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1.
This study has been conducted to evaluate the usefulness of carbon isotope discrimination (δ) in mature kernels as a criterion for the improvement of water-use efficiency and yield under drought in durum wheat. For this purpose, Triticum durum‘Om Rabi 5’ was crossed with T. polonicum pseudochrysospermum 9 (Tp9) which has been found to be more drought tolerant and to have a lower carbon isotope discrimination value of the grain. The F2 population showed a wide segregation for carbon isotope discrimination. Further, divergent selections (selection of plants most different in carbon isotope discrimination) were made among individual F2 plants, and for carbon isotope discrimination in F3 progenies under field conditions. Selected F3 and F4 progenies were evaluated under field conditions for morphological and agronomical traits. Broad-sense heritability (h2b), response to selection and realized heritability (h2r) were high. The narrow-sense heritability (h2n= 0.37 ± 0.047) indicated that additive and dominance effects were involved in the genetic control of carbon isotope discrimination. Negative correlations were noted between carbon isotope discrimination and grain yield and between carbon isotope discrimination and biomass yield within years and generations. An explanation of this result is attempted by analysing the relationships between carbon isotope discrimination and several phenological and morphological traits influencing the water-use efficiency. The divergent groups selected for low and high carbon isotope discrimination exhibited significant differences for days to heading, plant height, shape of the spike and number of spikelets per spike. Correlations were also found between carbon isotope discrimination and plant height, harvest index, shape of the spike, spike length, and number of spikes per plant. The potential use of carbon isotope discrimination as a criterion for the improvement of water-use efficiency in durum wheat is discussed by considering the genetics of this trait (variability, heritability, response to selection) and also the associations with phenological and morphological traits.  相似文献   

2.
Summary Water is often the most limiting factor to winter wheat (Triticum aestivum L.) production in the southern Great Plains of the U.S.A., yet the lack of reliable screening criteria has precluded direct selection for drought resistance in breeding programs. Previous work showed that leaf relative water content (RWC) was highly heritable when measured under field-drought conditions, but its adoption as a screening tool for yield improvement requires further investigation of the genetic relationship between grain yield and RWC. Plants representing high and low yield potential under drought stress, and a random group of plants, were selected from an F2 population having the pedigree, TAM W-101/Sturdy. Two sets of entries, each comprised of the two parents and 24 F2-derived lines, were evaluated under a rainshelter in the F3 (1986) and F4 (1987) generations to determine differences in leaf RWC during reproductive development. One set of entries did not receive any water after the jointing stage, and the other set was grown under well-watered conditions. A positive relationship was observed between grain yield and RWC measured during anthesis and mid-grain fill, as the high-yield selections maintained a significantly higher RWC than the low-yield selections. Grain yield and RWC were also positively associated among random selections segregating for both traits. Subsequent adjustment of genotype means for differences in reproductive development at time of sampling underscored the need to consider differences in maturity when RWC is the selection criterion.  相似文献   

3.
Three durum and three bread wheat genotypes were crossed to produce three tetraploid, three hexaploid and nine interspecific (pentaploid) F1 hybrids. All genotypes were evaluated for heat tolerance in the field and for drought using polyethylene glycol in vitro. Chromosome numbers and meiotic behavior in pentaploid F1 hybrids (2n=5x=35, genomes AABBD) were confirmed. Heat stress significantly reduced grain yield/plant and 1000-kernel weight (1000-KW), while grain protein content (GPC) was increased. Drought caused a significant reduction in root length, shoot length and seedling fresh weight, whereas root/shoot ratio was increased. P3 (durum), P4 (bread) and their pentaploid F1 hybrid could be considered as the most heat-tolerant genotypes. However, P2 (durum), P6 (bread) and their F1 were most tolerant to drought. The addition of a D genome single dose into pentaploid F1 hybrids obviously reduced grain yield/plant, 1000-KW and seedling traits, however GPC was increased. Moderate to high broad-sense heritability and genetic advance were obtained for the most investigated traits. Grain yield/plant was strongly positively correlated with stress tolerance index (STI), yield index (YI), mean productivity (MP), geometric mean productivity (GMP) and harmonic mean (HM) under heat stress and with root length under drought condition, suggesting that STI, YI, MP, GMP and HM are powerful indices for heat tolerance, while root length is most effective for drought. Successful interspecific hybridization obtained in the study is only an initial step for desired genes introgression. Successive progenies are going to be evaluated for further genetic studies aiming at improving abiotic stress tolerance in wheat.  相似文献   

