Photosystem II and cellular membrane stability evaluation in hexaploid wheat seedlings under salt stress conditions

Salinity limits crop production in large areas of the world. The application of in vitro Photosystem II (PS-II) activity measurements to screen hexaploid wheat (Triticum aestivum, L.) genotypes for NaCl tolerance has been investigated by comparing their responses under stress and control (no added NaCl) conditions. One of the four cultivars used in the study was 'Kharchia' known for its high salt tolerance. Wheat seedlings were grown hydroponically in environmental chambers and treated with a range of NaCl concentrations (0.034 M, 0.17 M, 0.68 M, or 3.42 M) over a 1, 3, and 5-day period. The salt treatments were started in the appropriate time so that they were all ten-day-old during harvest. Cellular membrane stability (CMS) as measured by a conductivity method and PS-LT. activity values were affected adversely by NaCl concentration and duration of treatment. Both methods clearly distinguish between salt-sensitive and salt-tolerant genotypes. Statistical analysis showed that PS-II activity and CMS measurements are well correlated (r=0.7589) suggesting that PS-II activity would be used as an additional screening method besides CMS to evaluate salt tolerance of wheat.