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  • Articles  (1,365)
  • wheat  (649)
  • Solanum tuberosum L.  (270)
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  • Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition  (1,365)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 31 (2000), S. 525-532 
    ISSN: 1432-0789
    Keywords: Key words Ferrihydrite ; Phosphate ; Polygalacturonic acid ; Root mucilage ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  This study was conducted to determine the influence of root mucilage (RM) from Zea mays, polygalacturonic acid (PGA), and galacturonic acid (GA), on the adsorption, desorption, and exchangeability of orthophosphate (P) on a synthetic ferrihydrite in deionized water. The adsorption rate and affinity on the oxide decreased in the order P〉GA〉PGA≥RM. The results suggest that P and GA were adsorbed by ligand exchange on Fe-OH surface sites, while RM and PGA might in addition also be adsorbed by hydrogen and van der Waals bonds to the oxide surface. Whereas P and GA could be adsorbed at sites located inside the micropores of ferrihydrite aggregates, PGA and RM probably remained on the external surfaces because of their large molecular weight. The preliminary adsorption of organic compounds decreased the subsequent P adsorption. The larger decrease of P adsorption occurred when dry ferrihydrite powder was directly added to the RM/water suspension. This effect was due to the flocculation of ferrihydrite aggregates, which limited the transport of P to the adsorption sites. Preliminary adsorption of GA also decreased P adsorption, because both compounds competed for the same Fe-OH sites. The ability of the organic compounds to desorb P from the ferrihydrite was not very pronounced and decreased in the order GA〉PGA≥RM. The preliminary adsorption of organic compounds on the oxide resulted in an increase in isotopically exchangeable P in 300 min compared to the treatment without organic compounds. However, because of its higher affinity for the oxide surface, P exchangeability was not modified when P was added before the organic compounds.
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  • 2
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    Biology and fertility of soils 31 (2000), S. 348-355 
    ISSN: 1432-0789
    Keywords: Key words Agroforestry ; Land use ; Nitrate leaching ; Zea mays ; Musa spp.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  We hypothesized that the integration of trees and shrubs in agricultural landscapes can reduce NO3 – leaching and increase utilization of subsoil N. A field survey was conducted on 14 farms on acid soils in the subhumid highlands of Kenya, where there is little use of fertilizers, to determine the effect of vegetation types (VT) on soil NH4 + and NO3 – to 4 m depth. The VT included maize (Zea mays) with poor growth and good growth, Markhamia lutea trees scattered in maize, natural weed fallow, banana (Musa spp.), hedgerow, and eucalyptus woodlot. The effect of VT on NH4 + was small (〈1 mg N kg–1). NO3 – within a VT was about constant with depth below 0.25 m, but subsoil NO3 – varied greatly among VT. Mean NO3 –-N concentrations at 0.5–4 m depth were low beneath hedgerow and woodlot (〈0.2 mg kg–1), intermediate beneath weed fallow (0.2–0.7 mg kg–1), banana (0.5–1.0 mg kg–1) and markhamia (0.5–1.6 mg kg–1), and high beneath both poor (1.0–2.1 mg kg–1) and good (1.9–3.1 mg kg–1) maize. Subsoil NO3 – (0.5–4 m) was agronomically significant after maize harvest with 37 kg N ha–1 m–1 depth of subsoil beneath good maize and 27 kg N ha–1 m–1 depth beneath poor maize. In contrast, subsoil NO3 – was only 2 kg N ha–1 m–1 depth beneath woodlot and hedgerow. These results demonstrate that the integration of perennial vegetation and the rotation of annual and perennial crops can tighten N cycling in agricultural landscapes.
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  • 3
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    Springer
    European journal of plant pathology 106 (2000), S. 693-698 
    ISSN: 1573-8469
    Keywords: differential gene expression ; grey mould ; ribosomal biogenesis ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To identify genes of the necrotrophic pathogenic fungus Botrytis cinerea that are expressed during infection of tomato leaves, a differential screening of a genomic library with radioactively labelled cDNA was performed. This resulted in the identification of a B. cinerea gene, denominated Bcubi4, which encodes a precursor protein consisting of four identical head-to-tail repeats of a 76 aa ubiquitin unit. Subsequently a gene denominated Bcubi1CEP79, encoding a single ubiquitin unit joined to a Carboxyl Extension Protein of 79 amino acids, was isolated. The expression of the two ubiquitin genes was studied during pathogenesis of B. cinerea on tomato. Bcubi1CEP79, but not Bcubi4, mRNA was transiently induced at 16 h after inoculation. The increased expression of the Bcubi1CEP79 gene at this stage of pathogenesis might be required for enhanced ribosomal biogenesis.
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  • 4
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    European journal of plant pathology 106 (2000), S. 465-473 
    ISSN: 1573-8469
    Keywords: tomato ; powdery mildew ; Oidium lycopersici ; host range ; host resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nine accessions of three cucurbit species, ten of eight legume species, three of lettuce (Lactuca sativa) and 34 of 14 Solanaceae species were inoculated with a Dutch isolate of the tomato powdery mildew fungus (Oidium lycopersici) to determine its host range. Macroscopically, no fungal growth was visible on sweet pepper (Capsicum annuum), lettuce, petunia (Petunia spp.) and most legume species (Lupinus albus, L. luteus, L. mutabilis, Phaseolus vulgaris, Vicia faba, Vigna radiata, V. unguiculata). Trace infection was occasionally observed on melon (Cucumis melo), cucumber (Cucumis sativus), courgette (Cucurbita pepo), pea (Pisum sativum) and Solanum dulcamara. Eggplant (Solanum melongena), the cultivated potato (Solanum tuberosum) and three wild potato species (Solanum albicans, S. acaule and S. mochiquense) were more heavily infected in comparison with melon, cucumber, courgette, pea and S. dulcamara, but the fungus could not be maintained on these hosts. All seven tobacco (Nicotiana tabacum) accessions were as susceptible to O. lycopersici as tomato (Lycopersicon esculentum cv Moneymaker), suggesting that tobacco is an alternative host. This host range of the tomato powdery mildew differs from that reported in some other countries, which also varied among each other, suggesting that the causal agent of tomato powdery mildew in the Netherlands differ from that in those countries. Histological observations on 36 accessions showed that the defense to O. lycopersici was associated with a posthaustorial hypersensitive response.
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  • 5
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    European journal of plant pathology 106 (2000), S. 589-592 
    ISSN: 1573-8469
    Keywords: Closterovirus ; Crinivirus ; ToCV ; tomato ; whiteflies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tomato chlorosis virus (ToCV), a new whitefly-transmitted and phloem-limited Crinivirus infecting tomatoes in Europe, is reported for the first time in Portugal. Tomato plants with symptoms of interveinal chlorosis, collected during autumn 1998 and summer and autumn 1999 in Algarve, southern Portugal, were positive in RT-PCR assays using ToCV-specific primers. The amplified 439 bp fragment was sequenced and showed 99% homology with the ToCV sequence in the GenBank database. A digoxigenin–DNA probe was produced and tested in dot-blot with total RNAs extracted from tomato samples. Both the RT-PCR and dot-blot hybridisation procedures enabled rapid and reliable detection of ToCV from field samples.
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  • 6
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    Nutrient cycling in agroecosystems 57 (2000), S. 75-82 
    ISSN: 1573-0867
    Keywords: nitrogen ; leaching ; paddy soil ; wheat ; rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrogen in percolation water was observed in paddy field soil under rice/wheat rotation. Different N-application rates were designed. Porous pipes were installed in triplicate at depths of 30, 60 and 90 cm to collect the water in the period of wheat growth. Suction cups were installed in triplicate at the same depths to collect the water during the period of rice growth. NH4 +, NO3 - and total N in the water were analysed with a continuous-flow nitrogen analyzer. Results showed that nitrate was the predominant form of nitrogen in percolation water during the period of wheat growth. Nitrate leaching was high in early spring after the `tillering fertilisation'. More than 50 mg l-1 of nitrate concentration in percolation water was observed for 30 and 60 cm in depth and more than 15 mg l-1 were observed for 90 cm. The concentration decreased quickly and was very low, less than 2 mg l-1 usually, in the earring stage of wheat. Nitrate in water was low, less than 1.5 mg l-1 usually, when the field was flooded during the period of rice growth. Some soluble organic N existed in the water. Nitrate in percolation water increased when the field was drained. The leaching loss of nitrogen during winter wheat growth period was estimated to be about 3.4% of the N-fertiliser applied at the normal application rate of farmers; for the rice growth period it was around 1.8%. Although a reduced N-application decreased N leaching, it caused a marked decrease in crop yield.
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  • 7
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    Nutrient cycling in agroecosystems 58 (2000), S. 131-139 
    ISSN: 1573-0867
    Keywords: automated closed chamber method ; wheat ; cowpea ; slow-release nitrogen fertilizer ; residue management ; denitrification ; methane sink ; rainfall
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rainfed rice (Oryza sativa L.)-based cropping systems are characterized by alternate wetting and drying cycles as monsoonal rains come and go. The potential for accumulation and denitrification of NO3 − is high in these systems as is the production and emission of CH4 during the monsoon rice season. Simultaneous measurements of CH4 and N2O emissions using automated closed chamber methods have been reported in irrigated rice fields but not in rainfed rice systems. In this field study at the International Rice Research Institute, Philippines, simultaneous and continuous measurements of CH4 and N2O were made from the 1994 wet season to the 1996 dry season. During the rice-growing seasons, CH4 fluxes were observed, with the highest emissions being in organic residue-amended plots. Nitrous oxide fluxes, on the other hand, were generally nonexistent, except after fertilization events where low N2O fluxes were observed. Slow-release N fertilizer further reduced the already low N2O emissions compared with prilled urea in the first rice season. During the dry seasons, when the field was planted to the upland crops cowpea [Vigna unguiculata (L.) Walp] and wheat (Triticum aestivum L.), positive CH4 fluxes were low and insignificant except after the imposition of a permanent flood where high CH4 fluxes appeared. Evidences of CH4 uptake were apparent in the first dry season, especially in cowpea plots, indicating that rainfed lowland rice soils can act as sink for CH4 during the upland crop cycle. Large N2O fluxes were observed shortly after rainfall events due to denitrification of accumulated NO3 −. Cumulative CH4 and N2O fluxes observed during this study in rainfed conditions were lower compared with previous studies on irrigated rice fields.
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  • 8
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    Plant and soil 222 (2000), S. 139-147 
    ISSN: 1573-5036
    Keywords: elemental sulphur ; oilseed rape ; sulphate ; sulphur fertilisers ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A pot experiment was conducted to compare the availability and efficiency of three sulphur (S) fertilisers to wheat in the first year and oilseed rape in the second year, using six agricultural soils. Four treatments were applied in the initial year: control (no S), two forms of elemental S (either micronised S° particles or a bentonite + S° mixture) and a sulphate fertiliser (ammonium sulphate). In the first year, the micronised S° was as effective as the sulphate fertiliser, both producing similar increases of wheat grain yield (on average 36%) and S uptake (on average 164%) over the control. In contrast, responses to the bentonite + S° form were minimal, indicating a limited S supply. In the second year the control treatment failed to produce seeds in most soils, whereas the micronised S° and sulphate treatments increased seed yields of oilseed rape to an average of 13.4 and 12.9 g pot-1, respectively. The performance of the bentonite + S° varied between soils: two soils produced yields similar to those of the other S fertilisers, while the remaining soils had low yields. To test whether the poor performance of the bentonite clay + S° fertiliser was due to the lack of exposure of the prills to physical weathering in the glasshouse, the effect of freeze-thaw action on the fertilisers performance was assessed in a separate pot experiment. The responses in wheat yield and S uptake showed that freeze-thaw did not enhance the physical disruption of the prills or fertiliser effectiveness. These results suggest that the release of available S from the bentonite + S° mixture was too slow to meet the requirement of wheat and oilseed rape.
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  • 9
    ISSN: 1573-5036
    Keywords: biological control ; Paecilomyces lilacinus ; Pseudomonas aeruginosa ; root-knot nematode ; root-infecting fungi ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Efficacy of Pseudomonas aeruginosa alone or in combination with Paecilomyces lilacinus was evaluated in the control of root-knot nematode and root-infecting fungi under laboratory and field conditions. Ethyl acetate extract (1 mg/ml) of P. lilacinus and P. aeruginosa,respectively, caused 100 and 64% mortality of Meloidogyne javanica larvae after 24 h. Ethyl acetate fractions of biocontrol agents were more effective than hexane extracts in the suppression of M. javanica larvae, indicating that active nematicidal compounds are intermediary in polarity. In field experiments, biocontrol fungus and bacterium significantly suppressed soilborne root-infecting fungi including Macrophomina phaseolina, Fusarium oxysporum, Fusarium solani, Rhizoctonia solani and Meloidogyne javanica, the root-knot nematode. P. lilacinus parasitized eggs and female of M. javanica and this parasitism was not significantly influenced in the presence of P. aeruginosa. P. aeruginosa was reisolated from the inner root tissues of tomato, whereas P. lilacinusdid not colonize tomato roots.
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  • 10
    ISSN: 1573-5087
    Keywords: abscisic acid (ABA) ; dormancy ; mature germination ; seed ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seed dormancy develops latein embryogenesis after a period of potential prematuregermination and has been associated with levels ofabscisic acid (ABA) in, and sensitivity to, ABA ofembryos. In wheat (Triticum aestivum L.)embryos, there are two peaks in levels of ABA duringdevelopment: the first occurs 25 days afterpollination (DAP) and the second from 35 to 40 DAP. The first peak of ABA appears to be associated withthe development of the embryo's sensitivity to ABAsince such sensitivity was altered in seeds on earsthat were incubated in a solution of ABA from 15 and20 DAP. In the embryos of Kitakei wheat, a line thatexhibits dormancy, the second peak, at around 35 DAP,was more prolonged in comparison to Chihoku, anon-dormant line. The results support the proposedinvolvement of ABA in the formation and maintenance ofseed dormancy during middle and late embryogenesis. When developing embryos were incubated in water,embryonic ABA leaked out from the embryos, inparticular between 30 and 40 DAP. Prematuregermination observed between 30 and 40 DAP might berelated to such leakage of ABA from embryos.
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  • 11
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    Plant growth regulation 32 (2000), S. 151-155 
    ISSN: 1573-5087
    Keywords: ATP production ; ATPase ; auxin ; membrane vesicles ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Microsomal membrane vesicles and purified plasma membranevesicles obtained from coleoptiles of maize (Zea mays L.) weresubjected to pH shifts from pH 7.8 to 4.7. In the presence of ATPaseinhibitors such as vanadate, net accumulation of radiolabelled butyricand indole-3-acetic acid (IAA) remained higher than in controls. When 2min after the pH shift, at 4°C, the microsomal vesicles weredenatured the amount of ATP could be determined using theluciferin/luciferase assay. Significantly increased ATP production overcontrol values – no pH-shift or ionophore treatment – wasfound. Therefore, such vesicles might produce ATP for in vitrotransport processes such as auxin efflux.
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  • 12
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    Genetic resources and crop evolution 47 (2000), S. 281-284 
    ISSN: 1573-5109
    Keywords: agronomic traits ; isozymes ; landrace ; Triticum aestivum ; variation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A sample of an Argentinean landrace of wheat showed considerable variation in most of the evaluated morphological and agronomic characters. However, analyses with high molecular glutenins and two isozyme systems, known to be highly polymorphic among current cultivars, revealed very little or no variation, respectively. The large difference in the observed variation between morphoagronomic and biochemical characters is discussed.
