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  • Articles  (21)
  • maize  (21)
  • Springer  (21)
  • American Society of Civil Engineers
  • Cambridge University Press
  • Thomas Telford
  • 2010-2014
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  • Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition  (20)
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  • Sociology
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  • Articles  (21)
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  • Springer  (21)
  • American Society of Civil Engineers
  • Cambridge University Press
  • Thomas Telford
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  • 2010-2014
  • 1995-1999
  • 1990-1994  (21)
  • 1950-1954
  • 1945-1949
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 131 (1991), S. 59-66 
    ISSN: 1573-5036
    Keywords: maize ; mechanical stress ; penetrometer ; root growth ; sandy loam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Root penetration resistance and elongation of maize seedling roots were measured directly in undisturbed cores of two sandy loam soils. Root elongation rate was negatively correlated with root penetration resistance, and was reduced to about 50 to 60% of that of unimpeded controls by a resistance of between 0.26 and 0.47 MPa. Resistance to a 30° semiangle, 1 mm diameter penetrometer was between about 4.5 and 7.5 times greater than the measured root penetration resistance. However, resistance to a 5° semiangle, 1 mm diameter probe was approximately the same as the resistnace to root penetration after subtracting the frictional component of resistance. The diameter of roots grown in the undisturbed cores was greater than that of roots grown in loose soil, probably as a direct result of the larger mechanical impedance in the cores.
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  • 2
    ISSN: 1573-5036
    Keywords: cassava ; Guelph permeameter ; leaching ; maize ; methylene blue ; rice ; rooting depth ; soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Under high rainfall conditions on acid soils with shallow crop root systems the rate of N leaching is high. A simple model predicts nitrogen uptake efficiency as a function of the amount of rainfall in excess of evapotranspiration, rooting depth and degree to which N leaching is retarded in comparison with water transport. Field observations on acid soils in S.E. Nigeria and S. Sumatera (Indonesia) showed that this model should be amended to include the role of old tree root channels. Crop roots can follow these channels, which are coated with partly decayed organic matter, into the acid subsoil. Measurements of water infiltration with a Guelph permeameter and a methylene blue dye showed that such channels form the major infiltration sites during rainstorms. Implications for nitrogen use efficiency and cropping pattern are discussed.
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  • 3
    ISSN: 1573-5036
    Keywords: aluminium ; calcium ; groundnut ; gypsum ; limestone ; magnesium ; maize ; soil solution ; ultisol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field experiment was conducted on an Ultisol in Malaysia to assess changes in soil solution composition and their effects on maize and groundnut yields, resulting from limestone and gypsum application. The results showed that soil solution Ca in the lime treatment remained mainly in the zone of incorporation, but in the gypsum treatment some Ca moved into 15–30 cm zone. Al3+ and AlSO4 + were dominant Al species in the soil solution of nil treatment. Liming decreased Al3+ and AlSO4 +, but increased hydroxy-Al monomer activities. However, gypsum application resulted in an increase of AlSO4 + activity and in a decrease of Al3+ activity. Relative maize and groundnut yields were negatively correlated with Al3+, Al(OH)2+ and Alsum activities. Likewise, relative yields were negatively correlated with Al concentration and the Al concentration ratio and positively correlated with soil solution Mg concentration and Ca/Al ratio.
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  • 4
    ISSN: 1573-5036
    Keywords: cadmium ; copper ; extraction method ; iron ; maize ; manganese ; nickel ; root exudate ; tobacco ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soluble root exudates were collected from three plants (Nicotiana tabacum L., Nicotiana rustica L. and Zea mays L.), grown under axenic and hydroponic conditions, in order to study their metal-solubilizing ability for Cd and other cations (Cu, Fe, Mn, Ni, Zn). Nicotiana spp. and Zea mays L. root exudates differed markedly in C/N ratio, sugars vs. amino acids ratio and organic acids content. Metals from two soils were extracted with either root exudate solutions, containing equal amounts of organic carbon, or distilled water as control. In the presence or absence of root exudates, the solubility of Fe and Mn was much higher than of the four other metals tested. Root exudates increased the solubilities of Mn and Cu, whereas those of Ni and Zn were not affected. Root exudates of Nicotiana spp. enhanced the solubility of Cd. The extent of Cd extraction by root exudates (N. tabacum L. N. rustica L. Zea mays L.) was similar to the order of Cd bioavailability to these three plants when grown on soil. An increase in Cd solubility in the rhizosphere of apical root zones due to root exudates is likely to be an important cause of the relatively high Cd accumulation in Nicotiana spp.