4.
Summary The evaluation aimed at identifying landrace genotypes adapted to the rather unfavourable growing conditions of durum wheat in Sicily, to be used as parental material in a breeding programme. The trial was carried out in three seasons experiencing varying climatic conditions, and included 75 landraces, 25 of which were selected under severe drought in Syria. Wide differences were observed for most traits among genotypes and seasons of evaluation. Yields of the best performing entries identified in each season never significantly differed from that of the best check variety. The top-yielding landraces were consistently better than the remaining entries for the three yield components, viz. number of spikes per plant, number of kernels per spike and mean kernel weight. In the driest season they were also significantly earlier in heading, confirming the importance of earliness under drought. An analytical breeding approach relying on an array of morpho-physiological traits as selection criteria did not seem appropriate for the given environment, as the variable stress level enhanced the importance of specific traits under specific situations. The genotypic response was largely season-specific. Nonetheless, five landraces were in the best group in all seasons. The selection made in Syria also appeared somewhat effective in Sicily, particularly in the less favourable seasons.  相似文献   

5.
Summary Some 238 landraces from Algeria and Tunisia representative of the mediterraneum typicum durum wheat type and 265 landraces from Syria and Jordan representing the syriacum type were grown in a semi-arid Mediterranean environment of Northern Syria characterized by moderate drought stress. The germplasm types were compared for mean value, level of variation and relationships with grain yield of various morpho-physiological traits possibly usable for indirect selection of best yielding materials. The syriacum germplasm showed higher yield mainly due to greater earliness of cycle, slightly longer grain filling period, shorter stature, lower early growth vigour and higher drought tolerance expressed by a visual score recorded in another, more stressful environment in the region. It also showed lower variation for all morpho-physiological characters except plant glaucousness, for which it was more variable. The wheat types differed not only for architecture but also for optima of individual morpho-physiological traits required to maximize the yield response in the given environment. Higher yield of syriacum materials was attained at same heading and three to four days delayed maturity with respect to average phenology of three well-adapted control cultivars, and it was favoured by increasing number of kernels per spike, early vigour and drought tolerance. Higher yield of mediterraneum typicum landraces was related to heading and maturity dates approaching those of the control cultivars and to increasing kernel weight, early vigour and drought tolerance. Plant stature hardly affected the yield. Both absent and strong glaucousness could confer a yield advantage in syriacum materials.  相似文献   

6.
Growing in Central Europe winter instead of spring durum wheat would substantially increase yield potential but is currently hampered by the lack of knowledge of frost tolerance present in elite material. The objectives of our survey were to (i) study the genetic variability and heritability of frost tolerance and its association with other important agronomic and quality traits in durum wheat, (ii) examine the potential to combine frost tolerance with high quality and high grain yield and (iii) investigate the consequences of the heritabilities and associations among traits on the optimum design of a multistage selection programme for winter durum wheat. We investigated 101 elite winter durum wheat lines and four commercial checks in field trials at four locations. Four agronomic as well as nine quality traits were recorded. In addition, frost tolerance was evaluated using a semi‐controlled test resulting in high‐quality phenotypic data. Genotypic variances (σ²G) were significantly larger than zero for all traits, and heritabilities were moderate to high. Several elite durum wheat lines exhibited a frost tolerance comparable to that of two frost‐tolerant Triticum aestivum varieties. Frost tolerance was not negatively associated with other important agronomic and quality traits. The high quality of the phenotypic data for frost tolerance evaluated in a semi‐controlled test suggests that this is a cost‐efficient approach to consider frost tolerance at early stages of a multistage durum wheat breeding programme.  相似文献   

