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1.
Summary Seed dormancy in wheat (Triticum aestivum L. em Thell) is important for minimizing pre-harvest sprouting. To facilitate breeding cultivars that tolerate pre-harvest sprouting conditions, we assessed mode and magnitude of variation of seed dormancy among genotypes and investigated involvement of endogenous water-soluble inhibitor(s) in seed germination. Embryo bio-assays established that water-soluble inhibitor was ubiquitous among the wheat cultivars studied and did not diminish in quantity during after-ripening. Germination response of embryos was decreased by endogenous inhibitor, but the effect markedly declined as embryos aged at room temperature. Variation in dormancy among cultivars was primarily caused by differential response of their embryos to endogenous inhibitor. Gibberellic acid counteracted the initial inhibitory effect of endogenous inhibitor on germination but not the subsequent inhibitory effect on seedling growth. We concluded that pre-harvest sprouting resistance involves multiple factors, particularly embryo receptivity to endogenous inhibitor, and that variation in inhibitor quantity is not solely responsible for genotypic differences in susceptibility to pre-harvest sprouting. The possibility of additional approaches to breeding for pre-harvest sprouting resistance is indicated.Contribution no. 81-389-j, Department of Agronomy, Kansas State University, Manhattan, KS 66506, U.S.A.  相似文献   

2.
In marginal, agroclimatic zones, yield is often affected by flooding, but the effect is much less for winter spelt (Triticum spelta L.) than for winter wheat (Triticum aestivum L.). This study evaluates the reaction of a wheat x spelt population (F5 RILs of Forno x Oberkulmer) to flooding stress in the early phase of germination. Lines with greater tolerance to 48 h flooding just after imbibition showed less electrolyte leakage (r = -0.79) indicating greater membrane integrity and better survival. Five QTL explaining 40.6% of the phenotypic variance for survival to flooding were found, and localized on the chromosomes 2B, 3B,5A, and 7S. The tolerance to 48 h flooding four days after sowing was best correlated with the mean germination time (r = 0.8), indicating that the plants with a fast coleoptile growth during flooding are less susceptible to flooding. Ten QTL were found for seedling growth index after flooding explaining 35.5% of the phenotypic variance. They were localized on chromosomes 2A, 2B, 2D, 3A, 4B, 5A, 5B, 6A, and 7S. Standard varieties of spelt and wheat showed the same tolerance characteristics. The possibility to use marker assisted selection for flooding tolerance is discussed. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

3.
Seeds of Paceño and Cuarenteño cultivars of cowpea (Vigna unguiculata L. Walp.) were tested for salt and drought tolerance at germination, seedling emergence and early seedling growth in NaCl and PEG‐8000 solutions of different osmotic potentials (0, ?0.2, ?0.4, ?0.6, and ?0.8 MPa). Daily and final germination and emergence percentage, as well as germination and seedling emergence rate, and seedling growth were recorded under controlled conditions. Results showed that germination and emergence rate were delayed by both solutions in both cultivars, with differences between cultivars among growth stages, given that cultivar Cuarenteño, showed a higher germination rate than Paceño in NaCl, but Paceño was less affected by NaCl and PEG solutions at the emergence stage. Sodium chloride had a lesser effect on both cultivars in terms of germination rate, emergence rate and the final germination and emergence percentage than did PEG‐8000. This conclusively proves that the adverse effect of PEG‐8000 on germination, emergence and early seedling growth was due to the osmotic effect rather than the specific ion. Seedling growth was reduced by both stresses, but NaCl usually caused less damage than PEG to cowpea seedlings, suggesting that NaCl and PEG acted through different mechanisms.  相似文献   

