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  • Articles  (522)
  • maize  (312)
  • tomato  (212)
  • Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition  (522)
  • 101
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    Euphytica 92 (1996), S. 129-134 
    ISSN: 1573-5060
    Keywords: common bean ; correlations ; intercropping ; maize ; selection gains ; selection methods ; yields ; Phaseolus vulgaris ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Despite the growing industrialization, technification and transformation that is happening in the agriculture around the world, and despite that agricultural research has always concentrated its effort on sole crops, multiple cropping systems have historically been important for common bean production in tropical countries. The reasons for this fact, are economical and social, as well as biological. Bean breeders have always been questioned on their work, because the development of new varieties is usually done in sole crop, but the varieties are grown in either systems. This paper addresses a set of questions that are usually presented to the breeders, in light of the evidence obtained from many trials conducted in Brazil and in the U.S.A.: Will the genotypes bred for sole crop conditions, perform well when grown in intercrop; How different should a genotype be, for cultivation in intercropping compared to genotypes developed for sole crop conditions; Is there a need for special breeding programs for intercropping and How could a breeding program focus the question of multiple (associated) cropping?
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  • 102
    ISSN: 1573-5036
    Keywords: maize ; nitrate ; nitrogen fertilizer ; root zone ; soil solution ; soil solution sampler with looped hollow fiber (LHF-sampler) ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of inorganic nitrogen (N) fertilizer on the ionic composition of the soil solution under maize (Zea mays L.) was studied. A pot experiment was carried out with two treatments combined factorially, with or without N application (Ca(NO3)2; +N and −N treatments, respectively), and with or without plants. Three looped hollow fiber samplers were installed in each pot to sample soil solutions nondestructively from the root zone, seven times during the 50-day growth period. Plants were harvested on the 50th day, and their nutrient contents determined. Effects of N fertilizer on the soil solutions were observed by the first sampling, 2 days after sowing. The concentrations of Ca and NO3 − and electrical conductivity (EC) increased significantly in the +N treatments as direct effects of fertilizer application. In addition, the concentrations of Mg, K, Na and H+ also increased and that of P decreased significantly as indirect effects caused by the re-establishment of chemical equilibria. This suggested the greater supply as well as the greater possibility of leaching loss not only of NO3 − but also of Ca, Mg and K. In the treatments with plants, the concentrations of NO3 −, Ca, Mg and K decreased with time and pH increased significantly compared with the unplanted soil. The depletion of N in the soil solution roughly agreed with the amount of N taken up by the plant. The depletions of K from the soil solution amounted to less than 10% of the amount of the K taken up, suggesting intensive replenishment of K from exchange sites in the soil. Depletions of Ca and Mg were several times higher than the amounts taken up, indicating that the depletions resulted from the adsorption of the divalent cations by the soil rather than uptake by plants. Because NO3 − is hardly absorbed by exchange sites in soil and was the dominant anion in solution, it was concluded that NO3 − had a major role in controlling cation concentrations in the soil solution and, consequently, on their availability for uptake by plants as well as their possible leaching loss. ei]H Marschner
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  • 103
    ISSN: 1573-5036
    Keywords: barley ; chloride ; foliar absorption ; maize ; saline sprinkling ; salinity ; sodium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Above-canopy sprinkler irrigation with saline water favours the absorption of salts by wetted leaves and this can cause a yield reduction additional to that which occurs in salt-affected soils. Outdoor pot experiments with both sprinkler and drip irrigation systems were conducted to determine foliar ion accumulation and performance of maize and barley plants exposed to four treatments: nonsaline control (C), salt applied only to the soil (S), salt applied only to the foliage (F) and salt applied to both the soil and to the foliage (F+S). The EC of the saline solution employed for maize in 1993 was 4.2 dS m−1 (30 mM NaCl and 2.8 mM CaCl2) and for barley in 1994, 9.6 dS m−1 (47 mM NaCl and 23.5 mM CaCl2). The soil surface of all pots was covered so that in the F treatment the soil was not salinized by the saline sprinkling and drip irrigation supplied nutrients in either fresh (treatments C and F) or saline water (treatments S and F+S). Saline sprinkling increased leaf sap Na+ concentrations much more than did soil salinity, especially in maize, even though the saline sprinkling was given only two or three times per week for 30 min, whereas the roots of plants grown in saline soil were continuously exposed to salinity. By contrast, leaf sap Cl− concentrations were increased similarly by saline sprinkling and soil salinity in maize, and more by saline sprinkling than saline soil in barley. It is concluded that barley leaves, and to a greater extent maize leaves, lack the ability to selectively exclude Na+ when sprinkler irrigated with saline water. Moreover, maize leaves selectively absorbed Na+ over Cl− whereas barley leaves showed no selectivity. When foliar and root absorption processes were operating together (F+S treatment) maize and barley leaves accumulated 11–14% less Na+ and Cl− than the sum of individual absorption processes (treatment F plus treatment S) indicating a slight interaction between the absorption processes. Vegetative biomass at maturity and cumulative plant water use were significantly reduced by saline sprinkling. In maize, reductions in biomass and plant water use relative to the control were of similar magnitude for plants exposed only to saline sprinkling, or only to soil salinity; whereas in barley, saline sprinkling was more detrimental than was soil salinity. We suggest that crops that are salt tolerant because they possess root systems which efficiently restrict Na+ and Cl− transport to the shoot, may not exhibit the same tolerance in sprinkler systems which wet the foliage with saline water. ei]T J Flowers
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  • 104
    ISSN: 1573-5036
    Keywords: barley ; chloride ; foliar absorption ; maize ; salinity ; sodium ; sprinkler irrigation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Brief pre- and post-irrigation sprinkling treatments using freshwater were tested to determine if these practices could reduce the uptake of salts through leaves when saline water is used to sprinkler irrigate crops. Maize and barley were sprinkler irrigated 2 to 3 times per week for 30 min with saline water (4.2 dS m−1, 30 mmol L−1 NaCl and 2.8 mmoles L−1 CaCl2 for maize and 9.6 dS m−1, 47 mmoles L−1 NaCl and 23.5 mmoles L−1 CaCl2 for barley) in separate experiments with plants grown in pots outdoors. The soil surface of all pots was covered to prevent salinization of the soil by the sprinkling water. One half of the sprinkled plants was grown in nonsaline soil to study the effects of pre-wetting and post-washing when ion uptake was primarily through leaves. The other half of the sprinkled plants was grown in soil salinized by drip irrigation, in order to evaluate the effects of pre-wetting and post-washing when Na+ and Cl- uptake was through both leaves and roots. Post-washing with freshwater (5 min) reduced the leaf sap concentrations of Cl- in saline-sprinkled plants from 56 to 43 mmol L−1 in maize and from 358 to 225 mmol L−1 in barley (averages for plants grown in nonsaline and saline soil). Na+ concentrations in leaf sap were reduced from 93 to 65 mmoles L−1 (maize) and from 177 to 97 mmoles L−1 (barley) by the post-washing. Pre-wetting had a small effect on ion uptake through leaves, the only significant reduction in seasonal means being in leaf Na+ concentrations for plants grown in nonsaline soil. Pre-wetting and post-washing, when combined, reduced leaf Cl- concentrations to levels similar to those of nonsprinkled plants grown in saline soil; however, Na+ concentrations in leaves remained 3.5 times (maize) and 1.5 times (barley) higher than those of nonsprinkled plants. When pre-wetting and post-washing were not applied, sprinkled barley plants grown in saline soil had grain yields which were 58% lower than nonsprinkled plants grown in saline soil, but the reduction in grain yield was only 17% when the freshwater treatments were given. We conclude that a brief period of post-washing with freshwater is essential when saline water is employed in sprinkler irrigation. By comparison, the benefits from pre-wetting were small in these experiments. ei]T J Flowers
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  • 105
    ISSN: 1573-5036
    Keywords: biocontrol ; G. mosseae ; immunocytochemistry ; P. nicotianae var.parasitica ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tomato plants pre-colonised by the arbuscular mycorrhizal fungusGlomus mosseae showed decreased root damage by the pathogenPhytophthora nicotianae var.parasitica. In analyses of the cellular bases of their bioprotective effect, a prerequisite for cytological investigations of tissue interactions betweenG. mosseae andP. nicotianae v.parasitica was to discriminate between the hyphae of the two fungi within root tissues. We report the use of antibodies as useful tools, in the absence of an appropriate stain for distinguishing hyphae ofP. nicotianae v.parasitica from those ofG. mosseae inside roots, and present observations on the colonisation patterns by the pathogenic fungus alone or during interactions in mycorrhizal roots. Infection intensity of the pathogen, estimated using an immunoenzyme labelling technique on whole root fragments, was lower in mycorrhizal roots. Immunogold labelling ofP. nicotianae v.parasitica on cross-sections of infected tomato roots showed that inter or intracellular hyphae developed mainly in the cortex, and their presence induced necrosis of host cells, the wall and contents of which showed a strong autofluorescence in reaction to the pathogen. In dual fungal infections of tomato root systems, hyphae of the symbiont and the pathogen were in most cases in different root regions, but they could also be observed in the same root tissues. The number ofP. nicotianae v.parasitica hyphae growing in the root cortex was greatly reduced in mycorrhizal root systems, and in mycorrhizal tissues infected by the pathogen, arbuscule-containing cells surrounded by intercellularP. nicotianae v.parasitica hyphae did not necrose and only a weak autofluorescence was associated with the host cells. Results are discussed in relation to possible processes involved in the phenomenon of bioprotection in arbuscular mycorrhizal plants.
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  • 106
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    Plant and soil 184 (1996), S. 131-141 
    ISSN: 1573-5036
    Keywords: aerenchyma ; cryo-microscopy ; intercellular water ; maize ; root cortex ; solute diffusion ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract During a study of the diffusivity of sulphorhodamine G in the cortical apoplast of maize roots widely discrepant rates were found between different samples. In roots which had developed large aerenchyma spaces, the diffusion in some regions was very fast, indistinguishable from the rate in water. In other regions the rate was as much as 100 times slower. Examination of frozen intact roots with the cryo-scanning electron microscope showed the presence of liquid filling some of the aerenchyma spaces, while other spaces of the same root contained air. X-ray microanalysis of the liquid (for oxygen) showed that the liquid was water with few detectable ions. Similar liquid was present in small intercellular spaces within the spoke-like radial files of cells between the large spaces, or between remnants of collapsed cell walls at the edges of the large spaces. It is proposed that regions of roots with high diffusivity are those in which some of the aerenchyma spaces are filled with water. In seeking the origin of this liquid, the progress of aerenchyma formation could be followed in the frozen tissues. The first change observed in a group of contiguous cells was a loss of vacuolar solutes and of cell turgor. Next the walls broke apart and collapsed back onto the surrounding turgid cells leaving a volume of ion-poor liquid. The liquid was probably not that found in some aerenchyma spaces of the mature roots, because the final stage of space formation was a loss of the liquid, leaving an air filled cavity surrounded by a composite lining formed from the collapsed walls of the broken cells. It is likely that the liquid in the spaces of mature aerenchyma is exuded from the remaining living cortical cells at times when the root turgor is high. This would be consistent with several recent studies which have shown periodic exudation of water from the surface of turgid roots. The spasmodic occurrence of root cortex tissue with enhanced diffusivity would have important implications for the transport of nutrient ions across the root.
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  • 107
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    Plant and soil 178 (1996), S. 153-160 
    ISSN: 1573-5036
    Keywords: carbon flow ; maize ; rhizosphere ; root ; sugar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influx and efflux of sugar-C and the cycling of C within intact maize roots (Zea mays L.) was studied in sterile solution culture. Using metabolic inhibitors it was shown that roots could take up sugars against the concentration gradient probably via H+-ATPase dependent plasmalemma proton cotransporters. In contrast to this, no evidence was found for an ATPase mediated efflux of sugars from the root. All parts of the root were capable of taking up exogenous sugars. Examination of sugar exudation sites along the root slowed efflux at all locations, with the amount of efflux linearly correlated with internal cellular concentration. The results clearly indicated that the influxefflux mechanisms are linked both spatially, temporally and with respect to the sugars capable of transportation. The turnover of C within the root was found to be extremely rapid with turnover of the soluble sugar pool being 0.8 to 15 times daily depending on root spatial location. The results strongly suggest that the recapture of sugars from outside the root plays an important role in regulating the amount of C lost to the soil which in turn will reduce both pathogen attraction and the size of the rhizosphere microbial population and will also increase the plant's C efficiency.
