for this protein. The genomic sequence contains a single 916 bp intron. The deduced protein sequence from DNA shares significant homology with the recently reported lignin-bispecific caffeic acid/5-hydroxyferulic OMTs from alfalfa and aspen. It also shares homology with OMTs from bovine pineal glands and a purple non-sulfur photosynthetic bacterium. The mRNA of this gene is present at different levels in distinct organs of the plant with the highest accumulation detected in the elongation zone of roots. Bacterial extracts from clones containing the maize OMT cDNA show an activity in methylation of caffeic acid to ferulic acid comparable to that existing in the plant extracts. These results indicate that the described gene encodes the caffeic acid 3-O-methyltransferase (COMT) involved in the lignin biosynthesis of maize.
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    URL: http://dx.doi.org/10.1007/BF00027157
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    Effects of gene dosage and sequence modification on the frequency and timing of transposition of the maize element Activator (Ac) in tobacco (1993)
    Springer
    Plant molecular biology 21 (1993), S. 157-170 
    Details
    ISSN: 1573-5028
    Keywords: transposable element ; Activator ; gene dosage ; maize ; tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of Ac copy number on the frequency and timing of germinal transposition in tobacco was investigated using the streptomycin phosphotransferase gene (SPT) as an excision marker. The activity of one and two copies of the element was compared by selecting heterozygous and homozygous progeny of transformants carrying single SPT::Ac inserts. It was observed that increasing gene copy not only increases the transposition frequency, but also occasionally alters the timing of transposition such that earlier events are obtained. The result is that some homozygous plants generate multiple streptomycin resistant progeny carrying the same transposed Ac (trAc) element. We have also investigated the effect of modification of the sequence in the region around 82 bp downstream of the polyadenylation site and 177 bp from the 3′ end of the element on germinal excision frequencies. Alteration of three bases to create a BglII site at this location caused a minor decrease in germinal excision events, but insertion of four bases to create a Cla I site caused a 10-fold decrease in the transposition activity of the Ac element.
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    URL: http://dx.doi.org/10.1007/BF00039626
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    The cis-regulatory element CCACGTGG is involved in ABA and water-stress responses of the maize gene rab28 (1993)
    Springer
    Plant molecular biology 21 (1993), S. 259-266 
    Details
    ISSN: 1573-5028
    Keywords: ABA-responsive element ; maize ; tissue-specific factors ; rab genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The maize gene rab28 has been identified as ABA-inducible in embryos and vegetative tissues. It is also induced by water stress in young leaves. The proximal promoter region contains the conserved cis-acting element CCACGTGG (ABRE) reported for ABA induction in other plant genes. Transient expression assays in rice protoplasts indicate that a 134 bp fragment (-194 to -60 containing the ABRE) fused to a truncated cauliflower mosaic virus promoter (35S) is sufficient to confer ABA-responsiveness upon the GUS reporter gene. Gel retardation experiments indicate that nuclear proteins from tissues in which the rab28 gene is expressed can interact specifically with this 134 bp DNA fragment. Nuclear protein extracts from embryo and water-stressed leaves generate specific complexes of different electrophoretic mobility which are stable in the presence of detergent and high salt. However, by DMS footprinting the same guanine-specific contacts with the ABRE in both the embryo and leaf binding activities were detected. These results indicate that the rab28 promoter sequence CCACGTGG is a functional ABA-responsive element, and suggest that distinct regulatory factors with apparent similar affinity for the ABRE sequence may be involved in the hormone action during embryo development and in vegetative tissues subjected to osmotic stress.
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    URL: http://dx.doi.org/10.1007/BF00019942
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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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    URL: http://dx.doi.org/10.1007/BF00553752
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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/BF00554076
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  • 23
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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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    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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    URL: http://dx.doi.org/10.1007/BF02396214
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    Transformation and inheritance of a hygromycin phosphotransferase gene in maize plants (1992)
    Springer
    Plant molecular biology 18 (1992), S. 189-200 
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    ISSN: 1573-5028
    Keywords: hygromycin ; inheritance ; maize ; tissue culture ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Embryogenic maize (Zea mays L.) callus cultures were transformed by microprojectile bombardment with a chimeric hygromycin phosphotransferase (HPT) gene and three transformed lines were obtained by selecting for hygromycin resistance. All lines contained one or a few copies of the intact HPT coding sequence. Fertile, transgenic plants were regenerated and the transmission of the chimeric gene was demonstrated through two complete generations. One line inherited the gene in the manner expected for a single, dominant locus, whereas two did not.
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    URL: http://dx.doi.org/10.1007/BF00034948
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    Segregation of transgenes in maize (1992)
    Springer
    Plant molecular biology 18 (1992), S. 201-210 
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    ISSN: 1573-5028
    Keywords: maize ; transformation ; inheritance ; phosphinothricin acetyltransferase ; cotransformation ; microprojectile bombardment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Progeny recovered from backcrossed transgenic maize tissue culture regenerants (R0) were analyzed to determine the segregation, expression, and stability of the introduced genes. Transgenic A188×B73 R0 plants (regenerated from embryogenic suspension culture cells transformed by microprojectile bombardment; see [9]) were pollinated with nontransformed B73 pollen. Inheritance of a selectable marker gene, bar, and a nonselectable marker gene, uidA, was analyzed in progeny (R1) representing four independent transformation events. Activity of the bar gene product, phosphinothricin acetyltransferase (PAT), was assessed in plants comprising the four R1 populations. The number of R1 plants containing PAT activity per total number of R1 plants recovered for each population was 2/7, 19/34, 3/14 and 73/73. Molecular analysis confirmed the segregation of bar in three R1 populations and the lack of segregation in one R1 population. Cosegregation analysis indicated genetic linkage of bar and uidA in all four R1 populations. Analysis of numerous R2 plants derived from crossing transformed R1 plants with nontransformed inbreds revealed 1:1 segregation of PAT activity in three of four lines, including the line that failed to segregate in the R1 generation. Integrated copies of bar in one line appeared to be unstable or poorly transmitted.
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    URL: http://dx.doi.org/10.1007/BF00034949
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    Nucleotide sequence of a cDNA clone that encodes the maize inhibitor of trypsin and activated Hageman factor (1992)
    Springer
    Plant molecular biology 18 (1992), S. 813-814 
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    ISSN: 1573-5028
    Keywords: maize ; protease inhibitor ; trypsin ; activated Hageman factor ; cDNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1007/BF00020026
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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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    Molecular basis for extensin size heterogeneity in two maize varieties (1993)
    Springer
    Plant molecular biology 21 (1993), S. 885-893 
    Details
    ISSN: 1573-5028
    Keywords: cell wall ; deglycosylation ; extensin ; hydroxyproline-rich ; immunoprecipitation ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study concerned the molecular basis for the protein size heterogeneity of extensin from two maize (Zea mays L.) varieties. We studied the physical properties of extensin, a hydroxyproline-rich glycoprotein (HRGP), from the silk and pericarp of Golden X Bantam (GXB) sweet corn and Japanese Hulless (JHL) popcorn. Extensin from GXB has a molecular mass of 66 kDa whereas extensins from JHL have molecular masses of 76 and 66 kDa. Treatment with anhydrous hydrogen fluoride to deglycosylate proteins reduced the size of all extensins by 5 kDa. Probing with a 500 bp fragment from a genomic clone of maize extensin identified two transcripts (1.9 and 1.5 kb) on northern blots. JHL contained both transcripts and GXB contained only the 1.5 kb transcript. The probe also hybridized to two larger transcripts (6.2 and 4.5 kb) that were found in both varieties. We immunoprecipitated two proteins (66 and 56 kDa) from translated RNA isolated from JHL and one protein (56 kDa) from GXB. These results demonstrate that these extensins differ in the size of their peptide moiety and not in their extent of glycosylation.