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  • 13
    ISSN: 1573-5060
    Keywords: aluminum tolerance ; genetic control ; induced mutations ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The behavior of 17 gamma irradiation mutant lines derived from the aluminum sensitive wheat cultivar `Anahuac' was compared with two sensitive and three tolerant cultivars in nutritent solutions containing seven Al3+ concentrations (0; 0.5; 1; 2; 4; 6 and10 mg/liter), at a temperature of 25 °C and 4.0 pH. Tolerance was measured by the continued growth of the primary roots in a solution without aluminum after 48 hours in a solution containing a known concentration of aluminum. 14 mutant lines were as tolerant to the presence of 10 mg/liter of Al3+ in the treatment solutions as were the tolerant `BH-1146', `IAC-60' and `IAC-24' cultivars. Two mutant lines were tolerant and one was sensitive to the presence of 1 mg/liter of Al3+, while the cultivars `Siete Cerros' and `Anahuac' were sensitive to 1 and 0.5 mg/liter Al3+ in the solutions, respectively. F2 seedlings, obtained from cross among one sensitive and twelve tolerant mutant lines to the sensitive cultivars (`Siete Cerros' or `Anahuac') and the tolerant cultivars (`BH-1146' or `IAC-24') were assessed for tolerance to 2 mg/liter Al3+ in nutritient solutions. The twelve tolerant mutant lines and the tolerant `IAC-60' and `IAC-24' cultivars differed from the sensitive `Siete Cerros' or `Anahuac' cultivars by one pair of dominant alleles. The results indicated that tolerance in the induced mutants was due to a single pair of dominant alleles and that these alleles expressed the same tolerance as `BH-1146' and `IAC-24' cultivars.
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  • 14
    ISSN: 1573-5060
    Keywords: Fusarium head blight ; intermating breedingpopulation ; male-sterile gene ms 2 ; recurrent selection ; resistance ; Triticum aestivum L. ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Four cycles of recurrent selection for FHB resistance were conducted in an intermating wheat breeding population using the dominant male-sterile gene ms 2 during 1987–1991.Five cycles of phenotypic mass selection for male-sterile plants were evaluated using the soil-surface inoculation method in Experiment I. Experiment II evaluated changes in FHB scores during five cycles of progeny selection for fertile plants using the single-floret inoculation method. In Experiment I, the average level of FHB response increased to MR level in C4, compared to MS level in C0. The numbers of infected spikelets and diseased kernels decreased 0.32 and 2.68 per cycle, respectively. In Experiment II, the average level of FHB response increased to R level in C4F1. The numbers of infected spikelets and diseased kernels decreased 0.93 and 4.58 per cycle, respectively. In both experiments, the largest selection gains were realized in the first cycle. The frequencies of R and MR individuals were increased significantly. The frequencies of individuals with FHB response equal and/or superior to Sumai 3 were increased to 5–8% in C4 and 25% in C4F1after the fourth cycle. Agronomic traits tended to be slightly improved in selected populations. Compared to 2% in C0, about 34% of lines superior in both FHB resistance and agronomic traits in C4F1 were selected to enter the conventional breeding program for further evaluation. Sixty three semidwarf lines superior in both FHB resistance and yield potential were selected from the F5 generations derived from C1F1 to C4F1. From them, two resistant cultivars with high-yielding potential were developed and commercialized in the Lower Yangtze Valley. Recurrent selection appears to be highly effective and feasible in shifting the average FHB response of the intermating population in the desirable direction, thereby enhancing the frequency of resistant individuals.
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  • 15
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    Euphytica 112 (2000), S. 261-265 
    ISSN: 1573-5060
    Keywords: grain texture ; microtome ; quality ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Although grain texture has been extensively studied, there is still some controversy about its mode of inheritance. The aim of this study was to use a microtome method to determine the inheritance of grain texture. The backcross method was used with a hard, well adapted cultivar, M29519 as recurrent parent, and Edwall, a soft cultivar with good biscuit-making quality, as donor. Segregation ratio's for grain texture were calculated after each backcross. The backcross derivates M29519 (soft) and M29519 (hard) and the donor and recurrent parents were also compared for biscuit-making quality. The microtome method was found to be very effective to determine grain texture. In this study grain softness was determined by a single dominant gene. M29519 (hard) and the recurrent parent did not differ significantly for any quality characteristics. M29519 (hard) and M29519 (soft) differed significantly for seven characteristics associated with biscuit-making quality, and M29519 (soft) produced a significantly larger biscuit diameter than M29519 (hard). M29519 (soft) differed significantly from the donor parent for six of the measured characteristics. Despite this, M29519 (soft) produced a biscuit similar in diameter to that of the donor parent. Therefore, although the transfer of the softness genes into a different genetic background did not transfer all the factors generally associated with good biscuit-making quality, it did produce a biscuit that did not differ significantly from that of the donor.
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  • 16
    ISSN: 1573-5060
    Keywords: disease resistance ; incubation period ; infection frequency ; Stagonospora nodorum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Septoria nodorum blotch is the most important leaf disease of wheat in Western Australia. A potentially useful source of resistance has been identified in an accession of Aegilops tauschii. To study the genetics of resistance of this source a cross was made between the resistant Ae. tauschii accession, RL5271, and a susceptible accession, CPI110889. The resistant parent took significantly longer to develop symptoms, developed significantly fewer lesions and expressed significantly lower levels of disease than the susceptible parent. The F1 mean response for disease severity indicated there was no complete dominance. The F3 families were classified using three approaches. In the first approach the individual F3 plant response was used to classify the F3 families. In the second approach the F3 family means and standard errors were used to classify the F3 families. In the final approach Best Linear Unbiased Predictors of disease score and standard error for each F3 family derived from a REML analysis were used to classify the F3 families. The genotypic ratios generated by each of the approaches suggested that resistance is controlled by a single gene. The effectiveness of the resistance and its simple genetic control in the Ae. tauschii, accession RL5271 may be a useful resistance source for use in a bread wheat breeding program.
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  • 17
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    Plant growth regulation 32 (2000), S. 295-305 
    ISSN: 1573-5087
    Keywords: Cold stress ; Immunolocalization ; Phaseolus vulgaris ; Zeatin O-glycosyltransferase ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Zeatin O-glycosides have been reported as inactive and stable storage forms of cytokinins whose concentrations increase in cold stressed plants. Zeatin O-glycosides accumulation in developing bean seeds has been correlated with an increase of zeatin O-glycosyltransferase , which is specific to trans-zeatin, and catalyzes the conjugation of zeatin O-glycosides. When Phaseolus vulgaris and Zea mays seedlings were grown for 3 days at 25 and then incubated at 4 or 10 for 6 days no further growth was observed in roots. Hypertrophy was observed in the root tips of both species. In shoot-hypocotyl complexes, in contrast, growth occurred when seedlings were incubated at 10 . Western analysis, with Mabs specific to zeatin O-glycosyltransferase, detected antigenically related proteins in roots, shoot tips and cotyledons after seedlings were cold stressed for 1–6 days at 4 or 10 . Immunolocalization, of both maize and bean root sections grown at 25 revealed antigenically related proteins that were detected at low levels in cortical cells. The signal intensified upon cold stress. The localization of zeatin O-glycosyltransferase in Z. mays root tips was directly comparable to the distribution of the zeatin O-glycosides. The enzyme was detected in the nucleus, cytoplasm, and closely associated with the plasma membrane and in the cell wall of Z. mays root cells. Southern analysis suggested that more than one gene in Z. mays that were homologous to zeatin O-glycosyltransferase in P. vulgaris. Zeatin O-glycosyltransferase may be involved in modulation of cytokinins under cold stress.
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  • 18
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    Plant growth regulation 32 (2000), S. 219-230 
    ISSN: 1573-5087
    Keywords: Arabidopsis thaliana ; arbuscular mycorrhiza ; biosynthesis ; indole-3-acetic acid ; indole-3-butyric acid ; regulation ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Within the last ten years it has been established by GC-MS thatindole-3-butyric acid (IBA) is an endogenous compound in a variety ofplant species. When applied exogenously, IBA has a variety of differenteffects on plant growth and development, but the compound is stillmainly used for the induction of adventitious roots. Using moleculartechniques, several genes have been isolated that are induced duringadventitious root formation by IBA. The biosynthesis of IBA in maize(Zea mays L.) involves IAA as the direct precursor. Microsomalmembranes from maize are able to convert IAA to IBA using ATP andacetyl-CoA as cofactors. The enzyme catalyzing this reaction wascharacterized from maize seedlings and partially purified. The invitro biosynthesis of IBA seems to be regulated by several externaland internal factors: i) Microsomal membranes from light-grownmaize seedlings directly synthesize IBA, whereas microsomal membranesfrom dark-grown maize plants release an as yet unknown reaction product,which is converted to IBA in a second step. ii) Drought and osmoticstress increase the biosynthesis of IBA maybe via the increaseof endogenous ABA, because application of ABA also results in elevatedlevels of IBA. iii) IBA synthesis is specifically increased byherbicides of the sethoxydim group. iv) IBA and IBA synthesizingactivity are enhanced during the colonization of maize roots with themycorrhizal fungus Glomus intraradices. The role of IBA forcertain developmental processes in plants is discussed and somearguments presented that IBA is per se an auxin and does notact via the conversion to IAA.
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  • 19
    ISSN: 1573-5036
    Keywords: biomass ; intercepted radiation ; nitrogen nutrition ; oilseed rape ; radiation use efficiency ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We investigated the response of spring wheat and oilseed rape to nitrogen (N) supply, focusing on the critical period for grain number definition and grain filling. Crops were grown in containers under a shelter and treated with five combinations of applied N. Wheat and oilseed rape produced comparable amounts of biomass and yield when corrected for the costs of biomass synthesis (SC). From the responses of biomass and yield to late N applications and the apparent contribution of mobilised biomass to yield, it seems that the yield of oilseed rape was more source-limited during grain filling than that of wheat, particularly at the medium and high N levels. Both species recovered equal amounts of N from the total available N in the soil and had similar N use efficiencies, expressed as yield per unit of N absorbed. However, oilseed rape had higher efficiency to convert absorbed N in biomass, but lower harvest index of N than wheat. Oilseed rape had similar or lower root biomass than wheat, depending on N level, but higher root length per unit soil volume and specific root length. The specific uptake rate of N per unit root dry weight during the critical period for grain number determination was higher in oilseed rape than in wheat. In wheat, N limitation affected growth through a similar or lower reduction in radiation use efficiency corrected for synthesis costs (RUESC) than in the cumulative amount of intercepted photosynthetically active radiation (IPARc). In oilseed rape, lower growth due to N shortage was associated more with RUESC than IPARc, during flowering while during grain filling both components contributed similarly to decreased growth. RUESC and the concentration of N in leaves and inflorescence (LIN%) decreased from flowering to maturity and were curvilinearly related. Oilseed rape tended to have higher RUESC than wheat at high N supply during the critical period for grain number determination, and generally lower during grain filling. The reasons for these differences and possibilities to increase yield potential are discussed in terms of the photosynthetic efficiency of the different organs and changes in source–sink ratio during reproductive stages.
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  • 20
    ISSN: 1573-5036
    Keywords: amino acids ; chicory ; copper ; tomato ; xylem sap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of rooting media Cu concentration (0.05–20 mg Cu L-1) on amino acid concentrations and copper speciation in the xylem sap of chicory and tomato plants was measured using 6 week old plants grown in a nutrient film technique system (NFT). Irrespective of the Cu concentration in the nutrient solutions, more than 99.68% and 99.74% of total Cu in tomato and chicory xylem sap was in a bound form. When exposed to high Cu concentrations in the rooting media, amino acid concentrations in the sap increased. Relative to other amino acids, the concentrations of glutamine (Gln), histidine (His), asparagine (Asn), valine (Val), nicotianamine (NA) and proline (Pro) in tomato xylem saps, and His, γ-aminobutyric acid (Gaba), glutamic acid (Glu), leucine (Leu), NA and phenylalanine (Phe) in chicory xylem saps showed the greatest increases. The data indicate that induced synthesis of some free amino acids as a specific and proportional response to Cu treatment. For a single complexation amino acid, the solution Cu2+concentration vs pH titration curve for NA at 0.06–0.07 mM was most similar, closely followed by His at 0.5–0.6 mM, to the solution Cu2+concentration behaviour in both tomato and chicory xylem sap. It is concluded that increased Cu concentrations in the rooting media induced selective synthesis of certain amino acid which include NA, His, Asn and Gln which have high stability constants with Cu. NA and His have the highest binding constants for Cu and the concentrations of NA and His in chicory and tomato xylem saps can account for all the bound Cu carried in the sap.
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  • 21
    ISSN: 1573-5036
    Keywords: chicory ; Cu distribution ; Cu uptake ; free Cu2+ ; tomato ; xylem sap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The uptake and distribution of copper was examined in chicory (Cichorium intybus L. cv. Grasslands Puna) and tomato (Lycopersicon esculentumMill. cv. Rondy) plants grown in a Nutrient Film Technique System (NFT) with addition of 0.05, 5, 10 and 20 mg Cu L-1. Biomass production of shoots and roots of both chicory and tomato was strongly depressed by Cu concentrations higher than 5 mg Cu L-1 in the rooting media. Although Cu concentrations in both shoots and roots of both species increased with increasing Cu concentrations in the rooting media, the increase in roots was very much greater than that in shoots, in which the range of concentrations was small. A large proportion of total Cu uptake was retained by roots except when plants were grown in solution Cu concentrations of 0.05 mg Cu L-1. Copper retention by roots limited Cu translocation to xylem and shoots. Copper adsorption by the root appears to buffer against increases of Cu in the rooting media. A cupric-sensitive electrode used in conjunction with total Cu analysis by graphite furnace atomic absorption spectrophotometry (GFAAS) indicated that more than 99.6% of total Cu in xylem sap was in a complexed form. Large differences between measured and predicted Cu accumulation by shoots of tomato (0.134–0.243 mg Cu plant-1, 0.660–4.274 mg Cu plant-1, respectively) and chicory (0.095–0.203 mg Cu plant-1, 0.626–1.620 mg Cu plant-1, respectively) suggest that some xylem transported Cu is recirculated to roots via the phloem.
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  • 22
    ISSN: 1573-5036
    Keywords: Andisol ; phosphatases ; phosphorus ; roots ; VA mycorrhiza ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus deficiency is a major yield limiting constraint in wheat cultivation on acid soils. The plant factors that influence P uptake efficiency (PUPE) are mainly associated with root characteristics. This study was conducted to analyze the genotypic differences and relationships between PUPE, root length density (RLD), colonization by vesicular arbuscular and arbuscular mycorrhizal (V)AM fungi and root excretion of phosphatases in a P-deficient Andisol in the Central Mexican Highlands. Forty-two semidwarf spring-bread-wheat (Triticum aestivumL.) genotypes from CIMMYT were grown without (−P) and with P fertilization (+P), and subsequently in subsets of 30 and 22 genotypes in replicated field trials over 2 and 3 years, respectively. Acid phosphatase activity at the root surface (APASE) was analyzed in accompanying greenhouse experiments in nutrient solution. In this environment, PUPE contributed more than P utilization efficiency, in one experiment almost completely, to the variation of grain yield among genotypes. Late-flowering genotypes were higher yielding, because the postanthesis period of wheat was extended due to the cold weather at the end of the crop cycles, and postanthesis P uptake accounted for 40–45% of total P uptake. PUPE was positively correlated with the numbers of days to anthesis (at −P r=0.57 and at +P r=0.73). The RLD in the upper soil layer (0–20 cm) of the wheat germplasm tested ranged from 0.5 to 2.4 cm cm-3 at –P and 0.7 to 7.7 at +P. RLD was the most important root trait for improved P absorption, and it was positively genetically correlated with PUPE (at –P r=0.42 and at +P r=0.63) and the number of spikes m-2 (at –P r=0.58 and at +P r=0.36). RLD in the upper soil layer was more important with P fertilizer application. Without P fertilization, root proliferation in the deeper soil profile secured access to residual, native P in the deeper soil layer. (V)AM-colonisation and APASE were to a lesser degree correlated with PUPE. Among genoptypes, the level of (V)AM-colonisation ranged from 14 to 32% of the RLD in the upper soil layer, and APASE from 0.5 to 1.1 nmol s-1 plant-1 10-2.
