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  • Triticum aestivum  (853)
  • Springer  (853)
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  • 1
    ISSN: 1432-1890
    Keywords: Key words Glomus mosseae ; Hydroponics ; Nitrate uptake ; Root respiration ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Oxygen and CO2 fluxes were measured in hydroponically grown mycorrhizal and non-mycorrhizal Triticum aestivum L. cv. Hano roots. The NO3 – uptake of the plants was used to estimate the amount of root respiration attributable to ion uptake. Plants were grown at 4 mM N and 10 μM P, where a total and viable mycorrhizal root colonisation of 48% and 18%, respectively, by Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe (BEG 107) was observed. The O2 consumption and NO3 – uptake rates were similar and the CO2 release was higher in mycorrhizal than in non-mycorrhizal wheat. This resulted in a significantly higher respiratory quotient (RQ, mol CO2 mol–1 O2) in mycorrhizal (1.27±0.13) than in non-mycorrhizal (0.79±0.05) wheat. As the biomass and N and P concentrations in mycorrhizal and non-mycorrhizal wheat were the same, the higher RQ resulted from the mycorrhizal colonisation and not differences in nutrition per se.
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  • 2
    ISSN: 1432-1890
    Keywords: Key words Arbuscular mycorrhiza ; Hordeum vulgare ; Triticum aestivum ; Glomus intraradices ; Mycorrhiza-helper bacteria ; Secondary compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Colonization of Hordeum vulgare L. cv. Salome (barley)and Triticum aestivum L. cv. Caprimus (wheat) roots by the arbuscular mycorrhizal fungus Glomus intraradices Schenck & Smith leads to de novo synthesis of isoprenoid cyclohexenone derivatives with blumenin [9-O-(2′-O-β-glucuronosyl)-β-glucopyranoside of 6-(3-hydroxybutyl)-1,1,5-trimethyl-4-cyclohexen-3-one] as the major constituent and to transient accumulation of hydroxycinnamate amides (4-coumaroylagmatine and -putrescine). Accumulation of these compounds in mycorrhizal wheat roots started 2 weeks after sowing together with the onset of arbuscule formation and proceeded with mycorrhizal progression. Highest levels were reached in 3- to 4-week-old secondary roots (root branches of first and higher order) characterized by the formation of vesicles. In the final developmental stages, the fungus produced massive amounts of spores, enclosing the stele of older root parts (older than 5 weeks) characterized by cortical death. In these root parts, the secondary compounds were detected in trace amounts only, indicating that they were located in the cortical tissues. Some rhizosphere bacteria tested, i.e. Agrobacterium rhizogenes, Pseudomonas fluorescens, and Rhizobium leguminosarum, markedly stimulated both fungal root colonization and blumenin accumulation, thus, acting as mycorrhiza-helper bacteria (MHB). Application of blumenin itself strongly inhibited fungal colonization and arbuscule formation at early stages of mycorrhiza development. This was associated with a markedly reduced accumulation of the hydroxycinnamate amides 4-coumaroylputrescine and -agmatine. The results suggest that both the isoprenoid and the phenylpropanoid metabolism are closely linked to the developmental stage and the extent of fungal colonization. Their possible involvement in the regulation of mycorrhiza development is discussed.
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  • 3
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    Biology and fertility of soils 23 (1996), S. 327-331 
    ISSN: 1432-0789
    Keywords: CO2 emission ; Field method ; Soil respiration ; Triticum aestivum ; Soil moisture ; Carbon reservoirs ; Greenhouse effect ; Grey forest soil ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dynamics of the rate of CO2 evolution from soil in fallow and croplant under spring wheat (Triticum aestivum L.) was studied in a crop rotation in grey forest soil of the Baikal forest-steppe during the growing season and in different years. It was shown that the regional characteristics of soils and hydrothermal conditions in different years affect the rate of CO2 evolution in agroecosystems. The seasonal dynamics of CO2 is characterized by insignificant changes in the autumn to spring period and enhanced emission in hot and dry summers. CO2 evolution is assumed to increase due to enhanced mineralization and partial diffusion from the carbonate horizon at the depth of the seasonal frost. During the growing season the dynamics of CO2 evolution depends on the soil moisture regime. There was a strong correlation between the rate of CO2 emission and soil moisture in the particularly dry year of 1993 (η=0.86) and a moderate correlation in the other years (η=0.38–0.54). The effect of the previous crop and fertilizer application on the rate of CO2 emission was insignificant. In a continuous fallow the total carbon release into the atmosphere varied throughout the years studied from 558 to 1880 kg ha-1. Humus losses varied from 0.9% to 3.1%.
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  • 4
    ISSN: 1432-0789
    Keywords: Azospirillum brasilense ; Triticum aestivum ; Inoculation ; N and dry matter yield ; N percentages in plant parts ; Associative N2 fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Wheat plants (Triticum aestivum) grown in pots and in the field under the Mediterranean climate of the south of France were inoculated with a strain of Azospirillum brasilense. Comparisons with non-inoculated plants grown under the same conditions showed significant responses to inoculation with an increase in the number of fertile tillers, shoot and root dry weight, and root to shoot biomass ratio. The roots of inoculated plants attracted relatively more assimilates than those of the control plants until a late stage of growth (heading stage) but the rhizosphere respiration expressed per unit of root growth was not increased by inoculation. Nitrogen yield, both total and in grains, was also enhanced; however, N percentages of all aerial parts of the plants grown in pots were always statistically lower after inoculation than in the control. At maturity, the N % in seeds was 1.81 and 2.45, respectively. The possible mechanisms of this effect of inoculation under the experimental conditions of this study are discussed.
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  • 5
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    Biology and fertility of soils 5 (1987), S. 76-82 
    ISSN: 1432-0789
    Keywords: Biomass accumulation ; Decomposition ; Litter ; Soil organic matter ; Soil respiration ; 14C deposition ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In a field experiment with 14C-labeled winter wheat conducted in the north-central region of the United States, crop-accumulated carbon (grain excluded) returned to the soil was found to be 542 g m−2 year−1. Almost half of the carbon from the underground compartment was released in the form of CO2 during the first 3 months after harvest due to very favorable conditions for biological activity. After 18 months, no less than 80% of the carbon from the plant residues was mineralized. About 16% of straw carbon and 24% of root carbon was transferred into soil organic matter. The annual rate of soil organic matter decomposition was approximated as 1.7%.
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  • 6
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    Biology and fertility of soils 17 (1994), S. 232-236 
    ISSN: 1432-0789
    Keywords: 15N-labelled fertilizer ; Added N interaction ; Fertilizer N uptake ; Soil N uptake ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied the effects of 15N-labelled ammonium nitrate and urea on the yield and uptake of labelled and unlabelled N by wheat (Triticum aestivum L., cv. Mexi-Pak-65) in a field experiment. The dry matter and N yields were significantly increased with fertilizer N application compared to those from unfertilized soil. The wheat crop used 33.6–51.5 and 30.5–40.9% of the N from ammonium nitrate and urea, respectively. Splitting the fertilizer N application had a significant effect on the uptake of fertilizer N by the wheat. The fertilizer N uptake showed that ammonium nitrate was a more available source of N for wheat than urea. The effective use of fertilizer N (ratio of fertilizer N in grain to fertilizer N in whole plant) was statistically similar for the two N fertilizers. The application of fertilizer N increased the uptake of unlabelled soil N by wheat, a result attributed to a positive added N interaction, which varied according to the fertilizer N split; six split applications gave the highest added N interaction compared to a single application or two split applications for both fertilizers. Ammonium nitrate gave 90.5, 33.5, and 48.5% more added N interaction than urea with one, two, and six split N applications. A values were not significantly correlated with the added N interaction (r=0.557). The observed added N interaction may have been the result of pool substitution, whereby added labelled fertilizer N replaced unlabelled soil N.
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  • 7
    ISSN: 1432-0789
    Keywords: 15N-labelled fertilizer ; Added N interaction Fertilizer N uptake ; Soil N uptake ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of 15N-labelled ammonium nitrate, urea and ammonium sulphate on yield and uptake of labelled and unlabelled N by wheat (Triticum aestivum L. cv. Mexi-Pak-65) were studied in a field experiment. The dry matter and N yields were significantly increased with fertilizer N application compared to those from unfertilized soil. The wheat crop used 64.0–74.8%, 61.5–64.7% and 61.7–63.4% of the N from ammonium nitrate, urea and ammonium sulphate, respectively. The fertilizer N uptake showed that ammonium nitrate was a more available source of N for wheat than urea and ammonium sulphate. The effective use of fertilizer N (ratio of fertilizer N in grain to fertilizer N in whole plant) was statistically similar for the three N fertilizers. The application of fertilizer N increased the uptake of unlabelled soil N by wheat, a result attributed to a positive added N interaction, which varied with the method of application of fertilizer N. Ammonium nitrate, urea and ammonium sulphate gave 59.3%, 42.8% and 26.3% more added N interaction, respectively, when applied by the broadcast/worked-in method than with band placement. A highly significant correlation between soil N and grain yield, dry matter and added N interaction showed that soil N was more important than fertilizer N in wheat production. A values were not significantly correlated with added N interaction (r=0.719). The observed added N interaction may have been the result of pool substitution, whereby added labelled fertilizer N stood proxy for unlabelled soil N.
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  • 8
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    Biology and fertility of soils 23 (1996), S. 327-331 
    ISSN: 1432-0789
    Keywords: Key words CO2 emission ; Field method ; Soil respiration ; Triticum aestivum ; Soil moisture ; Carbon reservoirs ; Greenhouse effect ; Grey forest soil ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dynamics of the rate of CO2 evolution from soil in fallow and cropland under spring wheat (Triticum aestivum L.) was studied in a crop rotation in grey forest soil of the Baikal forest-steppe during the growing season and in different years. It was shown that the regional characteristics of soils and hydrothermal conditions in different years affect the rate of CO2 evolution in agroecosystems. The seasonal dynamics of CO2 is characterized by insignificant changes in the autumn to spring period and enhanced emission in hot and dry summers. CO2 evolution is assumed to increase due to enhanced mineralization and partial diffusion from the carbonate horizon at the depth of the seasonal frost. During the growing season the dynamics of CO2 evolution depends on the soil moisture regime. There was a strong correlation between the rate of CO2 emission and soil moisture in the particularly dry year of 1993 (η=0.86) and a moderate correlation in the other years (η=0.38–0.54). The effect of the previous crop and fertilizer application on the rate of CO2 emission was insignificant. In a continuous fallow the total carbon release into the atmosphere varied throughout the years studied from 558 to 1880 kg ha–1. Humus losses varied from 0.9% to 3.1%.
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  • 9
    ISSN: 1432-0789
    Keywords: Rhizosphere bacteria ; Nitrogenase activity ; Triticum aestivum ; Inoculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Wheat seedlings were inoculated with rhizosphere nitrogen-fixing bacteria and grown gnotobiotically for 15 days. The growth medium consisted of semisolid agar with or without plant nutrients. The bacteria, isolated from roots of field-grown wheat, were three unidentified Gram-negative rods (A1, A2, E1), one Enterobacter agglomerans (C1) and two Bacillus polymyxa (B1, B2). A strain of Azospirillum brasilense (USA 10) was included for comparison. Nitrogenase activity (acetylene reduction activity, ARA) was tested on intact plants after 8 and 15 days of growth. In semisolid agar without plant nutrients, five isolates showed ARA of 0.01–0.9 nmol C2H4 plant−1 h−1, while the two strains of B. polymyxa had higher ARA of 3.3–10.6 nmol C2H4 plant−1 h−1. Plant development was not affected by inoculation with bacteria, except that inoculation with B. polymyxa resulted in shorter shoots and lower root weight. Transmission electronmicroscopy of roots revealed different degrees of infection. A. brasilense, A1 and A2, occurred mainly in the mucilage on the root surface and between outer epidermal cells (low infectivity). B. polymyxa strains and E1 were found in and between epidermal cells (intermediate infectivity) while E. agglomerans invaded the cortex and was occasionally found within the stele (high infectivity).
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  • 10
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    Biology and fertility of soils 3 (1987), S. 199-204 
    ISSN: 1432-0789
    Keywords: Phosphatases ; Rhizosphere ; Organic phosphorus ; Allium cepa ; Brassica oleracea ; Triticum aestivum ; Trifolium alexandrinum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The distribution of phosphatase activity and of phosphate fractions of the soil in the proximity of roots was studied in order to evaluate the significance of phosphatases in P nutrition of various plants (Brassica oleracea, Allium cepa, Triticum aestivum, Trifolium alexandrinum). A considerable increase in both acid and alkaline phosphatase activity in all the four soil-root interfaces was observed. Maximum distances from the root surface at which activity increases were observed ranged from 2.0 mm to 3.1 mm for acid phosphatase and from 1.2 mm to 1.6 mm for alkaline phosphatase. The increase in phosphatase activity depended upon plant age, plant species and soil type. A significant correlation was noticed between the depletion of organic P and phosphatase activity in the rhizosphere soil of wheat (r = 0.99**) and clover (r = 0.97**). The maximum organic P depletion was 65% in clover and 86% in wheat, which was observed within a distance from the root of 0.8 mm in clover and 1.5 mm in wheat. Both the phosphatases in combination appear to be responsible for the depletion of organic P.
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  • 11
    ISSN: 1432-0789
    Keywords: Triticum aestivum ; T. turgidum ; Nitrogen fixation ; Field inoculation ; Acetylene reduction assay (ARA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Eight commercial Israeli spring wheat cultivars (six Triticum aestivum and two T. turgidum) grown with 40 and 120 kg N/ha were tested for responses to inoculation with Azospirillum brasilense. At the low level of N fertilization (40 kg/ha), five cultivars showed significant increases in plant dry weight measured at the milky ripe stage; however, by maturation only the cultivar “Miriam” showed a significant increase in grain yield. Two cultivars, which had shown a positive inoculation effect at the earlier stages, had a significant decrease in grain yield. No significant effect of inoculation was found at the high N level. To confirm those results, four wheat (T. aestivum) cultivars were tested separately over 4 years in 4 different locations under varying N levels. Only Miriam showed a consistently positive effect of Azospirillum inoculation on grain yield. Inoculation increased the number of roots per plant on Miriam compared with uninoculated plants. This effect was found at all N levels. Nutrient (N, P and K) accumulation and number of fertile tillers per unit area were also enhanced by Azospirillum, but these parameters were greatly affected by the level of applied N. It is suggested that the positive response of the spring wheat cultivar “Miriam” to Azospirillum inoculation is due to its capacity to escape water stresses at the end of the growth season.