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  • 108
    ISSN: 1573-5036
    Keywords: Key words ; bioavailability ; crop plants ; DTPA ; maize ; Ni uptake ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The presence of higher-than-normal quantities of nickel is one of the most general features of ultramafic soils and is often suspected as the reason for their infertility. This study on the bioavailability of Ni in ultramafic soils derived from peridotites in New Caledonia showed important variations depending on the position of the soil in the landscape. In piedmont and non hydromorphic colluvio-alluvial soils, Ni was poorly absorbed by cultivated plants. In contrast, crops species grown in the plain soils, especially those found in the colluvio-alluvial and plain soils subject to temporary reducing conditions, possessed very high and even toxic Ni concentrations. Extraction of Ni by DTPA 5 mM was an effective method of estimating Ni bioavailability in these soils. The regression equation developed with only DTPA-extractable ni explained 88% of the variability in tomato Ni concentration. Extractable Ni might originate from the association of Ni with primary alterable minerals, organic matter and goethite. ei]Section editor: L V Kochian
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  • 109
    ISSN: 1573-5036
    Keywords: maize ; net translocation rate ; micronutrient ; root zone temperature ; shoot base temperature ; shoot demand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of suboptimal root zone temperatures (RZTs) on net translocation rates from the roots to the shoots and the concentrations of Fe, Mn, Zn, and Cu were examined in maize grown in nutrient solution or soil. Plants were grown at 12 °C, 18 °C and 24 °C RZT. At each RZT, the growth-related shoot demand for nutrients was varied by independently modifying the temperature of the shoot base (SBT) including the apical shoot meristem. The net translocation rates of Mn and Zn from the roots to the shoots were reduced at low RZTs, irrespective of the SBT and of the substrate (soil or nutrient solution). Obviously, the net translocation rates of Mn and Zn at low RZT were mainly regulated by temperature effects on the roots and not by the chemical nutrient availability in the rhizosphere or by shoot growth rate as controlled by SBTs. When both RZT and SBT were reduced, the decrease in net translocation rates of Mn and Zn was similar to the decline in the shoot growth rate and concentrations of Mn and Zn in the shoot fresh matter were not greatly affected or were even increased by low RZT. However, at high SBT and low RZT in nutrient solution, the depressed net translocation rates of Mn and Zn combined with the increased shoot growth resulted in significantly decreased concentrations of Mn and Zn in the shoot, indicating that Mn and Zn may become deficient even at high chemical availability. By contrast to Mn and Zn, the net translocation rates of Fe and Cu at all RZTs were markedly enhanced by increased SBTs. Accordingly, the concentrations of Fe and Cu in the shoot fresh matter were not greatly affected by RZTs, irrespective of the SBTs. These results indicate that the ability of roots to supply Fe and Cu to the shoot was internally regulated by the growth related shoot demand per unit of roots.
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  • 110
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    Euphytica 87 (1996), S. 45-51 
    ISSN: 1573-5060
    Keywords: sweet corn ; Rp1 ; disease resistance ; plant breeding ; complex locus ; recombination ; Puccinia ; Zea mays ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The Rp1 locus of maize is a complex rust resistance locus where multiple resistance genes are clustered. Rare recombination events between Rp1 genes or alleles can produce two or more detectable genes linked in coupling phase. Such ‘compound’ genes can then be manipulated as a single gene in breeding programs. Several compound Rp1 genes, each carrying two or three tightly linked resistance genes, were constructed to test their utility in controlling common rust. While none of the lines carrying single Rp1 genes were resistant to all of the characterized North American P. sorghi biotypes, most of the two component and all of the three component Rp1 complexes were resistant. The potential for utilization of compound resistance genes in other crop species is discussed.
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  • 111
    ISSN: 1573-5060
    Keywords: embryogenesis ; wheat ; maize ; Triticum aestivum ; Zea mays ; haploidy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Embryogenesis was analyzed in wheat × maize hybrids using paraffin sectioning. Embryogenesis in wheat × maize hybrids is different from that in self-pollinated wheat plants. Development of the embryo is not accompanied by the formation of an endosperm. The endosperm nuclei remain free in the cytoplasm, fail to advance into the cellular stage, and degenerate at a later time. The antipodal cells quickly degenerate in the fertilized ovaries of wheat × maize hybrids similar to self-pollinated ovaries. The antipodal cells remain normal in unpollinated ovaries. The pre-embryo will abort if it is allowed to develop on the plant, because of a nutritional shortage in the absence of an endosperm. Therefore, embryo rescue is necessary for haploid production from a wheat × maize hybrids. Haploid polyembryos were obtained from spikelet culture of wheat × maize hybrids. The formation of polyembryos is due to the cleavage of the pre-embryo and the effect of 2,4-D. The frequency of haploid embryo production and plant regeneration is affected significantly by maize genotypes, but not by wheat genotypes. The concentration of 2,4-D affects only the size of the embryo.
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  • 112
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    Genetic resources and crop evolution 43 (1996), S. 569-574 
    ISSN: 1573-5109
    Keywords: bacterial wilt ; germplasm evaluation ; Lycopersicon esculentum ; Pseudomonas solanacearum ; resistance ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seedlings of two hundred and thirty-three accessions of the tomato collection maintained at the Centro Agronómico Tropical de Investigación y Enseñanza, Turrialba, Costa Rica (CATIE) and 7 cultivars used as controls were evaluated for host-plant resistance to 4 virulent strains of Pseudomonas solanacearum representing race 1 biovars 1 and 3. In general, biovar 3 strains wilted seedlings faster than biovar 1 strains but, after 20 days post-inoculation, no significant differences were noted in susceptible control ratings. Significant differences for disease index were noted, but no line with complete resistance was found. For the USA biovar 1 strain UW-25, only 5 accessions, CATIE 17331, 17334, 17349, 17739, 17740, and 2 of the control cultivars, ‘Hawaii 7998’ and ‘UC-82B’ showed some degree of resistance. Conversely, both the frequency and the degree of resistance were high for Costa Rican biovar 1 strain UW-256. For biovar 3, the Costa Rican strain UW-255 was more virulent than the Peruvian strain UW-130. Eight CATIE accessions, 5539, 17331, 17333, 17334, 17345, 17349, 17742, and MIP-CH1, were as resistant as the resistant control ‘Hawaii 7998’ to 3 strains and accession 17740 was as resistant as ‘Hawaii 7998’ to all 4 strains.
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  • 113
    ISSN: 1573-0867
    Keywords: alley cropping ; Leucaena hedgerows ; maize ; N-competition ; N-use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A two-year field experiment was undertaken on an Alfisol in the forest-savanna transition zone of southwestern Nigeria, to study the effect of alley cropping, root barrier, application of N fertilizer andLeucaena leucocephala (Lam.) de Wit. prunings, on N utilization by maize andLeucaena hedgerows. The trial was conducted using a split-plot design with three replications. Mainplot treatments were alley cropping withLeucaena leucocephala planted at 4m interhedgerow spacing and control (no hedgerows). Four subplot treatments were with and without addition of hedgerow prunings, and with and without presence of root barriers. There were no significant effects of presence ofLeucaena hedgerows and root barriers on maize grain yield.Leucaena hedgerows recovered about 7% of the 30 kgN/ha applied as (15NH4)2SO4 to maize during one year. Application of hedgerow prunings increased maize yield by 82% and N-uptake in the grain by 50% over the treatment without prunings. Recoveries of15N-labelled prunings and fertilizer N by maize plants were about 10 and 16% respectively. Prunings addition increased15N-fertilizer recovery in main season maize and the residual value during the minor season by about 36% over the treatment without prunings. Pruning N-use efficiency was higher for plants grown adjacent to the hedgerows than in the middle of alleys during main season and the reverse was observed during the minor season. Absence of a root barrier increased N-use from prunings. Large amounts of applied N in the system were unaccounted for. Results of the trial showed, that without root barrier there was no measurable below-ground N competition betweenLeucaena hedgerows and maize.
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  • 114
    ISSN: 1573-0867
    Keywords: China ; Loess Plateau ; maize ; 15N ; Nitrogen ; urea ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Field trials were carried out to study the fate of15N-labelled urea applied to summer maize and winter wheat in loess soils in Shaanxi Province, north-west China. In the maize experiment, nitrogen was applied at rates of 0 or 210 kg N ha−1, either as a surface application, mixed uniformly with the top 0.15 m of soil, or placed in holes 0.1 m deep adjacent to each plant and then covered with soil. In the wheat experiment, nitrogen was applied at rates of 0, 75 or 150 kg N ha−1, either to the surface, or incorporated by mixing with the top 0.15 m, or placed in a band at 0.15 m depth. Measurements were made of crop N uptake, residual fertilizer N and soil mineral N. The total above-ground dry matter yield of maize varied between 7.6 and 11.9 t ha−1. The crop recovery of fertilizer N following point placement was 25% of that applied, which was higher than that from the surface application (18%) or incorporation by mixing (18%). The total grain yield of wheat varied between 4.3 and 4.7 t ha−1. In the surface applications, the recovery of fertilizer-derived nitrogen (25%) was considerably lower than that from the mixing treatments and banded placements (33 and 36%). The fertilizer N application rate had a significant effect on grain and total dry matter yield, as well as on total N uptake and grain N contents. The main mechanism for loss of N appeared to be by ammonia volatilization, rather than leaching. High mineral N concentrations remained in the soil at harvest, following both crops, demonstrating a potential for significant reductions in N application rates without associated loss in yield.
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  • 115
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    Nutrient cycling in agroecosystems 46 (1996), S. 205-213 
    ISSN: 1573-0867
    Keywords: available potassium ; isotopic exchange ; leaching ; maize ; sustainability ; Togo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The transfers of native and applied K in a rhodic Ferralsol were studied in an agrosystem of southern Togo to propose sustainable cultivation strategies for K in kaolinitic soils. Potassium balance was measured over two years in field conditions under continuous maize cultivation with two K fertilisation levels (0 and 137 kg K ha−1 yr−1). Postassium leaching below the root zone, determined using ceramic cup samplers and Darcy's law, was on average 7.5 kg K ha−1 yr−1 with K fertilisation, i.e. 2% of the quantity of K applied, and 4.5 kg K ha−1 yr−1 without. The low leaching values resulted from a K concentration lower than 130 μM in the soil solution. The low K concentration in the soil solution was related to selective adsorption of K increased by a low content of exchangeable K, with a Gapon selectivity coefficient ranging from 7.9 and 11.5 M −0.5. So the level of exchangeable K must first be increased to raise K concentration in the soil solution. The fixation and release of K was analysed using the isotopic exchange method with 42K-ions and compartmental analysis of the kinetics of isotopic exchange. Potassium fixed in a form non available within one year accounted for 78% of the difference between the two treatments. The annual amount of K fertilisation must thus be based on the quantity of K removed in the grain and crop residues, with an extra addition to account for K fixation. Given a crop residue content of 85 kg K ha−1 yr−1 in the fertilised treatment, the return of crop residues is essential if sustainability is to be achieved with traditional cropping systems where little K fertiliser is added.
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  • 116
    ISSN: 1572-9680
    Keywords: beans ; hedgerow ; maize ; net present value ; partial budgeting ; sensitivity analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Although alley cropping has been shown elsewhere to permit continuous cropping, it has not been widely tested in the highlands of east and central Africa where it has the additional potential of controlling soil erosion. The effect of four rates (0, 30, 60 and 90 kg N ha−1) of inorganic N on the performance of alley cropping using Leucaena diversifolia as the hedgerow species was studied in the central highlands of Burundi. Significant increase in maize yield (average of 26%) due to alley cropping was only first realised in 1992, three years after the commencement of the trial. In 1993, the average yield advantage of the alley cropping plots was 21%. The prunings augmented the response of maize yield to inorganic N in 1992 and 1993. Compared with the control, economic benefits over the five-year period for all the treatments were negative.
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  • 117
    ISSN: 1572-9680
    Keywords: credit ; economics ; labour ; maize ; soil erosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soil erosion in the Philippine uplands is severe. Hedgerow intercropping is widely advocated as an effective means of controlling soil erosion from annual cropping systems in the uplands. However, few farmers adopt hedgerow intercropping even in areas where it has been vigorously promoted. This may be because farmers find hedgerow intercropping to be uneconomic compared to traditional methods of farming. This paper reports a cost-benefit analysis comparing the economic returns from traditional maize farming with those from hedgerow intercropping in an upland community with no past adoption of hedgerows. A simple erosion/productivity model, Soil Changes Under Agroforestry (SCUAF), is used to predict maize yields over 25 years. Economic data were collected through key informant surveys with experienced maize farmers in an upland community. Traditional methods of open-field farming of maize are economically attractive to farmers in the Philippine uplands. In the short term, establishment costs are a major disincentive to the adoption of hedgerow intercropping. In the long term, higher economic returns from hedgerow intercropping compared to open-field farming are realised, but these lie beyond farmers′ limited planning horizons.
