JWSS - Journal of Water and Soil Science

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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.

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To evaluate effects of different salinity levels on activity of antioxidant enzymes (CAT, APX and GPX) and osmotic components (carbohydrate and proline) in two sorghum genotypes, an experiment was conducted as completely randomized factorial design with three replications in Zabol university in 2007. Three levels of salinity control (0), 100 and 200 mM NaCl and two sorghum genotypes (Payam and Sistan) were compared. Results showed that by increasing salinity levels from 0 to 200 mM NaCl, the activities of these three antioxidant enzymes were significantly increased and the highest level of activity was observed in 200 mM salinity. Payam cultivar had the highest level of APX and GPX enzyme activity in these experiments. salinity significantly changed two osmotic adjustment concentrations (Carbohydrate and proline) and increased their concentrations. The highest proline and carbohydrate were showN in Sistan and Payam, respectively. In this study we found positive correlation between osmotic components and antioxidant enzyme activity. The results showed that in these two sorghum cultivars the two mechanisms help with salinity tolerance. A direct relationship between activity of the antioxidant- enzymes and accumulation of osmotic regulators (carbohydrate and proline) was observed. In Payam genotype, as the activity of the enzymes and accumulation of osmotic regulators increased, the weight of the plants decreased. The decrease in weight could mean some of plant energy is allocated to the production of antioxidant enzymes and osmotic regulators.