7.
Canada was the largest durum wheat (Triticum turgidum var durum) producer in 1994, and in recent years supplied over 70% of world export trade in durum. Breeding for pasta quality is, therefore, a primary objective in Canadian durum breeding programs. Control of cultivar registration and stringent grading standards ensure that durum of consistent high quality is produced for domestic and export markets. The objectives of breeding programs include: improvement of traits related to production concerns, such as grain yield, disease resistance and sprouting resistance, and those related to end-use quality, such as protein concentration and quality; milling quality factors, such as semolina yield; colour of the wheat, semolina and pasta; and cooking quality. Selection and testing for quality begins at very early generations and becomes more stringent for advanced inbred lines. Selection is practised at the F1 or F2, where appropriate, using monoclonal antibodies to identify desirable gamma gliadins (γ-45 ) or low molecular weight glutenin subunits (LMW 2) that have been shown to be related to end-use quality. Grain from early generation yield trials, starting at F4, is screened for protein concentration and pigment content by Near Infrared reflectance, and for gluten strength by sodium dodecyl sulphate (SDS) sedimentation and micro-mixograph. Promising lines entered into multi-location yield trials are screened with more time-consuming procedures to fully assess suitability for pasta processing. These tests include semolina yield, ash and colour, and predictions of gluten strength such as mixograph and alveograph, and cooking quality. Candidate cultivars with quality equal to or better than the mean of the check cultivars can be proposed for registration after three years in the Durum Cooperative Test. It takes approximately 10 years from performing a cross to registrating a new cultivar. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

8.
P. Annicchiarico    C. Royo    F. Bellah    M. Moragues 《Plant Breeding》2009,128(2):164-171
Breeding for specific or wide adaptation would be more cost-efficient if preliminary indications on genotype adaptive responses could be provided by easily-detectable morphophysiological or molecular characteristics. We investigated the consistency among adaptation parameters, morphophysiological traits and SSR markers in estimating and structuring the genetic diversity among 24 durum wheat genotypes. Additive main effects and multiplicative interaction adaptation parameters were estimated across 14 Algerian locations belonging to a low- or a high-elevation subregion. Eight morphophysiological traits were assessed in two locations per subregion. Genotype Euclidean distances based on adaptation parameters were closely related to those based on morphophysiological traits ( r  = 0.75, P = 0.01). Marker-based distances exhibited low correlation with those based on adaptation parameters ( r  = 0.26, P = 0.01) or morphophysiological traits ( r  = 0.32). The consistency between adaptation parameters and morphophysiological traits for genotype ordination and classification was greater than that between either information layer and SSR markers. Optima of phenology and plant height differed between subregions, whereas many kernels per spike and fertile tillers were associated with adaptation to both subregions.  相似文献   

9.
To identify scorable marker traits that can be used in cereal breeding programs for selecting drought tolerant individuals, we investigated the correlation among the drought-associated traits in two F2 populations derived from the crosses made between drought tolerant and sensitive barley and wheat parental genotypes. The parental genotypes of these crosses also differed by at least three other traits – paraquat tolerance, leaf size, and the relative water content. These three traits were scored in two F2populations of 80 individuals for each barley and wheat cross. Analysis of results indicated that the enhanced tolerance to paraquat was correlated with reduced leaf size and increased relative water content, two traits associated with water stress phenotypes of the drought tolerant barley and wheat parents. Our results suggested that the selection based on paraquat tolerance istechnically less demanding and thus useful for rapid screening of individuals for enhanced drought tolerance in segregating populations. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

