Mass screening for salinity tolerance in rice (Oryza sativa. L) genotypes at early seedling stage by hydroponics

Salinity is a major abiotic factor that affects rice cultivation in the world along the coastal areas. The salt affected areas in India is estimated to be around 8 to 10 million hectares that causes significant reduction in rice growth and yield. In order to improve the rice cultivars for salt tolerance, selection of the suitable genotypes is necessitated. Hence, in this experiment ninety seven rice genotypes including traditional landraces were collected and subjected to screening under salt stress by hydroponics system on Yoshida nutrient solution of EC 8 dSm-1and 12 dSm-1 with 4 replications. The genotypes were scored on 15th day after sowing based on standard evaluation scoring system of IRRI. Among the 97 rice genotypes scored, 5% were tolerant, 21% were moderately tolerant, 54% genotypes were susceptible and 18% were highly susceptible. The rice genotypes viz., Pokkali, FL478, Kuliyadichan, Gurukot and IR12L-107 revealed significant level of tolerance to salt stress. The rice genotypes, Pokkali and FL478 showed no symptoms at 8 dSm-1 and leaf rolling alone at 12dSm-1. Kuliyadichan, Gurukot and IR12L-107 showed leaf rolling at 8dSm-1 and leaf rolling and leaf tip burning at 12dSm-1. Screening of the rice genotypes for salinity tolerance only by visual symptoms is not reliable and hence the selected rice genotypes will further be characterized based on the morphological and biochemical parameters under salt stress in order to select elite salt tolerant rice genotypes for use in developing salinity tolerant somaclones by in vitro culture.