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  • 5
    ISSN: 1573-5060
    Keywords: Breeding ; heritability ; in vitro digestibility ; in vivo digestibility ; maize ; silage maize ; variation ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Variation and covariation for agronomic and digestibility traits of silage maize are reported from a compilation of 22 years of experiments with standard sheep. Genotype effects of DOM and DCF were highly significant, even when genotypes were nested in earliness groups or brown-midrib hybrids discarded (Table 2). The genetic variance of crude fiber content was low, but the variance of the DCF was high. The genetic variance of DOM was about 4 times lower than genetic variance of DCF, but broad sense heritability of DOM was higher because of lower residual variance (Table 3). Genetic correlations between grain or crude fiber content and DOM had similar absolute values, 0.65, so each of these two traits was an important but not the unique determinant of silage maize quality. There was no correlation between DCF and grain or crude fiber content. Yield was not related to DOM or DCF within each group of earliness, allowing some quality improvement without agronomic drift (Table 4). Except for late hybrids, most of DOM differences between groups of earliness came from lowering of minimum value, while maximum values were similar. It was the contrary for DCF, with similar minimum values for all groups (Table 5). There was no obvious correlation between year of registration of hybrids and DOM or DCF, but extra new variation seemed obtained only for low values (Figs 1, 2; Table 6). IVDOM according to the APC process was a poor predictor of DOM, especially when brown-midrib hybrids and earliness effects were discarded; but because heritability of this trait was similar to DOM heritability, such enzymatic processes could probably be used to avoid drift towards poor DOM with hybrids bred for higher stalk strength.
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  • 6
    ISSN: 1573-5036
    Keywords: alley cropping ; beans ; Erythrina ; Gliricidia ; humid tropics ; isotopically exchangeable P ; maize ; mulching ; phosphorus cycle ; P desorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus availability was measured in soils under five cropping systems: alley cropping with Erythrina poeppigiana, alley cropping with Gliricidia sepium, sole cropping with Erythrina poeppigiana mulch applied, sole cropping with Gliricidia sepium mulch applied, sole cropping with no mulch. The following parameters were measured: 1) plant-available soil P assessed by P uptake of maize and bean bioassay plants; 2) phosphate desorbable by anion exchange resin; 3) adsorption of added P into isotopically exchangeable and non-exchangeable pools. In the bioassay, P uptake of beans declined in the order: mulched sole-cropped〉unmulched sole-cropped〉alley-cropped soils. For maize the relative uptake was: mulched sole-cropped〉unmulched sole-cropped = alley-cropped soils. These results suggest trees had not incorporated a significant quantity of P into the system after seven years and, probably, there was a decrease in available soil P due to the sequestration of P in the tree biomass. Potentially resin-desorbable P was higher in alley-cropped and mulched sole-cropped soils than in unmulched sole-cropped soils. The adsorption and desorption of added P into and from exchangeable and non-exchangeable pools did not differ between alley-cropped and unmulched sole-cropped soils. Crop yield and crop N, P and K uptake were all higher in the alley crops than in the unmulched sole crop. The supply of P to the crop under alley cropping seems to be dependent on P cycled and released from the mulch. The P cycle in alley cropping appears to be self-sustaining at least under conditions of moderate P fertiliser input.
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  • 7
    ISSN: 1573-5036
    Keywords: fertilizer trials ; Kenya ; maize ; Striga hermonthica ; sunflower
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The adverse effect of the parasitic weed Striga hermonthica on yield of maize was studied in a fertilizer trial in Southwestern Kenya. In two years of experimentation (1987 and 1988), the weed had a highly significant, negative impact on maize yields. The spotty incidence of Striga disturbed the fertilizer trials. Inclusion of the degree of Striga infestation in a regression model caused an increase in the fraction of experimental variation that could be explained by the model. Several methods were tested to combat Striga. Hand-pulling reduced Striga incidence and increased grain yields during the following growing season. No clear effect was obtained from the trap crop sunflower, although such an effect may have been concealed by the success of hand-pulling. Application of mineral fertilizers or farmyard manure did not significantly reduce Striga infestation.