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    URL: http://dx.doi.org/10.1007/BF00027119
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    Isolation of a gene from maize encoding a chlorophyll a/b-binding protein (1992)
    Springer
    Plant molecular biology 19 (1992), S. 533-536 
    Details
    ISSN: 1573-5028
    Keywords: chlorophyll a/b-binding protein ; CAB gene ; nucleotide sequence ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023407
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    WIP1, a wound-inducible gene from maize with homology to Bowman-Birk proteinase inhibitors (1993)
    Springer
    Plant molecular biology 22 (1993), S. 783-792 
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    ISSN: 1573-5028
    Keywords: proteinase inhibitor ; wound induction ; wound-induced gene ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have cloned and sequenced a wound-inducible cDNA clone designated WIP1 (for wound-induced protein) from maize coleoptiles. It was isolated by differential screening of a cDNA library prepared from excised maize coleoptile segments. The deduced amino acid sequence predicts a secretory, cysteine-rich protein of 102 residues with a calculated molecular mass of 11 kDa and a typical N-terminal signal sequence. The protein has about 30% identity with various Bowman-Birk type proteinase inhibitors. Most interestingly, it is novel in that it is double-headed with exclusive specificity for chymotrypsin. WIP1 is strongly wound-induced in contrast to other members of the Bowman-Birk proteinase inhibitor family, which occur in seeds and are regulated during development. The response is fast, similar to defenceinduced genes, and measurable as early as 30 min after wounding. Induction can also be evoked in the intact coleoptiles and the signal is systemically transmitted in the coleoptile to adjacent regions of the wounded area. Isolation and analysis of the corresponding genomic clone reveals that WIP1 contains an intron of 90 nucleotides.
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    URL: http://dx.doi.org/10.1007/BF00027365
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    Maize polyubiquitin genes: structure, thermal perturbation of expression and transcript splicing, and promoter activity following transfer to protoplasts by electroporation (1992)
    Springer
    Plant molecular biology 18 (1992), S. 675-689 
    Details
    ISSN: 1573-5028
    Keywords: electroporation ; heat shock ; maize ; promoter ; splicing ; ubiquitin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two genomic clones (λUbi-1 and λUbi-2) encoding the highly conserved 76 amino acid protein ubiquitin have been isolated from maize. Sequence analysis shows that both genes contain seven contiguous direct repeats of the protein coding region in a polyprotein conformation. The deduced amino acid sequence of all 14 repeats is identical and is the same as for other plant ubiquitins. The use of transcript-specific oligonucleotide probes shows that Ubi-1 and Ubi-2 are expressed constitutively at 25°C but are inducible to higher levels at elevated temperatures in maize seedlings. Both genes contain an intron in the 5′ untranslated region which is inefficiently processed following a brief, severe heat shock. The transcription start site of Ubi-1 has been determined and a transcriptional fusion of 0.9 kb of the 5′ flanking region and the entire 5′ untranslated sequence of Ubi-1 with the coding sequence of the gene encoding the reporter molecule chloramphenicol acetyl transferase (CAT) has been constructed (pUBI-CAT). CAT assays of extracts of protoplasts electroporated with this construct show that the ubiquitin gene fragment confers a high level of CAT expression in maize and other monocot protoplasts but not in protoplasts of the dicot tobacco. Expression from the Ubi-1 promoter of pUBI-CAT yields more than a 10-fold higher level of CAT activity in maize protoplasts than expression from the widely used cauliflower mosaic virus 35S promoter of a 35S-CAT construct. Conversely, in tobacco protoplasts CAT activity from transcription of pUBI-CAT is less than one tenth of the level from p35S-CAT.
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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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    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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    Identification and characterization of a hypoxically induced maize lactate dehydrogenase gene (1992)
    Springer
    Plant molecular biology 19 (1992), S. 693-697 
    Details
    ISSN: 1573-5028
    Keywords: maize ; hypoxia ; lactate dehydrogenase ; anaerobic regulatory element
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In cereal root tissue, hypoxia induces the enzyme lactate dehydrogenase (LDH); (S)-lactate:NADH oxidoreductase, EC 1.1.1.27). In barley, both biochemical and genetic data indicate that five isozymes are induced under hypoxia. These isozymes are tetramers and arise from the random association of the products of two Ldh genes. The induction of LDH activity in root tissue has been shown to be correlated to an increase in LDH protein and Ldh mRNA. In order to more fully characterize the hypoxic induction of LDH, we have isolated a maize Ldh genemic clone which has strong homology at both the amino acid and nucleotide level to the barley LDH cDNA clones. The Ldh1 gene consists of two exons separated by a 296 bp intron, has the expected eukaryotic regulatory signals and a sequence that has strong homology to the maize anaerobic regulatory element.
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    URL: http://dx.doi.org/10.1007/BF00026795
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    Isolation and characterization of a genomic sequence encoding the maizeCat3 catalase gene (1993)
    Springer
    Plant molecular biology 22 (1993), S. 1031-1038 
    Details
    ISSN: 1573-5028
    Keywords: maize ; catalase ; genomic clone ; sequence ; gene structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A maize genomic DNA library (Zea mays L. W64A) was constructed using the lambda GEM-11 vector. A gene-specificCat3 cDNA probe was used to screen the library by plaque hybridization. Two independent clones, λ24C and gl27C, which hybridized to theCat3 cDNA probe, were isolated. Restriction maps were created for the two clones (λ24C and λ27C) encoding the maizeCat3 catalase gene. ASal I restriction fragment from each clone was subcloned into pBluescript KS+. Subsequent subcloning steps were performed to obtain plasmids suitable for sequencing. Both strands of the λ24C clone were sequenced. Computer analysis of the putativeCat3 promoter region has not revealed any known transcription factor binding motifs. Analysis of the deduced C-terminal amino acids encoded byCat3 shows that CAT-3 lacks the SRL peroxisomal targeting sequence contained in the CAT-1 and CAT-2 isozymes. The DNA sequence and physical structure of theCat3 gene presented here will be used in characterizingcis- andtrans-acting factors affectingCat3 gene expression.