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  • 23
    ISSN: 1573-5036
    Keywords: Crop residues ; dry-matter yields ; Medicago sativa ; N mineralization ; 15N uptake ; Zea mays ; VAM fungi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Legume crop residues serve as a source of nitrogen (N) for succeeding crops in low-input production systems, and characterizing the release of this N supports efforts to develop sound economic and environmental management practices. Nitrogen mineralization of 15N-labelled field crop residues was monitored in a Greenville sandy loam during a 140-day laboratory incubation at 25°C. Residue type strongly influenced the rate of N mineralization; decomposition rate constants were 0.283, 0.083, 0.00047 and 0.0014 day-1 for alfalfa (Medicago sativa L.) stover (above-ground plant parts), alfalfa roots, maize (Zea mays L.) stover (above-ground plant parts excluding cob and kernels) and maize roots, respectively. At the end of the incubation, 50% of alfalfa stover and 25% of alfalfa root residues N were mineralized, whereas these proportions were 8% for maize stover and 12% for root residues. Mineralization of 15N from alfalfa stover residues was also monitored in a greenhouse experiment to determine N availability during the growth of maize inoculated or not with vesicular-arbuscular mycorrhizal (VAM) fungi, and to evaluate the effects of the presence of plants on the decomposition of the residues. Stover and root dry matter yields were greatest for maize inoculated with VAM fungi and grown in residue-amended soil. At the final harvest, maize grown in residue-amended soils had accumulated 44% more dry matter and 40% more N than maize grown in unamended soils. Enhanced VAM colonization of roots inoculated with a mixture of three Glomus spp. increased the residue N accumulation in maize roots at 5 weeks after silking and at the final harvest. Alfalfa stover decomposed rapidly both in the presence and absence of maize plants, but the amount of 15N mineralized at the end of the experiment was influenced by the presence of living roots; 23% of the 15N in alfalfa stover residues was mineralized in soil without plants compared to about 38% when maize plants were present. These results suggest that N mineralization is enhanced by the presence of living roots.
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  • 24
    ISSN: 1573-5036
    Keywords: agricultural practices ; extra-radical mycelium ; Gliricidia sepium ; organic matter addition ; Peltophorum dasyrachis ; soil disturbance ; species richness of AMF ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two pre-established agricultural field trials were assessed for the abundance of arbuscular mycorrhizal fungi (AMF) in the soil (density of spores, species richness and lengths of extra-radical mycelium [ERM]) in association with one of three tropical plant species (Gliricidia sepium, Peltophorum dasyrachis and Zea mays). The trials were managed by one of three agricultural practices: soil disturbance in a monoculture system, a root barrier to prevent interactions between plants in an agroforestry system or the addition of organic matter (OM) in an agroforestry and a monoculture system. The lengths of ERM of AMF in the soil were greater in the agroforestry system than the monoculture system. These were greater when a root barrier was present, but decreased when OM was added. Soil disturbance reduced the density of spores, species richness and the lengths of ERM of AMF compared with the undisturbed soil. This work indicates that agricultural trials may provide a useful tool to monitor the abundance of AMF in the field. Clearly, there is potential to increase the abundance of AMF, from different genera, in the soil through the management of agricultural practices. The significance of the abundance of AMF for subsequent benefits to plant growth and development and ultimately the sustainability of tropical agro-ecosystems are discussed.
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  • 25
    ISSN: 1573-5060
    Keywords: Host plant resistance ; heat-sensitivity ; root-knot nematodes ; tomato ; virulence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Accessions of Lycopersicon peruvianum complex and their F1progenies were screened for genotype specific resistance to Mi-1-avirulent M. incognita and M. javanica biotypes at25 °C and at 32 °C (a temperature at which Mi-1resistance is not expressed), and to Mi-1-virulent M.incognita at 25 °C. All entries of the L. peruvianumChotano-humifusum race accessions LA2157 and LA2334 were resistantto Mi-1-avirulent biotype at 25 °C and at 32 °C,indicating that the accessions are homozygous for the heat-stableresistance. The L. peruvianum Maranon race accessions LA1626,LA1708, LA2172, LA2185, LA2326 and LA2328 segregated for heat-stableresistance to Mi-1-avirulent biotype. The F1 progeny tested ofLA392 × LA2157, LA2334 × LA2157, LA2328 × LA2326,LA2328 × LA2185, LA1708 × LA2328 andLA1626 × LA2172 were resistant to Mi-1-avirulent biotype at32 °C. There were differences in the segregating accessions andF1 hybrids for expression of heat-unstable and heat-stable resistanceto Mi-1-avirulent Meloidogyne spp. The L. peruvianumLA392 and LA2163 and L. chilense LA1968, LA1972, LA2404, LA2405,LA2406, LA2748, LA2930, and the L. peruvianum × L.chilense hybrids were homozygous susceptible with all entries testedsusceptible at 32 °C. Cuttings of these L. peruvianumaccessions and their F1 progenies were susceptible to Mi-1-virulent M. incognita biotype at 25 °C.
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  • 26
    ISSN: 1573-5060
    Keywords: Andean maize ; cold tolerance ; germplasm evaluation ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Cold in the initial growth stages is an important stressfactor for maize grown in regions with a temperate climate,particularly in case of early sowing. Sources of tolerancehave been identified in adapted genotypes, but promisinggenes for cold tolerance should also be found in materialdeveloped under the lower-temperature margins of the cropdistribution. This research was conducted in order to testAndean maize accessions for cold tolerance expressed duringboth the heterotrophic and early autotrophic growth stages.Experiments were conducted in controlled environments tostudy cold tolerance traits (germination %, germinationindex and plant growth rate) at continuous 10°C (heterotrophic growth) and at varying 10–16°C (autotrophic growth). An experiment was also performed inthe field with early sowing (both heterotrophic and autotrophic growth). In each experiment, a control trialwas conducted in more favourable conditions (i.e. continuous25°C in a controlled environment or late planting inthe field) so that cold tolerance traits could also beexamined as the ratio between the stress and the controltrial. None of the accessions was superior for all coldtolerance traits. However, several Andean maize accessionsoutperformed the US Corn-belt hybrid checks for one or moretraits, both in heterotrophic and autotrophic growth. Overall, BOZM 855, PMS 636, Poblacion D, Poblacion E andBOZM 696 were the best accessions, suggesting that they canbe a promising source of genes for improving cold toleranceof adapted maize genotypes.
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  • 27
    ISSN: 1573-5060
    Keywords: interplot interference ; Lycopersicon esculentum ; Lycopersicon pennellii ; Lycopersicon pimpinellifolium ; spider mites ; Tetranychus urticae ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We have previously found an accession of Lycopersicon pimpinellifolium (Jusl.) Mill. (`TO-937') that appeared to resist attack by the two-spotted spider mite (Tetranychus urticae Koch). L. pimpinellifolium is a very close relative of the cultivated tomato (Lycopersicon esculentum Mill.) and thereby a potential source of desirable traits that could be introgressed to the crop species. The objective of this study was to investigate the genetics of the resistance present in `TO-937'. Resistance to infestation by the spider mite was quantified in 24-plant plots of L. pimpinellifolium accessions `TO-937' and `PE-10', L. pennellii accession `PE-45', L. esculentum cultivars `Moneymaker', `Roma' and `Kalohi' (reported to be partially resistant: Stoner & Stringfellow, 1967), and the interspecific F1 cross, L. esculentum `Moneymaker' × L. pimpinellifolium `TO-937'. Only `TO-937', the F1, and`PE-45' were found to be resistant. Resistance of `TO-937' was complete when evaluated in two small greenhouses completely planted with `TO-937' so as to simulate the genotypic homogeneity usual in commercial crops. Generations (P1, P2, F1, F2, BC1P1, and BC1P2) of a P1 (susceptible) × P2 (resistant) cross (`Moneymaker' × `TO-937') were studied for resistance in a single-plant per plot design. Resistance of `TO-937' was inherited with complete dominance and appeared to be controlled by either two or four genes according to whether segregation in the F2 or the BC1P1, respectively, were considered. However, calculation of the number of genes involved in the resistance was complicated by negative interplot interference due to the high frequency of resistant genotypes within most of the generations.
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  • 28
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    Euphytica 111 (2000), S. 199-203 
    ISSN: 1573-5060
    Keywords: Diuraphis noxia (Mordvilko) ; protein ; Russian wheat aphid ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), has become a perennial, serious pest of wheat (Triticum aestivum L.) in the western United States. Current methodologies used to enhance RWA resistance in wheat germplasm could benefit from an understanding of the biochemical mechanisms underlying resistance to RWA. This study was initiated to identify specific polypeptides induced by RWA feeding that may be associated with RWA resistance. The effects of RWA feeding on PI 140207 (a RWA-resistant spring wheat) and Pavon (a RWA-susceptible spring wheat) were examined by visualizing, silver-stained denatured leaf proteins separated by two-dimensional polyacrylamide gel electrophoresis. Comparisons of protein profiles of noninfested and RWA-infested Pavon and PI 140207 revealed a 24-kilodalton-protein complex selectively inhibited in Pavon that persisted in PI 140207during RWA attack. No other significant qualitative or quantitative differences were detected in RWA-induced alterations of protein profiles. These results suggest that RWA feeding selectively inhibit synthesis and accumulation of proteins necessary for normal metabolic functions in susceptible plants.
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  • 29
    ISSN: 1573-5036
    Keywords: drainage ; duplex soil ; evapotranspiration ; lupin ; waterlogging ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of time of sowing and sowing density on evapotranspiration and drainage loss beneath wheat (Triticum aestivum cv. Spear) and lupin (Lupinus angustifolius cv. Gungurru) crops grown on a layered soil was investigated for three seasons in a Mediterranean climate in Western Australia. The aim of the study was to investigate whether managing crops to maximise their canopy growth would increase their water use and minimise groundwater recharge contributing to dryland salinity. A soil water balance approach was used to estimate evapotranspiration, with changes in soil water content measured with a neutron water meter. The study was carried out on a layered soil typical of agricultural soils in the region with variable depth to clay (0.22–0.38 m) and a marked contrast in hydraulic properties between the topsoil and subsoil. As a result of the low permeability subsoil, a perched water table occurred in the sandy topsoil in each of the three seasons under study during winter when rainfall was high and potential evaporation low. Perched water tables persisted for 2–3 months, with hydraulic gradients consistently downward causing drainage losses to occur. Although crop management had a large influence on shoot and root development, evapotranspiration from the different treatments was generally similar. Drainage losses were not influenced by either crop type, time of sowing or sowing density, because potential evaporation and hence evapotranspiration was low during the period when drainage losses occurred. The total drainage loss measured in each season was different, with losses ranging from 20.1 to 22.2 mm in 1990, from 40.4 to 46.7 mm in 1991 and from 49.4 to 66.6 mm in 1992. The increase in drainage loss from 1990 to 1992 was a result of progressively more seasonal rainfall in 1990, 1991 and 1992. It was concluded that there was little scope to increase water use and decrease deep drainage through crop management for sites with climatic conditions where winter rainfall exceeds potential evaporation.
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  • 30
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    Plant and soil 225 (2000), S. 187-191 
    ISSN: 1573-5036
    Keywords: Azospirillum brasilense ; 2 ; 4-D ; para-nodules ; saline stress ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of saline stress on the colonization of wheat was analyzed by using Azospirillum brasilense Cd carrying the fusion of the reporter gene lacZ (β-galactosidase) with the N2 fixation gene promoter nifA. Colonization was also studied by inducing para-nodules on wheat roots using 2,4-D, establishing that these structures acted as bacterium protected niches. Bacteria grown under standard conditions were distributed along the whole root system, except the elongation zone, and colonized the para-nodules. Bacteria experiencing saline stress were mainly localized at the root tips and the lateral roots. In 2,4-D treated plants, most of the bacteria were present around the basal surface of the modified lateral root structures. Using the MPN method, there were not statistical differences between the numbers of control and stressed bacteria. As this method estimates endophytic colonization in contrast with the one using X-gal, which emphasizes colonization on the root surface, both procedures demonstrated to be necessary, concluding that salt treatment reduced surface colonization (X-gal) but not colonization inside the root. The bacterial counts made on inoculated wheat roots indicated higher numbers of both control and stressed bacteria in roots treated with 2,4-D compared with untreated roots.
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  • 31
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    Plant and soil 226 (2000), S. 113-116 
    ISSN: 1573-5036
    Keywords: aluminium ; root cells ; stress adaptation ; structural response ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant cells respond to a certain stress factor in different ways depending on their developmental stage and type of tissue. Structural damage may be severe or even lethal in individual cells within a tissue that exhibits moderate or no effects of stress. In the case of aluminium toxicity, detailed observations of root tips of 3 day old Zea mays L., cv. TO360 seedlings revealed differences in the response of some cells. Two different structural changes appeared within root epidermis just behind the root cap. Cells with dark and shrunken cytoplasm occurred next to swollen cells with preserved cellular compartments. Within the root cortex, individual cells or a few cells of a file have severely damaged cytoplasm, in contrast to almost undisturbed cytoplasm of adjacent cells. Such extremely sensitive cells appear irregularly within the root apex. Their structural similarity with cells that are observed after a hypersensitive response in infected plant tissues suggests a role to accumulate aluminium, in order to allow the surrounding tissue to survive the stress.
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  • 32
    ISSN: 1573-5036
    Keywords: residual effect of gypsum ; rice ; selenium toxicity ; sulphur ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field experiment was conducted for 2 years on an alkaline calcareous seleniferous soil to study the effect of different levels of gypsum (0.2 – 3.2 t ha−1) applied to wheat only in the first year on Se accumulation by wheat (Triticum aestivum L.) – rice (Oryza sativa L.) cropping sequence. With gypsum application, grain yield of both rice and wheat crops increased by 0.4 – 0.5 t ha−1; the increase in straw yield was 0.4 – 1.1 t ha−1. Significant reduction in Se accumulation by wheat was observed with gypsum application up to 0.8 t ha−1 and its residual effect was evident on the following crops for 2 years. Reduction in Se accumulation varied from 53 to 64% in wheat grain, 46 to 49% in wheat straw, 35 to 63% in rice grain and 36 to 51% in rice straw with an application of gypsum at 0.8 t ha−1. A corresponding increase in S concentration was observed. In the gypsum-treated plots, the ratio of S:Se increased by 6 – 8 times in wheat and 3 – 6 times in rice. Reduction in Se accumulation by crop plants through gypsum application may help in lowering the risk of Se over-exposure of animals and humans that depend on diet materials grown on high selenium soils.
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  • 33
    ISSN: 1573-5060
    Keywords: barley ; GISH ; in situ hybridization ; translocation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheat-barley translocations were identified by genomicin situ hybridization (GISH) in backcross progenies originating from in vitro regenerated wheat (Triticum aestivum L. cv. Chinese Spring) × barley (Hordeum vulgare L. cv. Betzes) hybrids. The regenerated hybrids were pollinated with the wheat line Martonvásári 9 kr1. Five translocated wheat-barley chromosomes were recovered among 51 BC2F2 progeny from the in vitro regenerated wheat × barley hybrids. All were single breakpoint translocations with the relative positions of the breakpoints ranging from the centromere to about 0.8 of the relative arm length. Of the four translocations with intercalary breakpoints, three were transfers of terminal barley segments to wheat chromosomes; one was a transfer of a terminal wheat segment to a barley chromosome. Because of the absence of diagnostic N-bands, the identity of three barley segments could not be determined; in one translocation the barley chromosome involved had a NOR so it must have been 5H or 6H, and the centric translocation was 4HS.2BL. Following selfing, homozygotes of four translocations were selected. The experiment suggests that in vitro culture conditions are conducive for major genome rearrangements in wheat-barley hybrids.
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  • 34
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    Euphytica 112 (2000), S. 157-166 
    ISSN: 1573-5060
    Keywords: barley ; cer ; β-diketone ; glaucous ; pre-harvest sprouting ; waxes ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Morphological features of the cereal ear, including awns, alter pre-harvest sprouting damage by changing the rate of water absorption during rainfall. In this paper, the potential for wheat (Triticum sp.) arid barley (Hordeum vulgare L.) waxes to reduce sprouting by increasing water repellency of the mature ear has been examined. Six barley F2 populations segregating for different non-glaucous single-gene mutants controlling waxes on ears were examined. Water repellency was assessed by measuring both the contact angle of a water drop placed on the lemma surface (internal angle) and by repetitive weighings of whole ears during their exposure to simulated rainfall. The lemma of glaucous (wild type) lines had larger water drop contact angles, an indication of poorer spread of water over the surface. In simulated rainfall, ears of the glaucous lines showed a clear reduction of wetting (20–30% less) and, after 72 h of wetting, their in-ear sprouting was reduced by 50 to 65%. When pre-wet, the glaucous ears also shed water more readily when shaken to simulate the combined effect of wind and rainfall. To reduce pre-harvest sprouting of barley it may be possible to screen visually for ears that are more glaucous but a more specific screen would be to select for lemma water drop contact angle since it is a good indicator of ear wettability and so allows differences in surface properties to be assessed. For bread wheat (T. aestivumL.), as for barley, the more glaucous the ear, the greater the water drop contact angle and the more tubular surface wax coverage seen in scanning electron microscope images. In addition, surface wax amount apparently affected in-ear wettingin lines of durum wheat, (T. turgidum L.). Possible genetic relationships between waxy/waxless genes in wheat and barley are suggested with the aim, ultimately, of altering ear glaucousness to give increased water repellency and a reduction of in-ear sprouting of wheat.