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  • 8
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    Plant and soil 138 (1991), S. 139-142 
    ISSN: 1573-5036
    Keywords: maize ; manganese deficiency ; pollen viability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize (Zea mays L. cv. G2) was grown with 0.55 mg L−1 (sufficient), or 0.0055 mg L−1 (deficient) manganese in sand. Manganese-deficient plants developed visible deficiency symptoms and showed poor tasseling and delayed anther development. Compared to Mn-sufficient plants, Mn-deficient plants produced fewer and smaller pollen grains with reduced cytoplasmic contents. Manganese deficiency reduced in vitro germination of pollen grains significantly. Ovule fertility was not significantly affected by Mn. But in Mn-deficient plants seed-setting and development was reduced significantly.
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  • 9
    Electronic Resource
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    Plant and soil 134 (1991), S. 127-135 
    ISSN: 1573-5036
    Keywords: aluminium and acid saturation ; exchangeable aluminium and acidity ; lime requirement indices ; maize ; relative crop yields ; seasonal effects ; soil pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Due, in part, to the relative paucity of published comparisons based on field generated data, there is still poor agreement regarding the relative merits of lime requirement indices based on exchangeable Al and those based on pH. The objective of this study was to compare such indices using results obtained from long-term field experiments. Data were obtained over 22 site-years from lime trials conducted on clay (Typic Haplorthox) and sandy loam (Plinthic Paleudult) soils differing widely in organic carbon content. Relative maize (Zea mays L.) yields were used to compare the prognostic value of soil pH with indices obtained using exchangeable Al and exchangeable acidity (Al+H). Both within and across soils, pH proved to be markedly inferior to Al based indices. Exchangeable acid saturation of the effective cation exchange capacity, a readily obtained and popular index of lime requirement in some countries, proved as effective as less easily acquired indices based on exchangeable Al per se. The findings reported are consistent with those of many glasshouse studies and support the viewpoint that indices based on Al or acid saturation should replace pH as a measure of lime requirement.
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  • 10
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    Plant and soil 134 (1991), S. 277-280 
    ISSN: 1573-5036
    Keywords: bleeding rate ; maize ; root pruning ; root-study methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Current methods of studying roots are either labour intensive or require expensive equipment. In 1986 and 1987 root pruning treatments were given to maize plants grown indoors. In both years the amount of xylem exudate collected from plant stumps shortly after root pruning increased with the dry weight of roots attached to the plant. The measurement of xylem exudation is presented as an alternative for conventional laborious root-study methods.
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  • 11
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    Plant and soil 135 (1991), S. 213-221 
    ISSN: 1573-5036
    Keywords: maize ; plant growth-regulating substances ; plant hormones ; substrate dependend-cytokinin production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Glasshouse experiments were conducted to evaluate the influence of pretested cytokinin precursors, adenine (ADE) and isopentyl alcohol (IA), and a cytokinin producing bacterium, Azotobacter chroococcum added to soil, on the vegetative growth of maize (Zea mays L.). The combination of 2.0 mg ADE kg-1 soil, 13 mg IA kg-1 soil, plus an inoculum of A. chroococcum was the most effective in enhancing the vegetative growth of maize compared with the application of ADE plus IA, ADE plus A. chroococcum, or ADE, IA or A. chroococcum alone. The dry weight of root and shoot tissues was increased up to 5.57- and 5.01-fold, respectively, in comparison to the controls; however, the root/shoot ratios were similar. The increases in shoot height, internodal distance, stem and leaf width over the controls under the optimum treatment were: 2.07-, 2.81-, 1.46-, and 2.11-fold, respectively. The improvement in plant yield was primarily attributed to A. chroococcum production of cytokinins in the rhizosphere.
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  • 12
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    Plant and soil 138 (1991), S. 189-194 
    ISSN: 1573-5036
    Keywords: aggregate size ; carbon allocation ; maize ; shoot-root ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Shoot dry mass and leaf area of 16-d old maize plants decreased as soil aggregate size in greenhouse pots increased in diameter from 0.075–0.5 to 4–8 mm. Root length was also much greater on the finer aggregate beds, due primarily to increased growth of second-order laterals. In a subsequent experiment in which shoot dry matter again decreased with increasing aggregate size, it was found that a similar change in root morphology as noted in experiment I resulted in increased root dry mass as aggregate size increased. The associated change in shoot-root ratio was significant eight days after emergence. This change was due to a change in allocation of fixed carbon rather than allocation of seed reserves. Neither transpiration rate per unit leaf area, nor net assimilation rate were affected by aggregate size. Likewise nutrition could not account for the differences in shoot or root growth.