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  • 118
    ISSN: 1573-5060
    Keywords: anthocyanin ; candidate gene ; linkage ; maize ; RFLP ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Linkages between molecular markers and genes involved in the expression of agronomical traits have already been described in all of the major crops. In most cases, the genetic model underlying the Quantitative Traits Loci (QTL) is discussed. Here, Restriction Fragment Length Polymorphisms (RFLPs) and Mapmaker-QTL have been used to pinpoint seven regions of the genome significantly correlated with four pigmentation qualitative traits of maize (Zea mays L.). Two of these, located on chromosomes 2 and 10, explain most of the variation of these traits. The R and B gene loci known to be involved in the regulation of the anthocyanin pathway map to the same regions and we suggest that these loci could be the candidate genes involved in the correlations detected with RFLPs. This type of result is in accordance with the hypothesis of the candidate gene which supposes that, if we have a very high density map of randomly-selected cDNA clones, it should theoretically be possible to associate a cloned genic sequence with a phenotypic trait where correlations are found.
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  • 119
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    Euphytica 92 (1996), S. 241-247 
    ISSN: 1573-5060
    Keywords: earliness ; selection ; adaptation ; exotic germplasm ; maize ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The maturity rating of maize (Zea mays L.) grown in Galicia (Northwestern Spain) varies from FAO 200 to 600. Later germplasm has usually too much moisture content in the kernel at normal harvesting time so serious problems with storing could appear. Besides, farmers have tended to use earlier varieties in the last few years. All this imposes limitations on the amount of germplasm available to develop varieties adapted to this area. To study the possibility of adapting late, exotic material to the environment of the Atlantic coast of Galicia we carried out six cycles of individual selection on two non-adapted populations of maize (Purdue A and Purdue B). The criterion of selection was early silking and the criterion of response was moisture content of kernel at harvesting. The original populations and the populations obtained after each cycle of selection were crossed to the hybrids CM105 × CM109 (tester Reid) and H99 × H95 (tester Lancaster) and were evaluated in four environments to study the efficiency of the selection scheme. There were significant reductions in days to silking (6.1 and 6.7 days from cycle 0 to cycle 6 for Purdue A and Purdue B, respectively) and grain moisture at harvesting (3.0 and 3.9% from cycle 0 to cycle 6 for Purdue A and Purdue B, respectively). There were also reductions in plant height and yield in both populations. In general, the crosses ‘population × Lancaster’ were higher for yield than the crosses ‘population × Reid’. Yield of the population crosses by both testers decreased after the six cycles of selection probably because of the earlier maturity of the selected populations. Some inbreeding depression may also have occurred.
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  • 120
    ISSN: 1573-5036
    Keywords: biomarker ; copper ; (iso)peroxidase ; maize ; peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Changes in the growth parameters and in enzyme activities were studied in roots and leaves of 14-days old maize grown in a nutrient solution containing various copper concentrations (i.e. 0.01 to 10 μM). A significant decrease in root and leaf biomass was only found at 10 μM Cu. In contrast, changes in several enzyme activities occured at lower copper concentrations in the solution, corresponding to different threshold values which are lower than those observed for growth parameters. Peroxidase (POD) activity significantly increased in all investigated plant organs (i.e. 3rd-leaf, 4th-leaf and roots) in relation to their copper content. Additionally, glucose-6-phosphate dehydrogenase (G-6-PDH), and isocitrate dehydrogenase (ICDH) activities decreased in the leaves, especially in the 4th-leaf. However, the activity of malic enzyme (ME), G-6-PDH, glutamate dehydrogenase (GDH) and ICDH increased with the copper content in roots. According to the relationship between POD activity and copper content, the toxic critical value was set at 26 mg Cu per kg dry matter (DM) in roots and 21 mg Cu per kg DM in the 3rd-leaf. In roots, a new isoenzyme of peroxidase appeared for copper content above 12.6 mg Cu kg DM−1. Measurement of enzyme activity, especially that of POD and Cu-specific changes in the (iso)peroxidase pattern, might be used as biomarkers to assess the phytotoxicity for maize grown on copper-contaminated substrata.
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  • 121
    ISSN: 1573-5036
    Keywords: arbuscular mycorrhiza ; biological control ; Phytophthora nicotianae var.parasitica ; P nutrition ; root morphology ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to study the influence of Arbuscular Mycorrhiza (AM) on the development of root rot infection, tomato plants were raised with or withoutGlomus mosseae and/orPhytophthora nicotianae var.parasitica in a sand culture system. All plants were fed with a nutrient solution containing one of two phosphorus (P) levels, 32µM (I P) or 96µM (II P), to test the consequence of enhanced P nutrition by the AM fungus on disease dynamics. Mycorrhizal plants had a similar development to that of control plants. Treatment withPhytophthora nicotianae var.parasitica resulted in a visible reduction in plant weight and in a widespread root necrosis in plants without mycorrhiza. The presence of the AM fungus decreased both weight reduction and root necrosis. The percentage reduction of adventitious root necrosis and of necrotic root apices ranged between 63 and 89% The enhancement of P nutrition increased plant development, but did not appreciably decrease disease spread. In our system, mycorrhiza increased plant resistance toP. nicotianae var.parasitica infection. Although a contribution of P nutrition by mycorrhiza cannot be excluded, other mechanisms appear to play a crucial role.
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  • 122
    ISSN: 1573-0867
    Keywords: millet ; sorghum ; rice ; maize ; wheat ; nutrient harvest index ; post-anthesis nutrient uptake ; recovery fraction ; simulation modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In land use plans, fertilizer recommendations are indispensable to avoid soil nutrient depletion or soil water pollution. Nutrient relations of five cereals have been evaluated on the basis of a literature review with the aim of arriving at such fertilizer recommendations at regional level. Nutrients considered were nitrogen, phosphorus and potassium for millet, sorghum, maize, rice and wheat. The relevant nutrient relations are fertilizer nutrient application to nutrient uptake, and nutrient uptake to crop yield. In addition, post-anthesis nutrient uptake is considered. Subsequently, obtained results are used in simulation modelling exercises to calculate the time required to attain an equilibrium nutrient balance and to investigate the effect of erosion control and straw recycling. Although fertilizer requirements could be assessed for each of the five cereals, monitoring of nutrient supply from natural sources remains necessary. Moreover, research on fertilizer use should focus on improvement of fertilizer recoveries and multiperiod models for both N and P uptakes by crops to allow quantitative land use planning where the time scale is included.
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  • 123
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    Nutrient cycling in agroecosystems 43 (1995), S. 83-86 
    ISSN: 1573-0867
    Keywords: phosphorus fertilizers ; phosphate rock ; maize ; winter rape
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract North Carolina Natural Phosphate (NCNP) is a natural marine sediment, excavated, washed and sold in unprocessed form as a phosphate fertilizer. In vegetation and field experiments carried on in Poland in 1992–1994 with potatoes, rye, maize and winter rape the efficiency of phosphorus in NCNP was in the range of 75–100% of phosphorus in superphosphate. Blending and granulating of NCNP with urea and sulphur proved to be very effective. Further works on blending technology and the usability of NPS or NPKS blends are recommended.
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  • 124
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    Nutrient cycling in agroecosystems 40 (1995), S. 41-48 
    ISSN: 1573-0867
    Keywords: Arachis hypogaea ; intercropping ; maize ; N2 fixation ; N-transfer ; 15N ; Vigna radiata ; Vigna unguiculata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Grain legumes are used widely in intercropping systems. However, quantitative and comparative data available as to their N2 fixation and N beneficial effect on the companion crop in intercropping systems are scarce. Hence, studies were conducted to ascertain the above when cowpea (Vigna unguiculata L.), mungbean (Vigna radiata L.) and groundnut (Arachis hypogaea L.) were intercropped with maize. The study was15N-aided and made outdoors in basins (30 L) filled with 38 kg of soil.15N labelling was effected by incorporating15N-tagged plant material or applying15N-labelled fertilizer along with sucrose to stabilize15N enrichment in the soil during the experimental period. Intercropped groundnut fixed the highest amount of nitrogen from the atmosphere (i.e. 552 mg plant−1), deriving 85% of its N from the atmosphere. Intercropped cowpea and mungbean fixed 161 and 197 mg N plant−1, obtaining 81% and 78% of their N content from the atmosphere, respectively. The proportion of N derived by maize from the associated legume varied from 7-11% for mungbean, 11–20% for cowpea and 12–26% for groundnut which amounted to about 19–22, 29–45 and 33–60 mg N maize plant−1, respectively. The high nitrogen fixation potential of groundnut in dual stands and its relatively low harvest index for N have apparently contributed to greater N-benefical effect on the associated crop.
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  • 125
    ISSN: 1573-8469
    Keywords: disease progress ; disease spread ; Exserohilum turcicum ; maize ; northern leaf blight ; plant density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effect of plant density (37,037, 44,444 and 55,555 plants/ha) on the increase of northern leaf blight in time and space on two maize cultivars planted at spacings of 90, 75 and 60 between rows and 30 cm within rows was investigated.Exserohilum turcicum infested maize residue was used as an inoculum source. Maize density did not significantly affect the disease indices, but significantly influenced the grain yield of the two cultivars. In contrast, the two cultivars differed significantly (P≤0.01) in disease severity, but not grain yield. Higher disease severities and grain yields were associated with higher plant densities, whereas the apparent infection rate was lower in higher plant density. Distance from the maize residue (inoculum source) significantly influenced disease severity. The percentage leaf area blighted, area under disease progress curve and disease progress curve intercept decreased with distance from the maize residue area, but the apparent infection rate on EV8429-SR appeared to increase with distance. Disease gradients (b) were higher in closely planted maize and flattened with time in one location only.
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  • 126
    ISSN: 1573-5036
    Keywords: cadmium ; citric acid ; distribution ; roots ; tomato ; uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments were carried out to investigate the effects of root citric acid on uptake and initial distribution of cadmium (Cd) in tomato plants (Lycopersicon esculentum, cv. Tiny Tim). Cd was measured by γ-spectrometry, using 115Cd spikes. Citric acid was measured by UV-detection, and, after spiking with 14C-citric acid, by β-spectrometry. Cd was applied for 48 h periods, in control experiments, in the presence of citric acid, and after 24 h plant pre-incubation with citric acid. Pre-incubation resulted in two-fold increases in fast-exchangeable amounts of root citric acid, as measured by the presence of citric acid in xylem exudates of decapitated and pressurized roots. Simultaneous application of Cd and citric acid did not change Cd accumulation in total plants and in the roots, nor did any significant change occur with respect to Cd root-to-shoot transport, and Cd concentrations in shoot tissues and xylem fluid. After citric acid pre-incubation, total plant uptake of Cd increased twofold, without any significant change in Cd accumulation in the roots. Cd root-to-shoot transport was increased 5–6 fold, and Cd concentrations in shoot tissues and xylem fluid were increased 6–8 fold. Speciation calculations indicated that, under the conditions applied, xylem Cd may be, at least partly, complexed in citric acid. A C Borstlap Section editor
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  • 127
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    Plant and soil 172 (1995), S. 229-234 
    ISSN: 1573-5036
    Keywords: aluminium ; calcium ; maize ; nitrate ; roots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Aluminium toxicity has been shown to decrease NO3 - uptake in Zea mays seedlings during the first 30 minutes after addition of Al3+. This suggests that NO3 - uptake inhibition could be a primary response to Al addition. We therefore tested the hypothesis that NO3 - uptake and root elongation are affected differently by Al3+. Eight-day old seedlings were exposed to 100 μM Al3+ in the presence of 1 or 10 mM Ca2+, added as either CaSO4 or CaCl2. In the presence of Al3+, cumulative uptake of NO3 --N during an 8 h period was not affected by Ca2+ level (1 or 10 mM). Root elongation at 1 mM Ca2+ was decreased to 63% of the control by the presence of Al3+. Raising ambient Ca2+ from 1 to 10 mM in the presence of Al3+ restored elongation rates to 78% (CaCl2) and 88% (CaSO4) of elongation without Al. Because reductions in root elongation were partially overcome by added Ca2+, but lowered uptake of NO3 - was not, it was concluded that Al3+ toxicity decreased root growth and NO3 - uptake by different mechanisms.