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  • 35
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    Euphytica 113 (2000), S. 65-70 
    ISSN: 1573-5060
    Keywords: cross prediction ; grain yield ; recombinant inbred lines ; single seed descent ; wheat ; yellow rust
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Populations of F6 recombinant inbred lines, generated by single seed descent from a half diallel among eight bread wheat lines adapted to the East African highlands, were used to identify those crosses that were more likely to produce cultivars which combined resistance to yellow rust with improved yield. Crosses having the most resistant line as one parent offered the best prospect of success, particularly those which produced F1hybrids exhibiting better parent heterosis. For plot grain yield there was a highly significant correlation between the observed and predicted rankings of the recombinant inbred line populations for the proportion of individual lines equalling or surpassing the target value. For yellow rust severity, however, this correlation was non-significant when a target value of zero was used. Adopting a slightly less stringent target of 0.25, coupled with the omission of two aberrant populations, increased this correlation significantly. The plant breeding implications of these results are discussed.
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  • 36
    ISSN: 1573-5060
    Keywords: cultivars ; drought stress ; droughtsusceptibility index ; landraces ; wheat ; yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a 2-years experiment, 30 wheat cultivars and 21 landraces from different countries were tested under near optimum and drought stress conditions. Plant height, number of sterile spikelets per spike, spikelets per spike, number of kernels per spike, kernel weight per spike, 1000 kernel weight and grain yield were evaluated. The number of kernels per spike, 1000 kernel weight and especially yield were more sensitive to drought stress in the cultivars than plant height and number of spikelets per spike, while in the landraces these traits did not differ under drought stress compared to near optimum conditions. The average yield of cultivars was significantly better than the average yield of landraces under near optimum as well as drought stress conditions. Path coefficient analysis showed that for cultivars under near optimum conditions there was no significant direct association of any of the analysed characters with yield, while under drought stress conditions, number of kernels per spike had a significant positive direct effect. Under drought stress conditions, the number of sterile spikelets displayed a negative direct effect, while kernel weight per spike had a positive direct effect on yield. Hierarchical cluster analysis was used as a tool to classify cultivars and landraces according to their yield ability under near optimum and drought stress conditions. Among the cultivars, two groups out of five and among one of three in the landraces were characterised by high yields in both near optimum as well as under drought stress conditions. These genotypes may serve as sources of germplasm for breeding for drought tolerance.
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  • 37
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    Euphytica 115 (2000), S. 149-158 
    ISSN: 1573-5060
    Keywords: Maize ; mature plant resistance ; Striga hermonthica ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Twelve maize genotypes with different degrees of resistance were evaluated in plots inoculated with seeds of the phytoparasite Striga hermonthica (Del.) Benth. and in Striga-free (control) plots for three seasons between 1991 and 1993. Resistant genotypes, although showing similar levels of underground infection as susceptible 9 weeks after maize planting (WAP), had significantly fewer emerged parasitic plants and sustained lower damage. Host damage was not determined by the severity of infection. Percent height and dry matter reductions increased from 3 to 6 WAP for resistant and susceptible genotypes. While percent height and dry matter reductions for resistant genotypes declined at 9 and 12 WAP, susceptible genotypes either maintained or increased their levels of damage. Correlation between the severity of height and dry matter reductions at the vegetative (3 and 6 WAP) and reproductive (9 and 12 WAP) stages of maize growth were not significant, indicating that damage at early stages of growth cannot be used to predict mature plant response. Maize damage score (1–9) at 8 WAP, a non destructive and composite shoot indicator of host performance under Striga infestation, was significantly correlated (r = 0.88, r = 0.82; p 〈 0.01) to the level of shoot reduction at mature plant stages. Emerged Striga count at 8 WAP was significantly correlated (r = 0.98, p 〈 0.01) to the count at 10 WAP, the time when parasite emergence was highest. Under high and uniform infestation, mature plant resistance can be detected at 8 WAP, the onset of flowering in maize.
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  • 38
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    Euphytica 115 (2000), S. 167-172 
    ISSN: 1573-5060
    Keywords: alien genetic variation ; chromosome translocation ; powdery mildew ; resistance ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A powdery mildew resistant double disomic wheat-rye substitution line carrying rye chromosomes 1R and 2R was crossed with normal bread wheats. The F2 generation was analysed cytologically by C-banding. Wheat-rye chromosome translocations involving both rye chromosomes 1R and 2R were frequent in F2. Lines with translocations of 1R and 2R were harvested separately. After four generations of selfing and selection for mildew resistance and fertility, fully fertile resistant lines were selected and analysed cytologically. Lines with 1BL/1RS and 2BS/2RL translocations were identified. The resistance on chromosome 1RS could not be shown to be different from control varieties carrying the same rye segment, while the resistance on 2RL is much broader than the earlier known 2RL derived resistance in the line Transec.
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  • 39
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    Potato research 43 (2000), S. 287-295 
    ISSN: 1871-4528
    Keywords: nutrient analysis ; culture media ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Boron (B) requirements differ widely among plant species and the concentration range between toxicity and deficiency is less for B than for any other nutrient. Excess B can adversely affect calcium (Ca) uptake and plant growth. Potato cvs Bintje and Norland plantlets were micropropagated on Murashige & Skoog (MS) nutrient medium, supplemented with 3 (MS control level) or 9 mM Ca, and a range of H3BO3 levels (0.025 to 0.300 mM B). Medium B levels of 0.100 and 0.300 mM decreased Ca content in leaves and shoots of cv. Norland, but not Bintje. Medium B level of 0.025 mM, which is 25% of the control MS level, enhanced Ca uptake in cv. Norland and did not compromise normal plantlet growth in either cultivar. This lower H3BO3 level (0.025 mM B), and a B-free gelling agent such as Gelrite, could be used for micropropagation of potato and possibly other species susceptible to Ca defifiency disorders.
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  • 40
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; plant development ; antioxidant genes ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The expression of antioxidant genes has been analyzed in a potato plant and during tuber dormancy. Manganese superoxide dismutase (MnSOD), cytosolic copper and zinc superoide dismutase (Cu/ZnSOD), catalase class II, cytosolic ascorbate peroxidase (APX) and glutathione peroxidase (GPX) are expressed at the RNA level in all the contexts analyzed. By contrast, the expression of the iron superoxide dismutase (FeSOD) and plastidic Cu/ZnSOD seems to be limited to green tissues, as shown by northern blots and native gels. A complex DAB-peroxidase isozyme pattern (using diaminobenzidine as substrate) has been observed in different developmental contexts analyzed, but hardly observed in tubers. During tuber dormancy, MnSOD and cytosolic Cu/ZnSOD activity was relatively constant in both Désirée and Bintje varieties while catalase activity decreases. Moreover, tuber dormancy breakage did not involve significant changes in the activity of these enzymes. On the basis of these results, the possible link between active oxygen species (AOS) metabolism and dormancy is discussed.
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  • 41
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    Potato research 43 (2000), S. 43-48 
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; Decis® ; Colorado potato beetle ; tuber quality ; dry matter content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Tubers showed changes in their nutritional value caused by the treatment of the plants with the insecticide deltamethrin. The level of starch was increased in comparison with control tubers; but the amylose percentage was not affected. In contrast, the total protein content decreased in tubers from treated plants, whereas free amino acids level and ascorbic acid content increased. The results showed that the changes in the tubers caused by the treatment of potato plants with deltamethrin did not adversely affect the nutritional value of the progeny tubers.
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  • 42
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    Potato research 43 (2000), S. 97-106 
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; National List ; Recommended Trials ; growing crop ; tuber ; yield ; quality ; disease ; nematodes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In 1994, a postal questionnaire was sent to 41 institutes in 27 countries to obtain information on the national potato cultivar testing programmes in Europe. Responses were received from 19 countries. Foliage, tuber and yield characteristics were assessed in all countries but the number of sites and replicated varied considerably between the countries. Cooking and taste qualities were measured in most countries using relatively simple methods but processing characteristics were tested less commonly. Susceptibility to the most common diseases, i.e. late blight, common scab, leafroll and PVYo, was assessed in over 75% of the countries while resistance to another 21 disease and 4 potato cyst nematode pathotypes was assessed by various countries, depending on their national importance. Many of the assessments were based on records of natural infection although controlled inoculation tests were done more frequently for the more important diseases.
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  • 43
    ISSN: 1871-4528
    Keywords: actinomycetes ; resistance ; scab incidence ; Solanum tuberosum L. ; Streptomyces scabies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Concentrations of Ca, P, K, Mg, Al, Fe, Mn, Cu and Zn were determined in healthy tuber peelings of cultivars less (Karin, Santé and Symfonia) and more (Agria, Désirée and Tomensa) susceptible to common scab when grown at two sites that differed in the level of scab incidence. The accumulation of some elements was significantly influenced by site, year, cultivar, maturity and the age of tuber periderm. At both sites, Ca and P in periderm tissue declined but Mg increased during the growing season. The Ca/P ratios in tuber periderm of all cultivars greatly decreased 83 days after planting. Concentrations of mineral elements measured at harvest may not reflect conditions present during the infection period, and consequently may not be related to scab incidence or severity.
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  • 44
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; prickle pollination ; ploidy level ; flow-cytometry ; adventitious shoots ; in vitro tuber induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary For the induction and selection of double mutants with altered starch composition, a uniform (homohistont) amylose-free (amf) monoploid as basic plant is of vital importance. Therefore, newamf monoploids had to be developed via prickle pollination. And 26 monoploids were obtained which were screened in vitro for vigour, leaf size and for the percentage of monoploid cells. The number of monoploid cells was underestimated at about 28%. Seven vigorous monoploids were tested in vitro for tuberization capacity, which varied from 0 to 100%. After regeneration in vitro, 0 to 3.7 adventitious shoots per leaf explant were formed. The tuberization capacity of these shoots varied from 0 to 48. Twoamf monoploids were selected which were vigorous and tuberized well in vitro. They are the basis for the application of an in vitro mutation breeding protocol that should lead to the induction and selection of new starch mutants in potato.
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  • 45
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    Potato research 43 (2000), S. 253-261 
    ISSN: 1871-4528
    Keywords: laboratory tests ; storage ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary After a wet autumn and harvesting under wet conditions, slugs brought into potato stores via clods and soil adhering to tubers may cause substantial damage by feeding on the tubers. A carvone sprout inhibitor, Talent®, applied in the potato stores at a dose of 50 ml per tonne potatoes, controlled slugs within a few days. A dose of 25 ml carvone was insufficient. Using a laboratory box test, the slug (Deroceras reticulatum) affected only wounded tubers and, although slime was present on the unwounded potatoes, they were not damaged by slugs.
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  • 46
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    Potato research 43 (2000), S. 273-278 
    ISSN: 1871-4528
    Keywords: cold storage ; store management ; potato handling ; tuber temperature ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of using radiant heat to quickly warm potatoes and reduce damage in handling after cold storage was investigated. Two treatments were investigated: tubers dropped 350 mm with no radiant heat applied, and tubers dropped with radiant heat applied. Both treatments were compared with a control set of tubers which were taken directly out of store. The mean damage index per tuber was significantly reduced following radiant heat treatment although there were cultivar and size variations. The temperature profile under radiant heat was also measured which showed an increase in the outside flesh temperature of 8–12°C depending on tuber colour.
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  • 47
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; damage ; bruising ; blackspot ; handling ; velocity change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Potatoes are exposed to mechanical forces which can lead to subcutaneous tissue discoloration resulting in losses. We investigated the number and intensity of impacts in different phases of representative Dutch ware potato handling chains using an instrumented sphere (IS). Other questions we asked were, to which drop height onto a defined surface do measured impacts correspond, and what is the relation between the number of impacts and damage? Close relationships between peak acceleration and velocity change for different drop heights were found for various cushioning materials, thus allowing interpretation of impact measurements in terms of drops. The IS recorded c. 340 impacts exceeding 30g. The contribution to the total number of impacts was 11% for Harvest, 0% for Storage, 10% for Transport and 79% for Packaging. The number and intensity of impacts correlated well with the amount of subcutaneous tissue discoloration. It is concluded that the produce-friendliness of the handling chains can be improved.
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  • 48
    ISSN: 1871-4528
    Keywords: chemical inducible gene expression ; glutathione S-transferase ; Solanum tuberosum L. ; herbicide safener ; tuber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Chemically inducible gene regulation systems provide a mechanism for a temporal control of expression of transgenes. In this study expression from the herbicide safener inducible maize GST-27 promoter was tested in potato, with the aim of using this to provide inducible expression of transgenes implicated in dormancy control. A binary vector comprising 3.8 kb of the GST-27 promoter was fused to the β-glucuronidase (GUS) reporter gene and transformed into potato. Application of the chemical inducer elevated the expression of GUS up to 40 fold in leaf tissue. However in stems, roots and tubers the GST-27 promoter caused high levels of expression of GUS in the absence of safener, demonstrating that in these tissues it acts as a constitutive promoter. A deleted promoter region of the GST-27 promoter displayed a similar expression pattern. Analysis of GUS activity in dormant and sprouting tubers showed that the GST-27 promoter was a strong constitutive promoter throughout the tuber life cycle.
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  • 49
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    Potato research 43 (2000), S. 49-59 
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; soil fertility ; soluble salts ; plant spacing ; Rhizoctonia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Excessive fertilizer application in North Carolina, USA results in high residual soil levels of P, K and total soluble salts in potato fields. Our objectives were to determine the salt sensitivity of three common cultivars (Atlantic. Snowden and Superior), and the effects of planting density and fertilization on stand establishment, soilborne disease, and yield. Greenhouse results suggest that potato growth and emergence, but not shoot initation, are reduced by high salinity. On a Portsmouth fine sandy loam, high fertilizer rates did not reduce stands of cv. Atlantic in the field in 1996 or 1997. Excess N resulted in moreRhizoctonia stem canker in 1996, and lower yields at the lower planting density in 1997. Yield compensation for reduced plant density occurred in 1997 at the lower N rates (56 and 112 kg N ha−1) and at the high PK rate (49 kg P and 139 kg K ha−1).
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  • 50
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; potato tuberization ; growth regulators
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A reverse of the delaying effect of gibberellic acid (GA3) was observed in in vitro tuberization of potato plantlets when the medium contained 0.8×10−5 M jasmonic acid (JA). The promoting effect of JA seemed to be correlated with the initial absence of growing roots, probably through direct activity of JA in microtuber-producing buds in the stoloniferous shoots. This is based on the fact that JA did not inhibit root growth a posteriori. Endogenous gibberellins (GAs) synthesized by roots did not interfere with the previous activity of JA in tuberization. The absence of a JA promoting-effect on tuberization of previously-rooted plantlets could be related to the capacity of potato roots to synthesize endogenous GAs which might antagonize the JA effect on buds of stoloniferous shoots.
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  • 51
    ISSN: 1871-4528
    Keywords: transgenic plants ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Helicoverpa armigera is one of the important insect pests adversely affecting the yield of potatoes in India. A synthetic gene encoding the insecticidal crystal protein (Cry1Ab) ofBacillus thuringiensis (Bt) has been introduced into five genotypes of potato usingAgrobacterium tumefaciens. Southern analysis of DNA from transgenic plants confirmed the integration and copy number of the transgene. Double-antibody quantitative sandwich ELISA analysis demonstrated high levels of Cry1Ab protein expression in transgenic plants. Insect bioassays on the leaves of transgenic plants showed considerable protection against the larvae ofH. armigera in terms of leaf area consumed and larval weight reduction.