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    URL: http://dx.doi.org/10.1007/BF00028975
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    Isolation of matrices from maize leaf nuclei: identification of a matrix-binding site adjacent to theAdh1 gene (1993)
    Springer
    Plant molecular biology 22 (1993), S. 1135-1143 
    Details
    ISSN: 1573-5028
    Keywords: maize ; Adh1 gene ; nuclear matrix ; MAR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nuclear matrices were isolated from maize leaves by the two conventional methods usually employed for the preparation of the corresponding structures of animal origin. It is demonstrated that functionally competent matrices, recognizing and specifically binding the MAR-containing DNA of the mousek-immunoglobulin gene may be prepared by both 2 M NaCl and LIS extractions of maize nuclei. A DNA region with a high affinity for the nuclear matrix was identified at the 5′ end of the maizeAdh1-S gene, distal to the promoter region. The presence of sites of reported altered chromatin structure in this particular region is discussed. While the proximity and the cohabitation of MARs with different regulatory elements is a common feature of matrix association regions in animal systems, this is the first plant MAR identified in a region of known significance for gene regulation.
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    URL: http://dx.doi.org/10.1007/BF00028982
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    Molecular characterization of maize extensin expression (1993)
    Springer
    Plant molecular biology 23 (1993), S. 685-695 
    Details
    ISSN: 1573-5028
    Keywords: extensin ; gene expression ; hydroxyproline ; maize ; silk ; vegetative tissues
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study concerned the developmental regulation of wall-localized, hydroxyproline-containing proteins in maize tissues and organs. Silk and pericarp cell walls contained more peptidyl hydroxyproline than did walls of any vegetative tissue, although all tissues and organs accumulated these proteins as they matured. In many tissues, hydroxyproline-rich proteins are first associated with the wall in a soluble form before being insolubilized through covalent attachment to the matrix. Because hydroxyproline was more soluble earlier than later in development, it appears that insolubilization was occurring in maize tissues and organs as well. Tissue prints reacted with an anti-extensin antibody gave positive results, indicating the presence of a soluble form of this common hydroxyproline-rich glycoprotein (HRGP). Silk and pericarp cells actively synthesized this extensin from abundant transcripts. In vegetative tissues, extensin transcripts were somewhat more abundant in seedlings than in pre-anthesis or mature plants, but levels were much lower than in silk and pericarp. Southern blots of maize genomic DNA indicated that these extensin transcripts are encoded by a small multigene family. Potential roles for extensin in reproductive/protective tissues versus the embryo or vegetative tissues are suggested.
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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 
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    ISSN: 1573-5028
    Keywords: maize ; microsporogenesis ; pollen ; polygalacturonase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1007/BF00014505
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    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.
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    URL: http://dx.doi.org/10.1007/BF00226531
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    Agrobacterium tumefaciens-mediated expression ofgusA in maize tissues (1993)
    Springer
    Transgenic research 2 (1993), S. 252-265 
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    ISSN: 1573-9368
    Keywords: Agrobacterium tumefaciens ; maize ; GUS ; gusA/intron ; particle bombardment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To develop a system forAgrobacterium-mediated transformation of maize (Zea mays L.), we have investigated histochemically the transient expression of β-glucuronidase (GUS) activity in maize seedling tissue segments using binary vectors that allow minimal (pKIWI105 and pCNL1) or undetectable (p35S-GUS-INT and pCNL56) levels of GUS activity inA. tumefaciens. Tissue segments from three- to five-day-old sterile seedlings of maize genotype A188 were inoculated withA. tumefaciens. Four days after inoculation, transient expression of GUS activity was found in mesocotyl segments originating from the intercalary meristem region. This GUS activity was specific to the vascular cylinder and was not found in the internal cortical or epidermal layers, nor was it found in mature mesocotyl tissue (segments 5 mm below the coleoptilar node). Transient GUS activity was also detected in leaf and coleoptile tissues of shoot segments, but not in the shoot apexper se or in leaves younger than the first leaf. Maize tissues inoculated withA. tumefaciens strains that harbourgusA-containing binary vectors but no Ti-plasmid did not show GUS activity, supporting evidence from previous work thatvir gene activity was essential for the observed GUS activity.A. tumefaciens strains containing different types of Ti-plasmids were also tested. A strain harbouring an agropine-type Ti-plasmid was the most effective for expressing GUS activity in mesocotyl segments, whereas a strain harboring a nopaline-type Ti-plasmid was most effective for expression of GUS activity in the apical meristem-containing segment. These results indicate that different interactions occurred between the differentA. tumefaciens strains and the susceptible plant tissues. Maize genotype specificity for GUS activity in mesocotyl tissues was observed; variations in the cocultivation medium had a profound effect on the frequency of expression of GUS activity.
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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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    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 
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    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.
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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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    Potential errors caused by roots in analyses of rhizosphere soil (1992)
    Springer
    Plant and soil 143 (1992), S. 223-231 
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    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 
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    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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    Rapid methods for quantifying VAM fungal infections in maize roots (1992)
    Springer
    Plant and soil 147 (1992), S. 317-319 
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    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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    Mechanism of sugar retention by roots of intact maize and field bean plants (1993)
    Springer
    Plant and soil 155-156 (1993), S. 99-102 
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    ISSN: 1573-5036
    Keywords: field bean ; maize ; plasmalemma ATPase ; proton motive force ; retrieval mechanism ; root exudates ; sugar/proton cotransport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The re-uptake of sugars driven by the proton gradient was studied in sugar net-release and net-uptake experiments using roots of intact maize (Zea mays cv. Blizzard) and field bean (Vicia faba L. cv. Alfred) plants. The net release of sugars into the root medium (0.1 mM CaSO4) was stimulated by: the protonophore CCCP (10 μM); the sulfhydryl reagent NEM (300 μM); the specific inhibitor of plasmalemma ATPase vanadate (0.5 mM); and the inhibitor of the glucose carrier phlorizin (2 mM). Net uptake of glucose, fructose and arabinose from 10 μM external concentrations was also inhibited by these substances. Surprisingly fusicoccin, a stimulator of net proton release did not effect net sugar uptake. Medium pH values only influenced sugar net uptake if the pH was above 7. It is concluded that a degradation of the proton gradient across the plasmalemma stimulates net sugar release because of disturbed re-uptake of sugars (in particular glucose) via a proton/sugar cotransport system. Thus, the retention of sugars by root cells not only depends on the plasmalemma permeability but also on the electro-chemical proton gradient. If an electro-chemical proton gradient is established by plasmalemma ATPase activity the re-uptake of sugars by proton/sugar cotransport minimizes the release of sugars into the rhizosphere.
