Evaluation of relationship between physiological and agronomic traits related to salinity tolerance in bread wheat (Triticum aestivum L.) genotypes

Effects of salinity on morpho-physiological traits of twenty-five hexaploid wheat genotypes (landraces, commercial cultivars, promising breeding lines, and Arg, Bam, Ofogh and Sistan as checks), were studied. Bread wheat genotypes were evaluated in randomized complete block design with three replications in each of the environmental conditions (saline and non-saline conditions) at the research filed station of Birjand, Iran in 2012-2014 cropping seasons. Combined analysis variance revealed significant differences among grnotypes for the studied traits. In saline condition, the maximum grain yield (5517, 5322, 5317 kg.ha-1) obtained in genotypes No. 25, 22 and 20, respectively and in non saline condition the maximum grain yield (7869, 7728 and 7706 kg.ha-1) obtained in genotypes No. 1 (Sistan), 20 an 25, respectively. Results showed salinity led to decreased Kﳖ ratio of flag leaf, grain yield, biological yield, flag leaf area, length of penultimate, length of peduncle, plant height and increased Na content of flag leaf and canopy temperature as compared with non-stress condintion. In saline condition, grain yield was significantly and positively correlated with grain yield in non-stress, biological yield (BY), Kﳖ ratio, chlorophyll content (SPAD), relative water content (RWC), harvest index (HI), length of spike, length of peduncle, thousand grain weight (TGW), while it was negatively correlated with Na content of flag leaf. Stepwise regression analysis in saline condition showed BY, HI, Kﳖ ratio, Na content of flag leaf, length of spike and width of flag leaf justified the majority of grain yield variation and can be used for indirect selection of grain yield. Factors analysis identified five factors which explained 80.46% of the total variation. On the basis of these results, it is concluded that criteria such as BY, HI, Kﳖ ratio, Na content of flag leaf, length of spike, chlorophyll content, RWC and TGW could be considered as effective criteria for selecting to improve grain yield in the national wheat breeding programs for tolerance to salinity stress. Genotypes No. 25, 22, 20, 21, 24, 13 and 23 were determined as more tolerant genotypes even more than check cultivars. These genotypes have salt tolerant parents shuch as: Karchia, Sakha8 and 1-66-22 in their pedigrees.