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  • 12
    ISSN: 1432-0789
    Keywords: Biopores ; Root growth ; Transpiration ; Simulations ; Mechanical impedance ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The use of vertical biopores by wheat (Triticum aestivum) seminal roots for easy access to the subsoil and the consequences for plant water supply and yield has been investigated by computer simulation. Parameters included were: biopore density and diameter, depth of cultivation and strength of the subsoil — all under a wide range of seasonal weather conditions. The model predicts that biopores add significantly to root penetration at depth, even at a density of 0.1% v/v of small, vertical pores, while 1.5% to 2.0% v/v can ensure maximum root penetration. When the growing season is shorter a larger number of biopores is needed to ensure timely root penetration to depth. With shallow tillage, biopores occur closer to the soil surface, and their importance is increased. Deeper root penetration invariably gives greater water uptake and transpiration, but may have a negative effect on grain yield, especially under the driest climatic conditions. An increase in early water use may result in less soil water being available during the grain-filling period. The effect of biopores on plant transpiration varies from year to year, depending on the amount of rain and its distribution in time, and on the amount of soil water stored at time of sowing.
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  • 13
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    Biology and fertility of soils 9 (1990), S. 281-282 
    ISSN: 1432-0789
    Keywords: Surface sterilization ; Contaminants ; Sterile plant selection ; Axenic seedlings ; Triticum aestivum ; Trifolium pratense ; Trifolium repens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Sterile seedlings are required for the investigation of interactions between microorganisms and plants. The present study was designed to develop a simple and reliable method for the selection of sterile seedlings by the use of liquid nutrient media, avoiding some of the disadvantages of solid media. The method of germinating surface-sterilized seedlings on solid water agar or nutrient media was compared with our method for sterility control in nutrient broth. Sterile plant selection in liquid media was the most sensitive method for detecting bacterial and fungal contaminants. Sterile plants grow with the same vigour as unsterilized plants and can be used for sterile plant experiments.
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  • 14
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    Biology and fertility of soils 7 (1988), S. 67-70 
    ISSN: 1432-0789
    Keywords: Root activity ; Soil C mineralization ; 14C-labelled plant material ; Decomposition stages ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two different soils were amended with 14C-labelled plant material and incubated under controlled laboratory conditions for 2 years. Half the samples were cropped with wheat (Triticum aestivum) 10 times in succession. At flowering, the wheat was harvested and the roots removed from the soil, and a new crop was started. Thus, the soil was continuously occupied by predominantly active root systems. The remaining samples were maintained without plants under the same conditions. The aim of the experiment was to study the effects of active roots on C-mineralization rates during different stages of decomposition and during long-term incubation. During the first 200 days, corresponding to the active decomposition stages, the roots weakly reduced 14C mineralization. With a lower level of decomposition, when more than 60% of the initial 14C was mineralized and when the available nutrients were markedly exhausted by plant uptake, the roots stimulated 14C mineralization.[/ p]
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  • 15
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    Nutrient cycling in agroecosystems 39 (1994), S. 43-57 
    ISSN: 1573-0867
    Keywords: Bicarbonate soil test phosphorus ; relative effectiveness ; rock phosphate ; superphosphate ; Triticum aestivum ; ×Triticosecale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of water supply on the response of wheat (Triticum aestivum) and triticale (×Triticosecale) to levels of freshly-applied rock phosphate and superphosphate, and the residues of these fertilizers applied 9 years previously in the field, was studied in three glasshouse experiments. The 〈 2 mm fraction of the top 10 cm of soil was used (1.8 kg soil per pot), and in one experiment, freshly-applied fertilizer was also added to the more acidic subsoil (10 to 20 cm). There were two water treatments: the soil was returned to field capacity by watering to weight, either daily (W1, adequate water) or weekly (W2, water stress). Yield of dried tops was used to calculate fertilizer effectiveness. The phosphorus (P) concentration in dried tops was used to determine critical P, which is the P concentration related to 90% of the maximum yield. Just before sowing, soil samples were collected to measure bicarbonate-extractable (soil test) P which was related to plant yield. Water stress reduced yields and maximum yield plateaus by 20 to 40%. Water stress reduced the effectiveness of all P fertilizers by between 20 to 60%, largely because of a reduction in the maximum yield potentials. In the field, water supply is seasonally dependent and it can affect the yield response of plants to freshly-applied rock phosphate and superphosphate and the residues of these fertilizers applied to the field in previous years. Relative to placing fertilizer in the topsoil, placing fertilizer in the subsoil improved effectiveness by about 26% for rock phosphate and 12% for superphosphate. The relationship between yield and P concentration in dried tops, and critical P, differed for W1 and W2. The soil test P calibration, which relates yield to soil test P, and the soil test P required to produce the same yield also differed for W1 and W2. Consequently critical P and soil test P calibrations depend on water supply, which in the field varies within and between growing seasons. This is so for freshly- and previously-applied rock phosphate and superphosphate.
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  • 16
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    World journal of microbiology and biotechnology 15 (1999), S. 417-423 
    ISSN: 1573-0972
    Keywords: 15N ; nitrogen mineralization ; Pseudomonas fluorescens ; rhizosphere ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The effects of an antibiotic-producing Pseudomonas fluorescens strain (F113) carrying the marker gene cassette lacZY and a marked, non-producing strain (F113G22) on the uptake of nitrogen from 15N-enriched organic residues incorporated into a sandy soil were investigated in microcosm studies. Strain F113 produces the antibiotic 2,4-diacetylphloroglucinol (DAPG), whilst its modified derivative strain F113G22 has DAPG production deleted by Tn5 mutagenesis. Uptake of nitrogen by wheat (Triticum aestivum) from 15N-enriched organic residues was estimated using stable isotope-ratio mass spectrometry of shoot and root material of 17-day-old plants. In addition, plant growth and active microbial biomass in soil were monitored. In contrast to results obtained in our previous study on pea (Pisum sativum), it was found that in wheat, inoculation with either strain F113 or F113G22 decreased the proportion of nitrogen derived from 15N-labelled organic residues incorporated into soil as compared to non-inoculated controls. It is therefore suggested that these strains decreased mineralization of organic residues in the rhizosphere of wheat, making less inorganic N (15N) available for plant uptake. The results of this study indicate that the effects of introduced Pseudomonas fluorescens strains on nitrogen mineralization in the rhizosphere are plant-species dependent, and highlight the importance of testing microbial inocula on a range of plant species.
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  • 17
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    Biologia plantarum 39 (1997), S. 463-466 
    ISSN: 1573-8264
    Keywords: dry mass ; fresh mass ; Triticum aestivum ; water content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Shoot and root fresh and dry matters and their Cu content were determined in 7-d-old seedlings of Triticum aestivum L. cv. Alkora treated with Cu (10,20, 40 µg cm-3) and Si (500 µg cm-3). Si significantly reduced the toxic effect of Cu on fresh and dry matter production of wheat seedlings. Moreover, plants treated with Cu and Si absorbed less Cu from the solution and had higher water content in shoots and roots than that treated with Cu only.
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  • 18
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    Biologia plantarum 40 (1997), S. 103-108 
    ISSN: 1573-8264
    Keywords: auxin ; Avena sativa ; Hordeum vulgare ; Secale cereale ; Setaria italica ; Sorghum durra ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wounding-induced extracellular pH shifts were characterized previously in excised segments of maize (Zea mays L.) coleoptiles. In the present study it is demonstrated that similar pH shifts also occur in Triticum aestivum L., Secale cereale L., Hordeum vulgare L., Avena sativa L., Sorghum durra (Forsk.) Stapf, and Setaria italica (L.) Beauv., with characteristic quantitative differences between the species. Indole-acetic acid induces pronounced drops of the medium pH in all species except Setaria italica.
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  • 19
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    Biologia plantarum 40 (1997), S. 357-364 
    ISSN: 1573-8264
    Keywords: active oxygen species ; ascorbate peroxidase ; carotenoids ; chlorophylls ; glutathione reductase ; oxidative injury ; oxidative stress ; Triticum aestivum ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The role of plant antioxidant system in water stress tolerance was studied in three contrasting wheat genotypes. Water stress imposed at different stages after anthesis resulted in a general increase in lipid peroxidation (LPO) and decrease in membrane stability index (MSI), and contents of chlorophylls (Chl) and carotenoids (Car). Antioxidant enzymes like glutathione reductase and ascorbate peroxidase significantly increased under water stress. Genotype C 306, which had highest glutathione reductase and ascorbate peroxidase activity, also showed lowest LPO and highest MSI, and Chl and Car contents under water stress in comparison to susceptible genotype HD 2329, which showed lowest antioxidant enzyme activity as well as MSI, Chl and Car contents and highest LPO. HD 2285 which is tolerant to high temperature during grain filling period showed intermediate behaviour. Thus, the relative tolerance of a genotype to water stress as reflected by its comparatively lower LPO and higher MSI, Chl and Car contents is closely associated with its antioxidant enzyme system.
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  • 20
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    Biologia plantarum 41 (1998), S. 65-73 
    ISSN: 1573-8264
    Keywords: ascorbate peroxidase ; catalase ; flavonoids ; superoxide dismutase ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In wheat seedlings (Triticum aestivum L. cv. 2329) oxidative stress caused by UV-B radiation led to lipid peroxidation of thylakoid membrane; it was expressed in term of malondialdehyde (MDA) formation. The peroxidation of lipids of thylakoid membrane in isolated chloroplasts was prevented when flavonoids quercetin and rutin were supplied into the incubation medium. The activities of superoxide dismutase, ascorbate peroxidase, and catalase increased during the first hours of UV-B exposure. A comparative study of UV-B and temperature effects showed different profiles of the antioxidant enzymes and MDA, suggesting that these two stresses have distinct sites of action. In addition to quantitative increase in flavonoids, qualitative change in flavonoid composition was also marked during UV-B stress, and a new peak at 330 nm was found as compared to control.
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  • 21
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    Biologia plantarum 41 (1998), S. 387-394 
    ISSN: 1573-8264
    Keywords: active oxygen species ; ascorbate peroxidase ; ascorbic acid ; catalase ; hydrogen peroxide ; oxidative injury ; oxidative stress ; superoxide dismutase ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The role of plant antioxidant systems in stress tolerance was studied in leaves of three contrasting wheat genotypes. Drought imposed at two different stages after anthesis resulted in an increase in H2O2 accumulation and lipid peroxidation and decrease in ascorbic acid content. Antioxidant enzymes like superoxide dismutase, ascorbate peroxidase and catalase significantly increased under water stress. Drought tolerant genotype C 306 which had highest ascorbate peroxidase and catalase activity and ascorbic acid content also showed lowest H2O2 accumulation and lipid peroxidation (malondialdehyde content) under water stress in comparison to susceptible genotype HD 2329 which showed lowest antioxidant enzyme activity and ascorbic acid content and highest H2O2 content and lipid peroxidation. HD 2285 which is tolerant to high temperature during grain filling period showed intermediate behaviour. Superoxide dismutase activity, however, did not show significant differences among the genotypes under irrigated as well as water stress condition. It seems that H2O2 scavenging systems as represented by ascorbate peroxidase and catalase are more important in imparting tolerance against drought induced oxidative stress than superoxide dismutase alone.
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  • 22
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    Biologia plantarum 41 (1998), S. 427-434 
    ISSN: 1573-8264
    Keywords: phloem ; rubidium ; strontium ; Triticum aestivum ; xylem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Detached wheat shoots (ear with peduncle and flag leaf) were incubated for 4 d in a solution containing 1 mM RbCl and 1 mM SrCl2 as well as 10, 40 or 160 µM NiCl2 and CoCl2. The phloem of some plants was interrupted by steam-girdling the stem below the ear to distinguish between xylem and phloem transport. The phloem-immobile Sr flowed mainly to the leaf lamina and to the glumes via the xylem. The Sr transport was not sensitive to steam-girdling. In contrast, the phloem-mobile Rb accumulated during the incubation time mainly in the stem and the leaf sheath. The Rb transport to the grains was impaired by steam-girdling as well as by elevated Ni and Co concentrations in the incubation solution indicating that Rb was transported via the phloem to the maturing grains and that this transport was affected by the heavy metals. Ni was removed more efficiently from the xylem in the peduncle than Co (but far less efficiently than Rb). It became evident that the two heavy metals can also be transferred from the xylem to the phloem in the stem of wheat and reach the maturing grains via the phloem.
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  • 23
    ISSN: 1573-8264
    Keywords: carboxylation efficiecy ; carotenoids ; chlorophyll ; growth analysis ; net photosynthetic rate ; photochemical efficiency ; ribulose 1,5-bisphosphate carboxylase/oxygenase ; stomatal conductance ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wheat plants were grown from sowing to day 18 in 26-dm3 chambers at three different CO2 concentrations: 150 (-CO2), 350 (C, control), 800 (+CO2) μmol mol-1. Afterwards, plants of the three variants were grown at the same natural CO2 concentration. Plant characteristics were measured just before the transfer (0 days after CO2 treatment, DAT), and at 5 – 8 DAT on the 1st leaf, and at 12 – 22 DAT on the 4th leaf. Decreased or increased CO2 concentrations caused acclimations which persisted after transplantation to natural CO2 concentration. At 5 – 8 DAT, stomatal density, stomatal conductance (gs), CO2 saturated net photosynthetic rate (PNsat0), radiation saturated net photosynthetic rate (PNsat1), and carboxylation efficiency (τ) were higher in -CO2 plants and lower in +CO2 plants than in C plants. As compared with C plants, the photochemical efficiency (α) was lower in -CO2 and higher in -CO2 plants, however, chlorophyll (Chl) a, Chl b, Chl a–b and carotenoid contents were lower in both -CO2 and +CO2 plants. On the 4th leaf, which emerged on plant after finishing CO2 treatments, at 12 – 22 DAT, no differences in stomatal density and g, between treatments were observed. In -CO2 plants, pigment content and PNsat0 were higher, α was lower, and PNsat1 and τ were not different from C plants. In contrast, in +CO2 plants, pigment content, PNsat1 and τ were lower, and PNsat0 and α were unchanged. Leaf area, dry mass, and tiller development increased in +CO2 plants and decreased in -CO2 plants. In the interval between 8 and 22 DAT, lower net assimilation rate in +CO2 than in -CO2 plants was observed.