10.
The aim of this study was to evaluate the performance of three species of unhulled-wheat (Triticum monococcum L., Triticum dicoccum Schubler and Triticum spelta L.) with respect to durum wheat (Triticum durum Desf. cv. Trinakria) in southern Italy's flat environment.
As far as yield is concerned, the mean yield was significantly different among species. Durum wheat yielded 16.1 %, 37.6% and 69.5 % more than dicoccum, spelta and monococcum species, respectively.
Among unhulled-wheat species, only Triticum dicoccum showed some similarity with durum wheat, such as one-thousand kernels weight, plant height and number of spikes per m2.
Among the factors studied, the days to reach heading represented the factor that mostly influenced yield  相似文献   

11.
Genetic architecture of seedling drought tolerance is complex and needs to be better understood. To address this challenge, we developed a protocol to identify the most promising drought-tolerant genotypes at the seedling stage in winter wheat. A population of 146 recombinant inbred lines (F9) derived from a cross between wheat cultivars, ‘Harry’ (seedling drought tolerant) and ‘Wesley’ (seedling drought susceptible) were used in this study. All genotypes were sown in three replications in a randomized complete block design under controlled conditions in a greenhouse. Seven traits were scored and grouped into tolerance traits; days to wilting, leaf wilting, and stay green and survival traits; days to regrowth, regrowth, drought survival rate, and recovery after irrigation. Three selection indices were calculated (1) tolerance index, (2) survival index, and (3) drought tolerance index (DTI). The same set of genotypes were also tested for grain yield in two low rainfall environments for two seasons. High genetic variation was found among all genotypes for all seedling traits scored in this study. Correlations between tolerance and survival traits were weak or did not exist. Heritability estimates ranged from 0.53 to 0.88. DTI had significant phenotypic and genotypic correlations with all seedling traits. Genotypes were identified with a high drought tolerance at the seedling stage combined with high grain yield in low rainfall. Breeding for tolerance and survival traits should be taken into account for improving winter wheat drought tolerance at seedling stage. The selected genotypes can be used for to further improve drought tolerance in high yielding wheat for Nebraska.  相似文献   

12.
Impacts of drought during the reproductive development phase of wheat have been thoroughly investigated, while studies of the early-season drought effects are lacking. Field experiments were conducted to study the effect of duration of drought stress during the period from emergence to the end of tillering on the growth and performance of different wheat cultivars, and to identify traits that could be associated with the resistance to early season drought. Experiments were conducted on a Vertic Calcixerol soil in the semiarid cereal-growing region of Morocco in 1995 and 1996. Six spring durum wheat (Triticum durum Desf.) cultivars selected on the basis of variation in morphology, phenology, and zone of adaptation were subjected to four water regimes, including a well-irrigated control. The three water stress treatments were imposed by withholding water during the period from emergence to either the onset, middle, or the end of tillering. Subsequent irrigations provided adequate soil moisture for the remainder of the growing season. Results from both years were generally consistent. The differential responses of the six cultivars was mainly due to differences in numbers of kernels produced. High yields under early-season drought were attributed to high leaf area index under stress and, upon recovery, and to high tiller survival rate. The consistency observed over years in the relationships between grain yield and those traits that proved to be most associated with the resistance to early-season drought, would suggest the usefulness of these traits as selection criteria for breeding for improved drought resistance in a Mediterranean climate type of North Africa. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

13.
Manganese (Mn) deficiency is a major constraint of alkaline soils around the world, particularly for cultivation of durum wheat, which is more intolerant of low Mn levels than either common wheat or barley. Genetic variation for Mn efficiency exists in the current germplasm of durum wheat. Several restriction fragment length polymorphisms (RFLPs) previously shown to be linked to the Mel1 locus for Mn efficiency on chromosome 4HS of barley were tested on 88 selected F2 plants of the durum cross, ‘Stojocri 2’ (Mn efficient) בHazar’ (Mn inefficient). The Mel1‐linked RFLP marker Xcdo583a was closely linked to the trait and explained over 42% of the total variation for Mn efficiency in the ‘Stojocri 2’/‘Hazar’ F2 progeny. This marker has the potential to provide a valuable tool for the marker‐assisted selection of Mn‐efficient durum progeny derived from crosses with ‘Stojocri 2’.  相似文献   