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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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    In-situ determination of the P-relations around the primary root of maize with respect to inorganic and phytate-P (1993)
    Springer
    Plant and soil 157 (1993), S. 1-9 
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    ISSN: 1573-5036
    Keywords: autoradiography ; freeze-cutting ; maize ; P-accumulation ; P-depletion ; phytate-P
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Autoradiographs of soil slices mapping the distribution of phytate-derived33P around the primary root of 6-day-old maize seedlings were used to investigate the uptake of phytate by the root. Analysis of the autoradiographs with a laser densitometer and processing of the data with image analysing software resulted in a resolution of 40 μm. The effect of33P-crossfire was corrected by analysis of the apparent33P-gradient around a phosphate-impermeable teflon tube that was inserted into the labeled soil as a standard. In spite of the high resolution achieved, a significant depletion zone could not be detected when the soil was equilibrated with33P-phytate. However, with33P-inorganic phosphate, 2 concentric zones were obvious. Within the inner zone, P was accumulated by about 20%, while in the outer zone a corresponding depletion of P could be detected. The accumulation zone coincided with the extension of the root hair cylinder, whereas the depleted area was clearly beyond the range of the root hairs.
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    Inhibition of nitrate uptake by aluminium in maize (1993)
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    Plant and soil 151 (1993), S. 97-104 
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    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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    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.
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    In-situ determination of the P-relations around the primary root of maize with respect to inorganic and phytate-P (1993)
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    Plant and soil 157 (1993), S. 1-9 
    Details
    ISSN: 1573-5036
    Keywords: autoradiography ; freeze-cutting ; maize ; P-accumulation ; P-depletion ; phytate-P
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Autoradiographs of soil slices mapping the distribution of phytate-derived 33P around the primary root of 6-day-old maize seedlings were used to investigate the uptake of phytate by the root. Analysis of the autoradiographs with a laser densitometer and processing of the data with image analysing software resulted in a resolution of 40 μm. The effect of 33P-crossfire was corrected by analysis of the apparent 33P-gradient around a phosphate-impermeable teflon tube that was inserted into the labeled soil as a standard. In spite of the high resolution achieved, a significant depletion zone could not be detected when the soil was equilibrated with 33P-phytate. However, with 33P-inorganic phosphate, 2 concentric zones were obvious. Within the inner zone, P was accumulated by about 20%, while in the outer zone a corresponding depletion of P could be detected. The accumulation zone coincided with the extension of the root hair cylinder, whereas the depleted area was clearly beyond the range of the root hairs.
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    Effect of soil water content on the gravitropic behavior of nodal roots in maize (1993)
    Springer
    Plant and soil 152 (1993), S. 261-267 
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    ISSN: 1573-5036
    Keywords: gravitropism ; growth angle ; maize ; nodal roots ; soil water content ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The direction of root growth is an important factor that determines the spatial distribution of roots in the soil. The influence of soil water content on the direction of growth of maize nodal roots was studied both in the field and in the greenhouse. In the field experiment, the one plot was regularly irrigated (I-plot) and the other non-irrigated (N-plot). In the greenhouse experiment, three water treatments were conducted on plants grown in pots: continuously wet (CW), early drying (ED), and late drying (LD). The direction of root growth was quantified by the angle from the vertical, measured at 1 cm intervals for 10 cm from the first five internodes. Nodal roots grew more vertically in the N-plot and ED treatment than those in the I-plot and CW treatment. This was due to the decrease of the initial angle and/or the liminal angle. It is therefore thought that two events regulate the growth direction of nodal roots under dry soil conditions: gravitropic bending at root emergence from the stem and the later establishment of the angle of growth. Nodal roots appearing after rewatering in the ED treatment grew in a similar direction as those in the CW treatment. It follows from this that the water content of the surrounding soil has a direct effect on the direction of growth. Nodal roots that emerged in rapidly drying soil in the LD treatment ceased growing after showing negative gravitropism. The possible mechanisms determining the growth direction of nodal roots in drier soils are discussed.
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    Mulching effect of plant residues with chemically contrasting compositions on maize growth and nutrients accumulation (1993)
    Springer
    Plant and soil 153 (1993), S. 179-187 
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    ISSN: 1573-5036
    Keywords: alfisols ; maize ; mulch quality ; nutrient uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effects of application of prunings of three woody species (Acioa barteri, Gliricidia sepium and Leucaena leucocephala), maize (Zea mays L.) stover and rice (Oryza sativa L.) straw as mulch on maize were studied on an Alfisol in southern Nigeria in 1990 and 1991. Maize dry matter and grain yield were higher with applications of plant residues and N fertilizer in both years. Addition of Leucaena prunings gave the highest maize grain yield in both years. Compared to the 1990 results, Acioa showed the least grain yield decline among the mulch treatments in 1991. Nutrient uptake was enhanced by applications of plant residues. Leucaena prunings had the highest effect in both years and increased the mean N, P, and Mg uptake by 96%, 84%, and 50%, respectively, over the control. Addition of Acioa prunings increased K and Ca uptake by 59% and 92%, respectively, over the control. ‘High quality’ (low C/N ratio and lignin level) plant residues enhance crop performance through direct nutritional contributions, whereas ‘low quality’ (high C/N ratio and lignin level) plant residues do so through mulching effects on the microclimate. ‘Intermediate quality’ plant residues have no clear effects on crop performance.
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    The effect of phytase on the availability of P from myo-inositol hexaphosphate (phytate) for maize roots (1993)
    Springer
    Plant and soil 154 (1993), S. 189-196 
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    ISSN: 1573-5036
    Keywords: bioavailability ; maize ; myo-inositol ; phosphorus ; phytase ; phytin ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of adding phytase to the root medium of maize plants on the P-availability of added myo-inositol hexaphosphate (phytin) has been studied in pot experiments. When 40 mM phytin-P in nutrient solution was incubated in quartz-sand for 15 days in the absence of plants, 80% of it could be recovered from the solution as soluble organic P. Maize plants growing on this mixture assimilated P from phytin at rates comparable to those from inorganic phosphate (Pi). At a lower addition rate (2 mM phytin-P) only 10% was recovered in the soil solution, and plant growth was severely limited by P. At this low phytin level, the addition of phytase (10 enzyme units per kg sand) increased the plants' dry weight yield by 32%. The relative increases of the Pi concentration in the solution and of the amount of P in the plants were even higher, indicating that the observed growth stimulation was due to an increased rate of phytin hydrolysis. The enzyme-induced growth stimulation was also observed with plants growing in pots filled with soil low in P, when phytin was added. However, on three different soils the addition rates of phytin and phytase necessary for obtaining a significant phytase effect were both about 10 times higher than those required in quartzsand. It is concluded that the P-availability from organic sources can be limited by the rate of their hydrolytic cleavage.