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  • 24
    ISSN: 1573-8264
    Keywords: ascorbic acid ; ascorbate peroxidase ; active oxygen species ; catalase ; hydroger ; peroxide ; oxidative stress ; superoxide dismutase ; temperature stress ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An experiment was conducted with three wheat (Triticum aestivum L.) genotypes C 306, HD 2285 and HD 2329 (differently susceptible to water and temperature stress) to study the extent of oxidative injury and activities of antioxidant enzymes in relation to heat stress induced by manipulating dates of sowing. Increase in temperature by late sowing significantly decreased leaf relative water content (RWC), ascorbic acid content, and increased H2O2 content and lipid peroxidation in all the genotypes at 8 and 23 d after anthesis. Temperature tolerant genotypes C 306, closely followed by HD 2285 were superior to HD 2329 in maintaining high RWC, ascorbic acid content, and lower H2O2 content and lipid peroxidation (malondialdehyde content) under high temperature (late sowing) at the two stages. Activities of superoxide dismutase and catalase were highest in HD 2285 followed by C 306 and minimum in HD 2329 while ascorbate peroxidase activity was highest in C 306.
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  • 25
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    Biologia plantarum 43 (2000), S. 309-311 
    ISSN: 1573-8264
    Keywords: grains ; maturation ; radioisotopes ; transport ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Steam-girdling experiments with detached wheat shoots showed that cesium was eliminated from the xylem sap and loaded into the phloem during acropetal transport. This transfer is important for the accumulation of cesium (especially also of the radiopollutants 134Cs and 137Cs) in maturing wheat grains.
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  • 26
    ISSN: 1573-8264
    Keywords: active oxygen species ; catalase ; chloroplast ; glutathione reductase ; lipid peroxidation ; nitrate reductase ; proline ; superoxide dismutase ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We induced an oxidative stress by means of exogenous hydrogen peroxide in two wheat genotypes, C 306 (tolerant to water stress) and Hira (susceptible to water stress), and investigated oxidative injury and changes in antioxidant enzymes activity. H2O2 treatment caused chlorophyll degradation, lipid peroxidation, decreased membrane stability and activity of nitrate reductase. Hydrogen peroxide increased the activity of antioxidant enzymes, glutathione reductase and catalase. These effects increased with increasing H2O2 concentrations. However, no change was observed in the activity of superoxide dismutase and proline accumulation.
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  • 27
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    Biologia plantarum 43 (2000), S. 559-562 
    ISSN: 1573-8264
    Keywords: phenolics ; susceptibility ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Polyphenol oxidase activity was higher in resistant wheat cultivar ACC-8226 than in susceptible cultivar MP-845 in control sets and after inoculation of Alternaria triticina. However, similar polyphenol oxidase isozyme pattern was found in control and inoculated sets of both the cultivars, but the band intensity was higher after inoculation. Three and four peroxidase isozymes were found in ACC-8226 and MP-845, respectively. An extra peroxidase isozyme band was observed in both the cultivars after inoculation. The results suggest an active role of peroxidase and polyphenol oxidase in defence mechanism of wheat plants.
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  • 28
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    Biologia plantarum 41 (1998), S. 287-292 
    ISSN: 1573-8264
    Keywords: enzyme activities ; liquid culturing ; protein ; starch ; sugars ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Effect of fluoride (10 and 50 mM) on the activities of sucrose metabolizing enzymes, alkaline inorganic pyrophosphatase, and transaminases in relation to the accumulation of free sugars, starch, and soluble protein was studied in detached ears of wheat cultured in a liquid medium. Culturing for 5 d in the presence of fluoride reduced the amount of grain starch whereas contents of total free sugars, particularly sucrose, and soluble protein increased. Fluoride inhibited the activities of soluble acid and neutral invertases, as well as sucrose synthase acting in the cleavage direction. Uptake of uniformly labelled 14C-sucrose or fructose was also drastically reduced by fluoride. Glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) activities also increased with fluoride addition in correspondence with an increase in soluble protein. Apparently, the wheat grain responds to fluoride-mediated disruption of carbon metabolism by a compensatory effect on nitrogen metabolism.
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  • 29
    ISSN: 1573-8264
    Keywords: Brassica napus ; ex vitro acclimation ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The greatest growth of wheat and rape plants in vitro was reached on media with 5 or 9 % sucrose, respectively. The highest efficiency for transfer of these plants to ex vitro conditions was found at the same sucrose concentrations. The content of endogenous non-structural saccharides (glucose, fructose, sucrose, starch and fructans) increased with increasing sucrose concentration in the medium up to 10 %.
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  • 30
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    Biologia plantarum 43 (2000), S. 61-66 
    ISSN: 1573-8264
    Keywords: lipids ; polypeptide pattern ; salt stress ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wheat seedlings of a salt tolerant cultivar were grown hydroponically in presence and absence of 100 mM NaCl. Roots were harvested, and the plasma membrane (PM) fraction was purified. PM ATPase required a divalent cations for activity (Mg 〉 Mn 〉 Ca 〉 Co 〉 Zn 〉 Ni 〉 Cu), and it was further stimulated by monovalent cations (K 〉 Rb 〉 NH4 〉 Li 〉 choline 〉 Cs). The pH optima were 6.0 and 5.6 in absence and presence of 25 mM KCl, respectively. The enzyme was sensitive to vanadate and DCCD but insensitive to azide, oligomycine and nitrate. The enzyme displayed a high preference for ATP but was also able to hydrolyze other nucleotide tri- and diphosphates. The enzyme activity showed a simple Michaelis-Menten kinetics for the substrate Mg2+-ATP in both control and salt exposed roots. The polypeptide patterns of control and salt stressed PM fractions, detected by SDS-PAGE, were very similar. NaCl substantially reduced the PM ATPase specific activity, whereas it had little effect on the apparent Km for Mg2+-ATP. Since the root PM ATPase of salt sensitive and resistant genotypes responded similarly to salinity stress, it seems unlikely that the mechanism of salt tolerance in wheat is primarily based on differences in PM ATPase characteristics.
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  • 31
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    Biologia plantarum 43 (2000), S. 257-262 
    ISSN: 1573-8264
    Keywords: nitrate assimilation ; Triticum aestivum ; Zn toxicity ; Cu toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of Zn2- on nitrate reductase (NR, EC 1.6.6.1) activity was studied in botá wheat (Triticum aestivum cv. Oasis) leaves and in the NR enzyme partially purified from wheat leaves. Leaf segments were floated on 0 to 5 mM ZnSO4 solutions (pH 6.0) for 24 h under continuous light. Zn2- at 250 μM decreased NR activity and increased membrane permeability. However, parameters of cellular oxidative damage were scarcely affected by Zn2- treatments. Accordingly, the decrease of NR activity induced by Zn2- was not prevented by benzoate (a scavenger of oxygen radicals). The effect of Zn2- was dependent on leaf age: it decreased NR activity in mature but not in young leaves. Zn2 inhibited the partially purified NR. This inhibition was not reversed by either co- or post-incubation with cysteine, and the amount of -SH groups of the purified NR was not affected by Zn2+ indicating that Zn2- inhibition does not involve key -SH groups of the enzyme. However, o-phenantroline both prevented and reversed Zn2+-induced NR inhibition. We concluded that the effect of Zn2+ on NR activity in vivo is not associated with an increase in active oxygen generation and involves a direct and reversible inhibition of the enzyme.
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  • 32
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    European journal of plant pathology 96 (1990), S. 29-34 
    ISSN: 1573-8469
    Keywords: Triticum aestivum ; simulation ; SUCROS87 ; NWHEAT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting Om systemen voor geleide bestrijding van ziekten te verbeteren, werd de vraag gesteld of schaderelaties, vastgesteld in jaren met specifieke weersomstandigheden, ook gebruikt kunnen worden in andere jaren. Twee bestaande modellen van tarwe en een combinatie van beide, werden gebruikt om het effect van weer op opbrengst te berekenen, eerst bij afwezigheid van meeldauw. De berekende opbrengsten in verschillende jaren toonden geen samenhang met de behaalde opbrengsten, gecorrigeerd voor een jaarlijkse toename, in Nederland. Verschillen tussen de modellen konden worden toegeschreven aan de wijze waarop de groei en ontwikkeling van tarwe vroeg in het seizoen wordt berekend.
    Notes: Abstract A vital question to upgrade disease management systems is whether damage functions, established in years with specific weather conditions, can be applied also in other years. A simulation approach was used to explore effects of weather on yield and damage. Two existing models of wheat and a third, a combination of both, were used to compute yield, first in absence of mildew. In a second paper, effects of mildew will be reported. Yields simulated for different years were not significantly correlated with yields harvested, adjusted for their increase over years, in the Netherlands. Differences in performance between the models could be attributed to the method of simulating development and growth early in the cropping season.
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  • 33
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    European journal of plant pathology 96 (1990), S. 17-28 
    ISSN: 1573-8469
    Keywords: Puccinia rcondita ; Triticum aestivum ; model ; photosynthesis ; competition for light
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting Verschillen tussen zeven wintertarwegenotypen in opbrengstderving door bruine roest, zoals waargenomen in een veldexperiment, werden geanalyseerd met een simulatiemodel. In dit model werd het effect van de ziekte op gewasgroei en opbrengst beschreven op basis van lichtinterceptie, fotosynthese, ademhaling en assimilatenverdeling. Het model gaf een goede beschrijving van de waargenomen opbrengstverschillen tussen de genotypen, zowel bij aanwezigheid als bij afwezigheid van bruine roest. Van de totale opbrengstreductie werd, volgens modelberekeningen, 66% veroorzaakt door versnelde afname van groen bladoppervlak en 18% door het wegvangen van licht door dood bladweefsel boven in het gewas. De genetische variatie in opbrengstreductie werd zodoende vooral verklaard uit de waargenomen verschillen in bladveroudering tussen de genotypen. De fotosynthese per eenheid resterend groen bladoppervlak werd niet beïnvloed door bruine roest. Respectieven voor selectie op afzonderlijke schadecomponenten werden geëvalueerd op basis van hun gesimuleerde effect op korrelopbrengst, in combinatie met hun genetische en toevalsvariatie.
    Notes: Abstract Differences in yield reduction among seven winter wheat genotypes due to leaf rust, as observed in a field experiment, were analysed using a simulation model. In this model, the effects of the disease on crop growth and yield were described on the basis of light interception, photosynthesis, respiration and assimilate partitioning. The model properly described the observed yield difference between the genotypes, both in the absence and in the presence of leaf rust. According to the model, 66% of total yield reduction was due to an accelerated decrease in green leaf area and 18% was due to light capture by dead leaf tissue at the top of the canopy. Genetic variation in yield reduction was, therefore, mainly explained by variation in leaf senescence. Leaf rust did not affect the photosynthetic rate of the remaining green leaf area. Opportunities of selection for individual damage components were assessed from their simulated effect on grain yield, together with their estimated genetic and environmental variance.
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  • 34
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    European journal of plant pathology 96 (1990), S. 35-46 
    ISSN: 1573-8469
    Keywords: Triticum aestivum ; Erysiphe graminis DC. ex Merat ; Blumeria graminis (DC.) Speer ; simulation ; SUCROS87 ; sensitivity analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting Opbrengstderving van wintertarwe werd berekend aan de hand van het effect dat meeldauw heeft op de blad-fotosynthese. Een rekenmodel voor de gewasgroei van tarwe werd uitgebreid met meeldauw. Met inachtneming van de vertikale en horizontale verdeling van meeldauw in het gewas, werd meeldauw in het model gekwantificeerd door vijf parameters. De belangrijkste parameters waren die van de meeldauwintensiteit, de verdeling van meeldauw in het gewas en het effect van meeldauw op de assimilatie bij een overvloed aan licht. Epidemieën van meeldauw, gemeten in veldproeven in drie verschillende jaren, werden gebruikt om opbrengstdervingen te berekenen. Gemiddeld kwam deze redelijk overeen met de in de veldproeven gemeten opbrengstderving. De gemeten opbrengstderving werd echter onderschat, vooral bij vroege epidemieën van meeldauw door de wijze waarop de (her)verdeling van assimilaten wordt berekend. Andere mechanismen, die een onderschatting van opbrengstderving kunnen veroorzaken worden besproken. Of deze modellen als methode gebruikt kunnen worden om systemen voor de geleide bestrijding van ziekten te verbeteren wordt bediscussieerd.
    Notes: Abstract Wheat yield losses caused by powdery mildew were computed based on effects of the disease on leaf photosynthesis. Powdery mildew was introduced in a crop model of wheat by quantification of five parameters, taking the vertical and horizontal distribution of mildew in the crop into account. The most important parameters were those of the mildew intensity, the distribution of mildew in the crop, and the effect of mildew on assimilation at light saturation. Measured mildew epidemics in field experiments in three different years, were used to compute yield losses. Computed losses were compared to measured losses. On average, computed yield loss approached measured, but measured yield loss was underestimated, especially in early mildew epidemics due to the computation of partitioning and reallocation of assimilates. Other processes which may cause an underestimation are described. The use of crop models as a method to upgrade disease management systems is discussed.
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  • 35
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    European journal of plant pathology 96 (1990), S. 251-260 
    ISSN: 1573-8469
    Keywords: Triticum aestivum ; Pseudocercosporella herpotrichoides ; Rhizoctonia cerealis ; Gaeumannomyces graminis ; epidemiology ; weather ; forecasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting Een honderdtal percelen wintertarwe werd in 1974–86 jaarlijks op voetziekten geïnventariseerd. In het voorjaar, tijdens het, eerste en tweede knoopstadium van het gewas, was gemiddeld 6% van de spruiten aangetast door oogvlekkenziekte. De intensiteit van de ziekte was hoog in jaren met een hoge gemiddelde wintertemperatuur. Tijdens het melkrijpe stadium, in juli was gemiddeld 13% van de halmen aangetast door oogvlekkenziekte. De aantasting in juli was hoog in jaren met een hoge temperatuur in april en veel neerslag in de maanden maart, april en mei. Met deze gegevens kunnen adviessystemen worden verbeterd. Scherpe oogvlekkenziekte was op gemiddeld 2% van de halmen in juli aanwezig. De ziekte nam geleidelijk met de jaren toe. De jaarlijkse intensiteit was niet gecorreleerd met droge perioden in de herfst, voorjaar of zomer. Symptomen van halmdoder waren op gemiddeld 0.2% van de halmen aanwezig. De intensiteit van de ziekte was hoog in jaren met weinig neerslag in maart, april, mei en juni en met een lage temperatuur in mei en juni.