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  • 52
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; damage ; bruising ; impact ; blackspot ; handling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In the chain of handling operations from harvesting to packaging inclusive, potatoes are exposed to many brief mechanical forces (impacts) and to long-term pressure. Impact and pressure can lead to subcutaneous tissue discoloration causing qualitative and quantitative losses. We investigated the characteristics of construction and utilization of representative Dutch ware potato handling chains and found that the number and height of drops appeared to be too high, the use of cushioning materials insufficient and the speed of the transporting parts too high and not in balance with each other. The contribution to the total amount of subcutaneous tissue discoloration was 16% for the harvesting to bin filling phases inclusive, 22% for the storage phase, 27% for the shovelling to truck loading phases inclusive and 35% for the truck unloading to packaging phases inclusive. These contributions varied considerably within phases and within links. The results can be used to develop equipment, upgrade present chains and design new, produce-frendly handling chains.
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  • 53
    ISSN: 1871-4528
    Keywords: Helminthosporium solani ; storage conditions ; disease resistance ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Optimum storage conditions to identify resistance to silver scurf among commercially grown potato cultivars were determined in a series of experiments. Inoculation of field-grown tubers with a conidial suspension ofH. solani (concentration 104 conidia per ml of water) and incubation at 15°C with 95% RH for 1 month followed by 2 months at 85% RH produced the greatest differences in disease severity between potato cultivars. Results with glasshouse-grown tubers were comparable with those from field-grown tubers, indicating that the test could be used to identify resistance in wild species of potato and to understand the inheritance of this resistance.
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  • 54
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    Molecular breeding 6 (2000), S. 169-174 
    ISSN: 1572-9788
    Keywords: AFLP ; flour colour ; STS ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Flour colour is an important quality trait in the production of bread, noodles and other related end products. Current screening for flour colour in breeding programs requires several grams of flour to be milled. In order to screen large numbers of plants, a rapid PCR-based assay is required. We report here the conversion of a codominant AFLP marker linked to a major locus controlling flour colour in hexaploid wheat, to a sequence tagged site (STS) marker for use in marker-assisted selection (MAS). The two-allelic AFLP bands were cloned and sequenced to allow specific primers to be designed. The primers amplified bands of the expected size in the parental varieties and co-segregated with the original AFLP marker in the mapping population. The primers also amplified alleles of the expected size from the DNA of parental lines of two other related mapping populations. Cultivars that contributed to the pedigree of the original parent `Schomburgk' used to generate the mapping population were also screened to determine the origin of the `yellow' allele.
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  • 55
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; Storite Clear ; Storite Flowable ; radionuclide ; scintillation counting ; sprout suppression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The use of imazethapyr as a sprout suppressant in potatoes has been investigated. Novel radionuclide techniques were developed to establish the patterns of uptake and movement of imazethapyr in potatoes. Protocols for tissue analysis were established to homogenise potato tuber tissue samples, enabling radiolabel recovery by liquid scintillation counting to approach 100%. The movement of imazethapyr was also examined in the presence of an acidic formulation of thiabendazole which caused increased uptake. The movement of imazethapyr within the tuber was also influenced by pH and ion trapping.
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  • 56
    ISSN: 1871-4528
    Keywords: root-water uptake ; modeling ; SWACROP ; Ferralsols ; tropics ; Cuba ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The SWACROP root-water uptake function for potatoes was determined in the 1994–95 crop season on a Ferralsol in Havana province, west Cuba. The maximum pressure-heads under which water is optimally extracted by potato roots were very similar to the original Feddes function. Nevertheless, the anaerobiosis point and the wilting point pressure-head in both functions were not in agreement. However, the simulated values of soil water contents in the 0–40 cm soil depth by performing SWACROP runs in the 1995–96 potato crop season using both functions were very similar. The original Feddes function seems to be good enough for predicting soil water contents in the tropics and no specific other functions need to be developed for any particular soil or climate condition.
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  • 57
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; sexual reproduction ; oospores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The severity of late blight tuber rot in five potato cultivars (Green Mountain, Sebago, Dorita, AC Brador and Island Sunshine) resulting from inoculation with US-1/US-8 combinations of Canadian isolates ofPhytophthora infestans was evaluated. In addition, the potential for mixed (A1∶A2) inoculations to result in oospore formation was examined. In studies conducted in 1996 and 1997, cv. Dorita (and Island Sunshine in 1997) developed the least amount of surface or internal necrosis relative to the other cultivars following co-inoculation with US-1 and US-8 isolates ofP. infestans. Differences also were revealed among isolate combinations used for inoculation. The combination of a US-1 isolate from Prince Edward Island with a US-8 isolate from New Brunswick consistently produced the least amount of necrosis in tubers of the various cultivars. There was no evidence of oospore production in any of the tubers examined.
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  • 58
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    Integrated pest management reviews 4 (1999), S. 127-143 
    ISSN: 1572-9745
    Keywords: wheat ; stored-grain ; integrated pest management ; aeration ; biological control ; grain sampling ; insect monitoring ; modeling ; area-wide IPM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Management of stored-grain insect pests by farmers or elevator managers should be based upon a knowledge of the grain storage environment and the ecology of insect pests. Grain storage facilities and practices, geographical location, government policies, and marketing demands for grain quality are discussed as factors influencing stored-grain insect pest management decisions in the United States. Typical practices include a small number of grain samples designed to provide grain quality information for segregation, blending and marketing. This low sampling rate results in subjective evaluation and inconsistent penalties for insect-related quality factors. Information on the efficacy of insect pest management practices in the United States, mainly for farm-stored wheat, is discussed, and stored-grain integrated pest management (IPM) is compared to field-crop IPM. The transition from traditional stored-grain insect pest control to IPM will require greater emphasis on sampling to estimate insect densities, the development of sound economic thresholds and decision-making strategies, more selective use of pesticides, and greater use of nonchemical methods such as aeration. New developments in insect monitoring, predictive computer models, grain cooling by aeration, biological control, and fumigation are reviewed, their potential for improving insect pest management is discussed, and future research needs are examined.
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  • 59
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    European journal of plant pathology 105 (1999), S. 629-641 
    ISSN: 1573-8469
    Keywords: wheat ; Triticum spp. ; Septoria tritici ; septoria tritici blotch of wheat Stagonospora nodorum ; stagonospora nodorum blotch of wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 60
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    European journal of plant pathology 105 (1999), S. 363-372 
    ISSN: 1573-8469
    Keywords: Microdochium nivale ; Fusarium ear blight ; in vitro bioassay ; disease resistance breeding ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A novel in vitro bioassay is described for screening Fusarium ear blight (FEB) resistance in adult winter wheat plants. Seven winter wheat cultivars were assessed for components of partial disease resistance as 28 day-old detached leaf segments in the laboratory using isolates of Microdochium nivale var. nivale and M. nivale var. majus. Results were compared with disease data obtained at anthesis using the same cultivars as whole plants and the same isolates under glasshouse conditions. Significant cultivar differences were observed using detached leaves, with cv. Avalon (a Fusarium culmorum ear susceptible cultivar) having the shortest leaf incubation period, greatest leaf lesion development and shortest leaf latent period compared to cv. Spark (a Fusarium culmorum ear resistant cultivar), which had the longest leaf incubation period, least leaf lesion development and longest leaf latent period. Using whole plants, cv. Avalon had the shortest ear incubation period and greatest ear disease severity, whilst cv. Spark had the longest incubation period and least ear disease severity. Overall, cultivars of intermediate F. culmorum ear resistance expressed intermediate responses to M. nivale isolates, using both detached leaves and whole plants. Significant correlations were found with ear disease severity and ear incubation period in whole plants and components of partial disease resistance in detached leaves, with significant correlations obtained between leaf incubation period and ear disease parameters using the M. nivale var. nivale isolate. In addition, leaf latent period and leaf lesion size showed significant correlations with whole plant reactions using M. nivale var. nivale and var. majus isolates. The in vitro screening of cultivars as detached leaves using M. nivale isolates may offer a real possibility of a rapid bioassay for the early screening of FEB resistance in wheat and other cereals.
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  • 61
    ISSN: 1572-9680
    Keywords: A,nus rubra ; hedgerow intercropping ; Robina pseudoacacia ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of this study was to determine crop and tree productivity in several alley cropping planting patterns. The four- year study was conducted in western Oregon, United States and involved irrigated sweet corn (Zea mays) intercropped between hedgerows of red alder (Alnus rubra) and black locust (Robina pseudoacacia). Three alley cropping planting patterns with variable plant populations and tree-crop proximity were tested with each tree species in a randomized block design. Space available to trees and crops determined yield of both plant components. High crop yield coincided with low pruning yield, and vice versa. Compared to monocropping, yield reductions in traditional alley cropping planting patterns with widely spaced, double tree rows ranged from 5% to 15%. A. rubra and R. pseudoacacia coppiced readily and produced 0.9 to 4.7 tons of dry matter pruning biomass per growing season, depending on planting pattern and year. A. rubra yield continually increased during the trial, while the ability of R. pseudoacacia to produce green manure after frequent coppicing appeared to weaken. After four years, soil organic matter was 4 to 7% higher in the topsoil of an alley cropping system compared to a monocropping system. However, continuous growing of sweet corn resulted in decreased soil organic matter levels in both cropping systems compared to original levels. Crop yield reductions and the need for additional management inputs constrain the implementation of alley cropping in temperate climates. Only if benefits other than minor soil fertility improvements are realized is alley cropping a feasible alternative in temperate climate regions.
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  • 62
    ISSN: 1573-0654
    Keywords: cotton ; drainage ; irrigation ; salinity ; shallow groundwater ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In situ use of ground water by plants is one optionbeing considered to reduce discharge of subsurfacedrainage water from irrigated agriculture. Laboratory, lysimeter, and field studies havedemonstrated that crops can use significant quantitiesof water from shallow ground water. However, moststudies lack the data needed to include the crop wateruse into an integrated irrigation and drainage watermanagement system. This paper describes previousstudies which demonstrated the potential use of groundwater to support plant growth and the associatedlimitations. Included are results from three fieldstudies which demonstrated some of the managementtechniques needed to develop an integrated system. The field studies demonstrated that approximately 40to 45% of the water requirement for cotton can bederived from shallow saline ground water. Thatregulation of the outflow will result in increasinguse. Implementation of integrated management ofirrigation and subsurface drainage systems is a viableand sustainable alternative in the management ofsubsurface drainage water from arid and semi-aridareas only if soil salinity can be managed and if thesystem is profitable.
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  • 63
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    Nutrient cycling in agroecosystems 54 (1999), S. 73-80 
    ISSN: 1573-0867
    Keywords: anhydrous ammonia ; dicyandiamide ; nitrification inhibitor ; urea-ammonium nitrate ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract One approach to reduce NO3 movement to groundwater is increasing the proportion of N supplied to the crop as NH4–N. Nitrification inhibitors (NI's) can be used to enhance NH4–N supply, but most studies have focused on yield response, with little attention given to environmental impacts. To determine the effect of enhanced NH4 sources on corn grain yield, N uptake and NO3 movement to groundwater, three sidedress materials were compared during three different growing seasons. Application of anhydrous ammonia (AA) and addition of the NI, dicyandiamide (DCD) to urea-ammonium nitrate (UAN) both reduced NO3 leaching losses relative to that incurred with UAN. With AA and UAN + DCD (as compared with UAN) subsoil solution NO3 concentrations were reduced by an average of: 1.1 mg NO3–N kg-1 soil following (fall 1993) a dry growing season; 2.4 mg NO3–N kg-1 soil during (spring and summer 1994) and 1.4 mg NO3–N kg-1 soil after (fall 1994) a wet growing season; and 0.5 mg NO3–N kg-1 soil following (fall 1995) a growing season with intermediate rainfall. Based on average solution NO3 concentrations and approximate drainage after harvest, estimated N losses between harvest and freeze-up were 43, 22 and 19 kg N ha-1 with UAN, UAN + DCD and AA, respectively (average of 3 years). Grain yields and aboveground N uptake were greater with AA and UAN + DCD than with UAN, and residual fertilizer N (applied N less aboveground N uptake) was 18, 6 and -2 kg N ha-1 with UAN, UAN + DCD and AA, respectively (average of 3 years). As is often observed, the trend for greater yield with addition of the NI was not large or consistent enough to meet registration criteria. Data demonstrating reduced NO3 leaching are also relevant, and positive environmental impacts should be a criterion for registration. For growers who are reluctant to use AA, this would provide an alternative source to maximize yield while minimizing NO3 movement to groundwater.
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  • 64
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    Nutrient cycling in agroecosystems 54 (1999), S. 41-48 
    ISSN: 1573-0867
    Keywords: wheat ; potassium ; nutrition ; genotypic variability ; utilization efficiency ; uptake efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Pot and field experiments were carried out in order to study the genotypic variation in potassium uptake and utilization by winter wheat (T. aestivum L). Fifty-eight genotypes showed variation in K concentration, accumulation and potassium efficiency ratio (KER) in a field experiment. KER had significant positive correlation with grain weight per spike and harvest index (HI), and significantly negative correlation with stem K concentration at maturity. In a subsequent field experiment, three out of four genotypes, Yunmei 5, 94-18 and 94-6 differed in their KER, and had significantly higher grain yield with K application (K1) than without K application (K0). The 4th genotype Zhemei 1 showed no response to K. The yield increase due to K application was mainly due to the improvement in spike development from tillers. K concentration and accumulation in the plant varied between genotypes, K levels and plant parts. Among various plant parts, stem contained the highest K concentration and had the highest K accumulation at maturity, and changed considerably with the K level, while other plant parts remained relatively unchanged. All four genotypes had smaller KER in K1, as compared to K0, but there existed some difference in KER reduction among genotypes.
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  • 65
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    Nutrient cycling in agroecosystems 53 (1999), S. 139-146 
    ISSN: 1573-0867
    Keywords: critical levels of Mn ; soil extractants ; Mn-deficiency ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seven chemical extractants were tested for their relative performance to predict the response of wheat to Mn application in coarse textured alkaline soils of semi-arid region. Five out of the seven extractants were found to be promising for the estimation of critical level of available Mn in these soils, as the amount of Mn extracted by these extractants was positively and significantly correlated with relative grain yield as well as Mn uptake. The critical deficiency level of soil available Mn with 0.005 M DTPA, 0.02% hydroquinone, 0.02 N sodium pyrophosphate, 0.1N H3PO4 and 0.05N HCl+0.025N H2SO4 was 3.1, 13.8, 23.5, 5.3 and 17.8 mg kg-1 soil, respectively. The 1N ammonium acetate and 0.01M CaCl2 were found to be unsuitable extractants for these soils. Further field trials at eight locations with varying levels of Mn deficiency showed successive increase in the grain yield of wheat with foliar Mn application, emphasizing the need for Mn fertilization when wheat is grown on Mn deficient soils.
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  • 66
    ISSN: 1573-5036
    Keywords: macropores ; rhizosphere ; roots ; root-soil interplay ; soil properties ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Under certain soil conditions, e.g. hardsetting clay B-horizons of South-Eastern Australia, wheat plants do not perform as well as would be expected given measurements of bulk soil attributes. In such soils, measurement indicates that a large proportion (80%) of roots are preferentially located in the soil within 1 mm of macropores. This paper addresses the question of whether there are biological and soil chemical effects concomitant with this observed spatial relationship. The properties of soil manually dissected from the 1–3 mm wide region surrounding macropores, the macropore sheath, were compared to those that are measured in a conventional manner on the bulk soil. Field specimens of two different soil materials were dissected to examine biological differentiation. To ascertain whether the macropore sheath soil differs from rhizosphere soil, wheat was grown in structured and repacked cores under laboratory conditions. The macropore sheath soil contained more microbial biomass per unit mass than both the bulk soil and the rhizosphere. The bacterial population in the macropore sheath was able to utilise a wider range of carbon substrates and to a greater extent than the bacterial population in the corresponding bulk soil. These differences between the macropore sheath and bulk soil were almost non-existent in the repacked cores. Evidence for larger numbers of propagules of the broad host range fungus Pythium in the macropore sheath soil were also obtained.
