Evaluation of Early Generation Testing in a Diallel Cross Involving Four Winter Wheat Cultivars (Triticum Aestivum Vill., Host) PDF Download
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Author: Abderrazak Daaloul Publisher: ISBN: Category : Wheat Languages : en Pages : 140
Book Description
Factors which influence the effectiveness of making early generation selections within bulk populations were investigated. Material utilized included the parents, F1, and F2 through F5 bulk populations resulting from a diallel cross. Information concerning the response of two traits, plant height and grain yield, was obtained for these populations at three diverse experimental sites. Estimates of gene action were determined by calculating heterosis, inbreeding depression, narrow-sense heritability, and combining ability values. Results obtained suggested that selections for plant height could be effectively made as early as the F2 generation since this trait was largely controlled by additive gene action. Grain yield was found to be influenced significantly by non-additive gene action; however most populations were stabilized by the F3 generations where high yielding populations could be identified and effective selection practiced. Results from this study suggested that genotype x environment interaction could influence early generation selection by masking the additive genetic effects. Under very favorable growing conditions the non-additive gene action x environment interaction dominated the additive effects for grain yield and to a lesser degree plant height. However, under dry land conditions both non-additive and additive genetic effects were masked by the environment and could not be expressed fully for grain yield. It is evident that for simply inherited traits like plant height, selection in the F2 generation must be practiced under an environment where there is full expression for that trait, while selection for grain yield must be conducted under the same environments where the potential varieties are to be grown. The use of Average Combining Ability as an indirect method to evaluate the contribution of parents to performance of the progency was found to be valid by the predicted results obtained for the simply inherited trait plant height. This method could be used with some confidence to estimate contribution of parents for a complex trait like grain yield. Two parents were identified as the best combiners for grain yield. This confirms what was learned about them after fifteen years of actual experience indicating the importance of a technique whereby the breeder can determine in a very short period of time which parents to cross and then concentrate his efforts within the more promising segregating populations.
Author: Abderrazak Daaloul Publisher: ISBN: Category : Wheat Languages : en Pages : 140
Book Description
Factors which influence the effectiveness of making early generation selections within bulk populations were investigated. Material utilized included the parents, F1, and F2 through F5 bulk populations resulting from a diallel cross. Information concerning the response of two traits, plant height and grain yield, was obtained for these populations at three diverse experimental sites. Estimates of gene action were determined by calculating heterosis, inbreeding depression, narrow-sense heritability, and combining ability values. Results obtained suggested that selections for plant height could be effectively made as early as the F2 generation since this trait was largely controlled by additive gene action. Grain yield was found to be influenced significantly by non-additive gene action; however most populations were stabilized by the F3 generations where high yielding populations could be identified and effective selection practiced. Results from this study suggested that genotype x environment interaction could influence early generation selection by masking the additive genetic effects. Under very favorable growing conditions the non-additive gene action x environment interaction dominated the additive effects for grain yield and to a lesser degree plant height. However, under dry land conditions both non-additive and additive genetic effects were masked by the environment and could not be expressed fully for grain yield. It is evident that for simply inherited traits like plant height, selection in the F2 generation must be practiced under an environment where there is full expression for that trait, while selection for grain yield must be conducted under the same environments where the potential varieties are to be grown. The use of Average Combining Ability as an indirect method to evaluate the contribution of parents to performance of the progency was found to be valid by the predicted results obtained for the simply inherited trait plant height. This method could be used with some confidence to estimate contribution of parents for a complex trait like grain yield. Two parents were identified as the best combiners for grain yield. This confirms what was learned about them after fifteen years of actual experience indicating the importance of a technique whereby the breeder can determine in a very short period of time which parents to cross and then concentrate his efforts within the more promising segregating populations.
Author: Publisher: ISBN: Category : Agriculture Languages : en Pages : 812
Book Description
Includes abstracts of the annual meetings of the American Society of Agronomy; Soil Science Society of America; Crop Science Society of America ( - of its Agronomic Education Division).