    Notes: Abstract In the period 1974–1986, ca. 100 commercial winter wheat fields were surveyed annually for stembase diseases. In these years, on average 6% of the tillers was infected with eyespot in spring at the first-second, node stage. Eyespot intensity in spring was high in years with high temperature during winter. Eyespot, intensity in the milky-ripe stage in July, averaged 13% of the culms and was high in years with high temperature in April and high precipitation in March, April and May. These data may improve forecasts. In the milky-ripe stage, 2% of the culms were infected with sharp eyespot, but its intensity has gradually increased during the survey years. No significant correlation of sharp eyespot intensity with dry periods in autumn, spring or summer was found. Symptoms of take-all were found on 0.2% of the stem-bases during ripening. Its intensity was low in years with high precipitation in March, April, May and June and high temperature in May and June.
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  • 36
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    European journal of plant pathology 92 (1986), S. 197-206 
    ISSN: 1573-8469
    Keywords: Triticum aestivum ; epidemiology ; sampling method ; detection level
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting Aantallen puistjes meeldauw per blad werden geteld in praktijkpercelen en veldproeven met wintertarwe. De steekproefvariantie van het aantal puistjes was tamelijk constant in de jaren, rassen, gewasstadia en bladposities, maar was sterk afhankelijk van het gemiddeld aantal puistjes $$(\bar m):s^2 = 2,2\bar m^{1.5} $$ . Het effect van de steekproefgrootte op de nauwkeurigheid van de schatting wordt besproken en het blijkt dat het moeilijk is om lichte aantastingen nauwkeurig te schatten. Er worden schattingen gegeven van de detectiegrens in afhankelijkheid van de steekproefgrootte. Meeldauwaantastingen aan de onderkant van het blad, kunnen worden geschat uit de aantasting op de bovenkant van het blad. Deze methode levert een tijdsbesparing op, maar ook een extra onnauwkeurigheid. Alleen bij lichte aantastingen en kleine steekproeven is deze methode efficiënter dan een directe tweezijdige bemonstering. Het schatten van meeldauw op de bovenkant van bladeren is, hoewel algemeen gebruikelijk, waarschijnlijk niet de meest efficiënte methode.
    Notes: Abstract Assessments of pustule number and severity of powdery mildew on winter wheat in the Netherlands were made in commercial fields and in experimental plots. The sample variance (s2) of the number of pustules per leaf (m) was fairly constant over years, varieties, growth stages and leaf postitions, but depended strongly on the average pustule number: $$s^2 = 2 \cdot 2\bar m^{1.5} $$ . The effect of sample size on the precision of the estimate is discussed and it is concluded that it is difficult to estimate low disease intensities accurately. Estimates are given for the detection level of pustule counts in relation to sample size. Mildew intensity on the lower surface of leaves can be estimated from the intensity on the upper surface. This method reduces the duration of the observation, but introduces an additional error. At low disease intensities and small sample sizes this method is more efficient than sampling mildew on both surfaces of leaves. The common practice of assessments of the upper surface of leaves only may not be the most efficient method.
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  • 37
    ISSN: 1573-8469
    Keywords: Triticum aestivum ; epidemiology ; sampling method ; detection level ; multiple infection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting Het aantal puistjes meeldauw per blad en de fractie zieke bladeren werden bepaald in praktijkpercelen en veldproeven met wintertarwe. De fractie ziek bladoppervlak kon worden afgeleid uit het aantal puistjes. Het verband tussen de fractie zieke bladeren en de fractie ziek bladoppervlak werd bestudeerd. Bij aanname van een constante blad- en puistjesgrootte kan een blad maximaal Mm puistjes herbergen. Als het aantal meeldauwkolonies (elk bestaande uit n puistjes) een binomiale kansverdeling volgt, dan kan het verband tussen de fractie zieke bladeren (I) en de fractie ziek bladoppervlak (S) worden beschreven door: (1−S)=(1−I)n/M m. De overeenkomsten van dit model met andere modellen wordt besproken en schattingen van parameters worden vergeleken. Het model verklaart hoe blad-, puistjes- en koloniegrootte het verband tussen de fractie zieke bladeren en de fractie ziek bladoppervlak beïnvloedt. Het model beschreef het verband tussen de metingen goed maar niet volledig. De negatieve binomiaal beschreef het verband tussen de metingen slecht. Het model van Nachman gaf een goede beschrijving van het verband tussen het gemiddeld aantal puistjes kper blad $$(\bar m)$$ en de fractie zieke bladeren (I). Voor de praktijkpercelen werd dit verband beschreven door: $$ln(\bar m) = 1,48 + 1,14ln(ln[1/(1 - I)])$$ . De invloed van jaren, rassen, gewasstadia en bladpositie op het verband was niet significant. De fractie zieke bladeren kan gebruikt worden om het gemiddeld aantal puistjes per blad te voorspellen, maar deze methode is minder efficiënt dan een directe telling van het aantal puistjes. Schattingsfouten van het voorspelde aantal puistjes per blad worden gegeven.
    Notes: Abstract Assessments of pustule number, incidence and severity of powdery mildew on winter wheat in the Netherlands were made in commercial fields and in experimental plots. Assuming a constant leaf and pustule size, a leaf can carry at most Mm pustules. If the number of clusters, each consisting of n pustules, follows a binomial distribution, then the relation between incidence (I, proportion diseased leaves) and severity (S, proportion diseased leaf surface) is: (1−S)=(1−I)n/M m. The model explains the main effects of leaf, pustule and cluster size on incidence-severity relations and gave a good description of the measured relation. The negative binomial distribution poorly described the measured relation. The model of Nachman (1981) gave a good description of the relation between mean pustule number $$(\bar m)$$ and incidence (I). The relation found in commercial fields, irrespective of fungicide treatments, was: $$ln(\bar m) = 1.48 + 1.14ln(ln[1/(1 - I)])$$ . The effects of years, varieties, growth stages and leaf positions on this relation were not significant. Incidence assessments can be used to predict the pustule number, but this method is less efficient than the use of direct pustule counts. Estimates are given of the variance of the predicted pustule number.
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  • 38
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    European journal of plant pathology 94 (1988), S. 69-80 
    ISSN: 1573-8469
    Keywords: Triticum aestivum ; epidemiology ; vertical distribution ; AUDPC-value ; tolerance ; integrated control ; Mycosphaerella graminicola ; triadimefon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting In 1981 en 1983 werd in veldproeven met wintertarwe de relatie tussen schade (in kg are−1) en meeldauw onderzocht. Of de relatie onafhankelijk is van de stikstofbemesting (175 en 235 kg ha−1 N totaal), kon niet met zekerheid worden vastgesteld. De schaderelatie werd niet significant beïnvloed door de vier getoetste rassen. In de twee jaren werd een vergelijkbare schade van gemiddeld 0.0125 kg are−1 per puistdag meeldauw per blad gemeten, bij een opbrengstniveau van 70–90 kg are−1. Tevens werd de locatie van meeldauw in het gewas beschreven.
    Notes: Abstract The damage relation of powdery mildew in winter wheat was studied in field experiments in 1981 and 1983, in the Netherlands. No firm conclusion was obtained on the effect of nitrogen supply (175 and 235 kg ha−1 N totally) on the damage relation. The relation was not affected by cultivars (four) and did not differ significantly between both years. The measured relation averaged 0.0125 kg are−1 damage per pustule-day mildew per leaf, at yields of 70–90 kg are−1. The effect of the fungicide triadimefon on yield could be ascribed to its effect on diseases. The vertical distribution of mildew in the crop was described.
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  • 39
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    European journal of plant pathology 95 (1989), S. 85-105 
    ISSN: 1573-8469
    Keywords: Triticum aestivum ; Erysiphe graminis ; vertical distribution ; triadimefon ; AUDPC-value ; economic thresshold ; seed number
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting Opbrengstderving van wintertarwe door meeldauw werd bestudeerd in 11 veldproeven in Nederland. De schade bedroeg gemiddeld 0.013 (SE=0.003) kg are−1 per puistdag meeldauw per blad, vanaf het tweede-knoop stadium tot begin deegrijp bij opbrengstniveaus van 70 tot 90 kg are−1, in de blanco. Bij een ziektestress van 0 tot 2000 puistdagen meeldauw per blad werd geen afwijking van een rechtlijnig verband gevonden. De schaderelatie werd niet significant beïnvloed door de verschillende jaren, rassen of grondsoorten. Het effect van meeldauw op enkele opbrengstcomponenten werd aangetoond. Meeldauwprofielen in de onbehandelde veldjes konden worden beschreven met de vergelijking: CM=CLAb, waarin CM het cumulatieve aantal puistjes is en CLA het cumulatieve bladoppervlak, beide berekend van bovenin het bladerdek naar beneden, de totalen gestandaardiseerd op één. De gradiënt parameter b bedroeg gemiddeld 3.4 (SE=0.9). Waargenomen verschillen in steilte van de meeldauwprofielen beïnvloedde de schaderelatie niet aantoonbaar.
    Notes: Abstract Damage by mildew to winter wheat was studied in 11 field experiments in the Netherlands. Damage is described by the simple function: −0.013 (SE=0.003) kg are−1 per pustule-day of mildew per leaf, from second node stage to early dough at yield levels of 70 to 90 kg are−1, in diseasefree plots. No deviations from linearity at disease stresses from zero to two thousand pustuledays per leaf were observed. Years, cultivars or soil types did not affect the damage function significantly. The effects of mildew on some yield components were suggested. Mildew profiles in untreated plots could be described by the equation: CM=CLAb, in which CM and CLA are the cumulative pustule number and the cumulative leaf area, respectively, calculated both from top to bottom of the canopy, and totals standardized at unity. Estimates of the gradient parameter b aveaged 3.4 (SE=0.9). Observed differences in steepness of the profiles did not affect the damage function significantly.
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  • 40
    ISSN: 1573-8469
    Keywords: yellow (stripe) rust races ; Triticum aestivum ; Yr genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting Onder geconditioneerde klimaatsomstandigheden zijn 42 Ethiopische en CIMMYT rassen en lijnen van broodtarwe (Triticum aestivum) in het kiemplantstadium geïnoculeerd met 19 isolaten van gele roest die onderling verschilden in hun pathogeniteit voor 20 differentiërende tarwerassen waarvan de resistantie-achtergrond bekend is. De genom-gen relatie is toegepast om resistentiegenen te identificeren. Vier rassen en lijnen bleken resistent te zijn tegen alle isolaten. Verondersteld wordt dat hun resistentie berust op genen die niet eerder herkend waren of op een combinatie van bekende genen die niet compatibel was met de gebruikte isolaten. In het overige tarwemateriaal kon de aanwezigheid worden aangegeven van de resistentiegenenYr2, Yr3, Yr4, Yr6, Yr7, Yr9 enYrA. Het van rogge afkomstige en door het CIMMYT veel gebruikte resistentiegenYr9 was in 28 rassen en lijnen (67%) aanwezig. In het onderzochte tarwemateriaal isYr4 het enige voor Oost en Centraal Afrika effectieve resistentiegen omdat de daar voorkomende gele roest pathogeniteit bezit voor de overige genen. Het herkennen van pathogeniteit van gele roest voor bepaalde resistentiegenen is verbeterd door het toevoegen van tarwerassen met monogene resistentie aan het internatinale gebruikte tarwesortiment voor de determinatie van gele-roestfysio's.
    Notes: Abstract In a controlled environment, the reaction was observed of 42 bread wheat varieties and lines inoculated with 19 isolates of yellow rust differing in their virulence to 20 differential varieties. Five varieties and lines showed resistance to all isolates. The remaining ones appeared to have the genesYr2, Yr3, Yr4, Yr6, Yr7, Yr9 andYrA, either singly or in combination.Yr9 derived from rye was present in 67% of the varieties and lines.Yr4 is the only effective gene in that material as, in Eastern and Central Africa, yellow rust has virulence to the otherYr genes. Recognition of virulence toYr genes is enhanced by the use of a supplemental set of differential varieties supposedly carrying a single gene.
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  • 41
    ISSN: 1573-8469
    Keywords: Puccinia recondita ; Triticum aestivum ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting De relatie stussen de epidemiologie van bruine roest, bladveroudering en oprengstderving werden bestudeerd bij zeven wintertarwegenotypen die verschilden in partiële resistentie tegen bruine roest. Bruine roest versnelde de veroudering van blad en aar. Fotosynthesemetingen wezen echter uit dat de fotosynthesecapaciteit van het resterende groene oppervlak niet werd beïnvloed. Verschillen tussen de genotypen in opbrengstderving werden voornamelijk veroorzaakt door verschillen in bladveroudering en daarmee in cumulatieve lichtinterceptie (r=0.83) en gewasfotosynthese. De reductie in cumulatieve lichtinterceptie was nauw gerelateerd aan de cumulatieve ziektedruk (in puistdagen) (r=0.85), welke ook nauw was geassocieerd met de opbrengstderving (r=0.88). De opbrengstreductie werd echter even goed voorspeld door de tijdsduur tot 50% reductie van het groene bladoppervlak en de puistdichtheid halverwege de epidemie als door cumulatieve lichtinterceptie en cumulatieve ziektedruk, waardoor beide eerste criteria gebruikt kunnen worden in de selectie voor partiële resistentie tegen bruine roest.
    Notes: Abstract Relations between leaf rust progress, foliage senescence and yield reduction were studied for seven winter wheat genotypes, differing in their partial resistance to leaf rust. Leaf rust accelerated leaf and ear senescence. Photosynthesis measurements showed, however, that the photosynthetic capacity of the remaining green surface was not affected. Differences between genotypes in yield reduction were largely explained by differences in leaf senescence and, therefore, in cumulative light interception (r=0.83) and crop photosynthesis. Reduction in cumulative light interception was closely related to the area under the disease-progress-curve (r=0.85), which was also closely associated with yield reduction (r=0.88). However, the time taken to reach a 50% reduction of green leaf area and the pustule density on 1 July (i.e. halfway through the epidemic) were just as good predictors of yield reduction as cumulative light interception and area under disease-progress-curve, suggesting that the former are useful criteria in the selection for partial resistance to leaf rust.
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  • 42
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    Biologia plantarum 42 (1999), S. 119-123 
    ISSN: 1573-8264
    Keywords: anatomy ; epidermis ; heavy metals ; mesophyll ; Triticum aestivum ; vascular bundles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of 1 mM cadmium, lead and nickel on dry mass, Cd, Pb, and Ni contents, and changes in leaf structure in young wheat plants were studied. In leaves, Cd content was highest, followed by Pb and Ni, in roots Cd content was also highest, but followed by Ni and Pb. Roots accumulated considerably larger amounts of the three heavy metals than leaves. Largest reductions of leaf and root mass were obtained with Cd. Pb and Ni effects were almost equal. Ni excess had a strong negative effect on mesophyll thickness, while Cd mostly reduced the number and size of vascular bundles and vessel diameter. High Pb reduced the diameter of vessels causing their different deformations.