4.
A. C. Zeven 《Euphytica》1990,47(3):249-258
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5.
Drought stress and zinc (Zn) deficiency are serious abiotic stress factors limiting crop production in Turkey, especially in Central Anatolia. In this study, the effects of Zn deficiency and drought stress on grain yield of 20 wheat cultivars (16 bread wheat, Triticum aestivum; four durum wheat, Triticum durum cultivars) were investigated over 2 years under rainfed and irrigated conditions in Central Anatolia where drought and Zn deficiency cause substantial yield reductions. Plants were treated with (+Zn: 23 kg Zn ha−1, as ZnSO4·7H2O) and without (−Zn) Zn under rainfed and irrigated conditions. Both Zn deficiency and rainfed treatments resulted in substantial decreases in grain yield. Significant differences were determined between both bread wheat and durum wheat cultivars in terms of drought stress tolerance. Considering drought sensitivity indices over 2 years, the bread wheat cultivars Yayla‐305, Gerek‐79, Dagdas‐94 and Bolal‐2973 were found to be more drought‐tolerant than the other cultivars under both −Zn and +Zn treatments. Especially the durum wheat cultivars Cakmak 79 and Selcuklu 97 showed much greater drought susceptibility under Zn deficiency, and irrigation alone was not sufficient to obtain satisfying grain yield without Zn application. The results indicate that sensitivity to Zn deficiency stress became more pronounced when plants were drought‐stressed. The effect of irrigation on grain yield was maximized when Zn was adequately supplied, leading to the suggestion that efficient water use in Central Anatolia seems to be highly dependent on the Zn nutritional status of plants.  相似文献   

6.
Heat tolerance for yield and its components in different wheat cultivars   总被引：1，自引：0，他引：1  
L. Shpiler  A. Blum 《Euphytica》1990,51(3):257-263
Summary Twenty one diverse, standard and experimental cultivars of common spring wheat (Triticum aestivum L.) were tested for the effect of heat stress on phenology, yield and its components by growing the materials for 2 years under full irrigation during the hot summer (offseason), and the cool winter (normal) conditions. Heat tolerance was estimated for each variable by the heat susceptibility index (S) which scales the reduction in cultivar performance from cool to hot conditions relative to the respective mean reduction over all cultivars.Genotypes differed significantly in S for yield and its components. The ranking of cultivars in S over the 2 years was consistent for yield, kernels per spike and kernel weight, but not for spike number. Of the three yield components, the greatest genotypic variation in S was expressed for kernels per spike. However, S for yield could not be simply attributed to S in a unique component across all cultivars. On the other hand, a general linear model regression of summer yield on its components revealed that the most important yield component affecting yield variation among cultivars under heat stress was kernel number per spike. Kernel number per spike was positively associated across cultivars with longer duration and greater stabilty of thermal time requirement from emergence to double ridge. It is therefore concluded that kernel number per spike under heat stress is a reasonable estimate of heat tolerance in yield of wheat and that this tolerance is operative already during the first 2 to 3 weeks of growth.  相似文献   

7.
Summary A simple method is proposed to distinguish hexaploid (Triticum aestivum L.) from tetraploid (Triticum turgidum L., durum wheat) cultivated wheats on the basis of peroxidase isozymes coded by genome D. It can also be used as a first step to detect possible contamination by tetraploid genotype mixtures. The peroxidase patterns of endosperm and of embryo plus scutellum found among 349 entries of a durum wheat world basis collection are shown.  相似文献   