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  • 67
    ISSN: 1573-5036
    Keywords: barley ; genetic variation ; phosphate uptake ; rhizosphere ; root hairs ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Low phosphorus (P) availability in soils and diminishing P reserves emphasize the need to create plants that are more efficient P users. Knowledge of P efficient germplasm among the existing cereal varieties may serve as the basis for improving soil P use by selection and breeding. We had identified some cereal cultivars (winter wheat: Kosack and Kraka; winter barley: Hamu and Angora; spring barley: Canut, Alexis, Salka, Zita;) which differed (p〈0.05) in P depletion from thin slices (0.2 mm) of the rhizosphere soil under controlled conditions. In the present study, the same cultivars were studied under field conditions at three levels of P supply (no-P, 10 and 20 kg P ha-1) and the differences in P uptake as found in the previous work were confirmed. Under both conditions, the variation between the cultivars was greatest in soil without P fertilizers (no-P) for about 30 years. The variation in P uptake with most cultivars disappeared when 10 kg P ha-1 was applied. Root development did not differ between the cultivars much, but there was wide, consistent variation in their root hairs, regardless of growth media (solution, soil column and field). Increase in soil P level reduced the length of root hairs. The variation in root hairs between the cultivars was largest in no-P soil. When 10 kg P ha-1 was applied, the root hair lengths did not differ between the cultivars. Barley cultivars with longer root hairs depleted more P from the rhizosphere soil and also absorbed more P in the field. The relationship between root hairs and phosphorus uptake of the wheat cultivars was less clear. The wide variation in P uptake among the barley cultivars in the field and its relationship to the root hair development confirms that root hair length may be a suitable plant characteristic to use as criterion for selecting barley cultivars for P efficiency, especially in low-P soils.
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  • 68
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    Plant and soil 212 (1999), S. 163-171 
    ISSN: 1573-5036
    Keywords: amino acids ; carboxylic acids ; nicotianamine ; Tc ; tomato ; xylem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper deals with a new analytical approach for studying metal speciation in the xylem, as applied to the nuclear waste metal technetium (99Tc) in tomato plants (Lycopersicon esculentum Mill, cv. Tiny Tim). Special attention was paid to sampling protocols and sample handling so that metal oxidation/reduction processes during analytical procedures did not influence the results. Marker Tc-ligand complexes were synthesized in vitro (Tc-cysteine, Tc-histidine, Tc-citrate, and Tc-nicotianamine) and sampling was performed under both argon and atmospheric conditions. Analyses were carried out using paper chromatography, gel electrophoresis (PAGE), and reversed phase ion-pair chromatography (RP-IPC). The results show Tc to be present predominantly in the TcO4 − form in the xylem, indicating transport similarities with molybdenum and chromium. Probably, the approach used is also valuable in other metal-speciation studies in the xylem.
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  • 69
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    Plant and soil 212 (1999), S. 201-206 
    ISSN: 1573-5036
    Keywords: complexation ; CrIII ; organic acids ; root exudates ; solubilization ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Pot experiments were conducted to investigate the effect of various organic acids (carboxylic and amino acids) on the uptake and translocation of root-absorbed trivalent chromium by tomato ( Lycopersicum esculentum) plants grown in sand and soil culture. Statistically significant increases in chromium accumulation from Cr(III) treated plants in the presence of increasing concentrations of organic acid suggest the existence of Cr(III) — organic acid interactions in the soil-plant system. However, the amino acids have been less effective in the mobilization of chromium compared to carboxylic acids. The results are discussed on the basis of the potential of organic acids to form complexes with Cr(III).
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  • 70
    ISSN: 1573-5036
    Keywords: chelator ; genotypic differences ; HEDTA ; ion speciation ; micronutrient ; tolerance to zinc deficiency ; wheat ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The chelator-buffered nutrient solutions containing excess chelator have been used frequently in the micronutrient research, but potential toxicity of the excess chelator has not been ascertained. The present study was conducted to test effects of four concentrations of excess HEDTA [ N-(2-hydroxyethyl)ethylenedinitrilotriacetic acid] and two levels of total Zn on growth, root exudation, and nutrient uptake and transport by Triticum aestivum L. (cv. Aroona) and Triticum turgidum L. conv. durum (Desf.) MacKey (cv. Durati) genotypes differing in tolerance to Zn deficiency. Excess HEDTA at 50 μM reduced root and shoot growth and caused visual toxicity symptoms (necrotic lesions) on leaves; these effects were generally absent at lower concentrations of excess HEDTA. Root exudation of phytosiderophores increased with increasing concentrations of excess HEDTA at deficient and sufficient Zn levels, and was higher in Zn-deficiency-tolerant Aroona than in Zn-deficiency-sensitive Durati wheat. Shoot and root Zn concentrations showed a saturable response to increasing Zn2+ activities in solution. Excess HEDTA at 50 μM caused an increase in shoot concentrations of Fe and a decrease in concentrations of Mn and Cu. An average rate of Zn uptake increased with an increase in Zn2+ ionic activity in solution, with Zn-deficiency-tolerant Aroona having a higher rate of Zn uptake than Zn-deficiency-sensitive Durati in the deficiency range of Zn2+ activities. Average uptake rates of Mn and Cu decreased with an increase in concentration of excess HEDTA. Similar observations were noted for transport of Mn and Cu to shoots, while Zn transport to shoots was proportional to Zn2+ activities in solution. It was concluded that excess HEDTA at 50 μM adversely affects wheat growth and physiology, while excess of 25 μM or less does not cause measurable toxicity.
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  • 71
    ISSN: 1573-5036
    Keywords: ammonium ; H+ flux ; H+-selective microelectrode ; mineral uptake ; pH-indicator dye ; nitrate ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two methods for measuring proton fluxes along intact maize roots grown with NH 4 + or NO 3 − at pH 6.5 were compared. Videodensitometric measurement of changes in a pH-indicator dye by video camera was used to map pH around roots and determine the amounts of protons released by various root regions. This method was compared with potentiometric determination of the concentration of H+ in the unstirred layer at the root surface using ion-selective microelectrodes. With NH 4 + the roots released large amounts of H+ in preferential regions where the rate of flux can reach 1.4 or even 2.5 nmol m−1 s−1. Videodensitometry indicated a first region of root acidification in the subapical zone, but this was more difficult to localize with microelectrodes. With NO3 − both methods showed that the roots released small amounts of H+ and that the apical region took up H+ in the first 10 mm then sometimes released H+ over the following 10 mm of root. The H+ flux profiles obtained by both methods were in good agreement in terms of both order of magnitude of the fluxes and spatial differences along the root. These results suggest that videodensitometry, which is easier to use than potentiometry, can be used to screen different plant species or cultivars under various experimental conditions. The microelectrode technique is indispensable, however, for studying the underlying mechanisms of net H+ fluxes.
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  • 72
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    Plant and soil 211 (1999), S. 223-230 
    ISSN: 1573-5036
    Keywords: silicon absorption ; transport ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Although silicon (Si) is a quantitatively major inorganic constituent of higher plants the element is not considered generally essential for them. Therefore it is not included in the formulation of any of the solution cultures widely used in plant physiological research. One consequence of this state of affairs is that the absorption and transport of Si have not been investigated nearly as much as those of the elements accorded 'essential' status. In this paper we report experiments showing that Si is rapidly absorbed by wheat (Triticum aestivum L.) plants from solution cultures initially containing Si at 0.5 mM, a concentration realistic in terms of the concentrations of the element in soil solutions. Nearly mature plants (headed out) 'preloaded' with Si absorbed it at virtually the same rate as did plants grown previously in solutions to which Si had not been added. The rate of Si absorption increased by more than an order of magnitude between the 2-leaf and the 7-8 leaf stage, with little change thereafter.
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  • 73
    ISSN: 1573-5036
    Keywords: 14CO2 labelling ; flow detection of beta radiations ; rhizosphere respiration ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The present work describes an original method to follow rate of 14CO2 and total CO2 production from rhizosphere respiration after plant shoots had been pulse-labelled with 14CO2. We used a radioactivity detector equipped with a plastic cell for flow detection of beta radiation by solid scintillation counting. The radioactivity detector was coupled with an infrared gas analyser. The flow detection of 14CO2 was compared to trapping of 14CO2 in NaOH and counting by liquid scintillation. First, we demonstrated that NaOH (1 M) trapped 95% of the CO2 of a gaseous sample. Then, we determined that the counting efficiency of the radioactivity flow cell was 41% of the activity of gaseous samples as determined by trapping in NaOH (1 M) and by counting by static liquid scintillation. The sensitivity of the 14CO2- flow detection was 0.08 Bq mL−1 air and the precision was 2.9% of the activity measured compared to 0.9% for NaOH trapping method. We presented two applications which illustrate the relevance of 14CO2-flow detection to investigations using 14C to trace photoassimilates within the plant-soil system. First, we examined the kinetics of 14CO2 production when concentrated acid is added to NaH14CO3. This method is the most commonly used to label photoassimilates with 14C. Then, we monitored 14CO2 activity in rhizosphere respiration of 5-week old maize cultivated in soil and whose shoots had been pulse-labelled with 14CO2. We conclude that alkali traps should be used for a cumulative determination of 14CO2 because they are cheap and accurate. On the other hand, we demonstrated that the flow detection of 14CO2 had a finer temporal resolution and was consequently a relevant tool to study C dynamics in the rhizosphere at a short time scale.
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  • 74
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    Plant growth regulation 29 (1999), S. 1-21 
    ISSN: 1573-5087
    Keywords: drought resistance ; wheat ; small grains ; genetic analysis ; yield stability ; traits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Drought is a serious problem in many parts of the world where wheat, barley and other small-grained cereals are part of the staple diets. Even in parts of South-eastern Europe, seasonal rainfall for winter cereals has been falling gradually for many years. Thus, since 1981 across three sites in Yugoslavia (Novi Sad, Kragujevac and Zaječar), rainfall fell from a mean of 511 mm for October to July in 1981--1982 to about 453 mm during the same period for the 1995--1996 season. Nevertheless, average wheat yields for new varieties in Yugoslav Commission trials during this period have shown a steady increase from 7.6 to 8.8 t ha−1. This is due to increasing the yield potential of the new varieties, even in trials giving low average yields, caused largely by drought. Thus, breeders in Yugoslavia are succeeding in improving drought resistance in new wheat varieties. However, future progress in improving drought resistance may be helped by focusing on specific traits which will help to improve either crop water use, water-use efficiency or harvest index. Thus, for example, rapid early leaf area development not only improves subsequent crop growth rates, but increases competition with weeds for water and nutrients. The rate of leaf area development is closely associated with embryo size, so selection for large embryo size should improve early growth rates. Osmotic adjustment in wheat in response to drought appears to be important for maintaining yields, and selection for high osmotic adjustment has improved drought yields. Carbon 13 discrimination (Δ) is an integral measure of plant water-use efficiency. Selecting for low Δ has also resulted in increased yield under drought conditions. Other constitutive and induced traits, such as phenology, leaf xeromorphy, excised-leaf water loss, rooting behaviour, senescence and stored assimilates are also discussed in relation to improving yields in small-grain crops. Opportunities for marker-assisted selection are also considered. Incorporating specific drought resistance traits in breeding programmes should facilitate more rapid improvement in the drought resistance of wheat and other small-grained cereals.
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    Genetic resources and crop evolution 46 (1999), S. 81-85 
    ISSN: 1573-5109
    Keywords: aluminum tolerance ; germplasm ; rye ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Regional rye populations and wheat cultivars/lines were screened for aluminum tolerance using the hematoxylin staining method. Portuguese regional rye populations showed better tolerance than the Polish cv. Dank. Zlote, used as tolerant tester. In the group of bread wheats, EPM 305/81, a Barbela reselection, was the most tolerant genotype with the same behaviour as the cv. BH 1146, a tolerant tester. In a study with lines selected from a local Barbela landrace, aluminum tolerance variability was detected. Some lines were as tolerant, or higher, as wheat tester. As Portuguese rye populations and the Barbela wheat landrace have grown for centuries on an acid soil region, the data supports the idea that natural biotic or abiotic stresses associated to man selection, lead to the adaptation of genotypes to specific regional conditions and, in this case, to acid soils where aluminum toxicity occurs.
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  • 76
    ISSN: 1573-5060
    Keywords: diallel cross ; genotype-environment interaction ; marginal environments ; wheat ; yellow rust ; yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Complete F1 and F2 diallel crosses were used to investigate the inheritance of yield among eight Ugandan bread wheat lines grown in two low-yielding environments; one marginal because of the high incidence of yellow rust normally experienced there, the other a low-rust site. In the marginal, high-rust environment, mainly additive genetic variation was present, though in one season, when disease incidence was unusually low, non-additive variation due to dominance was also detected. Although yield was significantly higher at the low-rust site, no clear pattern of inheritance was apparent there. The results indicated that the low rust site was an intermediate environment, just below the crossover point of a crossover genotype-environment interaction. The implications of these results for wheat breeding in low-yielding and marginal environments in Uganda and elsewhere are discussed.
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  • 77
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    Euphytica 105 (1999), S. 125-131 
    ISSN: 1573-5060
    Keywords: disease resistance ; inheritance ; Karnal bunt ; Neovossia ; Tilletia indica ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Inheritance of resistance to Neovossia indica was studied in a Triticum aestivum line HD 29. To overcome the influence of environment on disease expression, the study was conducted by extensive evaluation of advanced generation (F8) recombinant inbred lines (RILs) developed by single seed descent from the cross WL 711 (susceptible) × HD 29 (resistant. The results suggested that HD 29 possesses three major genes for resistance to isolated Ni7 and two genes for resistance to isolate Ni8. One of the two genes controlling resistance to Ni8 is common with one of the genes conferring resistance to Ni7. These observations have important implications in breeding for Karnal bunt resistance.
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    Euphytica 107 (1999), S. 51-59 
    ISSN: 1573-5060
    Keywords: wheat ; plant breeding ; yield stability ; environmental index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of plant breeding on yield and their physiological determinants has been widely studied in wheat. However, it is poorly understood how, and to what extent, yield stability has been modified. To attempt a direct analysis of changes in absolute and relative yield stability, data of yield of cultivars released in different eras in different environments were obtained from records from our lab and from the literature. Depending on the availability of data, effects of plant breeding on yield stability of cultivars released in Argentina, Australia, Italy and the United Kingdom were evaluated using a quantitative approach. In this paper it was assumed that the slope of yield vs. environmental index estimates the instability of the cultivars. In addition, a more qualitative approach for Mexico, and the former USSR complemented this analysis. There was a clear decrease in yield stability assessed in absolute terms as a consequence of wheat breeding. In Argentina, Australia, Italy and the UK this decrease was related to the magnitude of yield increases. However, the decrease in yield stability in Argentina and Australia was less than for Italy and the UK, particularly so during the last 30 years. Modern cultivars released in Argentina and Australia showed a trend to maintain yield stability as a percentage of their yield similar to that of their predecessors, while the two European countries analysed tended to a slight decrease in yield stability even in relative terms. The complementary, less quantitative evaluation of Mexico and the former USSR appeared to confirm the quantitative trends described for the other countries, i.e. a general decrease in yield stability (assessed in absolute terms) with genetic gains in yield potential.
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  • 79
    ISSN: 1573-5060
    Keywords: chromatin ; breeding ; gel electrophoresis ; in situ hybridization ; rye ; rye-specific probes ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Chromosome arm 1RS of rye ( Secale cereale L.), when transferred to wheat ( Triticum sp.), significantly influences variety performance, because it carries genes for resistance to disease and insect pathogens. Inserted into wheat, 1RS also promotes haploid production, affects end-product quality, and sometimes affects yield. Therefore, its detection by breeders and geneticists is important. The entire 1RS arm is present in chromosome substitutions and in Robertsonian translocations involving chromosomes 1A, 1B, or 1D of wheat. In recombinant lines, a segment of 1RS has been exchanged with a segment of a group-1 wheat chromosome. Determining the wheat chromosome arm involved in a translocation, the source of rye chromatin, and the amount of 1RS chromatin introduced is necessary for a complete characterization of the introgressed segment. Biochemical, molecular, and cytogenetic technologies are described which enable such a characterization of 1RS in wheat. Examples of using gel electrophoresis, high-performance liquid chromatography, monoclonal antibodies, rye-specific molecular probes, RFLP and PCR assays, chromosome banding, in situ hybridization, and flow cytometry are provided. A comparison of these technologies is made and the advantages and disadvantages of each technology are discussed relative to modern wheat breeding efforts.