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  • 43
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    Biologia plantarum 43 (2000), S. 523-528 
    ISSN: 1573-8264
    Keywords: accumulation ; grains ; lithium ; mobility ; phloem ; potassium ; rubidium ; sodium ; strontium ; Triticum aestivum ; xylem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The alkali metals cesium, rubidium, lithium and sodium were introduced together with strontium via flaps into leaf laminas or into the stem of maturing, intact winter wheat (Triticum aestivum L. cv. Arina) grown in a field. Long-distance transport of these elements and the influence of the application date and of different application positions were investigated. The phloem-immobile Sr served as a marker for the distribution of the xylem sap in the plants. Dry matter accumulation in the grains and the transpiration per shoot were not markedly affected by the treatments as compared to control plants. The phloem mobility was rather high for Cs and Rb. Li was almost immobile in the phloem (similarly to Sr). An application into the cut stem xylem below the second leaf node contributed more to the contents in the grains than an application into the flag leaf. An earlier feeding date led to a higher accumulation in the grains. The marked losses of the elements applied during maturation (most pronounced for Li) can be explained by leakage in the rain.
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  • 44
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    Biologia plantarum 42 (1999), S. 217-222 
    ISSN: 1573-8264
    Keywords: chlorophyll ; photochemical activity ; photosystem 2 ; ribulose-1,5-bisphosphate carboxylase/oxygenase ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chlorophyll (Chl) a and b content, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) content and activity, and electron transport rate were measured in flag leaves of wheat genotypes Uniculm and Kalyansona, grown at suboptimal and optimal supply of nitrogen. The Chl content, RuBPCO activity, and electron transport rate were decreased due to suboptimal nitrogen supply only in Kalyansona. There was no change in the ratio of RuBPCO and photosystem 2 (PS2) activity at various stages which suggests that there was no alteration in distribution of N due to additional N supply.
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  • 45
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    Sciences of soils 5 (2000), S. 10-21 
    ISSN: 1432-9492
    Keywords: Soil temperature ; Triticum aestivum ; Stubble retention ; Nitrogen ; Early growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Early growth and development are often lower when wheat is sown into standing stubble. A study was conducted to determine whether this difference in early growth could be explained by the effects of stubble on soil temperature in the vicinity of the young plant. The roles of nitrogen nutrition and soil strength were also assessed. Three crops were monitored (1990–1992), with the wheat being sown into either standing wheat stubble after a no-till fallow (NT), or into no-tilled plots from which the stubble had been removed by burning (NB). Measurements were made of wheat growth and development, soil and plant N, soil temperature and penetration resistance. The site was on a black earth near Warialda in the northern wheatbelt of New South Wales, Australia. In 1992 wheat was also grown under simulated stubble to isolate the shading and soil temperature effects of stubble from other factors. A significant (P〈0.05) relationship was found between average soil temperature and above ground dry matter (DM) at 65 days after sowing (DAS) but not at 107 DAS. This relationship accounted for differences in DM production at 65 DAS between NT and NB treatments in 1991 and 1992, but not in 1990. In that year the lower DM production in NT plots was associated with poorer N nutrition, and possibly disease. Laboratory incubations indicate that immobilisation of N as stubble decomposed could have contributed to this. Burning stubble produced no immediate increase in soil N availability, so that it is unlikely that N contained in stubble contributed to the difference. Soil strength differences between treatments and phytotoxic effects are unlikely to have contributed to growth differences in this soil.
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  • 46
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    Biology and fertility of soils 23 (1996), S. 273-281 
    ISSN: 1432-0789
    Keywords: Wheat ; Triticum aestivum ; Rhizosphere ; Soil microflora ; Gram-negative bacteria ; API 20 NE ; Flavobacterium spp ; Cytophaga
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We identified 161 Gram-negative bacterial strains isolated from the root surface of wheat grown under different soil conditions. The strains were divided into seven groups based on major morphological and physiological properties. Taxonomic allocation of the groups was verified by guanine+cytosine contents of DNA. Except for one group, which may be assumed to include bacteria belonging to the genera Flavobacterium and Cytophaga, the various groups were taxonomically united. The distribution of the groups changed with soil improvement. Pseudomonads predominated in unimproved soil, but Flavobacterium and Cytophaga spp. were predominant in the most improved soil. As all the strains were non-fermentative by Hugh and Leifson's test, API 20NE identification was applied. However, many strains were misidentified by this system, especially in the Flavobacterium and Cytophaga spp. group. For ecological studies, the strains were classified to species level by the API 20 NE system and by the results of a combination of guanine+cytosine (mol%) and isoprenoid quinone data. The pattern of distribution of the bacteria on the root surface of wheat varied at species level within one genus depending on soil conditions.
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  • 47
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    Biology and fertility of soils 4 (1987), S. 37-40 
    ISSN: 1432-0789
    Keywords: Azospirillum brasilense ; Azospirillum amazonense ; rate reductase ; Inoculation ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Three field experiments with wheat were conducted in 1983, 1984, and 1985 in Terra Roxa soil in Paraná, the major Brazilian wheat-growing region, to study inoculation effects of various strains of Azospirillum brasilense and A. amazonense. In all three experiments inoculation with A. brasilense Sp 245 isolated from surface-sterilized wheat roots in Paraná produced the highest plant dry weights and highest N% in plant tops and grain. Grain yield increases with this strain were up to 31 % but were not significant. The application of 60 or 100 kg N ha−1 to the controls increased N accumulation and produced yields less than inoculation with this strain. Another A. brasilense strain from surface-sterilized wheat roots (Sp 107st) also produced increased N assimilation at the lower N fertilizer level but reduced dry weights at the high N level, while strain Sp 7 + Cd reduced dry weights and N% in the straw at both N levels. The A. amazonense strain isolated from washed roots and a nitrate reductase negative mutant of strain Sp 245 were ineffective. Strains Sp 245 and Sp 107st showed the best establishment within roots while strain Cd established only in the soil.
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  • 48
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    Biology and fertility of soils 4 (1987), S. 41-46 
    ISSN: 1432-0789
    Keywords: Competition ; Migration ; Colonization potential ; Replica printing ; Triticum aestivum ; Pseudomonas fluorescens ; Bacillus subtilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Colonization patterns of Pseudomonas fluorescens and Bacillus subtilis on roots of wheat seedlings growing on water agar were studied qualitatively by replica printing and quantitatively by the plate count method. The results indicated a stronger colonization potential for P. fluorescens (up to 107 cfu/cm root) than for B. subtilis (up to 105 cfu/cm root). Although the numbers of both species were lower when inoculated together, the observed colonization patterns on the roots were comparable to those found with single inoculations. For none of these bacteria was active migration along the root surface in any direction observed, indicating that distal positions are reached mainly by a passive displacement on the root tip and elongating cells. Ecological implications of the observed phenomena are discussed.
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  • 49
    ISSN: 1432-0789
    Keywords: Key words Phosphate-solubilizing microorganisms ; Mussoorie rock phosphate ; Vesicular-arbuscular mycorrhizae ; Triticum aestivum ; Nutrient-deficient soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The effect of inoculating wheat (Triticum aestivum L.) with the PO4 3–-solubilizing microorganisms (PSM) Bacillus circulans and Cladosporium herbarum and the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus sp. 88 with or without Mussoorie rock phosphate (MRP) amendment in a nutrient-deficient natural sandy soil was studied. In the sandy soil of low fertility root colonization by VAM fungi was low. Inoculation with Glomus sp. 88 improved root colonization. At maturity, grain and straw yields as well as N and P uptake improved significantly following inoculation with PSM or the VAM fungus. These increases were higher on combined inoculation of PSM and the VAM fungus with MRP amendment. In general, a larger population of PSM was maintained in the rhizosphere of wheat in treatments with VAM fungal inoculation and MRP amendment. The results suggest that combined inoculation with PSM and a VAM fungus along with MRP amendment can improve crop yields in nutrient-deficient soils.
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  • 50
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    Biology and fertility of soils 5 (1987), S. 31-35 
    ISSN: 1432-0789
    Keywords: Gaeumannomyces graminis ; VegVetative growth ; Pathogenicity ; Herbicides ; Diquat+paraquat ; Glyphosate ; Dicamba ; Trifluralin ; Chlorsulfuron ; Chlorthal dimethyl ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effects of Spray Seed (diquat + paraquat), Roundup (glyphosate), Banvel-D (dicamba), Treflan (trifluralin), Glean (chlorsulfuron) and Dacthal (chlorthal dimethyl) at concentrations of 0–500 ppm product on the vegetative growth, vigour and pathogenicity of Gaeumannomyces graminis var. tritici (Ggt) on wheat were examined. All herbicides with the exception of dicamba and chlorsulfuron inhibited fungal growth on potato dextrose agar (PDA) at concentrations 10–500-fold of rates recommended for use in the field. The vegetative growth of the pathogen growing out of straw colonized on PDA supplemented with 100 ppm diquat + paraquat or glyphosate was reduced by 47.4% and 42.4%, respectively. When portions of these colonies were subcultured onto unamended PDA, their growth and the pathogenicity of straw pieces colonized by these subcultures were found to be unaltered. Straw colonized by Ggt on agar amended with concentrations of diquat + paraquat or at all concentrations of glyphosate produced less root disease in wheat seedlings in comparison to those colonized on unamended agar. It is proposed that the reduced pathogenicity of inocula prepared on agar amended with these two herbicides is due to poor colonization by the pathogen of straw on these media, and that a similar effect on saprophytic colonization in the field could lead to a reduction in the field inocula of the pathogen.
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  • 51
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    Biology and fertility of soils 7 (1988), S. 71-78 
    ISSN: 1432-0789
    Keywords: Root activity ; Rhizosphere ; C metabolism ; Microbial biomass ; Microbial activity ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two different soils were amended with 14C-labelled plant material and incubated under controlled laboratory conditions for 2 years. Half the samples were cropped with wheat (Triticum aestivum) 10 times in succession. At flowering, the wheat was harvested and the old roots removed from the soil, so that the soil was continuously occupied by predominantly active root systems. The remaining samples were maintained without plants under the same conditions. During the initial stages of high microbial activity, due to decomposition of the labile compounds, the size of the total microbial biomass was comparable for both treatments, and the metabolic quotient (qCO2-C = mg CO2-C·mg−1 Biomass C·h−1) was increased by the plants. During the subsequent low-activity decomposition stages, after the labile compounds had been progressively mineralized, the biomass was multiplied by a factor of 2–4 in the presence of plants compared to the bare soils. Nevertheless, qCO2-C tended to reach similar low values with both treatments. The 14C-labelled biomass was reduced by the presence of roots and qCO2-14C was increased. The significance of these results obtained from a model experiment is discussed in terms of (1) the variation in the substrate originating from the roots and controlled by the plant physiology, (2) nutrient availability for plants and microorganisms, (3) soil biotic capacities and (4) increased microbial turnover rates induced by the roots.
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  • 52
    ISSN: 1432-0789
    Keywords: Wheat ; Paddy straw compost ; N and P enrichment ; Rock phosphate ; Pyrite ; Triticum aestivum ; Nutrient uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A nutrient-rich compost from paddy straw was prepared using urea and Mussoorie rock phosphate for N and P enrichment respectively. Inorganic N was partly conserved in the compost by the addition of pyrite. Citric-acid-soluble P also increased with the addition of pyrite. Compost containing about 1.6% total N and 3.3% total P was found to be a good source of P for a wheat crop and also supplied a significant amount of N to the plants.
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  • 53
    ISSN: 1432-0983
    Keywords: Triticum aestivum ; Genomic variability ; Mitochondrial DNA ; Somatic tissue culture ; Regeneration ability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Embryogenic and non-embryogenic long-term callus cultures of hexaploid wheat exhibit differences in the organization of their mitochondrial genome. Embryogenic and non-embryogenic fractions of callus cultures initiated from immature embryos of the wheat cultivar “Chinese Spring” have been isolated and subsequently subcultured. DNA-DNA hybridization experiments using labelled cloned wheat mitochondrial DNA fragments have shown that the mitochondrial DNA organization of embryogenic subcultures derived from embryogenic parts of “Chinese Spring” calli is closely related to that of the initial “Chinese Spring” calli, while non-embryogenic subcultures derived from non-embryogenic fragments of “Chinese Spring” calli exhibit a mitochondrial DNA organization similar to that found in non-embryogenic calli derived from cultivar “Aquila”. In addition, somatic tissue cultures initiated from three other non-embryogenic wheat cultivars (“Talent”, “Thésée” and “Capitole”) display mitochondrial DNA arrangements similar to those found in cultivar “Aquila”. These results strongly suggest that, in wheat callus cultures, a particular mitochondrial genome organization is correlated with the ability of cultured cells to regenerate whole plants.
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  • 54
    ISSN: 1432-0983
    Keywords: Triticum aestivum ; Secale cerele ; Ribosomal RNA genes ; Mitochondrial DNA ; Recombining-repeats ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mitochondrial genomes of wheat and rye each contain a three-member family of recombining repeat peat sequences (the “18S/5S repeat”) that encode genes for 18S and 5S rRNAs (rrn18 and rrn5) and tRNAfMet (trnfM). Here we present, for wheat and rye, the sequence and boundaries of the “common sequence unit” (CSU) that is shared between all three repeat copies in each species. The wheat CSU is 4,429 base-pairs long and contains (in addition to trnfM, rrn18 and rrn5) a putative promoter, three tRNA-like elements (“t-elements”), and part of a pseudogene (“ψatpA c”) that is homologous to chloroplast atpA, which encodes the α subunit of chloroplast F1 ATPase. The rye CSU is somewhat smaller (2,855 base pairs) but contains much the same genic and other sequence elements as its wheat counterpart, except that two of the three t-elements as well as ψatpA c are found in only one of the three downstream flanks of the 18S/5S repeat, outside the CSU boundaries. In interpreting the seuuence data in terms of the evolutionary history of the 18S/5S-repeat family of wheat and rye, we conclude that (1) the wheat-rye form of the 18S/5S repeat most likely originated between 3 and 14 million years ago, in a lineage that gave rise to wheat and rye but not to barley, oasts, rice or maize; (2) the close linkage (1-bp apart) between trnfM and rrn18 is similarly limited in its taxonomic distribution to the wheat/rye lineage; (3) the trnfM-rrn18 pair arose via a single mutation that inserted a sequence block containing trnfM immediately upstream of rrn18; and (4) the presence of a putative promoter upstream of rrn18 in all wheat and rye repeats is consistent with all three repeat copies being transcriptionally active. We discuss these conclusions in the light of the possible functional significance of recombining-repeats in plant mitochondrial genomes.