14.
S.R. Verma  M. Yunus  S.K. Sethi 《Euphytica》1998,100(1-3):15-18
Three populations of an intervarietal durum wheat cross IWP5308/PDW208, F5, F5BIP1 (population derived after intermating in F2) and F5BIP2 (population derived after intermating in BIPF1), were evaluated under three different agronomic environments for mean performance and stability of genotypes for grain yield, yield components and protein content. Though the biparental progenies indicated a higher mean performance, they did not differ significantly from progenies of the pedigree method for almost all characters. The biparental progenies, however, produced a higher number of stable genotypes for grain yield per plant, grains per ear and protein content. The F5 population had a higher number of stable genotypes for 1000 grain weight and number of tillers per plant. The BIP progenies also had a higher number of genotypes with above average mean performance, and many were significantly higher than the checks WH896 and WH542, compared with F5 progenies. Hence, in spite of high G x E interactions, the use of cycles of biparental mating and selection of top yielding lines on the basis of yield components can enable selection of stable genotypes with high protein content. Number of tillers per plant and 1000 grain weight were the yield component characters which made maximum contribution to phenotypic stability of the genotypes. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

15.
C. He  G. R. Hughes 《Plant Breeding》2003,122(4):375-377
Common bunt caused by Tilletia tritici and T. laevis has occurred worldwide and reduces yield and quality in common and durum wheats. The development of DNA markers linked to bunt resistance to race T1 in the cross, ‘Laura’(S) בRL5407’ (R), was carried out in this study based on the single head derived F4:5 and single seed derived F4:6 populations. Bulked segregant analysis was used to identify two random amplified polymorphic DNA (RAPD) markers linked to the gene for resistance to race T1 in the spelt wheat ‘RL5407′. The two markers identified, UBC548590 and UBC274988, flanked the resistance gene with a map distance of 9.1 and 18.2 cM, respectively. The former was linked in repulsion phase to bunt resistance while the later was in coupling phase. The two RAPD markers and the common bunt‐resistance gene all segregated in Mendelian fashion. Use of these two RAPD markers together could assist in incorporating the bunt‐resistance gene from spelt wheat into common wheat cultivars by means of marker‐assisted selection.  相似文献   

16.
Carbon isotope discrimination (Δ) has been proposed as a selection criterion for transpiration efficiency and grain yield in drought‐prone environments for several C3 species, including cereals. Δ analysis, however, has mainly been concerned with grain or culm tissues and little work has been devoted to other organs. The objective of this study was to describe Δ variation in different organs and to examine the relationships between Δ and grain yield across environments. Six durum wheat genotypes with contrasted grain Δ were cultivated under rainfed conditions during three successive years at Montpellier (South of France). Δ was measured on flag leaf, stalk, awns, chaff and rachis sampled at anthesis and maturity, and on mature grain. Higher genotypic variation and closer correlation with yield were noted for grain Δ compared to other plant parts. The genotype ranking across years was more consistent for grain Δ than for other organs. Consequently, the grain seems the most effective plant part for Δ analysis in durum wheat under Mediterranean conditions. The study of Δ variation in other organs may be useful, however, to evaluate the contribution of those organs to grain filling and final yield according to environmental conditions.  相似文献   

17.
Summary The effectiveness of the honeycomb selection method for yield in spring wheat (Triticum aestivum L.) was evaluated using progenies from two wheat crosses, Glenlea x NB131 and Glenlea x Era. Honeycomb selection was carried out in the F2 and F3 generations, grown at the University of Manitoba in the summers of 1980 and 1981, respectively. In both generations, divergent selection was made for both high and low yield. Plants selected in the F3 generation were entered in an F4 yield test in the summer of 1982. Results of the experiment showed that honeycomb selection for yield in the F2 and F3 generations was effective in identifying parents of high- and low-yielding lines. F3 plants from highyielding F2 selections gave higher yields than those from low-yielding F2 selections by 11.5% and 13.0% for Glenlea x NB131 and Glenlea x Era crosses, respectively. The F4 yield test showed that high yielding selections from both crosses significantly outyielded by 8.9% low yielding selections and by 14.4% the unselected composite lines. It is concluded that the honeycomb selection method can be used for early generation selection in spring wheat.  相似文献   

