Effect of NaCl salinity on photosynthetic rate, transpiration rate, and oxidative stress tolerance in contrasting wheat genotypes

Wheat (Triticum aestivium L.) genotypes K-65 (salt tolerant) and HD 2329 (salt sensitive) were grown in pots under natural conditions and irrigated with NaCl Solutions of electrical conductivity (ECe) 4.0, 6.0, and 8.0 dS m(-1). Control plants were irrigated Without saline water. Observations were made on the top most fully expanded leaf at tillering, anthesis, and grain Filling stages. The net photosynthetic rate (P-N), stomatal conductance (g(s)), and transpiration rate (E) were reduced with the addition of NaCl. The reduction was higher in HD 2329 than in K-65. Salinity enhanced leaf to air temperature gradient (AT) in both the genotypes. NaCl increased the activities of superoxide dismutase (SOD) and peroxidase (POX); the percent increment was higher in K-65. The sodium and potassium contents were higher in the roots and leaves of K-65 over HD 2329. Thus at cellular level K-65 has imparted salt tolerance by manipulating P-N, E, g(s), and K accumulation in leaves along with overproduction of antioxidative enzyme activities (SOD and POX).