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  • 128
    ISSN: 1573-5036
    Keywords: maize ; organic acids ; rhizosphere ; root
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influx and efflux of organic acids across the root-soil interface were investigated in intact, sterile maize (Zea mays L.) roots under a variety of experimental conditions. Under nutrient-sufficient conditions the efflux of organic acids was shown to constitute 〈 1% of the total C lost across the root-soil interface. Under severe nutrient stress, however, the rates of malate and citrate efflux from the root increased 33 and 12 fold respectively. Influx experiments indicated that roots could not directly reabsorb citrate-Fe3+ or other metal complexes from solution. Influx of citrate was observed only at high external citrate concentration (≥ 1 mM) or from solutions with low ionic strengths. It was postulated that citrate influx is of little importance in a soil environment.
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  • 129
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    Euphytica 82 (1995), S. 157-164 
    ISSN: 1573-5060
    Keywords: EPSP synthase ; glyphosate ; herbicide tolerance ; natural variation ; Zea mays ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Variation in susceptibility to the safe broad-spectrum herbicide glyphosate was investigated in maize. Eleven inbred lines, grown in a growth chamber, were evaluated for their tolerance to the herbicide at 2.4 mM (0.2 kg a.i. in 400 I ha-1 of water). Following treatment with glyphosate at the three-leaf stage, significant variation in damage, expressed as visual injury ratings scored 7, 14 and 21 days after the application of the herbicide, was found. Effects on dry weight and shoot height were consistent with visual scores and the carbon-exchange rate was found to be a sensitive index of differential injury. Biochemical characterization of 5-enol-pyruvyl-shikimate-3-phosphate (EPSP) synthase, the main target of the herbicide, ruled out the possibility that this differential susceptibility was due to variations in the sensitivity of the enzyme. On the contrary, a positive correlation was found between in vivo tolerance and EPSP synthase levels, measured at different stages during seedling growth. This result suggests that a naturally occurring difference in EPSP synthase levels in the tissues may contribute to the differential response observed in vivo in maize inbreds.
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  • 130
    ISSN: 1573-5036
    Keywords: alley cropping ; Chromolaena odorata ; Gliricidia sepium ; groundnut ; maize ; rice ; root length density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tree root systems may improve soil fertility through carbon inputs, uptake of leachable nutrients and maintenance of soil biomass, but can at the same time reduce crop yields by competition for water and nutrients. Quantitative information about the positive and negative effects of tree roots and their changes in space and time are necessary for the optimization of agroforestry associations. An alley cropping experiment was layed out as a randomized complete block design on a Plinthic Lixisol/Ferralic Cambisol with Gliricidia sepium hedgerows at 5 m distance, including a sole cropping control. The development of root systems was monitored by sequential soil coring (eight samplings) during one year, with maize and groundnut as crops. Additional information is presented from a single sampling for rice during the foregoing year. Pronounced fluctuations of live root length density indicated an important variability in the nutrient and water uptake capacity of the vegetation. At low total root length density, the hedgerows affected the root development in the agroforestry plots directly by the presence of their root systems. At high root length density, they affected root development mainly by improving crop root growth and influencing the composition of the spontaneous vegetation. The root length density of the hedgerows was too low to compete with the crops for soil resources. The hedgerows tended to increase root length densities in the subsoil when few roots were present, thus possibly reducing the risk of nutrient leaching. However, the length density of the perennial root systems decreased during the cropping season, presumably as an effect of repeated pruning, and attained minimum values almost at the same time as the crops. Trees with denser root systems which are less frequently pruned may be more efficient in achieving closer nutrient cycles, though at the cost of higher root competition with crops.
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  • 131
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    Plant and soil 171 (1995), S. 141-146 
    ISSN: 1573-5036
    Keywords: aluminium ; maize ; monomeric Al ; organo-Al complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract As aluminium (Al) severely inhibits magnesium (Mg) uptake by many plant species, Mg uptake and Mg-Al interactions in maize (Zea mays L.) were studied in a series of short and long-term experiments. A relationship between Mg uptake and the degree of Mg saturation of exchange or binding sites of the root apoplast (root-CEC) was studied by growing plants in solutions containing: (i) different concentrations of Al, calcium (Ca) and hydrogen (H) ions; and (ii) a number of organic complexes of Al. In short-term experiments, Ca had little effect on the Mg nutrition of maize plants. However, with increasing concentrations of Al and H ions in nutrient solution, there was a decrease in both the degree of Mg saturation of root-CEC and Mg uptake. Effects of pH on cation (H, Al, Mg, Ca) binding at the root apoplasm were pronounced and complicated because of a simultaneous change of H ion concentration, effective root-CEC and Al speciation. The behaviour of Al as organic Al complexes differed from that supplied as aluminium chloride (AlCl3). In the presence of organo-Al complexes, less Mg was replaced from apoplastic binding sites and Mg uptake was inhibited less severely than with AlCl3. In a long-term experiment, Al-citrate, in contrast with AlCl3, was not phytotoxic to maize, expressed by the lack of any inhibition of shoot biomass production.
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  • 132
    ISSN: 1573-5036
    Keywords: acidification ; Alfisol ; aluminum toxicity ; cowpea ; exchangeable acidity ; maize ; manganese toxicity ; nitrogen fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Increased use of N fertilizer and more intensive cropping due to the rising food demand in the tropics requires design and evaluation of sustainable cropping systems with minimum soil acidification. The objectives of this study were to quantify acidification of an Oxic Kandiustalf with different types of N fertilizer in two cropping systems under no-tillage and its effect on crop performance. Chemical soil properties in continuous maize (Zea mays L.) and maize-cowpea (Vigna unguiculata (L.) Walp) rotation were determined with three N sources (urea (UA), ammonium sulfate (AS) and calcium ammonium nitrate (CAN)) in Nigeria, West Africa, during five years. Chemical soil properties were related to grain yield and diagnostic plant nutrient concentrations. For the three N sources, the rate of decline in soil pH in maize-cowpea rotation was 57±7.5% of that in continuous maize, where double the amount of N fertilizer was applied. The rate of soil acidification during the five years was greater for AS than for UA or CAN in continuous maize, and not different for UA and CAN in both cropping systems. With AS, soil pH decreased from 5.8 to 4.5 during five years of continuous maize cropping. Exchangeable acidity increased with N fertilization, but did not reach levels limiting maize or cowpea growth. Return of residues to the soil surface may have reduced soluble and exchangeable Al levels by providing a source of organic ligands. Soil solution Mn concentrations increased with N fertilization to levels likely detrimental for crop growth. Symptoms of Mn toxicity were observed on cowpea leaves where AS was applied to the preceding maize crop, but not on maize plants. Soil acidification caused significant reductions in exchangeable Ca and effective CEC. Main season maize yield with N fertilization was lower with AS than with UA or CAN, but not different between UA and CAN during the six years of cropping. The lower maize grain yield with AS than with the other N sources was attributed to lower pH and a greater extractable Mn concentration with AS. When kaolinitic Alfisols are used for continuous maize cropping, even under no-tillage with crop residues returned as mulch, the soil may become acidifed to pH values of 5.0 and below after a few years. The no-till cereal-legume rotation with judicial use of urea or CAN as N sources for the cereal crop is a more suitable system for these poorly buffered, kaolinitic soils than continuous maize cropping. The use of AS as N source should be avoided. H Marschner Section editor
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    Plant and soil 176 (1995), S. 101-105 
    ISSN: 1573-5036
    Keywords: arbuscular mycorrhiza ; “criollo” ; growth ; inoculation ; maize ; mycorrhizal ; native ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We tested the effect of two single species inocula and a mixed inoculum of the native population of arbuscular mycorrhizal (AM) fungi on the growth response of “criollo” maize (Zea mays L.). To determine the inocula that produced the highest response on maize growth, we conducted a greenhouse experiment at 3 levels of P fertilization (0, 40 and 80 kg ha−1). Inoculation with Glomus mosseae (Nicolson and Gerdemann) Gerd. and Trappe (LMSS) produced the greatest shoot growth rates at the two lowest P fertilization levels. Inoculation with Acaulospora bireticulata Rothwell and Trappe (ABRT) and the native population (NP) resulted in similar shoot growth rates at all P levels. These rates were higher than the non-mycorrhizal control rate at the lowest P level but lower than the control at the highest P level. Also, ABRT and NP had significantly lower shoot growth rates than the inoculation treatment with G. mosseae at all P levels. The non-mycorrhizal control had the lowest growth rate at the lowest P level but its growth rate increased linearly with increased P fertilization. Inoculation with G. mosseae and A. bireticulata produced similar colonization rates which were lower than the native population colonization rate. There was no correlation between colonization and shoot growth rates.
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  • 134
    ISSN: 1573-5060
    Keywords: ELISA ; Lycopersicon hirsutum ; mechanisms of resistance ; potato virus Y ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Potato virus Y (PVY) infects most Solanaceous crops grown in Mediterranean countries in open fields and in greenhouses. Necrogenic strains, which have been isolated from diseased tomatoes in France since the 1980's, seriously cause yield and quality loss of tomato fruits. Lycopersicon hirsutum PI 247087 was found to be resistant to PVY. Virus could not be detected in inoculated leaves by ELISA and/or by back-inoculation on susceptible plants. This resistance was efficient against the 16 tested isolates or strains. Temperature and inoculum concentration did not affect its expression. All the F1 plants of (Momor × PI 247087), (PI 134417 × PI 247087) and (PI 247087 × PI 134417) had symptom scores and ELISA values similar to those of the susceptible parents. The mechanism of resistance could be immunity-like or inhibition of virus migration from cell to cell. The resistance of L. hirsutum PI 247087 appeared to be governed by two independent recessive genes. In a few F2 plants of (PI 134417 × PI 247087) and F2 (Momor × PI 247087), virus was able to multiply in the inoculated leaves but could not establish a systemic infection. This finding may suggest a mechanism which interfers with the long distance migration of the virus in the plant.
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  • 135
    ISSN: 1573-5087
    Keywords: adventitious rooting ; ethylene ; in vitro culture ; lavandin ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The role of ethylene in the formation of adventitious roots in vitro was studied in tomato (Lycopersicon esculentum Mill. cv. UC 105) cotyledons and lavandin (Lavandula officinalis Chaix × Lavandula latifolia microshoots. Both systems were able to form roots on hormone-free medium evolving low amounts of ethylene. The addition of 20–50 μM indole-3-acetic acid (IAA) inhibited root formation in tomato cotyledons while increasing ethylene production. Naphthaleneacetic acid (NAA, 3 μM) stimulated root number in lavandin explants and induced a transient rise in ethylene evolution. Enhanced ethylene levels via the endogenous precursors 1-aminocyclopropane-1-carboxylic acid (ACC, 25–50 μM) drastically impaired root regeneration and growth in tomato. In lavandin, 10 μM ACC stimulated ethylene production and significantly inhibited the rooting percentage and root growth. Conversely, ACC enhanced the root number in the presence of NAA only. Severe inhibition of rooting was also caused by ethylene reduction via biosynthetic inhibitors, aminoethoxyvinylglycine (AVG, 5–10 μM) in tomato, and salicylic acid (SA, 100 μM) in lavandin. A strict requirement of endogenous ethylene for adventitious root induction and growth is thus suggested.
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  • 136
    ISSN: 1572-9680
    Keywords: groundnut ; maize ; root biomass ; root turnover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A considerable amount of data is available about above-ground biomass production and turnover in tropical agroforestry systems, but quantitative information concerning root turnover is lacking. Above- and below-ground biomass dynamics were studied during one year in an alley cropping system withGliricidia sepium and a sole cropping system, on aPlinthic Lixisol in the semi-deciduous rainforest zone of the Côte d'Ivoire. Field crops were maize and groundnut. Live root mass was higher in agroforestry than in sole cropping during most of the study period. This was partly due to increased crop and weed root development and partly to the presence of the hedgerow roots. Fine root production was higher in the alleys and lower under the hedgerows compared to the sole cropping plots. Considering the whole plot area, root production in agroforestry and sole cropping systems was approximatly similar with 1000–1100 kg ha−1 (dry matter with 45% C) in 0–50 cm depth; about 55% of this root production occured in the top 10 cm. Potential sources of error of the calculation method are discussed on the basis of the compartment flow model. Above-ground biomass production was 11.1 Mg ha−1 in sole cropping and 13.6 Mg ha−1 in alley cropping, of which 4.3 Mg ha−1 were hedgerow prunings. The input of hedgerow root biomass into the soil was limited by the low root mass ofGliricidia as compared to other tree species, and by the decrease of live root mass of hedgerows and associated perennial weeds during the cropping season, presumably as a result of frequent shoot pruning.
