Assessment of agro-physiological traits for salt tolerance in drought-tolerant wheat genotypes

Salt stress is one of the major constraints for wheat cultivation in Iran and leads to a considerable loss in crop yield each year. In high salinity soils, the reduced osmotic potential of soil solutes may cause physiological drought. In this study the salt tolerance of different drought-tolerant bread wheat genotypes were studied by examining various agronomic and physiological traits, including Na+ and K+ concentrations, the Na+/K+ ratio in leaf and spike, shoot dry weight, leaf greenness, stomatal conductance, leaf area, osmotic potential, relative water content (RWC) and grain yield. Two pot experiments were conducted using a completely randomized design with three replications. Wheat genotypes were grown in pots and irrigated either with tap water (EC= 0.5 dSm(-1)) or saline water (EC approximate to 18 dsm(-1)) as control and salt stress treatments, respectively. Significant differences were observed in all measured traits between control and stress treatments except for the spike potassium concentration. Differences between genotypes were significant for all traits except for RWC and osmotic potential. Among the different genotypes, one drought-tolerant genotype appeared salt tolerant, three were semi-salt-tolerant, one drought-sensitive genotype appeared semi-salt-sensitive, and two drought-tolerant genotypes appeared salt-sensitive and semi-salt-sensitive. This study shows that drought tolerance does not necessarily lead to salt tolerance. Some physiological traits including Na+ content, leaf area, SPAD number, stomatal conductance and shoot dry weight, which are significantly correlated with grain yield and show remarkable variations among wheat genotypes, may be useful parameters for measuring the responses of other wheat genotypes to high-salinity soils in the field.