توصيفگر ها :
گندم نان , تنش شوري , تنش خشكي , مطالعه ژنتيكي , وراثت پذيري , كيفيت دانه
چكيده انگليسي :
Drought and salinity stress are the major environmental challenges negatively impacting crop growth and production via various morpho-phenological, physiological and grain quality characteristics. In current study, a salt tolerant (‘Barat’) and a salt-sensitive (‘Nogal’) wheat cultivar were crossed to produce the following filial and backcross progenies: F1, F2, F3, BC1, and BC2, which planted in normal and stress conditions (drought stress and salinity stress) using a randomized complete block design with three replicates for each of the conditions. In genetic studies, scaling tests did not support the three-parameter model (additive-dominance model). Hence, a six-parameter model was used to estimate the genetic effects for the studied traits in this study. In the first study, the genetic study of salinity tolerance in bread wheat under field conditions was evaluated. The combined analysis of variance (ANOVA) revealed that stress, generation and the interaction of stress × generation were significant for all the quantitative traits. Epistasis as well as additive and dominance gene actions were recorded to be significant for plant height, number of days to pollination, flag leaf area, chlorophyll index and K/Na ratio under salinity stress. The highest narrow heritability was observed for days to heading, peduncle length, number of spikes per plant, flag leaf area, K/Na ratio, total chlorophyll content, carotenoid content under salinity stress. In the second study, the genetics of salinity tolerance was investigated under greenhouse conditions. The combined ANOVA revealed that stress, generation and the interaction of stress × generation were significant for all the quantitative variables. The additive, dominance, and epistasis gene actions were found to be significant for the inheritance of shoot dry weight, plant height, fresh and dry weight of roots, root volume, chlorophyll index, proline content and membrane lipid peroxidation under salinity stress. In the third study, the genetics of end-of-season drought tolerance was investigated under field conditions. The combined ANOVA revealed that generation was significant for all the quantitative traits. The interaction of stress × generation was significant for all the traits except for the number of spikes per plant, number of grains per spike, plant height, carotenoid content and relative water content of the leaves. The gene actions of epistasis and additive dominance were found important for plant height, number of days to maturity, peduncle length, 100-grain weight, number of spikes per plant, relative leaf water content, chlorophyll index, proline content and total chlorophyll content under terminal drought stress. The highest narrow heritability was observed for plant height, days to maturity, peduncle length, flag leaf area and carotenoid content under terminal drought stress conditions. In the fourth study, the inheritance of drought tolerance was investigated under greenhouse conditions. The combined ANOVA revealed the significant effects of stress, generation and the interaction of stress × generation in all the traits. The gene actions of epistasis, additive, and dominance were shown important in governing all the traits except flag leaf area, relative leaf water content, membrane lipid peroxidation and hydrogen peroxide under drought stress condition.