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    URL: http://dx.doi.org/10.1007/BF00012524
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    Genotype selection via a new yield-stability statistic in maize yield trials (1993)
    Springer
    Euphytica 70 (1993), S. 105-111 
    Details
    ISSN: 1573-5060
    Keywords: maize ; genotype × environment interaction ; stability analysis ; cultivar testing ; YSi statistic ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Genotype × environment (GE) interaction complicates selection of superior genotypes across environments. The main objective of this study was to select maize (Zea mays L.) genotypes via a new yield-stability (YSi) statistic in yield trials conducted in Albania. Another objective was to estimate contribution of environmental index (% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\]·j − % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\].., where % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\]·j is mean of all genotypes in the jth environment and % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\]is mean of all genotypes across all environments), minimum temperature, maximum temperature, preseason rainfall, rainfall during the growing season, and relative humidity to GE interaction by determining heterogeneity (nonadditivity) attributable to each of these environmental factors. In five of eight trials, heterogeneity due to environmental index was significant. Heterogeneity due to the other environmental factors was not significant in any trial. A comparison of δ i 2 (stability-variance statistic derived from total GE interaction) and s i 2 (stability-variance statistic derived from residual GE interaction following removal of heterogeneity due to encovariate) helped identify genotypes that performed stably or unstably because of a linear effect of environmental index. In three of the five trials showing significant heterogeneity due to environmental index, the YSi statistic selected a reduced number of unstable genotypes as compared with selection based solely on yield. However, the circumstances or conditions under which YSi and solely yield-based method select the same or different genotypes are not fully understood.
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    URL: http://dx.doi.org/10.1007/BF00029647
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    Cytochemical investigation of long-term stored maize pollen (1993)
    Springer
    Euphytica 72 (1993), S. 87-94 
    Details
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; pollen storage ; pollen grain viability ; pollen enzymes ; pollen physiology ; enzyme cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Maize pollen quality was investigated after long-term storage both in a refrigerator and in liquid nitrogen by a combination of viability tests and cytochemical methods. Determination of the activities of a number of enzymes involved in important metabolic pathways was carried out. Quinone formation was also studied, as some products of secondary metabolism affect pollen grain viability. One year of pollen storage in liquid nitrogen had little effect on the activities of oxidoreductases and hydrolases and had no significant effect on pollen grain viability evaluated by acetocarmine, neutral red and acridine organe. Only the FCR test showed slightly decreased viability. After one and two years of storage in a refrigerator, pollen grain viability, tested using acetocarmine, neutral red and acridine orange, did not change substantially. Simultaneously the FCR test showed a considerable decrease in pollen grain viability. Long-term storage in a refrigerator resulted in the loss of cytochrome oxidase activity and rise of alcohol dehydrogenase, lactate dehydrogenase, peroxidase and polyphenoloxidase activities as well as of quinone formation.
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    URL: http://dx.doi.org/10.1007/BF00023776
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    Can CO2 assimilation in maize leaves be predicted accurately from chlorophyll fluorescence analysis? (1993)
    Springer
    Photosynthesis research 37 (1993), S. 89-102 
    Details
    ISSN: 1573-5079
    Keywords: C4 photosynthesis ; chlorophyll fluorescence ; CO2 assimilation ; maize ; Photosystem II ; quantum yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Analysis is made of the energetics of CO2 fixation, the photochemical quantum requirement per CO2 fixed, and sinks for utilising reductive power in the C4 plant maize. CO2 assimilation is the primary sink for energy derived from photochemistry, whereas photorespiration and nitrogen assimilation are relatively small sinks, particularly in developed leaves. Measurement of O2 exchange by mass spectrometry and CO2 exchange by infrared gas analysis under varying levels of CO2 indicate that there is a very close relationship between the true rate of O2 evolution from PS II and the net rate of CO2 fixation. Consideration is given to measurements of the quantum yields of PS II (φ PS II) from fluorescence analysis and of CO2 assimilation ( $$\phi _{CO_2 } $$ ) in maize over a wide range of conditions. The $${{\phi _{PSII} } \mathord{\left/ {\vphantom {{\phi _{PSII} } {\phi _{CO_2 } }}} \right. \kern-\nulldelimiterspace} {\phi _{CO_2 } }}$$ ratio was found to remain reasonably constant (ca. 12) over a range of physiological conditions in developed leaves, with varying temperature, CO2 concentrations, light intensities (from 5% to 100% of full sunlight), and following photoinhibition under high light and low temperature. A simple model for predicting CO2 assimilation from fluorescence parameters is presented and evaluated. It is concluded that under a wide range of conditions fluorescence parameters can be used to predict accurately and rapidly CO2 assimilation rates in maize.
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    URL: http://dx.doi.org/10.1007/BF02187468
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    Chilling and photosynthetic productivity of field grown maize (Zea mays); changes in the parameters of the light-response curve, canopy leaf CO2 assimilation rate and crop radiation-use efficiency (1993)
    Springer
    Photosynthesis research 38 (1993), S. 125-133 
    Details
    ISSN: 1573-5079
    Keywords: chilling ; photosynthesis ; crop radiation-use efficiency ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of growth temperatures on the photosynthetic performance of field grown maize (Zea mays cv. LG11) was examined for crops sown on 1 May and 28 June 1991. During the period of growth, 2 May to 10 August, the early-sown crop experienced temperatures below 10 °C on 33 occasions compared with only one for the crop sown on 28 June. The prolonged period of low temperatures throughout May and beginning of June were associated with a marked depression in CO2 assimilation rates at all light levels in the early-sown treatment. Chill-induced depression of the photosynthetic light-response curve reflected a sustained reduction in canopy leaf photosynthesis and crop radiation-use efficiency (RUE). During the early stages of growth, RUE was 65% lower in the early- than late-sown treatment, with no marked recovery observed in the former treatment until approximately three weeks after chilling conditions had ceased. Data show a close correlation between chill-induced depression of quantum yield (Φ) and RUE, with corresponding reductions in the light-saturated rates of CO2 assimilation (Pmax). The convexity of the light-response curve recovered most rapidly from chilling temperatures, and at least three weeks before any improvement in RUE. It is concluded that photosynthetic productivity of immature maize stands is less sensitive to changes in the convexity of the light response, than to changes in either Φ or Pmax.
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    URL: http://dx.doi.org/10.1007/BF00146411
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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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    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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    URL: http://dx.doi.org/10.1007/BF00010976
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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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    URL: http://dx.doi.org/10.1007/BF00009133
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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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    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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    URL: http://dx.doi.org/10.1007/BF00029088
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    Inheritance studies of low-phosphorus tolerance in maize (Zea mays L.), grown in a sand-alumina culture medium (1992)
    Springer
    Plant and soil 146 (1992), S. 189-197 
    Details
    ISSN: 1573-5036
    Keywords: diallel ; low-P stress ; maize ; sand-alumina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Inbred lines of maize selected as tolerant and intolerant to low-P stress using a sand-alumina culture medium were used to obtain F1 hybrids and advanced generations to be evaluated in diallel mating schemes and generation means analyses for the inheritance studies. Sand-alumina, a solid culture medium, which simulates a slow release, diffusion-limited P movement in soil solution was used in the inheritance studies. Tolerance to low-P stress conditions in maize seedlings is controlled largely by additive gene effects, but dominance is also important.
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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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    URL: http://dx.doi.org/10.1007/BF00012016
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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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    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.