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  • 137
    ISSN: 1573-5060
    Keywords: maize ; climatic factor ; genotype x environment interaction ; root trait ; statistical model ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The efficiency of genotopic and climatic characteristics in accounting for the interaction between genotypes and environments has been assessed in a three-year trial involving a set of genotypes presenting a range of root morphology characteristics (number and size). Climatic information on rainfall and temperature was recorded during the experiments, together with extra data on the growth and development of the genotypes. Their effects have been tested in factorial regression models. Climatic covariates were very powerful in accounting for the genotype by year interaction as well as the year main effect alone. For the number of adventitious roots on internode 7, the main effect of year could be described as a linear function of the average temperature and precipitation that occurred during the period of root initiation and growth. For internode 6, no clear conclusion was possible. For the root traits studied, 74 to 98% of the interaction could be explained by one climatic covariate. The regression coefficients can be considered as measures of genotypic stability. The genotypic covariates describing aerial development performed rather poorly, compared with environmental ones, even though the physiological and functional relationships between root and shoot are well known. Neither genotype main effect nor genotype by year interaction could be described sufficiently by factorial regression. Still, the genotypic covariates performing best clearly differed between root counts and size. Also the best genotypic covariates differed for main effect and interaction.
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  • 138
    ISSN: 1573-5060
    Keywords: pollen grain viability ; low temperature ; cold tolerance inheritance ; generation means analysis ; tomato ; Lycopersicon esculentum ; Lycopersicon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The different viabilities of pollen produced at low temperatures in intra- and inter-specific crosses of tomato were studied. Cultivars Red Top, Moneymaker, and Marroqui were crossed with cultivar E-15 and these four cultivars were hybridized with lines of the wild speciesL. pimpinellifolium PE-13,L. parviflorum PE-52,L. pennellii PE-47, andL. hirsutum PE-37 and PE-41. A six-generation family of the Moneymaker x PE-47 cross was obtained to carry out a more detailed genetical study of pollen grain viability at low temperatures. Pollen grain viability was evaluated during the winter via acetocarmine staining. When the parents were compared with their F1, the intra-specific tomato crosses showed dominance to better-quality pollen, theL. esculentum x L. pimpinellifolium inter-specific crosses showed positive heterosis, while the crosses ofL. esculentum with the tolerant speciesL. pennellii andL. hirsutum showed intermediate inheritance. However, in theL. esculentum x L. pennellii family, the dominance and the non-allelic interactions (homozygosis x homozygosis) were the most important factors, so that dominance to better viability at low temperatures appeared to be the general mode of inheritance. Genetical control of pollen grain viability at low temperatures seemed to be polygenetic.
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  • 139
    ISSN: 1573-5060
    Keywords: germplasm registration ; maize ; Zea mays ; Isozyme ; markers ; morphological traits ; morphological variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Genetic markers (isozymes), in addition to the traits recommended by the UPOV convention, have been used in France since 1989 to characterize the maize inbred lines submitted to registration. In the years 1989. 1990 and 1991, a total of 974 inbreds has been described according to this procedure. Relationships between genetic markers were investigated and underlined the occurrence of linkage disequilibria within the tested germplasm. These disequilibria appeared to depend strongly on the breeding history of the germplasm. In some cases, these disequilibria could be related to a major progenitor (foundation effect). Relationships between genetic markers and quantitative traits were also pointed out. High coefficients of determination (up to 60%) were in some cases observed at the within group level, and also appeared to be very dependent on the major progenitors of the group of interest. The consequences of these results for breeding and distinctiveness studies are discussed.
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  • 140
    ISSN: 1573-5060
    Keywords: diallel cross ; qualitative interactions ; recurrent selection ; stability analysis ; maize ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A 10×10 diallel cross experiment involving white modified opaque-2 maize inbred lines was grown at four sites. A stability analysis, based on both a combining ability and a heterotic pattern model, was developed. The stability analysis provided valuable information on the genotype x environment interaction properties of the 10 inbred lines. The Gail & Simon (1985) test for qualitative interactions provided a means of determining the nature of these interactions. The inbred, SO507W(M), is shown to have the best potential for use in a hybrid breeding programme, in terms of having the highest weighted general combining ability and line heterosis, and the best general adaptability to all four sites. The single cross, SO713W(P) x PO558W(F), has been identified as one of the genotypes to be used in a recurrent selection programme that favours specific combining ability.
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  • 141
    ISSN: 1573-5060
    Keywords: genetic control ; maize streak virus ; major genes ; minor genes ; resistance ; Zea mays ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary S1 to S5 inbred lines, derived from a maize population bred for its overall resistance to three tropical viruses, were screened for resistance to maize streak virus (MSV) by artificial plant infection using viruliferous leafhoppers. Symptoms were rated and intra-line frequency distributions studied for all pedigree inbred lines. Mortality due to MSV was very low among these inbreds. Symptoms appeared later, developed slower and were less severe than in the susceptible control hybrid. Results of a study of 500 S1 and 93 S2 lines suggested that resistance is under genetic control via a system involving loci with major genes (with dominance for resistance) controlling high to complete resistance, associated with a genetic system involving loci with minor genes controlling partial resistance. Lines expressing complete resistance to MSV were developed from 5 cycles of inbreeding and selection. The relevance of such complete and partial resistance is discussed.
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  • 142
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    Euphytica 81 (1995), S. 79-83 
    ISSN: 1573-5060
    Keywords: immature embryos ; kanamycin resistance ; non-callus growth ; nutrient media ; tomato ; Lycopersicon esculentum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A method is described for selecting resistant transformed tomato genotypes in vitro at the stage of immature embryos. The utilization of HLH nutrient medium with the selective agent kanamycin is proposed. Normal development of seedlings from immature embryos, which do not form callus, is a good and true indicator for isolation of resistant genotypes. The immature embryos do not germinate and develop on MS selective medium.
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  • 143
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    Euphytica 81 (1995), S. 109-114 
    ISSN: 1573-5060
    Keywords: branched broomrape ; genetic variation ; tomato ; Lycopersicon esculentum ; Lycopersicon pimpinellifolium ; Orobanche ramosa ; breeding ; tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Twenty five tomato cultivars and one accession of wild tomato were evaluated for their resistance to branched broomrape (Orobanche ramosa) infestation. Tomato cultivars were found different in their resistance to Orobanche based on different growth parameters. Total Orobanche number, haustoria development and number of emerged Orobanche shoots were all different between tomato cultivars. Differences in the growth and fruit yield among tomato cultivars were also found in response to Orobanche infestation. Ranking tomato cultivars for Orobanche resistance indicates the existence of different resistance mechanisms in these cultivars. Relatively high to moderate levels of resistance were obtained in Tiny Tim, Acora, Castler, Pomodora, Orient, Red Alert and the accession LA 1478 of L. pimpinellifolium. The cultivar Tiny Tim showed the highest level of resistance for all measured parameters and in all experiments.
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  • 144
    ISSN: 1573-5060
    Keywords: glyphosate ; herbicide tolerance ; non-target effects ; somaclonal variation ; Zea mays ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The progeny of 104 regenerated maize plants were screened for tolerance to the safe broad-spectrum herbicide glyphosate during seed germination and early growth. Seven somaclones showed varying degrees of resistance to the application of the herbicide at 1.2 mM (0.1 kg a.i. in 400 1 ha-1 of water). Plants capable of a normal growth following treatment with 2.4 mM (0.2 kg ha-1) glyphosate at the three leaf stage were selfed, and their progeny analyzed. A family able to tolerate the exposure to glyphosate at 2.4 mM was isolated and shown to maintain a photosynthetic rate comparable with control after the application of the herbicide. The selfed progeny of the tolerant somaclone was characterized as to the properties of two targets of glyphosate, the shikimate pathway enzymes 5-enol-pyruvyl-shikimate-3-phosphate (EPSP) synthase and 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase. In vitro tests ruled out the possibility that the tolerance was due to altered forms of these enzymes. Families showed significant variability with regard to EPSP and DAHP synthase levels, measured at different stages during seedling growth; however, not even these traits were correlated with in vivo response to glyphosate. The possible role of other physiological processes in determining the increased tolerance to the herbicide is discussed.
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  • 145
    ISSN: 1573-5060
    Keywords: Zea mays ; insect vectors ; resistance ; maize ; maize streak virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Settling, probing and oviposition behaviour ofCicadulina mbila, the main vector of maize streak virus (MSV) disease were studied on four maize genotypes, 100MSR, HASR, Reunion and H512. Of the four, only H512 was completely susceptible to MSV while the other three genotypes were all known to have some resistance to MSV. Generally,C. mbila settled in higher numbers on the MSV susceptible genotype compared to the three virus resistant ones. However, the number of probing marks left on H512 and 100MSR were similar while more marks were made on Reunion and HASR in increasing order. The oviposition patterns were similar to those observed for probing behaviour. The results suggest the existence of potentially useful resistance mechanisms against the vector. The possible implications of these results are discussed.
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  • 146
    ISSN: 1573-5060
    Keywords: AMMI ; best linear unbiassed prediction ; factorial regression ; genotype by environment interaction ; maize ; missing values ; multiplicative interaction ; reduced rank regression ; two-way table
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary As the sequel to a paper that dealt with the theoretical aspects of linear and bilinear models for the analysis of genotype by environment interaction in multi-environment trials, this paper presents an illustration of the application of these models to real life data. The data come from maize trials that were conducted within the ongoing evaluation programme for the Dutch Descriptive Variety List of Field Crops. The variable that is analyzed is dry matter content. It is shown how linear and bilinear models can be used supplementary to each other within a general strategy for dealing with genotype by environment interaction.
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  • 147
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    Euphytica 84 (1995), S. 57-65 
    ISSN: 1573-5060
    Keywords: bush bean ; Phaseolus vulgaris ; intercropping ; maize ; sole cropping ; Zea mays ; quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The intereropping of common bean (Phaseolus vulgaris L.) and maize (Zea mays L.) is a common practice in the Northwest of the Iberian Peninsula. In this experiment, 25 populations of bush bean were evaluated for nutritional and culinary traits of dry seed and immature pod in sole crop and in intercrop in two years and in two locations, in order to determine whether selection of bush bean in sole crop can result in genetic progress for intercrop. There were no differences in the population means between cropping systems. Significant differences were detected among populations for all traits tudied except starch content, crude ash, water absorption and coat proportion. Population x environment interaction was significant for pod thickness. Bean populations did not interact with cropping systems for any trait, although there were differences between cropping systems for crude protein. These results suggest that a sole crop system provides sufficient information to select bean populations efficiently for the bush bean-maize intercropping system, although the advanced generations of the breeding program should be tested for quantitative traits such as protein content in the appropriate cropping system (intercropping) to know the competitive ability with the associated species. This would permit to choose bush bean populations which complement more efficiently and would be less competitive with the maize population.
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  • 148
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    Euphytica 86 (1995), S. 111-115 
    ISSN: 1573-5060
    Keywords: inheritance ; black leaf mold ; Pseudocercospora fuligena ; host resistance ; tomato ; Lycopersicon esculentum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Inheritance of black leaf mold (BLM) (caused by Pseudocercospora fuligena) resistance was studied in four crosses involving two resistant Lycopersicon accessions (PI134417, L. hirsutum and PI254655, L. esculentum) and four susceptible Asian Vegetable Research and Development Center tomato lines (CLN657BC1F2-267-0-3-12-7, CL143-0-10-3-0-1-10, CLN698BC1F2-358-4-13 and CL5915-93D4-1-0-3). For each cross, six generations, i.e. P1, P2, F1, F2, BC1F1 and BC1F2 were evaluated following inoculations with isolate Pf-2 of P. fuligena. Chi-square analyses of the data based on the ratio of resistant to susceptible plants in the F2 in three of four crosses gave a good fit to a segregation ratio of 1 R : 15 S, and BC1F2 data in three of four crosses gave an acceptable fit to the segregation ratio of 1 R : 63 S. The results indicate that resistance to BLM may be conditioned by two recessive genes acting epistatically in both PI134417 and PI254655.
