Assessment of different wheat genotypes with altered genetic background in response to different salinity levels

This experiment was conducted in a glasshouse at the Agricultural and Natural Resources Research Center of Zarghan, Iran, in 2016. Sixteen wheat genotypes were compared under four salinity levels [control, 50, 100, and 150 mM sodium chloride (NaCl)] in terms of grain yield, chlorophyll (SPAD), flag leaf area, Na⁺/K⁺ ratio, catalase, and peroxidase activities in a randomized complete block design with three replications. Overall, results indicated that apparently no single parameter or a specific group of parameters could be suggested as factors of the most responsive element to different salinity stress levels. In other words, the tolerance mechanism of wheat genotypes is a complex response of multiple factors as a network path. Furthermore, different salinity levels led to different responses of wheat genotypes, which were detectable by the results of the mean comparison and analysis of variance. These results also proved the influential effects of the genetic background on salinity response and tolerance of wheat genotypes. In addition, antioxidants acting as defense barriers against reactive oxygen species are very important constituents against salinity, since higher antioxidant activity leads to alleviate the oxidative stress caused by salinity. Higher osmolyte concentration regulating the selective uptake of useful ions can prevent excess accumulation of toxic ions, which contribute to salinity stress damages. A high variation related to the measured traits in this study under both normal and salinity stress conditions was achieved, which could be applied in screening and breeding programs for salinity stress tolerance. Moreover, the responses of different genotypes varied regarding the different traits; SU-0129 as a novel genotype has proved to be the best choice for further breeding research based on the overall traits and, in particular, grain yield and tolerance stress index.