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 applicatio n of in vitro Photosystem II (PS-II) activity measurements to screen hexapl oid wheat (Triticum aestivum, L.) genotypes for NaCl tolerance has been inv estigated by comparing their responses under stress and control (no added N aCl) conditions. One of the four cultivars used in the study was 'Kharchia' known for its high salt tolerance. Wheat seedlings were grown hydroponical ly in environmental chambers and treated with a range of NaCl concentration s (0.034 M, 0.17 M, 0.68 M, or 3.42 M) over a 1, 3, and 5-day period. The s alt treatments were started in the appropriate time so that they were all t en-day-old during harvest. Cellular membrane stability (CMS) as measured by a conductivity method and PS-LT. activity values were affected adversely b y NaCl concentration and duration of treatment. Both methods clearly distin guish between salt-sensitive and salt-tolerant genotypes. Statistical analy sis 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 scree ning method besides CMS to evaluate salt tolerance of wheat.