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  • 149
    ISSN: 1573-5087
    Keywords: axillary meristem ; cytokinin ; ipt gene ; ls mutant ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied axillary meristem formation of the lateral suppressor (ls) mutant of tomato after elevating the endogenous cytokinin levels through introduction of the isopentenyltransferase (ipt) gene from Agrobacterium tumefaciens. Growth and development of several transformants were examined during in vitro culture. Transformants exhibited phenotypes varying in severity and were divided into four classes. A number of the ipt transformants had a normal phenotype, as non-transformed plants. Others showed a mild to severe ‘cytokinin-like’ phenotype. Transformants with a mild phenotype exhibited reduced internode length and reduced root development. Transformants with a severe phenotype showed even shorter internodes, loss of apical dominance, reduction of leaf size, production of callus at the basis of the shoots and absence of root development or development of green non-branching roots. The severity of the phenotype correlated well with the level of ipt gene expression, as measured by northern analysis. Transformants with a severe phenotype also exhibited increased levels of zeatin riboside, but zeatin levels were not elevated. The increase in endogenous zeatin riboside levels in the ls mutant did not restore axillary meristem formation, but sometimes bulbous structures were formed in the initially ‘empty’ leaf axils. Several adventitious meristems and shoots developed from below the surface of these structures. It is concluded that a reduced level of cytokinins in the ls mutant shoots is not responsible for the absence of axillary meristem formation.
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  • 150
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    European journal of plant pathology 101 (1995), S. 301-310 
    ISSN: 1573-8469
    Keywords: Bipolaris zeicola ; maize ; multilocus haplotypes ; Northern Corn Leaf Spot ; sexual reproduction ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Over 3 years 15 samples ofC. carbonum were collected from 11 corn fields in North Carolina and Tennessee. Among 514 isolates of race 2 and 319 isolates of race 3, five phenotypic characters (mating type, production of pseudothecia, production of asci and ascospores, tolerance to cycloheximide and carboxin, respectively) that are controlled by single genes at unlinked loci (Mat, Psu, Asc, Cyh, Crb) were examined. Gametic phase disequilibrium (GPD) was analyzed by three methods. First, observed and expected four-locus haplotype frequencies were compared inG-tests for goodness of fit (method 1) and second, four-locus disequilibrium was calculated using an index of association which is based on the variance of the number of loci at which two isolates in a given population differ (method 2). Third, observed and expected frequencies of allele pairs were compared in 2×2 contingency tables (method 3). Each test was performed on individual and pooled samples which also allowed assessment of heterogeneity among samples. In general this heterogeneity was low, i.e. the consistency of associations among samples was high. Four-locus disequilibrium was significant in race 2 with method 1 but not with method 2. In race 3 we found no disequilibrium with any of the two methods. Method 3 indicated that several allele pairs were significantly associated in race 2 but not race 3. Thus GPD was significant in race 2 but not in race 3. Mating type frequencies were close to 0.50 in race 2 and race 3. This and the non-significant index of association indicate that the sexual stage ofC. carbonum is operating within each of the two race populations. It is suggested that selection favours different haplotypes in the asexual than in the sexual stage of the pathogen. Such disruptive selection may have maintained polymorphisms of genes related to sexual fertility and stabilized gene frequencies inC. carbonum over a period of 15 years (1972–1987).
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  • 151
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    Nutrient cycling in agroecosystems 40 (1994), S. 85-88 
    ISSN: 1573-0867
    Keywords: irrigation frequences ; Lycopersicon esculentum ; nitrogen levels ; semi-arid ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of different irrigation frequencies (5, 7 and 9 days interval) and N rates (0, 50, 100 and 150 kg N ha−1) on applied N in tomato was studied in a field experiment during 3 growing seasons. The application of 100 kg N ha−1 with irriga tion scheduled at 7 days interal resulted in significantly higher N uptake and recovery rate than the other combinations of N rate and irrigation frequencies studied.
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  • 152
    ISSN: 1871-4528
    Keywords: scale leaves ; sclerotial viability ; seed tubers ; pure culture ; hyphal rings ; tomato ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Polyscytalum pustulans spread from infected buds of seed tubers on the nodal scale leaves of elongating stems and stolons. More eyes were infected at the apical end of developing tubers than at the stolon end. Sclerotia, first found within the agar of ageing cultures, appeared to form from thickened hyphal rings within the aerial hyphae and conidiophores. As infected plants senesced, sclerotia developed within single or groups of host cells in diseased stem bases and remained viable for seven years in undisturbed soil. Sclerotia were also found after harvest in skin spots on decayed seed tubers.
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  • 153
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    Plant and soil 162 (1994), S. 309-313 
    ISSN: 1573-5036
    Keywords: in vitro translation ; maize ; nutrient stress proteins ; Poly(A)+RNA ; sulphate deprivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Roots of ten-days-old seedlings obtained from a maize hybrid grown in complete or in sulphate-deprived medium were used to extract Poly(A)+RNA. The response to sulphate deprivation, which is known to increase the uptake capacity up to ten times, was manifested also by the expression of three mRNA species, as shown by the in vitro translation of the mRNA population. One hour after transfer to complete nutrient medium all three mRNAs were still present.
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  • 154
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    Plant and soil 165 (1994), S. 327-332 
    ISSN: 1573-5036
    Keywords: gravitropism ; maize ; nodal roots ; plagiogravitropism ; seminal roots ; 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 can be studied by analyzing the trajectories of roots growing in soil. Both the primary seminal root and nodal roots of maize attain a preferred, or liminal, angle of growth that deviates from the vertical. These roots are said to be plagiogravitropic. Experiments using plants grown in soil-filled boxes revealed that the primary seminal root is truly plagiogravitropic. It shows both positive and negative gravitropism in response to gravity stimuli and tends to maintain its direction even after growing around obstacles. These are experimental results suggesting that plagiogravitropic growth is controlled by internal factors. The orientation of the grain affects the establishment of the liminal angle of the primary seminal root, and both the position of their node of origin and the root diameter are closely related to the plagiogravitropic behaviour of nodal roots. Several external factors are also known to influence plagiogravitropism. Low soil water content causes a decrease in the angle of growth and soil mechanical resistance suppresses the gravitropic curvature. Plagiogravitropic behaviour of both seminal and nodal roots plays a significant role in shaping the root system.
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  • 155
    ISSN: 1573-5060
    Keywords: abscisic acid ; inheritance ; drought stress ; Zea mays ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This study analyzes the components of phenotypic variation for abscisic acid (ABA) content in maize (Zea mays L.) leaves and the correlations with drought sensitivity index (DSI) and silk delay (SD), involved in the reaction to water deficit. Eight early- and seven medium-maturity inbreds were examined in field trials: in 1990 with low irrigation volume and in 1991 with low and high irrigation volumes. ABA concentration and DSI were investigated at growth stages (S) corresponding to stem elongation (S3), appearance of the first husks (S4), and mid-end of silking (S5). The ABA concentration was significantly higher in conditions of water deficit and in the later growth stage. The genetic component for ABA concentration attained higher relative values than those shown by DSI in the same growth stages and by SD; moreover, it increased from growth stage 3 to stage 5. The genotype × year and genotype × irrigation volume interactions were smaller for ABA concentration than for DSI and SD. The broad sense heritability on a plant basis, estimated in drought conditions, for ABA concentration ranged from 21.4 to 55.1% according to maturity group and growth stage. A wide variation was observed among lines for ABA concentration: the medium-maturity group showed a three-fold range (from 219 to 605 ng ABA g−1 dry weight). No clear relationships between ABA concentration, DSI and SD were found. These results indicate the feasibility of a selection for ABA concentration within segregating populations derived from crosses between the inbred lines herein tested.
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  • 156
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    Plant and soil 164 (1994), S. 155-167 
    ISSN: 1573-5036
    Keywords: axile roots ; maize ; nodal roots ; root length ; root system ; seminal roots ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of this work was to study elongation curves of maize axile roots throughout their elongation period under field conditions. Relationships between their elongation rate and the extension rate of their branched region were also studied. Maize, early-maturing cultivar Dea, was grown on a deep, barrier-free clay loam (depth 1.80m). Trenches were dug during four periods until after silking and axile roots were excavated. Parameters measured were total length and the lengths of basal and apical unbranched zones. The rank of the bearing phytomer and general data about the carrying plant were also recorded. Results showed that axile roots from lower phytomers had similar elongation rates irrespective of the rank of the carrying phytomer. This elongation rate declined with root age. A monomolecular elongation model was fitted to the experimental data. Elongation was much slower in roots from upper phytomers. A rough linear relationship was found between the elongation rate of axile roots and the length of the apical unbranched zone. This result suggests that laterals appeared on a root segment a constant time after it was formed. Possible mechanisms with may account for the declining elongation rate with root age (increasing distance from aerial parts or adverse environmental conditions in deep soil layers) and variability between individual roots are also discussed.
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  • 157
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    Plant and soil 164 (1994), S. 169-176 
    ISSN: 1573-5036
    Keywords: branching ; growth ; lateral roots ; maize ; root morphology ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The architecture of the root system is related to its water and mineral uptake. In this paper, the number, growth, and branching of first-order lateral roots are studied on field grown maize (early maturing cultivar ‘Dea’), mainly in relation to the depth and to the rank of the bearing phytomer. The soil was a deep clay loam, without any barrier until 1.80 m. The branching density was studied along axile roots until 1.40 m from the base, on a sample of individually excavated axile roots. A strong gradient of density was shown: the mean branching density decreased from 12 roots.cm−1 near the base to 4 roots.cm−1 at a 60 cm depth. Seminal roots were less densely branched than nodal roots. The mean difference was about 4 roots.cm−1. The length and branching density of lateral roots were studied on mature parts of the root systems where the growth and branching of the laterals were completed, using samples extracted from large soil monoliths. The length distribution of lateral roots was highly asymmetrical, for every source phytomer (mean: 25 mm; median: 16 mm). Many lateral roots were very short, and only 2 % reached a length higher than 10 cm. Only 29 % of all the laterals bore second-order lateral roots. Vigorous laterals branched more systematically and more profusely: the branching density varied from 2 to 5 roots.cm−1 according to the length of the mother lateral root. Both the number and length of lateral roots appeared to be affected by the soil bulk density which varied with the depth.
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    Plant and soil 163 (1994), S. 1-12 
    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 intact Zea mays. L. roots to regulate the amount of free amino-acids present in the rhizosphere. Using metabolic inhibitors it was demonstrated that the release of amino-acids from the root occurred by passive diffusion, whilst free amino-acids outside the root could be re-captured by an active transport mechanism. The influx of amino-acids into the root was shown to be relatively independent of spatial location along the root and was little affected by the presence of other organic compounds in solution. It was deduced from root concentration gradients that the main site of amino-acid exudation was at root tips. Amino-acid uptake by the root was shown to be independent of both inorganic-N concentration and the presence of other organic solutes in solution. A computer simulation model was constructed to assess the contribution of organic-N uptake (acidic, basic and neutral amino-acids) to the plant's N budget, in comparison to the inorganic solutes NO3 and NH4. Simulations of N uptake from a 0.5 mm radius rhizosphere indicated that when inorganic-N concentrations in soil were limiting (≤0.1 μmoles cm-3 soil), the uptake of amino-N accounted for up to 90% the total N taken up by the roots. In situations where fertilizer inputs are high, and levels of organic matter in soil are low, the contribution of amino-N might still be expected to form 〈30% of the total N taken up by the root system. It was concluded that the uptake of amino-acids from the rhizosphere may be important in both N nutrition and in the minimization of root C and N losses to the soil. Consequently this may be important in governing the size of the rhizosphere microbial population.
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    Plant and soil 167 (1994), S. 143-148 
    ISSN: 1573-5036
    Keywords: β-naphthoxy acetic acid (NOA) ; calcium ; gibberellin ; heat ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two cultivars of tomato with contrasting response to elevated temperature were compared: sensitive-Roma and tolerant-Robin. Experiments were done on fruit explants and on rooted cuttings with small fruits. In both cases45Ca was poorly transported to the fruits. Nevertheless in fruit explants elevated temperature (40°C) increased45Ca import into the fruits in both cultivars. In the compared cuttings, treated or not treated with growth regulators and at various temperatures, the greatest differences were observed in the amount of45Ca transported to the fruits. Sensitive Roma cuttings scantily supplied their fruits with45Ca both under optimal temperature and heat stress. In plants previously treated with NOA+GA3 high temperature increased45Ca transport to the fruits. Robin cuttings inversely responded to heat stress by transporting a much higher portion of45Ca to the fruits, both in control and NOA+GA3 cuttings. The diversity of45Ca distribution during elevated temperature in cuttings, but not in fruit explants of both cultivars seems to be connected with an ability to control calcium supply to fruit or at least to prevent its decrease; this mechanism is perhaps located outside the cluster.
