Differential response of wheat genotypes to long term salinity stress in relation to oxidative stress, antioxidant activity and osmolyte concentration

Effect of long term soil salinity was studied in wheat cvs, Kharchia 65 (tolerant) and KRL 19 (moderately tolerant) under control and two levels of salinity (ECe=5.4 and 10.6 dS m−1). Salinity stress decreased relative water content (RWC), chlorophyll (CHL), carotenoids (CAR), membrane stability index (MSI), biomass and grain yield, and increased hydrogen peroxide (H2O2), thiobarbituric acid reactive substances (TBARS), proline, glycine-betaine (GB), soluble sugars, superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) activity in both the genotypes and at all the stages. Salinity induced decrease in RWC, CHL, CAR, MSI, biomass and grain yield were significantly higher in KRL 19 than more tolerant Kharchia 65. Kharchia 65 recorded higher activity of SOD, CAT, GR, as well as contents of proline, soluble sugar, GB and K, and comparatively lower H2O2 and TBARS contents compared with KRL 19. KRL 19 also showed higher Na and Na/K ratio. Results show that salinity tolerance of Kharchia 65 as manifested by lower decrease in biomass and grain yield is associated with higher antioxidant activity, osmolyte concentration and potassium contents, and lower H2O2, TBARS and sodium contents than KRL 19.