Investigation Of Differences In Salt Tolerance Mechanisms In Contrasting Bread Wheat Genotypes

Abstract

The genotypic differences regarding Na+ accumulation and transport in plant along with physiological response to improve salt tolerance were studied in bread wheat genotypes.Four wheat genotypes; Kharchia-65, SARC-3, S-9476 and S-8189 were grown under salt stress (75 and 150 mM NaCl) in nutrient solution with five replications. Shoot dry weight, relative growth rate (RGR), chlorophyll index, leaf water relations, Na+ content and transport in plant were measured.The increase in NaCl stress decreased all growth parameters, however, variations were observed among genotypes. Kharchia-65, S-9476 and SARC-3 had better growth and water relations compared to salt sensitive genotypes S-8189. The low rate of Na+ transport and better ability to restrict Na+ in the root was main reason of genetic variation among different genotypes, especially, when growth characteristic did not vary significantly under salt stress. Na+ partition was also recorded in wheat genotypes as salt sensitive genotypes had higher Na+ accumulation in shoot while it was reverse in tolerant ones. The differences in root Na+ were not significant among all genotypes. In many crop plants, over-accumulation of Na+ in shoot is the main cause of yield reduction due to toxicity. In this study, wheat genotypes differed mainly because of low rates of Na+ uptake and transport from root to shoot. Therefore, in this study, it was concluded that wheat genotypes with contrasting leaf Na+ uptake rates and transport from root to shoot had resulted in differences in salinity tolerance. The wheat genotypes having ability to reduce Na+ accumulation in shoot by retaining it at root level had better salt tolerance. The genotypes with the highest Na+ uptake had lower chlorophyll, more electrolyte leakage, and a slightly lower RGR.