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    URL: http://dx.doi.org/10.1007/BF00779183
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    Nitrogen cycling in leucaena (Leucaena leucocephala) alley cropping in semi-arid tropics (1993)
    Springer
    Plant and soil 148 (1993), S. 63-72 
    Details
    ISSN: 1573-5036
    Keywords: alley cropping ; C/N ratio ; decomposition ; fertilizer N ; leucaena N ; leucaena residues ; lignin ; maize ; N mineralization ; 15N recovery ; N uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The success of alley cropping depends to a large extent on the efficiency of transfer of nitrogen (N) from the legume hedgerow plants to the non-legume crop. Here the idea is examined that leucaena prunings (residues) can supply enough N to maize plants to significantly reduce the degree of N deficiency. Two experiments on decomposition of leucaena leaf, stem, and petiole and mineralization of N from leucaena residues were conducted in field microplots which received application of either15N-labelled leucaena materials or ammonium sulphate fertilizer. The microplots were installed in alleys formed by leucaena hedgerows spaced 4.5 metres apart and cropped with maize. The decomposition of leucaena leaves, stems and petioles was estimated by several methods. The decomposition ranged from 50–58% with leaves, 25–67% with stems and 38–51% with petioles 20 days after addition. More than 55% of the N was released in 52 days during decomposition of leucaena residues. By 20 days after application of15N-labelled leucaena 3.3–9.4% of the added15N was found in the maize plants, 32.7–49.0% was in the leucaena residues, 36.0–48.0% in the soil and 0.3–21.9% lost (deficit). By 52 days 4.8% of the15N applied in leucaena prunings was taken up by maize, 45.1% was detected in the residues, 24.9% in the soil and 25.2% lost. However, when N fertilizer was applied, 50.2% of the fertilizer N was recovered by maize, 35.5% was retained in the soil and 14.3% apparently lost. There was a marked increase in maize plant dry matter and N uptake in the microplots with addition of leucaena prunings compared with those in the microplots without leucaena added. Most of the15N remaining in the soil profile, derived from leucaena residues, was detected in the top 25 cm soil with less than 2% found below 25 cm. ei]H Lambers
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    URL: http://dx.doi.org/10.1007/BF02185385
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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.
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    URL: http://dx.doi.org/10.1007/BF00012523
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    Species-related differences in the electrophoretic behavior of CP 29 and CP 26: An immunochemical analysis (1992)
    Springer
    Photosynthesis research 34 (1992), S. 249-262 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; light-harvesting chlorophyll-protein complex ; spinach ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The monomeric chlorophyll-protein complexes, CP 29 and CP 26 seen in the Camm and Green (1980) and Dunahay and Staehelin (1986) green gels do not always migrate in the order of the apparent molecular weight of their apoproteins as determined by denaturing gel electrophoresis. In barley and corn they do, but in spinach they do not. In addition, in some higher plant species these chlorophyll-protein complexes comigrate on green gels causing confusion in the literature. To remedy this situation and circumvent future confusion, we propose that the CP 29 and CP 26 complexes be named according to the relative molecular weight of their apoproteins on denaturing gels. Our proposal is supported by the results obtained from four antibodies used on Western blot samples of whole thylakoids, grana membranes, and PS II preparations from different plants. The higher molecular weight proteins (proposed CP 29's) react strongly to one set of antibodies, and the lower molecular weight proteins (proposed CP 26's) react strongly to a different set. In spinach, CP 26 antibodies react also with CP 29, but the extent of the cross-reactivity depends critically on the gel electrophoresis system used. Accordingly, a lack of antibody reactivity under certain conditions may not indicate two proteins are unrelated, just simply that a particular epitope is no longer accessible following gel electrophoresis with a particular buffer system.
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    URL: http://dx.doi.org/10.1007/BF00033442
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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 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF01195850
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    Sources of microorganisms in pozol, a traditional Mexican fermented maize dough (1993)
    Springer
    World journal of microbiology and biotechnology 9 (1993), S. 269-274 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00327853
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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 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF00988324
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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 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF01050371
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    Nitrogen fertilizer in leucaena alley cropping. II. residual value of nitrogen fertilizer and leucaena residues (1993)
    Springer
    Nutrient cycling in agroecosystems 34 (1993), S. 1-8 
    Details
    ISSN: 1573-0867
    Keywords: leucaena ; maize ; 15N recovery ; residual15N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Legume residues have been credited with supplying mineral nitrogen (N) to the associated cereal crop and improving soil fertility in the long term. Few studies using15N have reported the fate of legume N and fertilizer N in the presence of legume residues in soil-plant systems over periods of two years or longer. A field experiment was conducted in microplots to evaluate: (1) the residual value of the15N added in leucaena residues; (2) the residual value of fertilizer15N applied in the presence of unlabelled leucaena residues in the first year to maize over three subsequent years; and (3) the long-term fate of residual fertilizer and leucaena15N in a leucaena alley cropping system. There was a significant increase in maize production over three subsequent years after addition of leucaena residues. The residual effect of fertilizer N increased maize yield in the second year when N fertilizer was applied at 36 kg N ha−1 in the first year in the presence of leucaena residues. Of the leucaena15N applied in the first year, the second, third and fourth maize crop recovered 2.6%, 1.8% and 1.4%, respectively. The corresponding values for the residual fertilizer15N were 0.7%, 0.4% and 0.3%. About 12–14% of the fertilizer15N added in the first year was found in the 200 cm soil profile over the following three years. This differed from the 38–41% of leucaena15N detected in the soil over the same period. Most of the residual fertilizer and leucaena15N in the soil was immobilized in the top 25 cm with less than 1% leached below 100 cm. More than 36% of the leucaena15N and fertilizer15N added in the first year was apparently lost from the soil-plant system in the first two years. No further loss of the residual leucaena and fertilizer15N was detected after two years.
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    URL: http://dx.doi.org/10.1007/BF00749953
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    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.
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    URL: http://dx.doi.org/10.1007/BF00705626
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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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    URL: http://dx.doi.org/10.1007/BF00705238
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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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    Cluster analysis of RFLP data from related maize inbred lines of the BSSS and LSC heterotic groups and comparison with pedigree data (1992)
    Springer
    Euphytica 60 (1992), S. 139-148 
    Details
    ISSN: 1573-5060
    Keywords: coancestry coefficient ; genetic similarity ; maize ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In this study, 31 elite inbred lines of maize (Zea mays L.) were analyzed with 149 clone-enzyme combinations for their respective RFLP profiles. Objectives were (1) to determine the utility of RFLPs for estimation of genetic similarties among 16 inbred lines from the Iowa Stiff Stalk Synthetic (BSSS) and among 15 inbred lines from the Lancaster Sure Crop (LSC) heterotic groups and (2) to compare genetic similarities based on molecular markers with those based on pedigree information. Coefficients of genetic similarity (GS) and coancestry (f) between pairs of lines from the same heterotic group were calculated from RFLP and pedigree data, respectively. For lines from the BSSS heterotic group, cluster analyses based on RFLP and pedigree data revealed similar associations. GS and f values were closely correlated (r=0.70) for related BSSS lines. For lines from the LSC heterotic group, considerable discrepancies existed between the GS and f values, especially for those pairs involving inbreds Va22 and Lo924. Effect of selection and/or erroneous pedigree records are discussed as possible explanations for the low correlation of GS and f values (r=0.07) for related LSC lines. RFLPs seem useful for investigation of relationships among maize inbreds, verification of pedigree records, and quantification of the degree of relatedness.
