Salt Tolerance Evaluation of Rice (Oryza sativa L.) Genotypes Based on Physiological Characters Contributing to Salinity Resistance

Salt Tolerance in Rice Genotypes

Abstract

Seven newly developed rice cultivars i.e., KS-133, DR-83, DR-64, BR-601, Gomal, JP-5 and Gomal-6, were evaluated for salinity tolerance in a glasshouse along with three varieties of known salinity tolerance i.e., KS-282 (tolerant), IR-6 (medium tolerant) and Basmati-385 (susceptible). Based on the survival percentage at 50 mol/m3 sodium chloride salinity imposed at seedling stage, rice cultivars KS-133, Gomal, and DR-83 showed high survival comparable to that of salinity tolerant cultivars like KS-282, and were thus placed in tolerance range. Survival percent- age of JP-5, Gomal-6 and DR-64 remained in medium tolerance range (35 to 38%) as that of IR-6. The rice cultivar BR-601 showed only 13% survival and was found to be as sensitive towards salinity as Basmati-385. The results of rice survival in saline medium showed good uniformity and the check varieties showed results corresponding to those found elsewhere. Sodium (Na+) and potassium (K+) concentrations in the third leaf showed variations among different rice cultivars under salinity. There was an inverse correlation between varietal leaf Na+ vs survival percentage (r = -0.808) and Na+ vs leaf chlorophyll (r = -0.857). The correlation between K+ and final survival percentage was direct (r = 0.744) and also leaf chlorophyll vs survival (r = 0.952). The shoot fresh and dry weights were greater in the rice genotypes having higher final survival percentage under saline conditions. Therefore, in addition to final survival percentage, the higher shoot fresh and dry weight under salinity could be also used as criterion for evaluation of salinity tolerance of rice.