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  • 13
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; genetic variation ; nitrate accumulation ; N use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The objective of this research was to obtain information about expression of genes controlling N concentration in the lower stalk internodes of maize at silking stages and in two other stages during the grain filling period. The inheritance of nitrate-N concentration, total N concentration, and the nitrate-N/total N ratio in the lower stalk internodes was measured in an eight-line diallel cross experiment and in an experiment involving segregating generations. The results show that the parameters examined, particularly nitrate-N concentration, are genetically controlled and that maize plants differ in this respect. Moreover, the magnitude of the general combining ability effects in relation to the size of specific combining ability obtained from the diallel analysis and the mean squares of the analysis of variance of generation means indicated additive heritability of nitrate-N concentration and other N-related traits in maize stalks. These findings suggest to us that a cyclic selection program in maize should be effective in modifying the level of N-related traits concentration in the stalks.
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  • 14
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; prediction ability ; discrimination ability ; yield ; digestibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The identification of environments suitable for selection should enable plant breeders to test reliably a larger number of genotypes with given resources. This research was undertaken to evaluate discrimination ability (DA) and prediction ability (PA) of eight environments involving two locations. Eckartsweier (Eck) 1 and Voelkenrode (Voe); 2 yer. 1984 (84) and 1985 (85); and two harvests, silage harvest (I) and later (II). It was based on dry matter yield of plant (PDMY), ear (EDMY) and stover (SDMY) and on in vitro digestible organic matter (IVDOM), neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) of stover of 12 inbred lines and their 66 diallel crosses in maize (Zea mays L.). Linear regression coefficient of the performance of genotypes in an environment on that averaged across all environments and its degree of determination were used as measures of the DA and PA of environments, respectively. In hybrids, the DA of environments differed significantly for all traits except SDMY and ADL. Environment Eck851 showed better PA (≥0.63) than other environments for PDMY, EDMY, IVDOM, NDF, and ADF. Among the 12 two-environment combinations. EckI was a better predictor for PDMY, EDMY, IVDOM and NDF (PA≥0.80). The more productive environments showed better DA and PA for PDMY and FDMY than less productive ones. For IVDOM and NDF the first harvest provided better discrimination and prediction than the second harvest. In inbred lines the DA of environments differed significantly for EDMY only. In the present study, PA and DA seemed to be functions of the environments, PA was improved by combining two environments, and some environments seemed to be suitable for preliminary selection of genotypes for such diverse traits as yield and digestibility.
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  • 15
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    Nutrient cycling in agroecosystems 30 (1991), S. 39-46 
    ISSN: 1573-0867
    Keywords: Rock phosphate ; single superphosphate ; P uptake ; VAM fungi ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of inoculation with fourteen endomycorrhizal species belonging to the generaGigaspora, Scutellospora, Glomus, Acaulospora andEntrophospora on the growth of maize (Zea mays L.) was evaluated under glasshouse conditions in an unsterilized tropical virgin soil using two P sources with different solubility. In both P treatments the population of indigenous mycorrhiza species was not affected and growth of maize was enhanced. Introducing VAM species additionally modified the growth pattern of maize. Using a low-grade rock phosphate (Patos de Minas) from Brazil all endophytes with exception ofGigaspora margarita, Scutellospora verrucosa, Scutellospora gregaria, Entrophospora colombiana andGlomus pallidum improved shoot dry weight. In the treatment with single superphosphate, dry matter production was not significantly enhanced byGigaspora margarita, Gigaspora gigantea, Scutellospora verrucosa, Scutellospora reticulata, Scutellospora gilmorei andGlomus manihotis. When rock phosphate was added root fresh weights were enhanced only by three endophytes (Gigaspora margarita, Gigaspora gigantea andAcaulospora rehmii); with single superphosphate none had a significant effect. The percentage of P in shoots was almost equal in non-inoculated and inoculated plants and yield responses did not always follow the pattern of P uptake. Mycorrhizal root infection was always highest in the treatment with single superphosphate and in most cases a correlation with plant growth was found. The present results show that introduced vesicular arbuscular mycorrhiza species differently promote growth of maize according to their adaptability to the P source and to their capability to compete with native VAM endophytes.