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  • 80
    ISSN: 1573-5060
    Keywords: disease assessment ; maturity ; resistance ; Septoria tritici ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nineteen cultivars, with large differences in heading date, were evaluated for their response to septoria tritici blotch in two experimental setups in Njoro, Kenya. Due to the more or less constant temperatures during the growing season and the overhead irrigation applied the epidemic conditions were similar over the whole observation period for the early and late cultivars. In experiment 1 the cultivars were assessed for disease severity at the same moment irrespective of the developmental stage, while in experiment 2 the cultivars were assessed at the same developmental stage. Measured at the same time, the disease severity was highest in the early maturing cultivars and lowest in the late maturing cultivars (r = –0.78). When assessed at the same development stage the disease build up was independent of heading date (r = –0.10) but strongly dependent on resistance level. There were no indications that early heading cultivars were more susceptible than late heading cultivars.
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  • 81
    ISSN: 1573-5087
    Keywords: auxin biosynthesis ; auxin inhibitors ; indole analogues ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize liquid endosperm extracts contain the enzymes necessary for all of the steps of the plant IAA biosynthetic pathway from tryptophan, and provide a means to assay the pathway in vitro. We have analyzed the reactions in the presence of a series of indole and indole-like analogues in order to evaluate the potential of these compounds to act as inhibitors of IAA biosynthesis. Such inhibitors will be useful to investigate the tryptophan to IAA pathway, to determine the precursors and intermediates involved, and to select for mutants in this process. A number of such compounds were tested using in vitro enzyme assays for both the tryptophan dependent IAA biosynthesis pathway and for tryptophan synthase β activity. Some compounds showed strong inhibition of IAA biosynthesis while having only a slight effect on the reaction rate of tryptophan synthase β. These results: (1) show that IAA biosynthesis can be selectively inhibited relative to tryptophan biosynthesis; (2) suggest potential ways to screen for IAA biosynthetic pathway mutations in plants; and (3) provide additional tools for studies of IAA biosynthesis in plants.
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  • 82
    ISSN: 1573-5087
    Keywords: flooding ; kinetin ; leaf relative water content ; membrane stability ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheat plants, 22d. old, were exposed to wide range of soil water osmotic potential (Ψs = 0 to −1.2 MPa) induced by NaCl and CaCl2 treatments in combination with roots maintained under aerobic (drained at field capacity) or nonaerobic (flooded) conditions in the soil, and sprayed with 10 mg L−1 kinetin solution. In drained plants, not receiving kinetin, increased soil salinity resulted in appreciable inhibition of shoot growth and reduction in chlorophyll (Ch1.), soluble sugars (SS) contents and grain yield. Shoot growth, Ch1. content, soluble sugars and grain yield were significantly lower for flooded plants than unflooded analogues over the entire Ψs range. Both salinity and waterlogging synergize to increase Na+, Ca+ and Cl− accumulation in shoot tissues and to decrease the stability of leaf membranes to either dehydration (40% polyethylene glycol 6000) or heat (51 °C) stress. The ratio of K+/Na+ transported to shoots under aerobic and anaerobic conditions decreased progressively on salinization. The association between the internal mineral element concentrations was largely affected by kinetin treatment. Kinetin application ameliorated the deleterious effects of salinity and oxygen deficiency. It reduced Na+, Ca2+ and Cl− accumulation and improved K+ uptake under salinity and waterlogging stresses. Increased K+/Na+ ratio helped the plants to avoid Na+ toxicity and enhanced shoot growth and grain yield. Kinetin also reduced membrane injury by dehydration and heat stresses and improved the water status of plants under both aerobic and anaerobic conditions. The effects of single factors (Soil salinity ‘Ψs’, soil waterlogging ‘WL’ and Kinetin ‘Kin’) and their interactions (Ψs × WL, Ψs × Kin, WL × Kin and Ψs × WL × Kin) were shown by analysis of variance to be statistically significant for most parameters tested. Calculation of the coefficient of determination (η+) led to three important findings. (1) Salinity (Ψs) was dominant in affecting leaf relative water content (RWC), shoot dry mass, grain yield, stability of leaf membranes to dehydration stress and the contents of Na+, Ca2+, Mg2+ and Cl−. (2) Kinetin (Kin) had a dominant effect on the stability of leaf membranes to heat stress as well as on chlorophyll and soluble sugars contents. (3) The share of waterlogging (WL) was dominant for K+ content. It can be concluded that kinetin application helped wheat plants to grow successfully in the areas subjected to combined effects of salinity and oxygen deficiency, such as in salt marshes.
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  • 83
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    Plant growth regulation 28 (1999), S. 187-197 
    ISSN: 1573-5087
    Keywords: ABA ; grain filling ; water stress ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of in situ water stress on the endogenous abscisic acid (ABA) content of the endosperm and the in vitro application of ABA on some important yield regulating processes in wheat have been studied. Water stress resulted in a marked increase in the ABA content of the endosperm at the time close to cessation of growth. Application of ABA to the culture medium of detached ears reduced grain weight. Exogenously applied ABA, at the highest concentration (0.1 mM) reduced transport of sucrose into the grains and lowered the starch synthesis ability of intact grains. In vitro sucrose uptake and conversion by isolated grains was stimulated by low ABA concentrations (0.001 mM) in the medium but was inhibited by higher concentrations. ABA application had no effect on sucrose synthase (SS) and uridine diphosphate glucose pyrophosphorylase (UDP-Gppase) activities, whereas adenosine diphosphate glucose pyrophosphorylase (ADP-Gppase), soluble starch synthase (SSS), and granule-bound starch synthase (GBSS) activities were reduced. These results raise the possibility that water stress-induced elevated levels of endogenous ABA contribute to reduced grain growth.
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  • 84
    ISSN: 1573-5087
    Keywords: abscisic acid ; gene-expression ; H1 histone ; tomato ; water-deficit-stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Many genes are induced by periods of water deficit, and a subset of these are dependent on elevated ABA content for expression. A number of drought-induced genes are not induced in leaves of the ABA-deficient mutant flacca from tomato (Lycopersicon esculentum) but are induced in detached, wilted wild-type leaves and ABA-treated leaves of both genotypes. The nucleotide sequence of the cDNA and corresponding genomic DNA fragment of one of these genes, his1-s (formerly called le20), encodes an amino acid sequence that is rich in Lys, Ala, and Ser. The predicted protein contains the tripartite structure of H1 histone and is similar to other H1 histones, especially in the globular domain. Since, his1-s is more closely related to a stress-induced gene from Lycopersicon pennellii than to another H1 histone in the tomato genome it is considered a stress-induced variant of H1 histone. his1-s mRNA accumulated in vegetative plants in response to other abiotic stress treatments, including application of polyethylene glycol, and salt. The mRNA preferentially accumulated in leaves as compared to roots. his1-s mRNA accumulation was controlled during development; the level was higher in developing seeds of mature green fruit than in detached wilted leaves. H1 histones have been implicated in the general repression of gene expression and in the regulation of specific genes. The rapid accumulation of his1-s mRNA during stress may indicate that this unique, stress-induced H1 histone is involved in controlling gene expression during plant stress.
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  • 85
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    Plant and soil 208 (1999), S. 149-159 
    ISSN: 1573-5036
    Keywords: abscisic acid ; drought ; soil water content ; water potential ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to investigate the effects of soil texture on possible non-hydraulic signals under field conditions, spring wheat plants (Triticum aestivum L. cv. Cadensa) grown in sand and loam soils and with a well developed root system were exposed to slow soil drying in the late vegetative stage of growth. Soil water potential and content were measured daily at different depths and plant responses were measured in flag leaves. When the average soil water potential in the top soil layers (0–25 cm depth in sand and 0–45 cm depth in loam) dropped to –60 or –70 kPa and the lower soil layers were still at field capacity, morning xylem [ABA] (0.03–0.04 vs. 0.06–0.08 mmol m-3) and midday leaf ABA concentration increased (250–300 vs. 400–450 ng/g DW) and leaf conductance decreased relatively to well-watered (control) plants (0.75–0.88 vs. 0.64–0.70 mol m-2 s-1). These responses took place before any decrease in leaf water potential occurred as compared with control plants, indicating that they were triggered by root-borne signals due to reduced root water status in the top soil layers. At this stage the soil water content was as low as 6% by volume, the fraction of roots in ‘wet’ soil was 0.12 and relative available soil water was 45% in sand and still high 20%, 0.48 and 70%, respectively, in loam of the whole soil profile indicating that roots were responding to soil water availability and not soil water content at a certain evaporative demand. In addition, similar responses occurred at high and low evaporative demands (3.4–5.2 vs. 0.6–4.0 mm/day of potential evapotranspiration).
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  • 86
    ISSN: 1573-5036
    Keywords: hydraulic conductivity ; leaf growth ; phosphorus ; Rhizoctonia ; water status ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheat seedlings infected with a pure inoculum of the root-rotting fungus Rhizoctonia solani were grown in pots designed to fit in pressure chambers, to allow the effects of the Rhizoctonia infection on leaf growth to be studied while maintaining the leaves at elevated water status. Wheat was grown to the third leaf stage in soil inoculated with three different levels of Rhizoctonia, and the pots were then pressurised for seven days to maintain the leaf xylem at the point of bleeding (ie. the leaves were at full turgor). The reduction in leaf expansion caused by Rhizoctonia was not overcome by pressurisation, indicating that a reduced supply of water to the leaves was not responsible for reduced leaf growth. The addition of phosphorus to pots marginally deficient in P did not increase the leaf growth of Rhizoctonia-infected plants, despite increased P uptake to the leaves. These results indicate that a reduced supply of water to the leaves and a supply of phosphorus that was bordering on deficient was not the cause of the growth reduction in seedlings with Rhizoctonia infection. The nature of this reduced growth remains uncertain but may involve growth regulators produced by the fungus, or by the plant as a result of the infection process. The mechanism of these growth reductions is of interest as it may provide a key to the development of plant resistance mechanisms.
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  • 87
    ISSN: 1573-5036
    Keywords: flax ; nitrate dissimilation ; Pseudomonas ; rhizosphere ; soil ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The distribution of nitrogen dissimilative abilities among 618 isolates of fluorescent pseudomonads was studied. These strains were isolated from two uncultivated soils (C and D; collected at Châteaurenard and Dijon, France, respectively) and from rhizosphere, rhizoplane and root tissue of two plant species (flax and tomato) cultivated on these two soils. According to their ability to dissimilate nitrogen, the isolates have been distributed into three metabolic types: non-dissimilators, NO2 - accumulators and denitrifiers. While the three metabolic types were recovered in all the compartments of soil D experiments, only two (non-dissimilators and denitrifiers) were recovered in all the compartments of soil C experiments. Even under the contrasting conditions of the two soil types, both plants were able to select the nitrate dissimilating community among the total community of fluorescent Pseudomonas, but the mode of this selection seems to be dependent on both plant and soil type. The soil type appears to be unable to significantly modulate the strong selective effect of tomato. Indeed, similar dissimilator to non-dissimilator ratios were found in the root tissue of this plant species cultivated in both soils. In contrast, the different dissimilator to non-dissimilator ratios observed in flax roots between soils C and D suggest that the selective effect of flax was modulated by the soil type. Taxonomic identifications showed that the 618 isolates were distributed among three species (P. chlororaphis, P. fluorescens, P. putida) plus an intermediate type between P. fluorescens and P. putida. However, no clear relationship between the distribution of the metabolic types (functional diversity) and the distribution of bacterial species has been found.
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  • 88
    ISSN: 1573-5036
    Keywords: banded wetting agent ; furrow sowing ; lupins ; press wheels ; water repellent soils ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The rates of emergence of wheat and lupin were measured in 13 field experiments on water repellent sands. Conventional sowing was compared with furrow sowing either with or without the use of a press wheel and several rates of banded wetting agent. Measurements included, severity of water repellence, plant emergence, rainfall, soil temperature at sowing and, at one site, the area of wet soil after sowing. All ameliorative techniques improved emergence, with responses being greatest when seeds were sown into dry soil. Compared with conventional sowing, furrow sowing increased wheat and lupin emergence by an overall average of 16 and 41%, respectively. The benefits were greater at the drier sites. Increases in emergence due to the use of a press wheel were sometimes small, although they always occurred (1–19%). It was visually observed that press wheel use gave more uniform seeding depth, reduced clods and ensured more accurate placement of banded wetting agent. Banded wetting agent consistently improved wheat and lupin emergence, particularly where early rains were light and press wheels were used. The wetting agent increased the cross-sectional area of wet topsoil (0–10 cm) which was positively related with increased wheat emergence (R2 = 0.91). At 0.5 L ha−1 of banded wetting agent, the soil along the furrow was four times wetter than without wetting agent. Wetting agent at 0.5 and 1 L ha−1 (with press wheels) increased wheat emergence by 6 and 11% and lupin emergence by 13 and 11%, respectively. The high rates of banded wetting agent gave highest plant densities. Grain yield was only measured at three sites. Furrow sowing did not increase grain yield, however, press wheels use with furrow sowing increased grain yield by 30%. Banded wetting agent increased grain yield and they were positively correlated. The highest rate increased grain yields by a further 9% above press wheels and furrow sowing.
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  • 89
    ISSN: 1573-5036
    Keywords: field root studies ; modelling ; root ; root growth ; root mapping ; root orientation ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Root length density (RLD) is an important determinant of crop water and nutrient acquisition, but is difficult to measure in the field. On a soil profile, in-situ counts of root impacts per unit surface on soil profiles (NI) can be used to calculate RLD if crop-specific parameters for preferential root orientation (anisotropy) are known. An improved method for field determinations of RLD was developed and validated for maize at sites in Côte d'Ivoire and Burkina Faso. Root anisotropy was measured with cubes of undisturbed soil with 0.1 m sidelength, based on NI observed on three planes oriented perpendicularly to each other. RLD was also measured for the enclosed volume. Repetition of such measurements enabled estimation of the robustness across sites of empirical and geometric models for the relationship between RLD and NI:RLD = NI CO, with CO being the coefficient of root orientation, theoretically equals 2 for an isotropic distribution. Root systems were found to be nearly isotropic, except near the root front (0.3 to 0.5 m), where roots had a preferentially orthotropic orientation. Measured RLD was generally about 50% larger than RLD calculated from observed NI and CO, indicating that at least one of the measurement techniques had a systematic error. The ratio between measured and calculated RLD (CE), which ranged from 0.8 to 2, increased with the age of the plants and decreased with soil depth. CE was therefore introduced as an additional coefficient, resulting in RLD = NI CO CE. The empirical value for CO CE was between 2 and 5. The empirical coefficients CO and CE were the same for the sites in Cote d'Ivoire (oxisol with an iron pan at 0.6 to 0.9 m) and Burkina Faso (alfisol with an iron pan at 0.4 to 0.8 m). The model was validated with independent data sets at both sites, and gave satisfactory predictions of RLD on the basis of NI obtained from single soil planes, which can be easily measured in the field.
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  • 90
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    Plant and soil 215 (1999), S. 65-72 
    ISSN: 1573-5036
    Keywords: barley ; boron deficiency ; Hordeum vulgare ; Triticum aestivum ; variation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Responses of a range of barley (Hordeum vulgare L.) genotypes to boron (B) deficiency were studied in two experiments carried out in sand culture and in the field at Chiang Mai, Thailand. In experiment 1, two barley genotypes, Stirling (two-row) and BRB 2 (six-row) and one wheat (Triticum aestivum L.) genotype, SW 41, were evaluated in sand culture with three levels of applied B (0, 0.1 and 1.0 μM B) to the nutrient solution. It was found that B deficiency depressed flag leaf B concentration at booting, grain number and grain yield of all genotypes. In barley Stirling, B deficiency also depressed number of spikes plant-1, spikelets spike-1 and straw yield. However, no significant difference between genotypes in flag leaf B concentration was found under low B treatments. Flag leaf B concentration below 4 mg kg-1 was associated with grain set reduction and could, therefore, be used as a general indicator for B status in barley. In experiment 2, nine barley and two wheat genotypes were evaluated in the field on a low B soil with three levels of B. Boron levels were varied by applying either 2 t of lime ha-1 (BL), no B (B0) or 10 kg Borax ha-1 (B+) to the soil prior to sowing. Genotypes differed in their B response for grain spike-1, grain spikelet-1 and grain set index (GSI). The GSI of the B efficient wheat, Fang 60, exceeded 90% in all B treatments. The B inefficient wheat SW 41 and most of the barley genotypes set grain normally (GSI 〉80%) only at the B+. In B0 GSI of the barley genotypes ranged from 23% to 84%, and in BL from 19% to 65%. Three of the barley with severely depressed GSI in B0 and BL also had a decreased number of spikelets spike-1. In experiment 3, 21 advanced barley lines from the Barley Thailand Yield Nursery 1997/98 (BTYN 1997/98) were screened for B response in sand culture with no added B. Grain Set Index of the Fang 60 and SW 41 checks were 98 and 65%, respectively, and GSI of barley lines ranged between 5 and 90%. One advanced line was identified as B efficient and two as moderately B efficient. The remaining lines ranked between moderately inefficient to inefficient. These experiments have established that there is a range of responses to B in barley genotypes. This variation in the B response was observed in vegetative as well as reproductive growth. Boron efficiency should be considered in breeding and selection of barley in low B soils.