8.
Summary Diverse landraces of wheat, collected from the semi-arid (150 to 250 mm of total annual rainfall) Northern Negev desert in Israel were considered as a potential genetic resource of drought resistance for wheat breeding. These materials were therefore evaluated for their reponses to drought stress in agronomical and physiological terms. Up to 68 landraces, comprising of Triticum durum, T. aestivum, and T. compactum were tested in two field drought environments, in one favourable field environment, under post-anthesis chemical plant desiccation which revealed the capacity for grain filling from mobilized stem reserves, under a controlled drought stress in a rainout shelter and in the growth chamber under polyethylene glycol (PEG)-induced water stress. Biomass, grain yield and its components, harvest index, plant phenology, canopy temperatures, kernel weight loss by chemical plant desiccation, growth reduction by PEG-induced drought stress and osmotic adjustment were evaluated in the various experiments.Landraces varied significantly for all parameters of drought response as measured in the different experiments, which was in accordance to their documented large morphological diversity. Variation in grain yield among landraces under an increasing drought stress after tillering was largely affected by spike number per unit area. Kernel weight contributed very little to yield variation among landraces under stress, probably because these tall (average of 131 cm) landraces generally excelled in their capacity to support kernel growth by stem reserve mobilization under stress. Yield under stress was reduced with a longer growth duration of landraces only under early planting but not under late planting. Landraces were generally late flowering but they were still considered well adapted phenologically to their native region where they were always planted late.Landraces differed significantly in canopy temperature under drought stress. Canopy temperature under stress in the rainout shelter was negatively correlated across landraces with grain yield (r=0.67**) and biomass (r=0.64**) under stress. Canopy temperature under stress in the rainout shelter was also positively correlated across landraces (r=0.50**) with canopy temperature in one stress field environment. Osmotic adjustment in PEG-stressed plants was negatively correlated (r=–0.60**) with percent growth reduction by PEG-induced water stress. It was not correlated with yield under stress in any of the experiments. In terms of yield under stress, canopy temperatures and stem reserve utilization for grain filling, the most drought resistant landrace was the Juljuli population of T.durum.  相似文献   

9.
Submergence is a major stress causing yield losses particularly in the direct-seeded rice cultivation system and necessitates the development of a simple, rapid and reliable bioassay for a large scale screening of rice germplasms with tolerance against submergence stress. We developed two new bioassay methods that were based primarily on the seedling vigor evaluated by the ability of fast shoot elongation under submerged conditions, and compared their effectiveness with two other available methods. All four bioassay methods using cultivars of 7 indica and 6 japonica types revealed significant and consistent cultivar differences in seedling vigor under submergence and/or submergence tolerance. Japonica cultivars were more vigorous than indica cultivars, with Nipponbare being the most vigorous. The simplest test tube method showed the highest correlations to all other methods. Our results suggest that seedling vigor serves as a submergence avoidance mechanism and confers tolerance on rice seedlings to flooding during early crop establishment. A possible relationship is discussed between seedling vigor based on fast shoot elongation and submergence tolerance defined by recovery from submergence stress.  相似文献   

10.
Low temperature seriously depresses seed germination and seedling growth in winter wheat (Triticum aestivum L.). In this study, wheat plants were sprayed with abscisic acid (ABA) and fluridone (inhibitor of ABA biosynthesis) at 19 days after anthesis (DAA) and repeated at 26 DAA. The seeds of those plants were harvested, and seed germination and offspring's seedling growth under low temperature were evaluated. The results showed that exogenous ABA application decreased seed weight and slightly reduced seed set and seed number per spike. Under low temperature, seeds from ABA‐treated plants showed reduced germination rate, germination index, growth of radicle and coleoptile, amylase activity and depressed starch degradation as compared with seeds from non‐ABA‐treated plants; however, activities of the antioxidant enzymes in both germinating seeds and seedling were enhanced from those exposed to exogenous ABA, resulting in much lowered malondialdehyde (MDA) and H2O2 concentrations and production rate. In addition, the maximum quantum efficiency of photosystem II was also enhanced in ABA‐treated offspring's seedlings. It is concluded that exogenous ABA treatment at later grain‐filling stage could be an effective approach to improve cold tolerance of the offspring during seed germinating and seedlings establishment in winter wheat.  相似文献   

11.
Summary Pre-soaking strawberry seed (Fragaria ananassa Duch.) in osmotic solutions accelerated and partially synchronized their germination. Pre-soaking advanced 50% germination from about 4 weeks to 4 or 5 days. Two to three weeks pre-soaking in a mineral solution of -106Pa nominal osmotic potential at about 20 C was satisfactory. The resulting synchronization of germination could allow seedlings to be selected for rate of growth by directly comparing seedling in bulk sowings.  相似文献   