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    URL: http://dx.doi.org/10.1007/BF00029669
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    Structural observations during androgenic microspore culture of the 4c1 genotype of Zea mays L. (1992)
    Springer
    Euphytica 65 (1992), S. 61-69 
    Details
    ISSN: 1573-5060
    Keywords: androgenesis ; in vitro culture ; maize ; microspores ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The capacity of the maize genotype 4c1 to regenerate microcalli and embryos from cultured microspores has been examined by comparing various cold pretreatments and culture media, using microspores and pollen at different stages of development. Viability of cultured cells was tested with FDA and their development was traced with light and fluorescence microscopy using DAPI as a nuclear dye. It was found that a pre-incubation of dissected flowers floating in a liquid nutrient medium at 8°C during 10–14 days was most successful for the induction of cell division. Among the developmental stages tested only the microspores appeared to regenerate. Subculture at 25°C in the same liquid medium, supplemented with 0.1 mg/l TIBA, gave highest rates of microspore division, i.e. up to 70% at 4 to 6 days of culture. All pathways described earlier for maize androgenic embryogenesis were observed within the 4c1 genotype. Symmetric divisions occurred in cultured microspores but most frequently asymmetric divisions lead to the formation of microcalli within 12 days of culture. In at least 60% of all dividing microspores cells were derived from the generative nucleus. Microcalli further developed either into loose or compact calli. Compact calli formed embryo-like structures.
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    URL: http://dx.doi.org/10.1007/BF00022200
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    Risk assessment of genetically modified crops. Potential of four arable crops to hybridize with the wild flora (1992)
    Springer
    Euphytica 66 (1992), S. 145-149 
    Details
    ISSN: 1573-5060
    Keywords: beet ; maize ; potato ; oilseed rape ; risk assessment ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The proposed introduction of genetically modified organisms into the environment has caused public and scientific concern. In response to this concern governments have set up biosafety regulations. In this paper a step-by-step scheme is described by which the safety of genetically modified organisms can be assessed. The first step is to determine the level of safety concern for the unmodified organism. Important aspects of the safety concern of the unmodified organism are the potential to hybridize with the wild flora and the ability of the crop to run wild. These aspects have been investigated by a desk study for four agricultural crops (potato, beet, oilseed rape and maize). Maize and potato are genetically isolated from the wild flora. Beet and oilseed rape on the contrary can potentially hybridize with wild relatives in the Netherlands. The risk assessment of the latter two species should focus entirely on the effects of the introduced genetic material.
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    URL: http://dx.doi.org/10.1007/BF00023519
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    Mid-parent heterosis and combining ability of European corn borer resistance in maize (1993)
    Springer
    Euphytica 72 (1993), S. 65-72 
    Details
    ISSN: 1573-5060
    Keywords: diallel analysis ; host plant resistance ; Ostrinia nubilalis ; plant breeding ; Zea mays ; maize ; European corn borer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Success in breeding maize resistant to the European corn borer has been limited, with the exception of leaf feeding resistance. The inheritance of resistance to leaf, sheath-collar and ear damage in four maize germplasms and their six F1 crosses was evaluated by diallel analysis. Plants in a completely randomized design were artificially infested at the whorl, anthesis or full silk stage of plant development and were evaluated in the field for insect damage. A damage index based on size, number and location of lesions was calculated for each stage. Stowell's Evergreen (susceptible) had a mean damage index three to six times that of Maiz Amargo (resistant) at the whorl stage and the progeny plants were more resistant than the susceptible parent. Maiz Amargo and its crosses had significantly lower mean indices than Stowell's Evergreen for sheath-collar damage in Year 1 but not Year 2. Zapalote Chico, Maiz Amargo and their cross were significantly less damaged than other genotypes at the full silk stage. Heterosis values indicated an increase in resistance of crosses over the midparent average at all three stages of development. General combining ability (GCA) was highly significant for all types of damage, but specific combining ability was significant only for leaf damage. Based on estimates of GCA, Maiz Amargo was the best source of resistance to leaf and sheath-collar damage and both Zapalote Chico and Maiz Amargo would be good parents for ear damage resistance. Results suggest that resistance at different plant development stages can be combined.
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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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    URL: http://dx.doi.org/10.1007/BF00012848
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  • 88
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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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    URL: http://dx.doi.org/10.1007/BF00012850
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  • 89
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    Nutritional disorders between potassium, magnesium, calcium, and phosphorus in soil (1993)
    Springer
    Plant and soil 154 (1993), S. 21-28 
    Details
    ISSN: 1573-5036
    Keywords: activity ratio ; ammonium phosphate ; chloride ; maize ; sandy loam ; soil extracts ; sulphate ; superphosphate ; unbalanced nutrition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A new soil testing procedure has been used to demonstrate the effect of an overfertilization by potassium during the preceding years. The total concentration of cations was governed by the amount of soluble anions and the proportion between the different cations was dependent on exchange reactions and is described by activity ratio. High activity ratio between potassium and calcium induced Ca-deficiency, which resulted in a restricted root functioning shown by periodic decreases of nutrient uptake rates and plant growth rate. P-deficiency restricted root growth, but although ammonium phosphate was most effective to increase P-concentration in soil extracts and P-absorption by plants, ordinary superphosphate gave the highest yield and the best utilization of the absorbed phosphorus, magnesium, and calcium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00011066
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  • 90
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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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  • 91
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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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  • 92
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    Estimates of the residual nitrogen benefit of groundnut to maize in Northeast Thailand (1993)
    Springer
    Plant and soil 154 (1993), S. 267-277 
    Details
    ISSN: 1573-5036
    Keywords: added nitrogen interactions ; groundnut ; maize ; nitrogen ; 15N-isotope methodology ; residual effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Four cultivars of groundnut were grown in upland soil in Northeast Thailand to study the residual benefit of the stover to a subsequent maize crop. An N-balance estimate of the total residual N in the maize supplied by the groundnut was made. In addition three independent estimates were made of the residual benefits to maize when the groundnut stover was returned to the land and incorporated. The first estimate (Estimate 1) was an N-balance estimate. A dual labelling approach was used where 15N-labelled stover was added to unlabelled microplots (Estimate 2) or unlabelled stover was added to 15N-labelled soil microplots (Estimate 3). The nodulating groundnut cultivars fixed between 59–64% of their nitrogen (as estimated by the 15N isotope dilution method using non-nodulating groundnut as a non-fixing reference) producing between 100 and 130 kg N ha-1 in their stover. Although the following maize crop suffered from drought stress, maize grain N and dry weights were up to 80% and 65% greater respectively in the plots where the stover was returned as compared with the plots where the stover was removed. These benefits were comparable with applications of 75 kg N ha-1 nitrogen in the form of urea. The total residual N estimates of the contribution of the nodulated groundnut to the maize ranged from 16.4–27.5 kg N ha-1. Estimates of the residual N supplied by the stover and fallen leaves ranged from 11.9–21.3 kg N ha-1 using the N-balance method (Estimate 1), from 6.3–9.6 kg N ha-1 with the labelled stover method (Estimate 2) and from 0–11.4 kg N ha-1 with the labelled soil method. There was closest agreement between the two 15N based estimates suggesting that ‘apparent added nitrogen interactions’ in these soils may not be important and that N balance estimates can overestimate the residual N in crops following legumes, even in very poor soils. This work also indicates the considerable ability of local groundnut cultivars to fix atmospheric nitrogen and the potential benefits from returning and incorporating legume residues to the soil in the upland cropping systems of Northeast Thailand. The applicability of the 15N methodology used here and possible reasons for the discrepancies between estimates 1, 2 and 3 are discussed.