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  • 160
    ISSN: 1573-5087
    Keywords: auxin-transport ; indoleacetic acid ; maize ; photoinhibition ; transport ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The uptake of IAA into excised mesocotyls of non-irradiated maize seedlings was linear up to a concentration of about 4×M and in this range there was a tight coupling between the IAA in the stele and the cortex. Prior irradiation with white light of intact seedlings unbalanced this coupling. Lateral and longitudinal transport were affected differently. In the stele, the effect of prior irradiation on longitudinal transport was multiphasic, with an initial stimulatory effect followed by a negative effect at longer prior irradiation times. The lateral transport from the stele to the cortex showed no stimulatory effect and appeared to be inhibited within at least 15 min. The effect of the prior irradiation on longitudinal transport in the stele appeared to be a high intensity effect. In contrast, the effect of the prior irradiation on the lateral transport from the stele to the cortex was saturated at much lower intensities. The data suggest that the light induced change in the lateral transport of IAA between the two tissues may be due to changes either in the number of open lateral transport channels/carriers or in the conductivity of these channels/carriers.
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  • 161
    ISSN: 1573-5087
    Keywords: flower ; organogenesis ; regeneration ; shoot ; thin-layer ; tissue-culture ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Thin layer explants taken from the pedicels and peduncles of flowering tomato plants yielded calli with great organogenetic potential. Of the 15 cultivars tested, 7 regenerated roots, shoots and eventually entire fruit-bearing plants. Calli grown on modified Murashige-Skoog medium responded to varied auxins and cytokinins with different morphogenetic patterns. Thus, naphthaleneacetic acid yielded root-producing calli, while the auxin precursor isatin (indole 2,3-dione) caused the production of calli with vegetative and floral shoots, rarely yielding roots. This may be related to isatin's slow, steady conversion to an active auxin (Plant Physiol 41:1485–1488, 1966) in contrast with naphthaleneacetic acid's immediate presentation of a high level of active auxin. The highest incidence of vegetative shoot (100%) and flower (50%) formation was obtained with 10 μM isatin and 3 μM zeatin. A few of the flowers developed into ripe fruits. The high frequency of induction of vegetative shoots and flowers before roots with isatin suggests its utility in micropropagation from plant tissue cultures.
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  • 162
    ISSN: 1572-9680
    Keywords: alley cropping ; Erythrina poeppigiana ; Gliricidia sepium ; weeds ; maize ; mulch ; weed competition ; weed reduction potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The potential of allye cropping systems to sustain a high productivity with low external inputs and the reduction of maize/weed competition through weed suppression in different alley cropping and sole-cropped mulched systems was studied in Costa Rica at CATIE. Data were recorded eight years after establishment of the experiment. Plant residues ofErythrina poeppigiana trees (10 t/ha dry matter) planted at 6 by 3 m reduced weed biomass by 52%, whileGliricidia sepium trees (12 t/ha dry matter) planted at 6 by 0.5 m reduced weed biomass by 28%, in comparison to controls.Erythrina had a considerable impact on grass weeds, whileGliricidia reduced the incidence of some dicot weeds. Weed competition significantly reduced maize yield in all systems. Nevertheless weed suppression contributed to the higher maize grain yield underErythrina andGliricidia alley cropping of 3.8 t per hectare as opposed to the unmulched control yield of 2.0 t per hectare.
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  • 163
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    Agroforestry systems 26 (1994), S. 249-254 
    ISSN: 1572-9680
    Keywords: phytotoxicity ; cowpea ; Gliricidia sepium prunings ; maize ; seedlings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phytotoxic effects ofGliricidia prunings were tested on maize seedlings in the laboratory and on maize and cowpea seedlings in the field. In the laboratory test, growth of maize seedlings was significantly depressed by addition of leachate ofGliricidia prunings. In the field, leaf, chlorosis of maize and cowpea seedlings occurred when mulched withGliricidia prunings; number of affected leaves increased with increasing mulch rate. Maize was more susceptible than cowpea. This phytotoxic effect, however, did not reduce growth of maize and cowpea seedlings in the field. ApplyingGliricidia mulch one week before planting eliminated the phytotoxic effects on maize.
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  • 164
    ISSN: 1572-9680
    Keywords: alley cropping ; leucaena mulch ; dairy cattle slurry ; maize ; cowpea ; lowland coastal tropics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of leucaena hedgerows, mulching with leucaena foliage (0,50 and 100% of harvested foliage), cowpea intercropping and adition of dairy cattle slurry (55 t ha−1 per maize crop) on the yield of maize from a sandy soil were assessed. The four-year results from five maize crops are reported. Except in the first year, yields of maize grain and stover were significantly reduced by 30% in the presence of leucaena hedgerows. Use of leucaena mulch eliminated this effect; application of all the harvested leucaena mulch (100%) increased the total maize grain yield of the five crops by 44% over sole maize. Hedgerow and mulching management required an additional 36 mandays labour ha−1 which was more than compensated by the increased maize yields. Furthermore leucaena hedgerows substantially depressed the growth of weeds between cropping seasons. Intercropping with cowpea significantly depressed yields of maize grain and stover when both crops were sown together, but not in later seasons when cowpea was sown four weeks after the maize. Application of slurry increased the total yields of maize grain and stover by 35 and 37%, respectively. The grain yield of maize in leucaena hedgerow treatments fertilized with slurry did not respond to application of more than 50% of leucaena foliage, which suggested that half of the foliage could be spared for feeding to livestock. The cumulative yield of maize grain from the highest yielding organic system was 85% of the yield from the fertilizer treatment. The study, which is continuing, demonstrates that large increases in agricultural productivity are possible through the intercropping of maize with woody forage and grain legumes and the integration of dairy cattle production into the system. It thus shows the importance of exploiting crop/livestock interactions.
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  • 165
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    Euphytica 79 (1994), S. 149-161 
    ISSN: 1573-5060
    Keywords: maize ; germplasm ; cluster analysis ; landraces ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two experiments were carried out with two objectives. First, to establish the phenetic relationships among the maize (Zea mays L.) landraces from Galicia (Northwestern Spain) maintained at the Misión Biológica de Galicia. Second, to assess the resemblance between a collection of Spanish populations (including the landraces from Galicia) and a set of US Corn Belt varieties. For the first objective 73 varieties from Galicia, along with 9 hybrid checks, were grown in 9×9 simple lattices at two locations for two years. For the second objective 131 populations from the US Corn Belt and Spain, along with 9 hybrid checks, were grown for three years in unreplicated experiments. Cluster analyses were carried out with the first principal components that accounted for a significant amount of the total variation. Four groups were found among the landraces from Galicia. The populations from Spain and America were classified as belonging to nine main groups. The replicated experiment was more accurate than the unreplicated one. However, it is concluded that an unreplicated test grown in several environments is accurate enough to detect the main groups, although some inaccuracies should be expected.
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  • 166
    ISSN: 1573-5060
    Keywords: maize ; Zea mays ; photoinhibition ; photosynthesis ; low-temperature adaptation ; breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Sixty-seven inbred lines of maize were evaluated for resistance to low-temperature photoinhibition of photosynthesis, using a pulse-modulated chlorophyll fluorescence technique. The evaluation procedure was based on leaf discs, which were exposed to a high irradiance (1000 µmol/m2/s) at 7°C. The efficiency of open PSII reaction centres as a reflection of overall photosynthesis was measured before and after a photoinhibition-inducing treatment. Exposure of leaf discs to photoinhibitory condition for 2, 4, and 8 hours resulted in an efficiency reduction of 30, 53 and 83%, respectively. Testing of inbred lines showed large differences for photoinhibition susceptibility. The difference in photosynthetic efficiency between the most extreme lines after a treatment of eight hours was 39%. Resistance to photoinhibition was shown to be relevant under cool field conditions. It proved to be a trait strongly amenable to selection.
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  • 167
    ISSN: 1573-5036
    Keywords: maize ; P placement ; P supply ; rooting zone ; VAM colonization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Colonization of plant roots by vesicular-arbuscular mycorrhizal fungi is known to be reduced as the phosphorus nutrition of the plant is increased. It is generally accepted that the concentration of P in the plant rather than the soil regulates VAM colonization. Whether it is the shoot P concentration, the mean P concentration in the root system or the P concentration in the specific root being colonized is not known, but is of agronomic significance because fertilizer P is frequently applied in concentrated zones which would be expected to result in higher P concentration in roots growing in the fertilized zone than in the remainder of the root system. Growth chamber and field experiments were conducted to determine the effect on colonization of supplying varying amounts of P to different portions of the rooting zone. In growth chamber studies using a split-pot technique, the proportion of maize (Zea mays L.) root length containing arbuscules in a high-P zone was lower than that of roots of the same plant growing in a low- or medium-P zone. Root P concentration was higher in the high-P zone. In a field experiment conducted over a two-year period, VAM colonization of roots of young maize plants growing in fertilized soil was affected differently than that of roots growing outside the fertilized zone. A small addition of fertilizer P increased colonization of roots in the fertilized soil, but further additions resulted in an abrupt decline followed by a slower further decline, although colonization was not eliminated even by rates of 1600 μg P g-1 soil. Colonization of roots growing outside the fertilized zone declined gradually with increasing P addition but the overall decline was less than for roots in the fertilized zone. The data support the hypothesis that it is P concentration in the portion of the root system being colonized rather than the general P status of the plant which regulates VAM colonization. The agronomic implication of this is that, although a fertilizer band may reduce VAM colonization of roots in the band volume, roots growing outside this volume may be well colonized so the mycorrhizal symbiosis may be an important contributor to P nutrition.
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  • 168
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    Euphytica 79 (1994), S. 13-18 
    ISSN: 1573-5060
    Keywords: Zea mays ; haploid induction ; maternal haploids ; inducer line ZMS ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Presented are the results of a two-year study of haploid maize plants in the field. The haploids were produced with the aid of inducer line ZMS. In total, 604 and 1030 haploids were obtained and studied in the first and second years, respectively. Tassels of haploid plants were found to be almost completley sterile. Fertility of ears was studied by pollinating them with the pollen from diploid inbred lines, the cross resulting in almost all of the haploid ears carrying kernels. On average 27.4 kernels per ear of haploid plant were obtained in the first year of study and 26.3 in the second. These gave rise to normal diploid plants. This property allows genotypes selected at the level of haploid plants to be involved in breeding process. Unusual plants were found among haploids, phenotypically resembling homozygous lines. It was assumed that the plants had resulted from spontaneous chromosome doubling in haploids. The results of comparative studies of progenies of unusual plants and inbred lines derived from the same synthetic population are presented.
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  • 169
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    European journal of plant pathology 100 (1994), S. 279-282 
    ISSN: 1573-8469
    Keywords: ascospores ; biological control ; chinese aster ; germination ; heat resistance ; seed coating ; survival ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Spores of the biocontrol agentTalaromyces flavus were recovered from coating material of chinese aster and tomato seeds in which they were incorporated 17 years before. The seeds had been stored at room temperature. About 20% of the ascospores had retained their heat resistance and survived treatment in aqueous suspension at 60°C for 30 min. None of the chinese aster seeds and 90% of the tomato seeds germinated after the storage period. Presence ofT. flavus during storage had not affected germinability of the seeds.
