Cell membrane stability and biochemical response of seven wheat cultivars under salinity stress

Wheat is one of the major crops occupying a large area in Iran where salt stress is the most limiting factor. Chlorophyll (CHL) and proline content, relative leaf water content (RLWC), Na+ and K+ ratio, and some oxidative stress indices were studied in leaves of seven wheat cultivars (Arg, Bam, Sistani, and Singh (as tolerant) and Ghods, Bahar, and Marvdasht (as sensitive)) grown under control(1.3) and two salinity treatments viz., 5 and 10 dS m(-1) two salinity treatments and control, viz., 1.3 (control), 5 and 10 dS m(-1) created by mixing calcium chloride and sodium chloride in 1: 10 ratio (Ca2+: Na+ ratio). The results indicated that there were non-significant differences between cultivar for RLWC content. Under high salinity level (10 dS m(-1)), significant increase in superoxide dismutase activity (SOD) was observed in salt-tolerant varieties, while, under salinity condition, the activity of SOD in sensitive cultivars was lower than tolerant cultivars. Membrane stability index of salinity-sensitive cultivars was lower than in the control. Salt-tolerant cultivars had higher values of K+/Na+ ratio, relative water content, proline content, and CHL content under salt stress, while sensitive ones demonstrated higher Na+ content at tillering stage. The evaluation of some physiological and biochemical characteristics at the critical growth stages of wheat may be useful for screening the salinity-tolerant genotypes.