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    URL: http://dx.doi.org/10.1007/BF00012532
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  • 93
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    Heterosis for leaf photosynthesis, grain yield and yield components in maize (1992)
    Springer
    Euphytica 61 (1992), S. 161-168 
    Details
    ISSN: 1573-5060
    Keywords: photosynthetic efficiency ; infra-red gas analyser ; heterosis ; biomass productivity ; Zea mays L. ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary One of the primary avenues of improving the biological efficiency of crop plants is through the improvement of the leaf and canopy photosynthetic rates. However, the question whether the superiority of hybrids in respect of productivity potential could be traced, in retrospective fashion, to the photosynthetic parameters should be answered first. Once established and standardized, such indices could be streamlined in innovative breeding to predict the heterotic combinations for final yield formation. To answer this question, the photosynthetic rate and other components of photosynthetic efficiency were monitored among eight inbred stocks of maize (selected for variable photosynthetic rate from a previous study) and their all possible one-way crosses. The results demonstrated extensive heterosis in respect of photosynthetic rate and other photosynthetic indices which, in turn, was also realized in terms of higher biomass productivity and yield. Nonetheless, high leaf photosynthesis alone did not result in higher grain yield. On the contrary, component interaction among the photosynthetic indices like photosynthetic rate, leaf area/plant, number of leaves and chlorophyll content on one hand and the complementary gene action on the other, could be held responsible for higher yields in hybrids. Since the components of photosynthetic efficiency can predict heterosis for biomass and grain yield upto a reasonable extent, judicious incorporation of such indices in selection parameters for applied genetic protocols can add yet another dimension to the strategies for future yield improvements.
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    URL: http://dx.doi.org/10.1007/BF00026807
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  • 94
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    The impact of genotype x soil texture interaction on the efficiency of selection for yield in maize (Zea mays L.) (1992)
    Springer
    Euphytica 61 (1992), S. 61-65 
    Details
    ISSN: 1573-5060
    Keywords: population improvement ; maize ; Zea mays ; honeycumb selection ; adaptability ; stability ; yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This study was undertaken to investigate the implications of genotype x soil texture interaction on response to selection in maize. Mass honeycomb selection for yield was applied for 11 cycles from the F2 of the single cross maize hybrid F68×NE2 in a field B with silty-clay-loam soil texture. Response to selection compared to the original single cross hybrid was estimated both in absence of competition and under solid stand in the selection field B and in a nearby field A differing in soil texture (clay-loam). A strong crossover type of interaction occurred both under solid stand and in the absence of competition in the two tests the improved population outyielded the hybrid in field B in the two densities, but lagged behing the hybrid in field A. The results suggest that interaction between genotype and soil texture might affect efficiency of selection detrimentally unless provision is taken for parallel selection early in the crop improvement program in fields differing in soil texture.
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    URL: http://dx.doi.org/10.1007/BF00035547
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  • 95
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    Variation among maize (Zea mays L.) accessions of Bendel State, Nigeria. Multivariate analysis of agronomic data (1992)
    Springer
    Euphytica 66 (1992), S. 65-71 
    Details
    ISSN: 1573-5060
    Keywords: cluster analysis ; principal component analysis ; accession ; landraces ; Zea mays ; maize ; dendrogram ; variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two multivariate techniques were used to characterize 30 maize accessions collected from three ecological zones of Bendel State, Nigeria. Differentiation of the 30 accessions into five distinct groups was achieved with the unweighted variable group method of the average linkage cluster analysis of 34 agronomic characters. Four of the taxonomic groups contained at least three accessions each, while a fifth group contained only one. The single accession contained in the fifth group was characterised by very early maturity, deeply pigmented leaves and ear husks and short statured plants. Clustering of the accessions into different phenetic groups followed substantially along geographical and traditionally trading routes. A few cases of overlapping of accessions from different geographical locations were obtained. Principal component analysis revealed that days to 50% tasseling and silking, number of nodes/plant, ear length, ear weight, leaf width, and kernel colour were the principal discriminatory characters that differentiated the accessions. Sixty-four percent of the total variation among the 34 characters were accounted for by the first five principal components while the first and second components accounted for 26 and 14 respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023509
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  • 96
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    Variation in resistance of Mexican landraces of maize to maize weevil Sitophilus zeamais, in relation to taxonomic and biochemical parameters (1993)
    Springer
    Euphytica 74 (1993), S. 227-236 
    Details
    ISSN: 1573-5060
    Keywords: resistance ; taxonomy ; maize ; maize weevil ; indigenous landraces ; phenolic acids ; life history components ; indirect selection ; Zea mays ; Sitophilus zeamais
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Accessions representing twenty eight landraces of maize were assessed for susceptibility to the maize weevil, Sitophilus zeamais in standardized resistance tests. Susceptibility parameters such as weight loss of grain, number of insect progeny produced, the Dobie index of susceptibility, and oviposition on grain were found to vary significantly by genotype, with exceptional resistance found in accessions representing the Naltel, Chapalote and Palomero landraces. As in improved genotypes, susceptibility was negatively correlated to phenolic and protein content of the variety tested but positively correlated to moisture content. A detailed analysis of the phenolics revealed the presence of diferulate which may contribute to mechanical resistance of the seed by cross-linking of cell wall hemicelluloses. A canonical discriminant analysis of the resistance data suggests that most of the five landrace groupings are significantly different. The ancient indigenous and prehistoric mestisos groupings are sources of resistant genotypes.
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    URL: http://dx.doi.org/10.1007/BF00040405
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  • 97
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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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    URL: http://dx.doi.org/10.1007/BF02372557
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    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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    URL: http://dx.doi.org/10.1007/BF02373137
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