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  • 55
    ISSN: 1432-0983
    Keywords: Light regulation ; psbN ; Triticum aestivum ; Etioplast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleotide sequence of a region of wheat chloroplast DNA containing the psbB gene for the 47 kDa chlorophyll a-binding protein of photosystem II has been determined. The gene encodes a polypeptide of 508 amino acid residues which is predicted to contain six hydrophobic membrane-spanning regions. The psbB gene is located 562 bp upstream of the psbH gene for the 10 kDa phosphoprotein of photosystem II. A small open reading frame of 38 codons is located between psbB and psbH, and on the opposite strand the psbN gene, encoding a photosystem II polypeptide of 43 amino acid residues, is located between orf38 and psbH. S1 nuclease mapping indicated that the 5′ ends of transcripts were located 371 and 183 bp upstream of the psbB translation initiation codon. Predominant transcripts of 2.1 kb and 1.8 kb for psbB and 0.4 kb for psbH were present in RNA isolated from etiolated and greening wheat seedlings. Immunodecoration of Western blots indicated that the 47 kDa polypeptide was absent, or present in very low amounts, in dark-grown tissue and accumulated on greening, whereas the 10 kDa polypeptide was present in similar amounts in both dark-grown and greening seedlings. The 10 kDa polypeptide was phosphorylated in vitro by incubating wheat etioplast membranes with [γ3 2P] ATP.
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  • 56
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    Russian journal of plant physiology 47 (2000), S. 734-739 
    ISSN: 1608-3407
    Keywords: Triticum aestivum ; bioelectric potentials ; frost resistance ; critical points
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Winter wheat (Triticum aestivum L.) seedlings of three cultivars differing in frost resistance were used to study cooling-induced changes in the bioelectric potential. Measurements were performed with nonfreezing graphite–glycerol electrodes in the regime of monitoring. Upon a gradual change in air temperature from 20 to –15°C at the rates of 20 and 2°C/h, the bioelectric potential underwent abrupt transitions at certain moments, indicating changes in the physiological condition of plants. The time required for the achievement of these critical states, as well as the survival of plants after thawing, depended both on the temperature and the cooling rate. Apparently, these characteristics were related to the dynamics of phase transitions of water. Cultivar-specific features were manifested in the different abilities of plants to maintain free water in a supercooled state. It is supposed that the critical points are related to the cold resistance of colloid systems and to the temperature lethal for plants.
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  • 57
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    Journal of plant research 106 (1993), S. 239-244 
    ISSN: 1618-0860
    Keywords: Chromosome breakage ; Gametocidal gene ; Healing ; Telomere repetitive sequence ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Telomere formation of the normal and broken chromosomes of common wheat,Triticum aestivum, was investigated byin situ hybridization using the biotin-labeled probe of telomere repetitive sequences (pAtT4) ofArabidopsis thaliana with subsequent amplification by an antibody. After double and triple amplification, prominent signals appeared at all the telomeric regions of the normal chromosomes. Prominent signals also emerged at the broken ends of the telocentric and deletion chromosomes that had passed through more than one generation since the appearance. However, broken ends that had passed through only the stages of gametogenesis, fertilization, embryogenesis and root development did not show complete signals such as found in normal telomeres. These findings indicate that a certain time or stage is required for synthesis of the telomeric repetitive sequences with a complete length. Nevertheless, because the broken ends without complete telomere sequences were also healed, restoration of the normal complement of telomere sequences is not necessary for healing of broken ends.
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  • 58
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    Journal of plant research 109 (1996), S. 375-380 
    ISSN: 1618-0860
    Keywords: Gravitropism ; Growth direction ; Seminal roots ; Triticum aestivum ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The seminal root system of wheat (Triticum aestivum L.) is composed of the primary seminal root, the first pair of seminal roots, and the second pair of seminal roots, which are known to grow in different directions. The direction of root growth, which can be expressed by ϑ (the angle between the root and the plumb line) and φ (the angle between the root and a vertical plane including the primary seminal root), was studied with special attention to the latter. It was measured on seedlings grown in a small hemispherical soil-filled mesh basket. There were varietal differences in the φ of the first pair of roots (φf) and in the φ of the second pair of roots (φs). (φf) and (φs) were significantly correlated. The mean distance (MD), a measure to evaluate the efficiency of root spacing, was correlated with the difference between (φf) and (φs). Neither experimentally applied low soil water potential nor the excision of the primary seminal root affected φ. When the grain was sown vertically with the tip of the embryo pointing downwards, it was found that the growth movement into a direction different from the plumb line and (φs) was greatly modified. it is suggested that certain internal mechanisms, possibly involving gravitropic reactions, are operating to control the direction of root growth. The significance of root growth direction at the seedling stage is discussed.
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  • 59
    ISSN: 1432-0983
    Keywords: Triticum aestivum ; Mitochondrial DNA ; Chloroplast DNA ; ATPase alpha subunit
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary An internal part of the chloroplast atpA gene has been identified in the mitochondrial DNA of Triticum aestivum. It is located near the 18S-5S ribosomal genes and partially contained within a repeated sequence. Comparison of the transferred sequence with the original ct sequence reveals several nucleotide changes and shows that neither 5′ nor 3′ ends are present in the mt genome. No transcript of this region could be detected by Northern analysis. This sequence is present in mitochondrial genomes of other tetraploid and diploid species of Triticum, also in the vicinity of the 18S-5S ribosomal genes, suggesting a unique transfer event. The date of this event is discussed.
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  • 60
    ISSN: 1432-0983
    Keywords: Triticum aestivum ; Plant mitochondrial DNA ; Ribosomal genes ; Sequence rearrangements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleotide sequence of the wheat mitochondrial 26S ribosomal RNA gene and flanking regions was determined and compared with mitochondrial 26S rRNA genes from maize and Oenothera. All three genes exhibit a high degree of homology except within two variable regions. When the plant mitochondrial 26S rRNA genes are compared with Escherichia coli 23S rRNA and chloroplast 23S and 4.5S rRNA genes, a third variable region is apparent close to the 3′ end of the gene. The 5′ and 3′ ends of the wheat mitochondrial gene were determined by S1 nuclease mapping. Computer analysis of the wheat mitochondrial gene revealed several small sequences present either in the 5′ region of the 26S rRNA gene or in the 18S rRNA gene.
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  • 61
    ISSN: 1432-0983
    Keywords: Mitochondrion ; Transcription ; Guanylyltransferase ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary To identify transcription initiation sites in wheat mitochondria, the nascent 5′-ends of transcripts were specifically labeled by incubation of wheat mitochondrial RNA with [α-32P]GTP in the presence of the enzyme guanylyltransferase. After separation of the resulting capped transcripts by electrophoresis in polyacrylamide gels, individual RNAs were recovered and directly sequenced. Four RNA sequences obtained in this way were localized upstream of the protein-coding genes atpA, coxII, coxIII and orf25. Comparison of mRNA and gene sequences allowed precise positioning of transcription initiation sites for these four genes. Sequence similarities immediately upstream of these sites define a conserved motif that we suggest as a candidate regulatory element in wheat mtDNA. The relationship between this motif and putative mitochondrial promoters in other plant species is discussed.
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  • 62
    ISSN: 1432-0983
    Keywords: Nuclear-cytoplasmic interactions ; Mitochondrial genome ; Chondriome variability ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Although the mitochondrial genomes of the Chinese Spring and Aquila varieties of wheat are normaly similar in organization, this is not so in tissue cultures initiated from their immature embryos where the mitochondrial genomes of both are rearranged and in different, characteristic, ways. However, the mitochondrial genomes of tissue cultures of reciprocal F1 crosses between these varieties were almost identical to one another, showing that nuclear genes control the rearrangement processes. These rearrangements are either due to the appearance of new structures or else result from changes in the relative amounts of subgenomic components. The severe reduction in the amount of certain molecular configurations in tissue cultures from reciprocal crosses is probably due to the presence of dominant information in the Aquila nuclear genome. Data obtained from tissue cultures initiated from F2 embryos of the cross Aquila x Chinese Spring suggest that at least two complementary genes are involved in this control. In contrast, the presence of new molecular arrangements appears to be under the control of a dominant allelic form of a Chinese Spring gene or genes. Thus, this study demonstrates that at least two sets of nuclear genes control the reorganization of the mitochondrial genome which occurs when tissue cultures are initiated from the immature embryos of wheat.
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  • 63
    ISSN: 1432-0983
    Keywords: Secale cereale ; Triticum aestivum ; Ribosomal RNA genes ; Mitochondrial DNA
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary The mitochondrial 18S and 5S ribosomal RNA (rRNA) genes of rye, plus a total of about 90 kilobase pairs of flanking DNA, have been cloned and maps of restriction enzyme cleavage sites have been constructed. Like their homologs from hexaploid wheat, the rye genes are closely linked and are part of a three-copy family of recombining repeats (the “18S/5S repeat”). The rye repeat probably also contains a mitochondrial tRNAfMet gene, which the wheat repeat is known to carry. However, despite the overall organizational similarity between the wheat and rye 18S/5S repeats in the immediate vicinity of their coding regions, extensive rearrangement of flanking sequences has taken place during evolutionary divergence of the two species. Our data provide additional support for an emerging picture of plant mitochondrial genomes as evolving much more rapidly in structure than in sequence.
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  • 64
    ISSN: 1432-0983
    Keywords: Triticum aestivum ; Tissue culture ; Mitochondrial DNA ; Genomic variability
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary Wheat mitochondria) DNA has been isolated from callus cultures initiated from both immature embryos and the corresponding parental cultivar. A Sall restriction pattern study has shown that the organization of callus culture mitochondria) DNA underwent extensive change, characterized by either the disappearance or the decrease in the relative stoichiometry of several restriction bands. Hybridization of labelled mitochondrial fragments obtained from a recombinant cosmid library to Southern blots of callus and parental line restricted mitochondria) DNAs has shown that a fraction of the mitochondria) genome was lost in callus cultures. Data from a Sall + HindIII restriction map of a defined part of the wheat mitochondria) genome concerned with some of these variations strongly suggest that the observed variations correspond to the disappearance of at least one mitochondria) DNA subgenomic molecule in callus cultures.
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  • 65
    ISSN: 1432-0983
    Keywords: Reciprocal recombination ; Mitochondrial genome ; Chondriome variability ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract The mitochondrial genome of the selfed progeny of a plant regenerated from long-term somatic tissue culture displays specific structural rearrangements characterized by the appearance of novel restriction fragments. A mitochondrial DNA library was constructed from this selfed progeny in the SalI site of cosmid pHC79 and the novel fragments were subsequently studied. They were shown to arise from reciprocal recombination events involving DNA sequences present in the parental plant. The regions of recombination were sequenced and the nucleotide sequences were aligned with those of the presumptive parental fragments. We characterized an imperfect short repeated DNA sequence, 242 bp long, within which a 7-bb DNA repeat could act as a region of recombination. The use of PCR technology allowed us to show that these fragments were present in both parental plants and tissue cultures as low-abundance sequence arrangements.
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  • 66
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    Plant cell reports 12 (1993), S. 149-153 
    ISSN: 1432-203X
    Keywords: Triticum aestivum ; microspore culture ; ovary co-culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Wheat microspores were isolated, without prior anther culture, from a range of genotypes and cultured to regenerate self-fertile plants. Microspores were isolated using a microblender and competent microspores were enriched by gradient centrifugation. The use of maltose as the sole carbohydrate in the culture medium and co-culture of microspores with wheat or barley ovaries were critical for development of microspore-derived embryos. Results were also improved when spikes were pretreated by emersion of the basal ends of detached heads in water at 25°C for 2d. This procedure leads to highly reproducible production of plants.
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  • 67
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    Theoretical and applied genetics 59 (1981), S. 313-316 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Wheat ; Puccinia graminis ; Stem rust resistance ; Monosomic analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Using monosomic analysis genes governing resistance in one wheat variety, ‘E5883’, against stem rust races 15C and 122, were located on specific chromosomes. Against race 15C, a major dominant gene, Sr6, was located on chromosome 2D of ‘E5883’ with minor modifiers found on chromosomes 4A and 6D. Against race 122, the presence of a recessive hemizygous ineffective gene, Sr8, was identified, located on chromosome 6A of variety ‘E5883’.
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  • 68
    ISSN: 1432-2242
    Keywords: Amphiplasty ; Ag-NOR ; Addition lines ; Nucleolar organizer ; Agropyron elongatum ; Triticum aestivum
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    Notes: Summary The nucleolar organizer activity of the Agropyron elongatum, its amphiploid with hexaploid wheat (Triticum aestivum) and the chromosome addition lines is analyzed by the silver-staining procedure. Four Ag-NORs are observed in A. elongatum corresponding to the chromosomes 6E and 7E. In the amphiploid T. aestivum — A. elongatum, eight Ag-NORs are observed which corresponds the wheat chromosomes 1B and 6B and to the elongatum chromosomes 6E and 7E. Thus, there is codominance in the nucleolar organizer activity of the chromosomes of the two species. However, a partial amphiplasty is detected since less than 8 Ag-NORs (7 up to 4) are observed in some metaphase cells; the chromosomes 6E and 7E are occasionally suppressed by wheat chromosomes. This conclusion is confirmed by the behaviour of the addition lines since only in those corresponding to the chromosomes 6E and 7E are the elongatum chromosomes nucleolar active although occasionally they can be suppressed by wheat chromosomes.
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  • 69
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    Theoretical and applied genetics 73 (1986), S. 122-128 
    ISSN: 1432-2242
    Keywords: α-amylase ; Triticum aestivum ; Secale montanum ; C-banding ; Meiotic pairing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A 5BS/5RmS translocation chromosome spontaneously recovered from a ‘Chinese Spring’ — Secale montanum wheat-rye telocentric 5RmS addition line has been identified and cytologically studied using C-banding in somatic and meiotic cells. Analysis of the translocated chromosome showed that a terminal segment of the short arm of 5B had been replaced by a short terminal region of chromosome arm 5RmS. The translocation led to the deletion of the genetic system promoting pairing located in 5BS, which is slightly compensated for when doses of 5RmS are increased, indicating homoeology to wheat chromosome 5BS. The α-amylase phenotype in 5B/5Rm translocated material was studied and found to be identical to that of ditelocentric line 5BL of ‘Chinese Spring’. An effect on the α-amylase activity was detected as a result of the removal of the terminal region of 5BS, perhaps as a consequence of variation in dormancy period duration.
