The response of sweet sorghum cultivars to salt stress and accumulation of Na+, Cl- and K+ ions in relation to salinity

Tolerance to high salinity concentrations in sorghum seems to be related to the genotype ability to avoid accumulation of harmful levels of Na+ and Cl- and to maintain adequate levels of K+ especially in shoot. In this study, the effect of salt stress (0, -0.4, -0.8, -1.2, -1.6 and -2 Mpa) on seed germination, seedling growth and Na+, K+, and Cl- concentrations of 18 sweet sorghum cultivars were evaluated. The results showed that Roce, Sumac and IS6973 cultivars had better tolerance to salt stress than other cultivars at germination stage. However, SSV84 had the highest germination percentage up to -1.6 MPa and at seedling growth stage it had the highest biomass than other cultivars. Therefore, it seems that among sweet sorghum cultivars, SSV84 was the most salt tolerant cultivar and it is suggested to be planted in salinity affected agricultural lands. In addition, IS6973 showed the highest seed germination and moderate seedling growth stage and was classified as moderate salt tolerant cultivar. Na+ and Cl- concentrations increased in shoots and roots especially in salt sensitive cultivars. Also, K+ concentration increased in salt tolerant cultivars while decreased in salt sensitive ones. Since K+/Na+ ratio concentration increased in salt tolerant cultivars and decreased in salt sensitive ones, it seems that this ratio among other parameters is a better indicator for selection of salt tolerant cultivars.