کنترل ژنتیکی تحمل به شوری در گندم با استفاده از تجزیه میانگین و واریانس نسل‌ها

Inheritance of physiologicaly related salt tolerance traits including Na+ and K+ contents, K+/Na+ ratio of young leaves and biological yield (BY) in six basic generations (P1, P2, F1, F2, Bc1 and Bc2) and their reciprocal crosses derived from crosses between Kharchia × Niknejad and Shorawaki × Niknejad were studied in sand culture under high salinity treatment (EC = 22.5 dS m-1). Generation means analysis indicated that a simple genetic model (including additive and dominance effects) is sufficient for Na+ and BY in Kharchia × Niknejad cross and for Na+, K+/Na+ ratio and BY in Shorawaki × Niknejad cross but, for other traits digenic interactions (additive × additive and dominance × dominance) were important parameters in the expression of salt tolerance of the various generations. Dominance genetic effects were predominant genetic components in most of the models. Weighted generation variances analysis suggested that dominance variance component was more important for Na+ and K+ content in both crosses. This result was confirmed by significant differences between back cross generations. Results also showed negligible dominance for K+/Na+ ratio in both crosses, multidirectional dominance for BY in Kharchia × Niknejad cross and absence of dominance gene action in Shorawaki × Niknejad. Kharchia × Niknejad cross showed, in general, more genetic variation, broad-and narrow sense heritabilities than Shorawaki × Niknejad cross, indicating the important role of primary differences between parents. These results revealed that recurrent selection followed by pedigree breeding or a selective diallel mating system may prove useful in improving salinity tolerance of wheat plants. The involvement of dominance × dominance interactions for some traits indicates that it is necessary to postpone selection for salt tolerance of wheat to advanced generations, when sufficient epistatic interactions have become fixed.