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  • 170
    ISSN: 1573-8248
    Keywords: Insect parasitoid ; parasitic nematode ; stem borer ; maize ; West Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Des enquêtes sur le terrain ont été effectuées entre 1990 et 1992 en vue d'étudier les espèces présentes et l'abondance relative des parasites des lépidoptères foreurs des tigesSesamia calamistis Hampson etEldana saccharina Walker dans des champs de maïs du sud-ouest du Nigéria. Parmi les espèces de parasitoïdes découvertes sur les deux foreurs de tiges figuraient les parasitoïdes des larves et pupes,Sturmiopsis parasitica Curran (Diptera: Tachinidae) etBrachymeria feae Masi (Hymenoptera: Chalcididae), ainsi que le parasitoïde des larves,Dolichogenidea polaszeki Walker (Hymenoptera: Braconidae). Des attaques du braconidéCotesia sesamiae (Cameron) ont été observées surS. calamistis. L'hyperparasitoïdeExoristobia dipterae (Risbec) (Hymenoptera: Encyrtidae) a été observé sur une pupe deS. parasitica. Des nématodes parasites appartenant àMermis sp. et/ouHexamermis sp. ont été observés sur des larves des deux foreurs des tiges. Dans l'ensemble, le parasitisme larvaire était faible avec des valeurs comprises entre 4.2 et 22.8% pourS. calamistis, et 1.2 et 13% pourE. saccharina. Parmi les parasitoïdes observés, l'espèce la plus courante étaitS. parasitica. Des attaques de quatre hyménoptères parasitoïdes des oeufs ont été observées surS. calamistis: Telenomus busseolae Gahan,T. isis Polaszek (Scelionidae),Lathromeris ovicida Risbec, etTrichrogrammatoidea eldanae Viggiani (Trichogrammatidae). Les oeufs étaient parasités à des valeurs comprises entre 0 et 33%. L'unique parasitoïde des oeufs observé surE. saccharina étaitT. applanatus Bin et Johnson (Scelionidae) qui ne provoquait qu'un parasitisme de 5%.
    Notes: Abstract Field surveys were conducted during 1990–92 to document the relative abundance of different species of parasites of the lepidopterous stem borersSesamia calamistis Hampson andEldana saccharina Walker in maize fields in southwestern Nigeria. Species of parasitoids detected on both stem borers included the larvalpupal parasitoidsSturmiopsis parasitica Curran (Diptera: Tachinidae) andBrachymeria feae Masi (Hymenoptera: Chalcididae), and the larval parasitoidDolichogenidea polaszeki Walker (Hymenoptera: Braconidae). The braconidCotesia sesamiae (Cameron) was found attackingS. calamistis. The hyperparasitoidExoristobia dipterae (Risbec) (Hymenoptera: Encyrtidae) was detected on a pupa ofS. parasitica. Parasitic nematodes belonging toMermis sp. and/orHexamermis sp. were found infesting larvae of both stem borers. Overall, larval/pupal parasitization levels at Ibadan were low and ranged from 4.2 to 22.8% forS. calamistis and 1.2 to 13% forE. saccharina. Of the parasites found,S. parasitica was the most common, followed by nematodes. Four hymenopteran egg parasitoids were found attackingS. calamistis: Telenomus busseolae Gahan,T. isis Polaszek (Scelionidae),Lathromeris ovicida Risbec, andTrichogrammatoidea eldanae Viggiani (Trichogrammatidae). Egg parasitization ranged from 13.4 to 41.5%. The only egg parasitoid detected onE. saccharina wasTelenomus applanatus Bin and Johnson, which inflicted only 5% parasitization.
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  • 171
    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.
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  • 172
    ISSN: 1572-9680
    Keywords: Erythrina ; Gliricidia ; alley cropping ; maize ; competition ; nitrogen availability ; Costa Rica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize growing next toErythrina hedgerows had 44% lower biomass (p〈0.01) and 35% lower N content (p〈0.1) than maize growing in the middle of the alleys. Maize growing next toGliricidia hedgerows had the same biomass but 56% higher N content (p〈0.1) than maize growing in the middle of the alleys. However these differences did not develop until 2 months after sowing of the maize. Spatial variability in soil nitrogen mineralization and mulch nitrogen release did not explain any of the differences in growth or N uptake of the maize with respect to distance from the trees. It is hypothesized that the slower growth of the maize next to theErythrina trees after 2 months is due to increasing light and/or nutrient competition from the trees as the trees recover from pollarding. The apparent lack of competition fromGlirigidia may be due to different rates of regrowth or different shoot and root architecture. A theoretical model is described demonstrating that if a crop is to take advantage of the higher nutrient availability under alley cropping it must complete the major part of its growth before the trees recover significantly from pollarding, and start competing strongly with the crop.
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  • 173
    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.
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  • 174
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    Plant foods for human nutrition 43 (1993), S. 87-95 
    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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  • 175
    ISSN: 1573-5036
    Keywords: Lycopersicon esculentum ; nitrate assimilation ; PEP carboxylase ; phosphorus deficiency ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tomato plants (Lycopersicon esculentum) grown in a complete nutrient solution for 8 days were transferred to a P-free solution of pH 6.0. Within 2 days of transfer the rate of alkalinization of the nutrient solution declined and by 4 days the solution had become acid. Nitrate transferred from roots to leaves was depressed over this period, and the rate of nitrate reductase activity in the leaves (the main site of assimilation of nitrate in tomato) had declined by 60% within 5 days of transfer. The activity of PEP carboxylase in the leaves of the P-deficient plants increased after 3 days, eventually becoming 3 times greater than in the leaves of plants adequately supplied with P. The PEP carboxylase activity in the roots of the P-deficient plants increased within 2 days, becoming 4 times greater after 8 days' growth. These results are discussed in relation to mechanisms for enhancement of P acquisition and maintenance of cation and anion uptake during P-deficiency.
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  • 176
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    Plant and soil 155-156 (1993), S. 99-102 
    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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  • 177
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    Plant and soil 155-156 (1993), S. 87-90 
    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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  • 178
    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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  • 179
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    Plant and soil 151 (1993), S. 97-104 
    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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  • 180
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    Plant and soil 155-156 (1993), S. 45-55 
    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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  • 181
    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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  • 182
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    Plant and soil 152 (1993), S. 261-267 
    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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  • 183
    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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  • 184
    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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  • 185
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    Euphytica 70 (1993), S. 105-111 
    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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  • 186
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    Euphytica 71 (1993), S. 125-130 
    ISSN: 1573-5060
    Keywords: black leaf mold ; epidemiology ; host resistance ; Lycopersicon species ; Pseudocercospora Fuligena ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Over 540 accessions of wild Lycopersicon species or their crosses with L. esculentum were screened for resistance in a series of trials. Forty-six accessions were selected for the final screening trial based on lower disease ratings in previous trials. Of these, L. hirsutum had the greatest number of resistant accessions, followed by L. esculentum and L. peruvianum. Twenty accessions were quantified for their levels of resistance based on leaf area infected, area under disease progress curve (AUDPC), and the degree of sporulation. There was a significant positive correlation between the AUDPC calculated from 20 accessions evaluated under growth room and field conditions. Five L. hirsutum accessions had no sporulation associated with leaf lesions, whereas L. esculentum accessions had an average of 1.6×104 conidia/cm2 of leaf tissue. There was significant positive correlation between the AUDPC values and the number of conidia per cm2 of leaf tissue.
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  • 187
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    Euphytica 71 (1993), S. 161-180 
    ISSN: 1573-5060
    Keywords: tomato ; Lycopersicon esculentum ; Indonesia ; ideotype ; quality problems ; consumer perceptions ; consumer preferences ; price-quality trade-off
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Consumer demands become increasingly strong in Western countries. Product quality has proven to be an important marketing tool to compete effectively on these saturated markets. Markets in developing countries are mostly producer dominated. Not much attention is paid to product quality. Agricultural researchers traditionally are producer-oriented, rather than consumer-oriented. Research on tomatoes in Indonesia has shown, that even in producer dominated markets, consumers have specific wishes regarding quality, which should be taken into consideration in order to develop demand and to enhance farmers' profitability. This paper sheds light on a research methodology to translate consumer preferences into an ideotype, a practical product profile consisting of optimal levels of relevant physical and chemical properties. This ideotype should be used to objectively evaluate agricultural research, aimed at improving product quality. In addition, a list of quality problems of current supply is presented. This priority list serves as a guideline for research planning. Finally, a method is presented to find out to what extend consumers are willing to pay a higher price for improved quality.
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  • 188
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    Euphytica 72 (1993), S. 87-94 
    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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  • 189
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    Euphytica 71 (1993), S. 151-154 
    ISSN: 1573-5060
    Keywords: inheritance ; host resistance ; Lycopersicon esculentum ; tomato ; tomato spotted wilt virus (TSWV) ; tomato chlorotic spot virus (TCSV)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Inheritance studies were conducted to determine the genetic basis of resistance in tomato (Lycopersicon esculentum) against two distinct Tospovirus species (tomato spotted wilt virus and tomato chlorotic spot virus) belonging to the ‘tomato spotted wilt virus complex’ identified in Brazil. F1, backcrosses and F2 populations were developed using the resistant parent ‘CNPH Tx 405’ and susceptible parent ‘IPA-5’. Segregation ratios indicated that the inheritance of resistance to both viruses fit a single dominant gene-model. Preliminary tests using data from 50 pairs of vegetatively propagated F2 plants (inoculated separately with each virus) indicated that the same gene (probably the Sw-5 gene) is controlling the resistance to both viruses. This gene displays a peculiar mode of action, closely resembling a vertical resistance response, but acting against a large number of phenotypic variants and species within the genus Tospovirus.
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  • 190
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    Euphytica 72 (1993), S. 43-49 
    ISSN: 1573-5060
    Keywords: tomato ; powdery mildew ; genetic variation ; Lycopersicon species ; Oidium lycopersicum ; resistance ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Since the late 1980s powdery mildew, designated Oidium lycopersicum, frequently invaded the tomato crop in Western Europe. All commercial cultivars are susceptible. To screen for resistance in wild species a reliable and efficient disease test was developed. Young plants with two to three true leaves are inoculated at high relative humidity by spraying with a freshly prepared suspension of 2×104 conidia, ml−1. Symptoms are periodically evaluated according to a scale based on the percentage of leaf area with mycelium. One hundred and twenty seven accessions, representing eight wild Lycopersicon species, were screened for resistance to O. lycopersicum. A large variation in resistance was found between species. L. hirsutum was the most resistant species; L. pennellii was moderately resistant; species of the subgeneric group of L. esculentum and of the ‘peruvianum-complex’ were all susceptible. L. parviflorum was classified separately due to a large variation between accessions. Except for this species, a low variation was found between accessions within species. High levels of resistance were observed in four accessions of L. hirsutum, in one of L. parviflorum and in one of L. peruvianum. This resistance is characterized by a very low disease incidence and a strongly restricted mycelium growth and lack of sporulation.
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  • 191
    ISSN: 1573-5060
    Keywords: PCR ; molecular tagging ; TMV ; resistance ; RAPD ; tomato ; Lycopersicon esculentum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A RAPD marker, linked to the Tm-2 agene engendering TMV resistance in tomatoes, was identified. The validity of the RAPD marker was corroborated by screening several tomato varieties, and correctly identifying those which carried Tm-2 a, as well as by F2 segregation analysis. All tested resistant varieties descending from a common Lycopersicon peruvianum/esculentum ancestor, LA1791, exhibited this marker.
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  • 192
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    Plant and soil 152 (1993), S. 187-199 
    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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  • 193
    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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  • 194
    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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    Plant and soil 154 (1993), S. 179-188 
    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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  • 196
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    Plant growth regulation 12 (1993), S. 155-160 
    ISSN: 1573-5087
    Keywords: diazocyclopentadiene ; tomato ; fruit ; ripening ; Lycopersicon esculentum ; ethylene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Diazocyclopentadiene (DACP) in the presence of fluorescent light delayed ripening of tomato fruits treated at the mature green (no visible red) stage. At 25 °C, ripening was delayed 10 days if DACP [185 µl/1 (gas)] was added as a single treatment and longer if DACP was added intermittently at 5-day intervals. The addition of 1000 µl/1 ethylene following DACP and light treatment did not hasten ripening. Little ripening delay was noted for fruit + DACP held in darkness. Tomatoes covered with aluminum foil so as to exclude light but not light-activated DACP, showed ripening inhibition. Apparently, the light-activated product from DACP is stable long enough to diffuse into fruit held in darkness. After an initial inhibition, ethylene production was greatly increased in tomatoes treated with DACP. Tomatoes with or without DACP treatment were held either in air or 5% O2/95% N2 for 12 days then treated with ethylene. Treatment with 5% O2 alone delayed ripening when compared to air alone, however, both groups reached 80% red color by 18 days. DACP treated fruit, whether held in air or 5% O2, still were green after 18 days and only approached 80% red color after approximately 27 days. Thus, 5% oxygen did not appear to slow the reversal of DACP inhibition of ripening.
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  • 197
    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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  • 198
    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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  • 199
    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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  • 200
    Electronic Resource
    Electronic Resource
    Springer
    Agroforestry systems 22 (1993), S. 241-258 
    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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