Difference in physiological and biochemical responses to salt stress between Tibetan wild and cultivated barleys

Soil salinity is one of the major abiotic stresses affecting crop growth and yield worldwide. Barley is a species with higher salt tolerance among cereal plants and rich in genetic variation. It is quite important to understand the physiological mechanisms of genotypic difference in salt tolerance. In this study, physiological and biochemical responses of a Tibetan wild barley genotype XZ16 (salt tolerant) and a cultivated cultivar Yerong (salt sensitive) to salt stress were investigated. The results showed that the two genotypes differed dramatically in their responses to salt stress (150 and 300 mM NaCl) in terms of plant biomass, Na⁺ accumulation and Na⁺/K⁺ ratio in roots and shoots, chlorophyll content, xylem sap osmolarity and electrolyte leakage. XZ16 showed less biomass reduction, lower Na⁺/K⁺ ratio and electrolyte leakage, higher xylem sap osmolarity, and vacuolar H⁺-ATPase and H⁺-PPase activities than Yerong under 300 mM NaCl. The higher salt tolerance of XZ16 may be attributed to its lower concentration of Na⁺ influx or more sequestration into the vacuoles. The results indicate that the Tibetan wild barley is useful for improvement of cultivated barley in salt stress tolerance.