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  • 70
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    Theoretical and applied genetics 73 (1986), S. 246-251 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; 2D electrophoresis ; Gene localization ; Gene regulation ; Homoeology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two-dimensional gel electrophoresis was conducted on denatured proteins of the 10-day-old first leaf (1F stage) of 18 homoeologous ditelosomic (DT) lines of wheat cultivar ‘Chinese Spring’. The observations, compared to the euploid control and relative to previous data found on 7-day-old etiolated seedlings (G7 stage) of the same lines lead to the following statements: 1) the structural genes of 24 spots can be assigned to 12 chromosome arms; 2) regulatory effects are completely different between the 1F and the G7 stages which may indicate that the regulation of protein amounts is often stage-specific; 3) no case of complete gene dosage compensation is observed among 4 groups of hypothesized homoeoallelic products; 4) homoeologous DT lines do not manifest similar effects which suggest the absence of homoeology for the detected regulatory effects.
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  • 71
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    Theoretical and applied genetics 71 (1985), S. 31-38 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; 2D electrophoresis ; Gene localization ; Homoeologous genes ; Genetic regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Among the 782 spots observed in two-dimensional gel electrophoresis of denatured proteins from etiolated wheat shoots, 185 were found to be variable between the euploid and 26 ditelosomic lines of ‘Chinese Spring’. Thirty-five structural genes were located on 17 chromosome arms. Numerous intensity changes showing alterations in protein levels were observed and led to the following statements: 1) regulators are frequently found and can be assigned for a same polypeptide to various chromosome arms; 2) for most polypeptides homoeologous arms do not manifest similar effects; 3) nevertheless, when affecting the same polypeptide, homoeologous arms display in most cases identical regulatory effects; 4) gene dosage compensation is observed in only one out of four homoeoallelic situations.
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  • 72
    ISSN: 1432-2242
    Keywords: Anther culture ; Pollen callus (plantlet) ; Induction frequency ; Triticum aestivum ; Agropyron glaucum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Experimental results showed that the use of potato extract as a basic component of culture medium had a promoting effect on producing calli in anther culture of the intergeneric hybrids of Triticum aestivum × Triticum-Agropyron (intermediate type). The induction frequencies of pollen callus on the Potato-II medium containing potato extract as the main component was much higher than that found on N6 and W5 media. The induction frequencies of pollen callus and green plantlets in four intergeneric hybrid material inoculated at the late-uninucleate pollen stage were all higher than those inoculated at the mid-uninucleate stage. Appropriate increases in culture temperature significantly increased pollen callus induction frequencies of the intergeneric hybrids. The genotype and physiological state of anther donor plants also influenced pollen callus and green plantlet induction frequencies.
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  • 73
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Agropyron caninum ; Elymus caninus ; Intergeneric hybrids ; Chromosome pairing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Intergeneric hybrids were produced between common wheat, Triticum aestivum (2n=6x=42, AABBDD) and wheatgrass, Etymus caninus (Agropyron caninum) (2n=4x=28, SSHH) — the first successful report of this cross. Reciprocal crosses and genotypes differed for percent seed set, seed development and F1 hybrid plant production. With E. caninus as the pollen parent, there was no hybrid seed set. In the reciprocal cross, seed set was 23.1–25.4% depending upon wheat genotype used. Hybrid plants were produced only by rescuing embryos 12–13 days post pollination with cv ‘Chinese Spring’ as the wheat parent. Kinetin in the medium facilitated embryo germination but inhibited root development and seedling growth. The hybrids were vigorous, self sterile, and intermediate between parents. These had expected chromosome number (2n=5x=35, ABDSH), very little chromosome pairing (0.51 II, 0.04 III) and some secondary associations. The hybrids were successfully backcrossed with wheat. Chromosome number in the BC1 derivatives varied 54–58 with 56 as the modal class. The BC1 derivatives showed unusually high number of rod bivalents or reduced pairing of wheat homologues. These were sterile and BC2 seed was produced using wheat pollen.
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  • 74
    ISSN: 1432-203X
    Keywords: Cell suspension ; Somatic embryogenesis ; Triticum aestivum ; Leymus angustus ; Plant regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Embryogenic cell suspension cultures were established from Triticum aestivum X Leymus angustus F1 hybrids, using compact nodular calli derived from inflorescence segments. Calli originating from leaf segments did not give rise to stable cell suspensions. Growth measurements of the cell suspensions revealed that they continued rapid growth up to 10 days after subculturing. Flow cytometric studies of the cell cycle over a 7 day culture period showed that the majority of cells were in G1 phase while the rest were either in S or G2. During the 7 days of culture, no significant differences in DNA distribution patterns were observed. The cells from suspension cultures produced somatic embryos when they were transferred to different solid media. The embryos germinated and gave rise to plantlets which were successfully rooted and transferred to soil.
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  • 75
    ISSN: 1432-203X
    Keywords: Triticum aestivum ; embryogenic suspension cultures ; protoplasts ; regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Highly regenerable callus cultures have been obtained from immature embryos of hexaploid wheat cv. Oderzo. Friable fast growing calli were induced at high frequency. Suspensions were initiated from the most friable callus lines: they became established in about two months. Suspensions consisted of cell aggregates of 30 to 1000 um in diameter. Upon plating on MS hormone-free medium, suspensions regenerated green plantlets, and their regenerative capability was maintained for at least 10 months. Protoplasts were isolated from 7–8 day old suspension cultures with a yield of 4–6×106 protoplasts/g fresh weight cells. Protoplast culture was either in liquid medium or in a bead-type system with agarose beads. First divisions were detected at day 5. At day 14 visible colonies were detected and the plating efficiency was evaluated between 2 and 8% over the initial number of protoplasts plated. Protoplast-derived calli were cultured in the presence of 1 mg/l IAA and 0.5 mg/l zeatin and were used for reinitiating new suspension cultures. Upon plating onto MS hormone-free medium, with or without the addition of 0.1 mg/l GA3, calliclones were induced to differentiate. Regeneration of complete plantlets, with shoot and roots took about two months. Plantlets were grown in sterile conditions until 12–15 cm height, and were subsequently transplanted in soil.
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  • 76
    ISSN: 1432-203X
    Keywords: cryopreservation ; Triticum aestivum ; abscisic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Spring wheat (Triticum aestivum L.) zygotic embryos were successfully cryopreserved, without the addition of exogenous cryoprotectants, using only an abscisic acid (ABA) pretreatment. Optimum survival was obtained when embryos were cultured in vitro for 10 days on semisolid Murashige and Skoog (MS) nutrient medium supplemented with 0.5 mg/L (±) ABA prior to cryopreservation. The embryos resumed growth within three days when returned to MS medium devoid of ABA but containing 2mg/L 2,4-dichlorophenoxyacetic acid. The embryogenic calli produced from these embryos exhibited normal plant regeneration on auxin-free media. Changes in dw/fw ratio, as well as the esterified fatty acid and sucrose concentrations correlated positively with the development of tolerance to cryopreservation.
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  • 77
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    Theoretical and applied genetics 50 (1977), S. 47-51 
    ISSN: 1432-2242
    Keywords: Glutamate Oxaloacetate Transaminase ; Isozymes ; Triticum aestivum ; Subunits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A simple procedure has been developed for the dissociation of active molecules of glutamate oxaloacetate transaminase (GOT: E.C. 2.6.1.1) into protomers and for the reassociation of the subunits into active enzymes. Results of experiments in which the protomers of genetically controlled electrophoretic variants of GOT of Triticum aestivum and of several related species were dissociated and recombined in crude tissue extracts and in partially purified preparations support the hypothesis that the enzyme exists functionally as a dimer in the Triticinae.
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  • 78
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    Theoretical and applied genetics 58 (1980), S. 247-252 
    ISSN: 1432-2242
    Keywords: Maternal tissues ; Grain weight ; Wheat ; Triticum aestivum ; Caryopsis ; Pericarp ; Endosperm ; Embryo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Reciprocal crosses were made between semi dwarf spring wheat cultivars (Triticum aestivum L.) differing in grain weight. The weights of the F1 grains (on maternal spikes), from intact as well as from defoliated plants, and those of the F2 grains (on f1 spikes), were examined. Grain weight was controlled primarily by the genotype of the maternal tissues (pericarp, testa or other floret or spikelet organs, including the vascular system), with complete dominance of heaviness. No indications suggesting maternal inheritance were obtained. The frequency distribution of the weights of the F2 grains indicated the presence of genotypic effects exerted by the endosperm or embryo. The embryo or endosperm factors for heaviness also seemed to be dominant.
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  • 79
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Glutenin ; Gliadin ; Electrophoresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Subunits of wheat endosperm proteins have been fractionated by two-dimensional electrophoresis. To determine which subunits in the two-dimensional electrophoretic pattern belong to gliadin or glutenin the endosperm proteins have also been fractionated by a modified Osborne procedure and by gel filtration on Sephadex G-100 and Sepharose CL-4B prior to separation by two-dimensional electrophoresis. The control of production of five major grain protein subunits is shown to be determined by chromosomes 6A, 6B and 6D by comparing two-dimensional electrophoretic protein subunit patterns of aneuploid lines of the variety ‘Chinese Spring’. From these and previous studies it is concluded that some α, β and γ gliadins (molecular weights by SDS-PAGE 30,000 to 40,000) are specified by genes on the short arms of homoeologous Group 6 chromosomes, the ω gliadins (molecular weights by SDS-PAGE 50,000 to 70,000) are specified by genes on the short arms of homoeologous Group 1 chromosomes and the glutenin subunits (molecular weights by SDS-PAGE 〉 85,000) are specified by genes on the long arms of homoeologous Group 1 chromosomes. No major gliadins or glutenin subunits were absent when any of the chromosomes in homoeologous Groups 2, 3, 4, 5 or 7 were deleted. However two gliadins whose presumed structural genes are on chromosome 6D were absent in aneuploid stocks of ‘Chinese Spring’ carrying two additional doses of chromosome 2A. Two out of thirty-three intervarietal or interspecific chromosome substitution lines examined, involving homoeologous Group 2 chromosomes, lacked the same two gliadins. All the subunits in the other thirty-one chromosome substitution lines were indistinguishable from those in ‘Chinese Spring’. It is therefore concluded that the major variation affecting gliadin and glutenins in wheat is concentrated on the chromosomes of homoeologous Groups 1 and 6 but Group 2 chromosomes are candidates for further study. An endosperm protein controlled by chromosome 4D in ‘Chinese Spring’ is shown to be a high molecular weight globulin.
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  • 80
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    Theoretical and applied genetics 60 (1981), S. 157-160 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Wheat ; Puccinia graminis ; Stem rust resistance ; Inheritance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two bread wheat accessions, E5008 and E6160, have been genetically analysed for resistance genes effective against Indian cultures of stem rust races, 15C and 122. The inheritance of resistance to each race has been determined from the F1 and F2 of the crosses (resistant parents with the susceptible variety, ‘Agra Local’) and F2 progenies from the backcross to ‘Agra Local’. Tests have been performed to see if the two varieties carry common genes/s for resistance. The identity of the genes for resistance has been established from relevant crosses with single gene lines carrying known genes for resistance. A single dominant gene effective to race 15C in E5008 has been demonstrated to be Sr9b. Of the two recessive genes, each producing distinct infection types (0; and 1–3) against race 122, one gene has been inferred to be Sr12 and the second to be a hitherto undesignated gene. The resistance of E6160 against race 15C is controlled by two genes, one dominant and one recessive. The dominant gene has been identified as Sr9b. The recessive gene has been inferred to be a new gene. Similarly, a dominant gene effective against race 122 in E6160 has been observed to be different from those so far designated. In addition, the presence of modifier gene/s in the variety, E6160 has been suggested.
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  • 81
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Wheat-phenolics-location
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Using thin-layer chromatography and nulli-tetrasomic and ditellosomic series of Triticum aestivum L. cv. ‘Chinese Spring’, it has been possible to relate the phenolic compounds found in adult plant leaves and 12 day-old seedling leaves with the chromosomes or chromosome arms 1 B, 2 BL, 3 BL, 5 A, 6 AL, 7 B and 7 DS.
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  • 82
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    Theoretical and applied genetics 61 (1982), S. 129-133 
    ISSN: 1432-2242
    Keywords: Interchange ; Chromosome arrangements ; Common wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chromosome arrangements of twenty-eight cultivars of common wheat, Triticum aestivum L., from or introduced into Spain are compared with that of ‘Chinese Spring’ taken as a pattern. All the cultivars analyzed differ from ‘Chinese Spring’ by one or two reciprocal translocations. When 12 out of 28 cultivars were compared it was concluded that a minimum number of thirteen interchanges are present, involving at least ten different chromosomes of the complement. The interest of a reappraisal of the rôle of interchanges in the evolution of Gramineae is pointed out.
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    Theoretical and applied genetics 61 (1982), S. 337-339 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; ‘Chinese Spring’ ; Chromosome banding ; Hydrolysis ; Feulgen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Terminal and/or interstitial N-bands were produced on the seven B-genome chromosomes and chromosomes 4 and 7 of the A-genome of Triticum aestivum cv. ‘Chinese Spring’ by a modified BSG technique following a standard Feulgen preparation. The banding was accomplished by modifying the barium hydroxide treatment.
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  • 84
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    Theoretical and applied genetics 63 (1982), S. 71-73 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Pollen ; Anther culture ; Callus ; Regeneration ; Plantlets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Pollen shed between 4–8 d from anthers of Triticum aestivum cultured in liquid medium gave rise to calluses. Tillers were harvested at the mid-to late-unicellular pollen stages and chilled for 8 d at 4–5 °C before the anthers were dissected out. Pollen cultures gave about 6 times as many calluses on a per anther basis as anthers cultured on solid medium. With the most productive of 5 cultivars tested, pollen culture results in roughly one callus for each anther used, though the calluses formed by pollen culture were less productive for the regeneration of shoots than calluses derived from anthers cultured on solid medium. The ratio of green to albino shoots is roughly 1∶ 1 for anther cultures but considerably less for pollen cultures.
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  • 85
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    Theoretical and applied genetics 63 (1982), S. 121-124 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Grainprotein ; Gene action ; Regression ; Diallel cross
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Diallel crosses between five divergent vulgare wheat cultivars were made in order to evaluate the mode of inheritance and combining ability of grain proteins. Significant differences in grain protein content were found between cultivars and their hybrids. It was established that the inheritance of seed protein in the F1 generation included both additive and non-additive gene action.