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  • 91
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    Plant and soil 209 (1999), S. 283-295 
    ISSN: 1573-5036
    Keywords: leaf emergence ; phosphorus ; photosynthesis ; tillering ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus (P) deficiency limits the yield of wheat, particularly by reducing the number of ears per unit of area because of a poor tiller emergence. The objectives of this work were to (i) determine whether tiller emergence under low phosphorus availability is a function of the availability of assimilates for growth or a direct result of low P availability, (ii) attempt to establish a quantitative relation between an index of the availability of P in the plant and the effects of P deficiency on tiller emergence, and (iii) to provide a better understanding of the mechanisms involved in tiller emergence in field-grown wheat. Wheat (Triticum aestivum L., cv. INTA Oasis), was grown in the field under drip irrigation on a typic Argiudol, low in P (5.5 μg P g-1 soil Bray & Kurtz I) in Balcarce, Argentina. Treatments consisted of the combination of three levels of P fertilization 0, 60 and 200 kg P2O5 ha-1, and two levels of assimilate availability, a control (non-shaded) and 65% of reduction in incident irradiance from seedling emergence until the end of tillering (shaded). Phosphorus treatments significantly modified the pattern of growth and development of the plants. Shading reduced the growth and concentration of water-soluble carbohydrates in leaves and stems. Leaf photosynthetic rate at saturating irradiance was reduced by P deficiency, but was not affected by shading. At shoot P concentrations less than 4.2 g P kg-1 the heterogeneity in the plant population increased with respect to the number of plants bearing a certain tiller. At a shoot P concentration of 1.7 g P kg-1 tillering ceased completely. Phosphorus deficiency directly altered the normal pattern of tiller emergence by slowing the emergence of leaves on the main stem (i.e. increasing the phyllochron), and by reducing the maximum rate of tiller emergence for each tiller.
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  • 92
    ISSN: 1573-5036
    Keywords: boron ; genotypic difference ; sterility ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two pot experiments at the Plant Environment Laboratory (PEL), Reading, UK investigated sterility, boron (B) accumulation and B partitioning of wheat cultivars grown with limited B in the growing medium. The first experiment evaluated nine cultivars of spring wheat with diverse field responses to low available soil B, supplied with or without 20 μM B. A second experiment examined the response of a susceptible (SW-41) and a tolerant (Fang-60) cultivar to B-deficiency. These cultivars were supplied with either 20 μM B from sowing to flag leaf emergence and no added B thereafter, or 20 μM B from sowing to maturity. When B was not supplied in the nutrient solution, the number of grains ranged from 4 per ear (cv. BL-1135) to 32 per ear (cv. BL-1249) and sterility of competent florets ranged from 39% to 93%. Boron concentration in the flag leaf at anthesis did not differ greatly when the growing medium contained limited B, but differences between cultivars were evident when B was unlimited. Tolerance of B-deficiency was not related to the B concentration in the flag leaf. Some cultivars produced viable pollen and set grains while others failed to do so at similar B concentrations in the flag leaf. The two contrasting cultivars did not differ much in their pattern of B partitioning when B supply was restricted from flag leaf emergence onwards. Similarly, little evidence was found that the tolerant cultivars translocated B from their leaves, roots or stems when the supply in the growing medium was restricted. The proportion of total B partitioned in different organs was the same irrespective of B supply and cultivar. On average, leaves contained 68% of the total B content in the whole plant compared to 16% in the roots, 10% in the ears and only 6% in the stems. Tolerant or susceptible cultivars of wheat could not be distinguished based on the B concentration and B content of the flag leaf.
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  • 93
    ISSN: 1573-5036
    Keywords: agriculture ; fertilisation ; nitric oxide flux ; nitrification ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The surface flux of nitric oxide from a wheat field was investigated from 23 March to 29 May 1997 in the Kerzersmoos, Switzerland. A plot fertilised with 19 kg N ha-1 in cattle slurry and 40 kg N ha-1 in mineral NH4NO3 fertiliser and a plot receiving no nitrogen containing fertiliser were compared. The flux was calculated based on hourly measurements of the NO soil–atmosphere concentration gradient using the one-dimensional soil diffusion model of Galbally and Johansson (1989). The soil bulk diffusion coefficient was determined from measurements of the 222Rn surface flux and the activity gradient between 10 cm depth and the surface. It ranged between 79% and 0.3% of the NO diffusion coefficient in air and was parameterised by air filled soil pore space. The indirectly determined NO flux agreed well with standard flux measurements using dynamic chambers. The largest NO emission was found following fertiliser application and irrigation. The emission occurred in pulses, which lasted for 4 days up to 3 weeks coinciding with elevated soil ammonium concentrations. Nitric oxide emission in 5 days following application of cattle slurry were 31 g NO-N ha-1 and 5 g NO-N ha-1 from the non-fertilised plot, respectively. Nitric oxide emission in 15 days following application of NH4NO3 was 95 g NO-N ha-1 and 10 g NO-N ha-1 from the non-fertilised plot, respectively. NO emission in 4 days following irrigation on 21 April were 36 g N ha-1 from the fertilised and 39 g N ha-1 from the non-fertilised plot. The daily NO emission before and after fertiliser and irrigation pulses was between 0.3 and 0.7 g NO-N ha-1 d-1. NO production and NO uptake of the soil was measured regularly. No systematic influence of management or climate on NO uptake was found. NO production was strongly stimulated by fertiliser input and soil moisture content. The simulation of NO production could be reproduced using a nitrification algorithm (Riedo et al., 1998) driven by soil temperature, moisture and ammonium concentration. A NO production rate constant of 1.1ċ10-3 h-1 at 15 °C was derived from a linear regression between nitrification and NO production. Introducing the parameterisation of NO production into the model of Galbally and Johansson (1989) the duration and the strength of the NO emission pulses could be reproduced and the total NO emission during the experiment was approximated within a factor of two.
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  • 94
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    Euphytica 107 (1999), S. 71-78 
    ISSN: 1573-5060
    Keywords: Russian wheat aphid ; resistance ; inheritance ; allelism ; segregation ratio ; wheat ; Triticum aestivum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), is an important pest of wheat (Triticum aestivum L.) in the United States of America. Developing adapted wheat cultivars with genetic resistance to RWA is an effective control strategy. Genetic studies were conducted to determine the mode of inheritance of gene(s) conferring resistance to RWA in an Iranian landrace wheat line, G 5864. For the inheritance study, G 5864 was crossed with the susceptible wheats ‘Yecora Rojo’ and ND 2375. Seedlings of F1, reciprocal F1, F2, BC1 to the susceptible parent (BCS), and BC1 to the resistant parent (BCR) were screened for RWA reaction. Several phenotypic segregation ratios were tested in the F2 populations for goodness of fit; the 9:3:3:1 ratio (resistant: rolled leaves: stunted plants: susceptible) was an acceptable fit in all cases. Thus, resistance in G 5864 seemed to be controlled by two independent dominant genes with additive gene effects. The allelic relationships of gene(s) in this line with genes in other resistant lines, PI 137739 (Dn1), PI 262660 (Dn2), PI 372129 (Dn4), PI 294994 (Dn5), and PI 243781 (Dn6), were also studied. Segregation patterns observed in G 5864 × resistant (R × R) F2 populations were inconclusive. However, no susceptible plants were observed in these F2 populations. If previous reports concerning the number of resistance genes present in the other resistant lines are correct, then given the high manifestation of resistance observed in G 5864, and given the absence of susceptible plants in the R × R F2 populations, it is indicated that RWA resistance in G 5864 is either controlled by different alleles at the same loci as the other resistance genes, or that G 5864 shares a resistance gene with each of the other resistant lines.
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    Euphytica 108 (1999), S. 193-198 
    ISSN: 1573-5060
    Keywords: K+/Na+ selectivity ; Lophopyrum elongatum ; salt-stress ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Accumulation of potassium ions (K+) in expanding or most recently expanded leaves and exclusion of sodium ions (Na+) from them (K+/Na+ selectivity) have been shown to be associated with salt stress tolerance in wheat and Lophopyrum elongatum, a highly salt stress tolerant relative of wheat. This physiological trait is expressed in an amphiploid from the cross of wheat (cv. Chinese Spring) × L. elongatum and the chromosomes controlling it have been identified in field studies employing Chinese Spring disomic substitution lines with individual L. elongatum chromosomes. In this paper the arm location of these genes was investigated by assessing K+/Na+ selectivity in lines harboring individual chromosomes and chromosome arms of L. elongatum. Lophopyrum elongatum chromosome arms 1ES, 7ES, and 7EL, were shown to enhance K+/Na+ selectivity in wheat.
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  • 96
    ISSN: 1573-5060
    Keywords: diallel analysis ; Fusarium culmorum ; heterosis ; resistance ; scab ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fusarium head blight (FHB, scab) caused by Fusarium spp. is a widespread disease of cereals causing relevant yield and quality losses and contaminating cereal products with mycotoxins. Breeding resistant cultivars is the method of choice for controlling the disease. Resistance to FHB is a quantitative trait and is most likely governed by several genes. We present the results of an F1 diallel analysis of FHB resistance involving six resistant and one susceptible European winter wheat genotypes of diverse origin in order to identify promising combinations for the selection of improved cultivars. Parents and F1s including reciprocals were evaluated for FHB resistance in an artificially inoculated field trial. Two traits were assessed: visual disease symptoms on the heads and the percentage of Fusarium damaged kernels in a harvested sample. General combining ability (GCA) and specific combining ability (SCA) effects were statistically significant for visual symptoms and kernel damage, whereas reciprocal effects were small or not significant. Heterosis for resistance was common, indicating that the parental genotypes possess different resistance genes. Selection of transgressive segregates should be feasible from such heterotic combinations.
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  • 97
    ISSN: 1573-5036
    Keywords: 2 ; 4-D ; germination ; growth ; salinity-tolerance ; seed treatment ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments were conducted under laboratory and greenhouse conditions to study the effect of 2,4-D on rooting and salinity tolerance of wheat. Seeds of one commercial wheat (Inqalab-91) and three salt-tolerant wheat lines (WL-41, WL-359, and WL-1073 developed through wide hybridization) were included in the study. Preliminary and short-term experiments were conducted to determine the level of 2,4-D (administered through seed soaking for 24.5 h. at 25 °C in the dark) at which the maximum number of roots emerged. Under hydroponic conditions, 2,4-D treatment of seeds caused an increase of 60 to 100% in the number of primary roots. The maximum increase in the number of roots was observed in one of the salt tolerant wheat lines (WL-41). The roots appeared in bunches but showed stunted growth at higher levels of 2,4-D. Dry matter accumulation decreased markedly; the effect was more pronounced in Inqalab-91 which is less tolerant to stress than other wheat lines. In all wheat types, allocation of dry matter to roots relative to shoot increased due to 2,4-D treatment. In soil, seeds treated with different levels of 2,4-D showed a germination delay of 1–3 days. Although the number of primary roots increased, 2,4-D treatment caused a decrease in total dry matter accumulation by plants grown for 40 days. In another experiment, conducted under greenhouse conditions, seed germination and growth of seedlings was significantly retarded in saline compared to that in non-saline (normal) soil. Initially, the pace of germination of treated seeds as well as seedling growth was slower in both soils, but after six weeks, the leaf area of seedlings raised from treated seeds was greater than those raised from untreated seeds. Towards maturity, plants arising from treated seeds developed wider and longer flag leaves leading to enhanced yield. Root biomass decreased in saline soil as compared to normal soil. However, 2,4-D treatment caused a substantial increase in root biomass in saline soil and the roots were harder in texture in wheats other than Inqalab-91. Seed treatment with 2,4-D led to a significant improvement in the number of productive tillers, yield of straw and grain, and grain protein content of all wheats grown in saline soil. Plants grown in normal soil did not show any marked effect of seed treatment on grain yield and other agronomic parameters. The four wheats showed substantial differences for different parameters but the salt tolerant wheat lines performed better compared to the commercial variety Inqalab-91.
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  • 98
    ISSN: 1573-5060
    Keywords: capillary electrophoresis ; cultivar identification ; gliadins ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Gliadin proteins extracted from fifteen Chinese and Yugoslav winter wheat cultivars were fractionated using a new separation technique – Capillary Zone Electrophoresis (CZE). Different CZE conditions were defined to optimize resolution and reproducibility of gliadin separations. Excellent resolution and high reproducibility of gliadin CZE patterns were obtained by using 47 cm length, 50 μm i.d. capillaries at 15 kV and 30° C in sodium borate buffer system with acetonitrile (ACN) and sodium dodecyl sulfate. By using these CZE conditions, gliadin proteins from each cultivar were easily separated into more than 35 components. This resolution is generally superior to that of one- and two-dimensional electrophoresis and RH-HPLC. Analysis of reproducibility of gliadin CZE patterns from Chinese cultivar ‘Lumai 6’ showed that the average relative standard deviation (RSD) for peak migration times and heights was 0.21% and 4.06%, respectively. Gliadin electrophoregrams of all cultivars studied showed clear qualitative and quantitative differences, including presence or absence of some major peak, migration times and heights of peaks. Specifically, some closely related cultivars that were not differentiable by A-PAGE, were readily differentiated by CZE. In addition, winter wheat cultivars from China and Yugoslavia showed greater differences in gliadin compositions revealed by CZE.
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  • 99
    ISSN: 1573-5060
    Keywords: functional male sterility ; hybrid seed production ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Data and findings concerning the development of an effective male sterility system (as already applied in the practice of producing tomato hybrid seed) through the use of the positional sterility (ps 2) gene are reported. Undesirable selfing and the necessity of emasculation are discussed as the two main disadvantages that limit the use of ps 2-sterile seed parents in tomato hybrid seed production. The following specific characteristics in the performance of ps 2-lines were evaluated: 1) the percentage of selfing in the ps 2-lines varies within and between the years of growing, being forever lowest during the period of hybrid seed production; 2) the percentage of selfed seeds when using a ps 2-line as seed parent in producing hybrid seed is significantly lower than the percentage of selfing, observed on this same line; 3) the ps 2-gene expressivity varies depending on the genotype. This enables the breeding of ps 2-lines exhibiting very low percentage of selfing; 4) stamen emasculation at anthesis (as applied in ps 2-lines) is significantly easier and more rapid than emasculation in floral buds. The easy maintenance of the sterile lines – by artificial selfing it is possible to produce 100% ps 2 progeny – and the high yield of hybrid seed obtained are discussed as important advantages in using this type of sterility in tomato hybrid seed production.
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  • 100
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 108 (1999), S. 145-150 
    ISSN: 1573-5060
    Keywords: maize ; North Carolina model 2 ; salinity tolerance ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The genetic basis of salt tolerance was examined in selected salt tolerant and sensitive material from a sample of accessions previously assessed for variability in salinity tolerance. The North Carolina Model 2 Design and analysis was followed, tolerance being assessed in 10-day-old seedlings grown in salinized solution culture at control (0 mM), 60 mM and 80 mM NaCl concentrations). Salinity tolerance was shown to be under the control of genes with additive and non-additive effects, with broad and narrow sense heritability estimates being approximately 0.7 and 0.4 over all treatments.
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