18.
Summary Stem solidness in the wheat plant provides resistance to the wheat stem sawfly, a pest of wheat in Montana and North Dakota, but some agronomists have been concerned that stem solidness might be related to low grain yields. We evaluated 17 spring wheat crosses for stem solidness, grain yield, and other agronomic traits in F2 through F4 generations from 1972 to 1975.Highly significant correlation (0.735) and regression (0.731) coefficients between F2 and F3 generations verify previous studies showing that stem solidness is highly heritable and that selection in F2 should be successful. Solid-stemmed F4 composites yielded more than hollow stemmed composites at Bozeman and equal yields were obtained at Huntley, indicating that stem solidness is not a deterrent to high grain yield.Joint contribution of Federal Research, Science and Education Administration, U.S. Department of Agriculture and the Montana Agricultural Experiment Station, Bozeman, MT 59717. Published with approval of the Director of the Montana Agricultural Experiment Station as Paper No. 815, Journal Series.  相似文献   

19.
Triticum turgidum ssp. durum (tetraploid durum) germplasm is very susceptible to crown rot, caused by the fungus Fusarium pseudograminearum. Screening activities to date have failed to identify even moderately susceptible lines. In contrast partial resistance to this disease has been identified in a number of Triticum aestivum (hexaploid wheat) lines, including 2-49 and Sunco. This study describes the successful introgression of partial crown rot resistance from each of these two hexaploid wheat lines into a durum wheat background. Durum backcross populations were produced from two 2-49/durum F6 lines which did not contain any D-genome chromosomes and which had crown rot scores similar to 2-49. F2 progeny of these backcross populations included lines with field based resistance to crown rot superior to that of the parent hexaploid wheat.  相似文献   

20.
Selection for biomass yield in wheat   总被引：2，自引：0，他引：2  
R. C. Sharma 《Euphytica》1993,70(1-2):35-42
Summary Biomass (above ground plant parts) yield may be a useful selection trait for yield improvement in wheat (Triticum aestivum L.). This study was conducted to estimate realized heritability of biomass yield and to determine the response to selection for high and low biomass yield in 8 genetically diverse populations of spring wheat under two production systems. Selections were made among the F3 lines. Progenies of the selected lines were evaluated in replicated field tests in the F4 generation under high fertility and low fertility production systems at Rampur, Nepal, in 1991. Fertility level had a significant effect on biomass yield, grain yield, effective tiller number, number of kernels per spike, thousand kernel weight, and harvest index. Selection in the F3 for high and low biomass yield was effective in identifying F4 lines with high and low biomass yield, respectively. Biomass yield differences between high and low selection groups in the F4 generation, expressed as percent of the mean of the low selection group and averaged over the eight populations, were 53.9 and 36.5% higher than the mean of the low selection group under the high and the low fertility production systems, respectively. The corresponding figures for grain yield were 48.8 and 34.9% under the high and the low production systems, respectively. Also, selection for high biomass yield resulted in higher effective tiller number, and number of kernels per spike, but lower harvest index. Realized heritability estimates for biomass yield were greater at high fertility (range 0.49 to 0.85) than at low fertility (range 0.22 to 0.44). Biomass yield showed positive genotypic correlations with grain yield, effective tiller number, and number of kernels per spike but a negative correlation with harvest index. The results indicated that selection for high biomass yield should bring about positive improvements in biomass yield, grain yield, effective tiller number, and number of kernels per spike. The correlation between F3 and F4 generations suggested that biomass yield in the F3 generation was a good predictor of biomass yield and grain yield in the F4 generation. Selection for biomass yield in wheat should be made under the standard production system to obtain a realistic response.  相似文献   

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