Author: Karen Sue Schumaker Publisher: ISBN: Category : Wheat Languages : en Pages : 118
Book Description
The nature of the genetic variation associated with a cross involving winter and spring wheat parents for four quality factors was evaluated. Yamhill, a soft white winter wheat, and Inia 66, a hard red spring wheat, were selected as parents for this study. They represented distinctly different phenotypes for the attributes measured. Parents, F1, F2 and reciprocal backcrosses were examined for protein and lysine content, kernel hardness, and sedimentation value. Significant differences were observed between the two parents for protein content. The F1 mean was lower than the low protein parent with the F2 mean intermediate between the two parents. This latter factor plus a high narrow sense heritability estimate suggest that the genetic variation associated with protein content was largely due to genes which act in an additive manner. Backcrosses to either parent shifted the population toward the mean of the recurrent parent. Transgressive segregation was observed in the F2 for both low and high protein content suggesting that selection for this trait should be effective in early generations. Parents differed significantly for lysine content with the winter parent, Yamhill displaying lysine values approaching the highest previously reported for wheat. Intermediate F1 and F2 population means and a high narrow sense heritability estimate suggest the genes involved function in an additive manner. The backcross progeny to Yamhill had a mean value approaching that of the recurrent parent. No transgressive segregation was observed in the F2 for lysine content higher than Yamhill. It appears that lysine content in this cross is qualitatively inherited and that selection for improved lysine content above Yamhill appears limited. The genetic variation associated with kernel hardness appears to be largely additive with F1 and F2 means intermediate between the two parents and a high narrow sense heritability estimate. Transgressive segregation was observed in the F2 generation for both soft and hard kernel types. Selection for this trait should be effective in early generations. Significant differences were observed for the parental types for sedimentation value. The F1 and F2 means were below the midparent value. No transgressive segregation was observed in the F2 for either low or high sedimentation value. One backcross to the low sedimentation parent brought the population back to the low parent mean. One backcross to the high sedimentation parent shifted the population toward the recurrent parent but no individuals were recovered that approached the high parent. From this study it appears that selection for high sedimentation value types would be very difficult. Evidence provided in this study supports the concept that winter x spring crosses can provide useable genetic variation for desirable quality factors.
Author: Publisher: ISBN: Category : Dissertations, Academic Languages : en Pages : 1086
Book Description
Vols. for 1973- include the following subject areas: Biological sciences, Agriculture, Chemistry, Environmental sciences, Health sciences, Engineering, Mathematics and statistics, Earth sciences, Physics, Education, Psychology, Sociology, Anthropology, History, Law & political science, Business & economics, Geography & regional planning, Language & literature, Fine arts, Library & information science, Mass communications, Music, Philosophy and Religion.
Author: Kamil Yakar Publisher: ISBN: Category : Wheat Languages : en Pages : 192
Book Description
The purpose of this study was to determine the nature and amount of genetic variation and possible associations between winterhardiness and earliness in winter x spring wheat crosses. Four winter wheat cultivars selected for differences in earliness and winterhardiness were crossed with a nonhardy, day length insensitive spring wheat cultivar. The following year, experiments containing parents, F1, BC, and F2 populations were planted at two environmentally diverse sites located at the Sherman Branch Experiment Station, Moro, Oregon (250 mm of moisture) and the Hyslop Agronomy Farm, Corvallis, Oregon (1000 mm of moisture). The amount and nature of genetic variation involved were determined by obtaining broad and narrow sense heritability estimates, evaluating the degree of dominance and estimating the number of genes influencing both earliness and winterhardiness. Also frequency distributions were developed for each of the populations. Both broad and narrow sense heritability estimates for earliness were higher than those observed for winterhardiness. Both winterhardiness and earliness appeared to be conditioned by both additive and nonadditive gene action. Degree of dominance estimates for the four wheat crosses grown at two locations differed for each cross and location. Earliness was influenced by one to six genes while winterhardiness appeared to be controlled by two genes. The estimation of genetic advance indicated that the crosses with high narrow sense heritability estimates and high phenotypic variance in F2 generation would result in greater gains under selection for both traits. Based on the results of this study, it seems that Moro is a proper site to select for winterhardiness and Corvallis for earliness. However, it might be better to select for both traits at the same time at another site such as Pendleton, Oregon, where a realistic selection pressure can be applied for winter survival and drought would not influence the selection procedure. Such a site could also provide an opportunity to evaluate earliness at the same time. Correlation coefficient estimates showed the presence of a positive association between earliness and winterhardiness. The possibility of using leaf damage readings to measure the winterhardiness levels in wheat populations also appears promising.
Author: Publisher: ISBN: Category : Agriculture Languages : en Pages : 712
Book Description
Sept.-Oct. issue includes list of theses and dissertations for U.S. and Canadian graduate degrees granted in crop science, soil science, and agronomic science during the previous academic year.
Author: Abderrazak Daaloul
Author: Abderrazak Daaloul
Author: Abderrazak Daaloul
Author: Oregon State University
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Author: Karen Sue Schumaker
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Author: Kamil Yakar
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