12.
C. Planchon 《Euphytica》1979,28(2):403-408
Summary Net photosynthesis, transpiration, and resistances to CO2 and water vapour transfer of two cultivars of each of four types (Triticum durum, Triticum aestivum. hexaploid Triticale, octaploid Triticale) were analysed. Hexaploid triticales have the highest net photosynthesis and the best water efficiency. Water efficiency was defined by the CER/transpiration ratio measured under saturating irradiance corresponding to full stomatal opening. Cultivated bread and durum wheat cultivars (Capitole, Champlein, Bidi 17) are characterised by a low CER associated with a large flag leaf area and a high mesophyll resistance. There is a close correlation between CER., flag leaf area, mesophyll resistance and total chlorophyll content.  相似文献   

13.
Six wheat ( Triticurn aestivum L.) and ten triticale (x Triticosecale Wittmack) cultivars were screened for water stress tolerance during germination and seedling stages in the laboratory and growth chamber, respectively. Germinating seeds and hydroponically-grown seedlings were subjected to osmotic stresses of –0.3 and –0.6 MPa using polyethylene glycol M. W. 8000. Both species and cultivar differences were found among the tested genotypes for all the parameters analyzed in both germination and seedling tests. Germination stress index was lower for seed exposed to -0.6 MPa than for -0.3 MPa osmotic stress. A significant relationship was found among plant height, fresh weight and dry weight stress indices evaluated during the seedling test. The cultivars that grew taller under stress conditions had greater dry matter accumulation, as well as higher germination and water uptake stress indices indicating the reliability of height to predict cultivar performance under such conditions. The cultivars Stacy (wheat) and Eu 14/15 (triticale) had higher dry matter accumulation, higher water uptake and leaf water potential, greater height and better germination under stress conditions than the other cultivars tested. Conversely, the cultivars GA 781014 (wheat) and Am 4147 (triticale) performed poorly with respect to all the parameters analyzed. Based on results from germination and seedling tests, the cultivars Stacy and Eu 14/15 were selected for more stress studies in the greenhouse and field.  相似文献   

14.
Summary Wheat has traditionally been grown by the Beduin population in the semi-arid (150 to 200 mm, mean total annual rainfall) northern Negev region of Israel.A collection was made in this area (the size of which is 150 km2) from small (0.1 to 0.5ha) fields of mixed wheat, resulting in 1553 collected spikes. Each spike was planted in a 1 m row at Bet Dagan, and grown under favorable conditions. Qualitative and quantitative data were collected from each row. Qualitative data were submitted to hierarchial clustering and the results were compared with published information on the identification, classification and distribution of the land-races of wheat in the Middle East. Triticum durum was represented in 84% of the collection. It was clustered into 22 populations, identified as 11 known varietas of T. durum. They were aggregated into five groups, similar to groups of old varieties recognized by Jacubziner (1932). While 38.5% of the collection consisted of T. durum groups villosa and sinaica, aboriginal to the northern Negev, it included also forms similar to several land-races found in the past in other parts of the Middle East. Each of the populations, and the durum collection as a whole, was very diverse for the quantitatively measured plant attributes. Triticum aestivum was represented in 15.6% of the collection, clustered into six populations. Most of the common wheat accessions were analogous to the old locally grown variety Hirbawi. Triticum compactum was represented in only eight accessions.The collection is now being evaluated as a potential genetic resource for durum wheat breeding.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel No. 374-E, 1982 series.  相似文献   