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  • 16
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    Agroforestry systems 14 (1991), S. 193-205 
    ISSN: 1572-9680
    Keywords: Acacia albida ; intercropping ; maize ; green gram ; coastal lowlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Long-term agroforestry demonstrations/trials using Acacia albida and other nitrogen fixing multipurpose trees/shrubs were initiated in mid-1982 to assess soil and crop productivity at a coastal lowland site characterized by low soil fertility, weed problems and consequent poor crop yields. Growth performance (height and diameter at breast height, dbh) of Acacia albida under eight densities rotationally intercropped with maize (Zea mays) and green gram (Phaseolus aureus), crop grain yields, soil fertility changes and weed control were assessed for a 5-year period (May 1982 to March 1987). A parallel-row systematic spacing field layout was used. Intercropped Acacia albida mean hight and dbh were 140 and 24% respectively higher than tree-only controls by the fifth year. Growth rate was low during the first year but increased in subsequent years to mean height and dbh of 9 m and 10 cm respectively by March 1987. While differences in dbh were significant, those between stand heights were not. Crop yields, especially under higher tree densities, declined considerably due to unexpected shade which also caused significant reductions in weed biomass. Soil fertility levels remained unchanged during the experimental period relative to the initial status, and differences between the intercropped Acacia albida plots and the tree — or crop — only control appeared not to be significant. We conclude that an understanding of the mechanism regulating leaf fall/retention phenomena of Acacia albida is crucial towards determining the intercropping potentials of the species.
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  • 17
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    Human ecology 19 (1991), S. 389-418 
    ISSN: 1572-9915
    Keywords: maize ; indigenous knowledge ; technological change ; Mexico
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Ethnic Sciences
    Notes: Abstract This paper presents a case study of the relationship between farmers' knowledge of maize varieties and their selection and management of these varieties under conditions of technological change. Research for this paper was done among Spanish-speaking small farmers in an ejidoof central Chiapas, Mexico. This ejido is well integrated into the market, and the use of modem technologies is widespread. This research demonstrates that farmers have an extensive and widely shared knowledge of their maize varieties. This knowledge reflects objective maize characteristics. Variation occurs in the farmers' selection and management of maize varieties, but on average the variation deviates from a random pattern in the direction predicted by the farmers' knowledge base. They have incorporated the technological changes brought about by development into their knowledge base. Farmers maintain maize varieties with contrasting traits, and their knowledge base provides important information about which traits and constraints are important to them.
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  • 18
    ISSN: 1573-5036
    Keywords: calcareous soil ; copper ; hyphal transport ; iron ; maize ; manganese ; phosphorus ; VA-mycorrhiza ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An investigation was carried out to test whether the mechanism of increased zinc (Zn) uptake by mycorrhizal plants is similar to that of increased phosphorus (P) acquisition. Maize (Zea mays L.) was grown in pots containing sterilised calcareous soil either inoculated with a mycorrhizal fungus Glomus mosseae (Nicol. and Gerd.) Gerdemann and Trappe or with a mixture of mycorrhizal fungi, or remaining non-inoculated as non-mycorrhizal control. The pots had three compartments, a central one for root growth and two outer ones for hyphal growth. The compartmentalization was done using a 30-μm nylon net. The root compartment received low or high levels of P (50 or 100 mg kg−1 soil) in combination with low or high levels of P and micronutrients (2 or 10 mg kg−1 Fe, Zn and Cu) in the hyphal compartments. Mycorrhizal fungus inoculation did not influence shoot dry weight, but reduced root dry weight when low P levels were supplied to the root compartment. Irrespective of the P levels in the root compartment, shoots and roots of mycorrhizal plants had on average 95 and 115% higher P concentrations, and 164 and 22% higher Zn concentrations, respectively, compared to non-mycorrhizal plants. These higher concentrations could be attributed to a substantial translocation of P and Zn from hyphal compartments to the plant via the mycorrhizal hyphae. Mycorrhizal inoculation also enhanced copper concentration in roots (135%) but not in shoots. In contrast, manganese (Mn) concentrations in shoots and roots of mycorrhizal plants were distinctly lower, especially in plants inoculated with the mixture of mycorrhizal fungi. The results demonstrate that VA mycorrhizal hyphae uptake and translocation to the host is an important component of increased acquisition of P and Zn by mycorrhizal plants. The minimal hyphae contribution (delivery by the hyphae from the outer compartments) to the total plant acquisition ranged from 13 to 20% for P and from 16 to 25% for Zn.
