Investigation of the Salt Tolerance of Wheat Genotypes: Changes in Antioxidants, Total Protein, K+/Na+ Ions and Grain Yield

Salt stress causes huge losses of agricultural productivity worldwide, negatively affects soil properties and limits plants growth. In the present study, response of 11 wheat (Triticum aestivum) landrace varieties, 2 commercial cultivars and 2 promising lines to three levels of salinity (EC= 7, 14 and 21 dS m-1) was assessed based on variations in grain yield, antioxidants, and Na+ and K+ ions. Pots were daily weighed and irrigation with saline solution (1:1 ratio of NaCl and CaCl2 salts) was performed based on field capacity (FC) 50 days after sowing at the four-leaf stage of growth. Results of linear regression showed that K+/Na+ ratio had strong direct relation (R2=0.98) in root and leaf. Correlation between grain yield in control and salinized conditions was supported by positive regression coefficient (b=0.853) in regression equation (R2=0.65). This correlation showed that superior genotypes in control condition produced higher grain yield under salinized conditions. Enzymatic antioxidants (superoxide dismutase, SOD and peroxides, POD) and total protein content were increased as the level of salinity increased from EC= 7 to EC=21 dS m-1. K+/Na+ ratio in the leaf and grain yield were reduced as the level of salinity increased. Overall, results showed that great variations was existed between genotypes for three types of traits and selections can be made using a weighted index defined based on changes in antioxidants, protein, ions and grain yield.