15.
Fifty-five spring bread wheat (Triticum aestivum L.) cultivars, mostly released between 1975 and 1991 in eight leaf rust-prone spring wheat growing regions of the former USSR, were tested in the seedling growth stage for reaction to 15 Mexican pathotypes of Puccinia recondita f. sp. tritici. In total, seven known and at least two unknown genes were identified, either singly or in combinations: Lr3 (7 cultivars), Lr10 (14), Lr13 (5), Lr14a (1), Lr16 (1), Lr23 (3); the unknown genes were identified in 14 cultivars. The first unknown gene could be either Lr9, Lr19, or Lr25; however, the second unknown gene in 9 cultivars was different from any named gene. Twelve of the 15 pathotypes are virulent for this gene, hence its use in breeding for resistance will be limited. The cultivars were also evaluated at two field locations in Mexico with two pathotypes in separate experiments. The area under the disease progress curve and the final disease rating of the cultivars indicated genetic diversity for genes conferring adult plant resistance. based on the symptoms of the leaf tip necrosis in adult plants, resistance gene Lr34 could be present in at least 20 cultivars. More than half of the cultivars carry high to moderate levels of adult plant resistance and were distributed in each region.  相似文献   

16.
Increased grain yield potential of newcultivars of wheat (Triticum aestivumL.) is attributed to morphological traits,but actual yield is determined mostly byenvironmental conditions. Our objectivewas to ascertain the contribution ofresistance to freezing, high temperature,drought, and defoliation to advances inyield of landmark cultivars of winter wheatin the U.S. Great Plains. Eight cultivarsthat represented significant improvementbetween 1874 and 1994 were compared bystandard electroconductivity measurementsof stability of seedling cell membranes tofreezing, high temperature, and desiccationand by grain yield and its components inplants subjected to freezing during theseedling stage and to high temperature,drought, and defoliation during maturation. Genetic changes relative to `Turkey'(introduced 1874) in stability of cellmembranes to freezing, high temperature,and desiccation were small andinconsistent. Advances in grain yieldunder control conditions were similar togains in field studies. Most cultivars hadlittle genetic change in yield afterfreezing, drought, or defoliation, probablybecause high levels of resistance areincompatible with high yield potential andthe stresses are episodic. Genetic advancein grain yield under high temperature wasphenotypically correlated with change inyield under control conditions, suggestingthat the trait is essential forproductivity because of the ubiquitousoccurrence of the stress in the region. Weconcluded that changes in resistances tofreezing, drought, and defoliationcontributed little to advances inproductivity of winter wheat in the GreatPlains, but that resistance to hightemperature was important for new cultivars.  相似文献   

17.
Differential tolerance to Fe and Zn deficiencies in wheat germplasm   总被引：3，自引：0，他引：3  
Z. Rengel  V. Römheld 《Euphytica》2000,113(3):219-225
Tolerance to Fe deficiency of wheat genotypes exhibiting differential tolerance to Zn deficiency is not known, even though the relationship between Fe nutrition and differential tolerance of wheat genotypes to Zn deficiency has been hypothesised frequently. In the present experiment, eight Triticum aestivum and two T. turigidum L. conv. durum cultivars were grown in nutrient solution deficient in either Znor Fe. Three indices of tolerance to nutrient deficiency were compared: relative [(-nutrient/+nutrient) × 100] shoot growth, shoot dry weight under nutrient deficiency and relative shoot/root dry weight ratio. Genotypes Aroona, Excalibur, Stilleto and Trident were classified as tolerant to both Zn and Fe deficiency, while durum wheats Durati and Yallaroi were sensitive to Zn deficiency and moderate to sensitive to Fe deficiency. Genotypes Excalibur, Stilleto and Trident come from the same breeding programme and have the common parent (line MEC3 =Sonora64//TZPP/YAQUI54) that could have been the donor of the genes for tolerance to Zn deficiency. When Fe-deficient, all wheat genotypes were severely chlorotic but kept producing shoot and root dry matter at a relatively high rate, making the relationship between the relative shoot growth and the relative leaf chlorophyll content poor. This is the first report of wheat genotypes exhibiting multiple tolerance to Zn and Fe deficiencies. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