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  • 19
    ISSN: 1573-5036
    Keywords: Glycine max (L.) Merr. ; intercropping ; maize ; N-depleted soil ; 15N dilution method ; N transfer ; soybean ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In 1985, 1986 and 1988, maize (Zea mays L.) was monocropped or intercropped with nodulating or nonnodulating soybean (Glycine max [L.] Merr.). In addition, nodulating soybean and nonnodulating soybean were each monocropped and grown as a mixture. In 1985 and 1986, treatments were grown at 0 and 60 kg N ha−1 and in 1988, the treatments were grown without N fertilizer, on N-depeted soil and on non-N-depleted soil. 15N enriched N was applied to soil in all the aforementioned treatments to test for N transfer from nodulating soybean to non-N2-fixing crops by the 15N dilution method. The 15N dilution method did not show the occurrence of N transfer in 1985 and 1986, but the N sparing effect was evident from the total N uptake of nonnodulating soybean, dwarf maize and tall maize, in 1986. In 1988, maize and nonnodulating soybean seed yields and seed N yields were higher on non-N-depleted soil than on N-depleted soil. On N-depleted soil, the 15N dilution method indicated N transfer from nodulating soybean to maize and to nonndulating soybean. At a population ratio of 67% nodulating soybean to 33% nonnodulating soybean, N transfer was also seen on non-N-depleted soil in 1988.
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  • 20
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    Plant and soil 132 (1991), S. 85-90 
    ISSN: 1573-5036
    Keywords: maize ; phosphate ; phosphatase ; roots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The long-term response of hydroponically grown maize plants to variations in the phosphate concentration in the growth medium was studied. There was a 5-week lag period before any differences between experimental and control groups could be seen. After this period, the plants grown without phosphate devoted a higher percentage of their total mass to roots than did the controls. The roots of the phosphate-free plants were longer and less bushy than those of the control plants. Plants grown without phosphate showed an increase in the amount of acid phosphatase extractable from the external surfaces of the roots by a high salt solution. These phosphate stress responses were induced by 5 μM phosphate but not by 25 μM phosphate.
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  • 21
    ISSN: 1573-5060
    Keywords: corn ; maize ; Zea mays L. ; aflatoxin ; resistance ; lfy gene ; Aspergillus flavus ; Aspergillus parasiticus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Aspergillus flavus Link ex Fries spores are commonly used as inoculum for screening maize (Zea mays L.) genotypes for resistance to aflatoxin accumulation on grain. Occasionally, A. parasiticus Speare is also used for this purpose. However, only limited data are available on whether one species is as effective as the other for identifying aflatoxin-resistant genotypes. Our objective was to determine relative aflatoxin accumulation on kernels of maize containing the leafy (Lfy) gene in response to A. flavus and A. parasiticus. Aflatoxin production by A. flavus and A. parasiticus on grain of seven maize synthetics containing the Lfy gene, viz., A619, A632, Mo17, B73, HY, Wf9, and 914, was examined in three environments in Louisiana. Ears were doubly inoculated at 14 and 21 days after mid-silk by atomizing over external silks a 2 ml suspension containing 2.0×107 spores ml-1 of either A. flavus or A. parasiticus. All genotypes responded similarly in the three environments to both the fungal species. Aflatoxin B1 and B2 production did not differ in the three environments. The seven genotypes did not differ in levels of aflatoxin accumulation in response to either A. flavus or A. parasiticus. Aflatoxin production by A. flavus was detected in maize samples from all three environments, but aflatoxin production by A. parasiticus was found only in samples from Winnsboro, where moisture stress occurred. Mean B1 and B2 production by A. flavus from the three environments was, respectively, four and one-half times and two times more than that by A. parasiticus.
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