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  • 86
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    Theoretical and applied genetics 68 (1984), S. 335-345 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; 2D electrophoresis ; Developmental genetics ; Cytoplasmic inheritance ; Genetic regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two-dimensional gel electrophoresis of denaturated proteins were performed at five developmental stages or organs (hereafter referred to as stage-organs) on two wheat lines with four different cytoplasms. Five hundred and fifty to 712 reproducible spots were scored depending on the stage-organ. Each stage-organ is unambiguously characterized and several types of control of protein quantity are recorded. Post-translational modifications are hypothetized and may sometimes be stagespecific. Two cytoplasmic patterns are found: one for the euplasmic lines with Triticum aestivum cytoplasm and one for the alloplasmic lines with Aegilops juvenalis, Ae. ventricosa and Ae. kotschyi cytoplasms. Cytoplasmic variation is observed for 28 spots showing position difference, all of which are probably products of the LS gene, and for four spots showing differences for regulation of protein quantity. Nuclear variation between ‘Chinese Spring’ and ‘Selkirk’ is found for 20 allelic differences and for 20 regulatory systems, the latter number being probably underestimated.
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    Theoretical and applied genetics 64 (1983), S. 255-258 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Wheat ; Malate dehydrogenase ; Chromosomal location
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The malate dehydrogenase (E.C. no 1.1.1. 37) of Triticum aestivum L. cv. Chinese Spring, shows two activity zones. The results obtained support the hypothesis that the malate dehydrogenase isozymes of zone II are dimers composed of the six possible combinations of subunits coded by triplicate genes located in the long arms of chromosomes of the homoeologous group 1.
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  • 88
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    Theoretical and applied genetics 66 (1983), S. 1-7 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Aegilops species ; Alloplasmic lines ; 2D gel electrophoresis ; Cytoplasmic inheritance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In this first analysis the protein patterns obtained by two-dimensional gel electrophoresis of 8 day-old leaves from 18 alloplasmic wheat lines are compared. From 440 spots retained on the basis of their reproducibility, 36 proteins were observed to vary in different cytoplasms, allowing us to distinguish the T. aestivum cytoplasm from 5 Aegilops cytoplasms. Twenty-four of the 36 variable proteins could be structurally related to the large subunit of RuBPCase. Nuclear variation between 3 wheat varieties was observed for 14 proteins.
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  • 89
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Gliadins ; Two-dimensional electrophoresis ; Hybridological analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Blocks of gliadin components found both in a number of varieties and in single F2 grains of winter wheat intervarietal hybrids have been studied by two-dimensional electrophoresis combining electrophoresis in acidic aluminium-lactate buffer (pH3.1) and SDS-electrophoresis. Gliadin components (spots) have been shown to be inherited as linked groups (blocks), codominantly and in accordance with a gene dosage in triploid endosperm. Blocks include components differing in their electrophoretic mobility and molecular weight. Some allelic variants of blocks differ only in presence of few additional components or in the electrophoretic mobility of components with similar molecular weights; other variants may contain no similar components. Apparently, in the course of evolution, mutations in individual genes of gliadin-coding loci and processes changing the number of expressing genes and the sizes of their structural part occurred.
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  • 90
    ISSN: 1432-2242
    Keywords: Intrachromosomal mapping ; Nucleolar organiser region ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Restriction enzyme digestion of the ribosomal RNA genes of the nucleolar organisers of wheat has revealed fragment length polymorphisms for the nucleolar organiser on chromosome 1B and the nucleolar organiser on 6B. Variation between genotypes for these regions has also been demonstrated. This variation has been exploited to determine the recombination frequency between the physically defined nucleolar organiser on 1B (designatedNor1) and other markers; two loci,Glu-B1 andGli-B1 which code for endosperm storage proteins andRf3, a locus restoring fertility to male sterility conditioned byT. timopheevi cytoplasm.Gli-B1 andRf3 were located on the short-arm satellite but recombine with the nucleolar organiser giving a gene order ofNor1 — Rf3 — Gli-B1. Glu-B1 is located on the long arm of 1B but shows relatively little recombination withNor1, which is, in physical distance, distal on the short arm. This illustrates the discrepancy between map distance and physical distance on wheat chromosomes due to the distal localisation of chiasmata. The recombination betweenNor1 andRf3 indicates that, contrary to previous suggestions, fertility restoration is not a property of the nucleolar organiser but of a separate locus.
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  • 91
    ISSN: 1432-2242
    Keywords: Line × tester analysis ; Triticum aestivum ; Gene action ; Combining ability ; Mating designs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary For studying the inheritance of metric traits, diallel cross and factorial mating designs are commonly used. Since factorial mating design is less restrictive in crossing plans, the genetic information drawn from it was compared with that from a diallel cross. The comparison was made using graphical, genetic components and combining ability analyses for grain yield, grain weight and spike length in a field experiment of bread wheat (Triticum aestivum L.). Analyses were made on a nine parent diallel cross and a 4 ♀ × 5 ♂ factorial mating design which was sampled from the diallel cross. In general, there was a high degree of agreement between the results obtained from factorial mating design and diallel cross analyses showing thereby that the former provides almost equivalent genetic information to the latter.
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  • 92
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    Theoretical and applied genetics 69 (1985), S. 583-589 
    ISSN: 1432-2242
    Keywords: Common wheat ; Triticum aestivum ; Electrophoresis ; Endosperm proteins ; Glutenins ; Gliadins ; Genetic control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Total endosperm proteins extracted from both several common wheat cultivars and some intervarietal substitution lines derived from them were fractionated according to their molecular weight in a high resolution one-dimensional gel electrophoresis. The four donor cultivars and the recipient one — ‘Chinese Spring’, possessed differentially migrating protein bands in the fractions of high molecular weight (HMW) glutenins and gliadins. Several of these bands were identified for the first time in this study. By utilizing intervarietal substitution lines the control of the HMW glutenins and gliadins by chromosomes of homoeologous group 1 was either reaffirmed or, for the new bands, established. Several HMW gliadin subunits showed a considerable variation in their staining intensity in the intervarietal substitution lines indicating that their expression was dependent on the genetic background.
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    Theoretical and applied genetics 59 (1981), S. 153-160 
    ISSN: 1432-2242
    Keywords: Mitochondrial heterosis ; Mitochondrial complementation ; Triticum aestivum ; Hordeum vulgare ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two families each of wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and maize (Zea mays L.) were studied for mitochondrial heterosis and in vitro mitochondrial complementation. Inbred parents and their hybrids were compared for seedling heights and rate of oxygen uptake by the whole tissue to find out if the hybrids showed greater growth and respiratory activity at the seedling stage. Further comparisons were made by isolating mitochondria from the seedling tissues and measuring their ADP∶0 ratio, respiratory control ratio and cytochrome c oxidase activity for mitochondrial heterosis. Mixtures of parental mitochondria were similarly compared with parental and hybrid mitochondria for in vitro mitochondrial complementation. No evidence for mitochondrial heterosis or in vitro mitochondrial complementation was found, nor any correlation between the different mitochondrial parameters, seedling heights or rates of oxygen uptake by seedling tissue. The suggested use of mitochondrial heterosis and in vitro mitochondrial complementation for plant breeding is discussed.
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    Oecologia 100 (1994), S. 221-228 
    ISSN: 1432-1939
    Keywords: Triticum aestivum ; Competition ; Abiotic stress ; Multiplicative interactions ; Nickel toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using recently developed solution culture techniques, the effect of a non-resource abiotic stress, nickel toxicity, was tested on intraspecific nutrient competition among wheat. The choice of an appropriate statistical model was of paramount importance in interpreting these effects. We argue that a multiplicative model is more appropriate for experiments on interactions of competition and abiotic stress. By such an analysis, nickel had no relative effect on the ability of competition to reduce plant size in two experiments, and caused a small reduction in competition in another. These results are contrary to other reports of the effect of a non-resource abiotic stress on competition and appear to be due to an increased demand for nutrients in the presence of toxic levels of nickel. The effects of an abiotic stress on competition may thus be specitic to the stress and not generalized across all abiotic stresses.
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    Oecologia 91 (1992), S. 82-92 
    ISSN: 1432-1939
    Keywords: Plant disease ; Genetic diversity ; Frequency-dependence ; Triticum aestivum ; Puccinia striiformis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The direct and indirect effects of plant genetic diversity on epidemics and the influence of disease on plant competition were investigated using the wheat (Triticum aestivum)/stripe rust (Puccinia striiformis) system. Replacement series consisting of a susceptible and a resistant wheat genotype or two wheat genotypes susceptible to different races of stripe rust were grown in the presence and absence of the pathogen. Stripe rust severity, number of seed heads, seed yield, and seed weight were determined separately for each wheat genotype in the mixtures and the pure stands. The frequency of susceptible genotypes in a mixture explained up to 67% of the variation in disease severity. However, competitive interactions among plant genotypes sometimes appeared to alter susceptibility and obscured the relationship. In pure stands of single genotypes, disease severity explained between 52 and 58% of the variation in seed yield. In mixtures, coefficients of determination were only 10 and 31%, suggesting a strong influence of plant-plant interactions on seed yield. These results suggest that host-parasite coevolutionary models need to account for the strong effect that specific plant genotype combinations may have on disease severity and plant reproduction.
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  • 96
    ISSN: 1432-1939
    Keywords: Multispecies canopy model ; Canopy photosynthesis model ; Triticum aestivum ; Avena fatua ; Ultraviolet-B radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Competition for light among species in a mixed canopy can be assessed quantitatively by a simulation model which evaluates the importance of different morphological and photosynthetic characteristics of each species. A model was developed that simulates how the foliage of all species attenuate radiation in the canopy and how much radiation is received by foliage of each species. The model can account for different kinds of foliage (leaf blades, stems, etc.) for each species. The photosynthesis and transpiration for sunlit and shaded foliage of each species is also computed for different layers in the canopy. The model is an extension of previously described single-species canopy photosynthesis simulation models. Model predictions of the fraction of foliage sunlit and interception of light by sunlit and shaded foliage for monoculture and mixed canopies of wheat (Triticum aestivum) and wild oat (Avena fatua) in the field compared very well with measured values. The model was used to calculate light interception and canopy photosynthesis for both species of wheat/wild oat mixtures grown under normal solar and enhanced ultraviolet-B (290–320 nm) radiation (UV-B) in a glasshouse experiment with no root competition. In these experiments, measurements showed that the mixtures receiving enhanced UV-B radiation had a greater proportion of the total foliage area composed of wheat compared to mixtures in the control treatments. The difference in species foliage area and its position in the canopy resulted in a calculated increase in the portion of total canopy radiation interception and photosynthesis by wheat. This, in turn, is consistent with greater canopy biomass of wheat reported in canopies irradiated with supplemental UV-B.
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    Plant cell reports 16 (1997), S. 663-667 
    ISSN: 1432-203X
    Keywords: Key words Embryogenesis ; Ovule culture ; Triticum aestivum ; Zygote
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ovules of the wheat breeding line Veery #5 were excised and transferred to culture within 24 h after pollination. When ovules were cultured on Phytagel-solidified medium, and the pericarp removed exclusively at the micropylar tip and the abaxial side, zygotes from up to 79.2% of the ovules underwent embryogenesis with the same developmental pattern as found in planta. Embryos from more than 50% of the cultured ovules germinated when transferred to regeneration medium. More than 100 plantlets were randomly chosen for transfer to soil, all of which developed to phenotypically normal and fertile plants. With this system, the entire process of zygotic embryogenesis can be studied using living material. Furthermore, the method could be used as an embryo rescue technique for plant breeding purposes.
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  • 98
    ISSN: 1432-203X
    Keywords: Key words Abscisic acid ; Anther culture ; Light ; Metallothionein ; Pollen embryogenesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cloned cDNA to the wheat (Triticum aestivum) early cysteine-labeled metallothionein has many characteristics of a molecular marker for pollen embryogenesis in this plant. This transcript was not detected in uninucleate microspores at the time of culture or in pollen at any stage during normal ontogeny; its mRNA did begin to increase in embryogenic microspores within 6 h of culture, peaked at around 24 h, declined, then leveled off through the 21-day-old embryoid stage. Additionally, the accumulation of the embryoid-abundant EcMt gene transcript showed a direct and positive correlation with an increase of ABA in embryogenic microspores and developing pollen embryoids. Irradiating cultures with high intensity white light or with far-red, or blue light, suppressed EcMt transcript accumulation and the ability of microspores to form embryoids; however, light did not affect ABA concentrations during the early stages of culture. These results suggest that although a promoter of pollen embryogenesis in bread wheat, ABA alone cannot maintain the sporophytic differentiation of microspores subjected to inhibitory regimes of light in vitro. Whether or not light acts directly or indirectly in suppressing EcMt gene expression and pollen embryogenesis remains unknown.
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  • 99
    ISSN: 1432-203X
    Keywords: Abscisic acid ; Anther culture ; Light ; Metallothionein ; Pollen embryogenesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cloned cDNA to the wheat (Triticum aestivum) early cysteine-labeled metallothionein has many characteristics of a molecular marker for pollen embryogenesis in this plant. This transcript was not detected in uninucleate microspores at the time of culture or in pollen at any stage during normal ontogeny; its mRNA did begin to increase in embryogenic microspores within 6 h of culture, peaked at around 24 h, declined, then leveled off through the 21-day-old embryoid stage. Additionally, the accumulation of the embryoid-abundant EcMt gene transcript showed a direct and positive correlation with an increase of ABA in embryogenic microspores and developing pollen embryoids. Irradiating cultures with high intensity white light or with far-red, or blue light, suppressed EcMt transcript accumulation and the ability of microspores to form embryoids; however, light did not affect ABA concentrations during the early stages of culture. These results suggest that although a promoter of pollen embryogenesis in bread wheat, ABA alone cannot maintain the sporophytic differentiation of microspores subjected to inhibitory regimes of light in vitro. Whether or not light acts directly or indirectly in suppressing EcMt gene expression and pollen embryogenesis remains unknown.
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    Plant cell reports 9 (1990), S. 14-16 
    ISSN: 1432-203X
    Keywords: Triticum aestivum ; Anther culture ; Sugars ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of employing different sugars in wheat anther culture has been investigated using four Spring wheat cultivars. The most responsive cultivar, Orofen, gave a three to four-fold increase in embryo yield when maltose was used in place of sucrose, with 50 embryos being produced for every 100 anthers cultured. Measurement of sugar concentrations in the culture media indicated that sucrose was more rapidly hydrolysed than maltose. However, neither the osmotic potential of the medium nor the concentration of glucose appeared to be critical factors in determining embryo yield.
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