18.
Summary A set of 105 European wheat cultivars, comprising 68 cultivars with known seedling resistance genes and 37 cultivars that had not been tested previously, was tested for resistance to selected Australian pathotypes of P. triticina in seedling greenhouse tests and adult plant field tests. Only 4% of the cultivars were susceptible at all growth stages. Twelve cultivars lacked detectable seedling resistance to leaf rust, and among the remaining cultivars, 10 designated genes were present either singly or in combination. Lr13 was the most frequently detected gene, present in 67 cultivars, followed by the rye-derived gene Lr26, present in 19 cultivars. Other genes present were Lr1, Lr3a, Lr3ka, Lr10, Lr14a, Lr17b, Lr20 and Lr37. There was evidence for unidentified seedling resistance in addition to known resistance genes in 11 cultivars. Field tests with known pathotypes of P. triticina demonstrated that 57% of the cultivars carried adult plant resistance (APR) to P. triticina. The genetic identity of the APR is largely unknown. Genetic studies on selected cultivars with unidentified seedling resistances as well as all of those identified to carry APR are required to determine the number and inheritance of the genes involved, to determine their relationships with previously designated rust resistance genes, and to assess their potential value in breeding for resistance to leaf rust.  相似文献   

19.
Z. Rengel  V. Jurkic 《Euphytica》1992,66(1-2):111-116
Summary Aluminium tolerance of 90 genotypes of Triticum aestivum L. germplasm from the breeding programmes of eight Croatian and Yugoslav institutions was evaluated in nutrient solutions having Al3+ activities of 0, 12.5 and 25M. Overall distribution of Al tolerance of wheat genotypes was skewed toward lower tolerance rankings. Average Al tolerance differed among gene pools created at different breeding institutions. Genotypes tolerant enough to be useful in the breeding programmes aimed at selecting cultivars with improved Al tolerance are identified in germplasm from four institutions. No correlation was found between chemical characteristics of soils used over the years by breeding institutions for their field trials and the Al-tolerance ranking of the corresponding germplasm material.Abbreviations HSD Tukey's Honestly Significant Difference - RRL-4 relative root length, in % (25M Al3+/0 Al)  相似文献   

20.
H. Ghiasi  K. A. Lucken 《Euphytica》1982,31(1):253-259
Summary Many conventional hard red spring wheat (Triticum aestivum L. em Thell) lines, including several North Dakota cultivars, carry a gene (or genes) which restore partial male fertility to male sterile plants with Triticum timopheevi Zhuk. cytoplasm. Since this gene has no fertility restoration function in T. aestivum cytoplasm, the postulation can be made that it is being retained in conventional lines because of pleiotropic effects, favorable linkages or chance. The research reported in this paper examined these possibilities. Forty F6 lines, derived from a single F2 plant which was heterozygous for a gene (or genes) for partial fertility restoration, were evaluated for two years in a yield trial planted at Fargo, North Dakota. The 40 lines were testcrossed to a male sterile line having T. timopheevi cytoplasm, and the mean seed set of testcrosses was used as a measure of a line's fertility restoration potential. Twenty-seven lines had the gene for partial fertility, and 13 lines apparently lacked this gene. The 40 lines differed for heading date, anther extrusion, plant height, grain yield, 200-kernel weight, test weight, and grain protein percentage. However, comparisons of lines having the restorer gene with those lacking the gene did not provide any obvious explanation for the retention of the partial fertility restorer gene in the breeding stocks of the North Dakota conventional hard red spring wheat breeding program. The possibility that the restorer gene was linked with genes for resistance to stem rust or leaf rust also was evaluated by testing lines for their reaction to several races of rust. No conclusive association was found.Contribution from the Agric. Exp. Sta., North Dakota State University, Fargo, ND 58105, Journal Article no.  相似文献   

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