Morphological Screening of Rice Genotypes for Salinity Tolerance at Seedling Stage.

Rice is one of the most important food crops in the world, consumed by more than 3 billion people. Salinity is an important stress factor in the rice growing areas and rice is very sensitive to salt stress particularly at early vegetative stages causing yield reductions. The objectives of this study were to determine the effect of different salt concentrations at seedling stage. 74 rice genotypes with varied stress tolerance were grown in PVC pots, filled with sandy soil and irrigated through an automated computer controlled drip system. The treatments imposed included control, medium salt stress (EC 6 dS m^-1) and high salt stress (EC 12 dS m^-1). The results showed significant decrease in most of the traits like shoots, roots and physiological growth with increasing salt stress. The 12 dSm-1EC caused the highest decline of shoot and root growth. The CSRI varied between 12 and 25.5 among the genotypes tested. Based on CSRI and standard deviation values, genotypes were classified in different categories with varying salt stress responses. Most of the genotypes (56%) showed moderate response to salt stress. 12 genotypes were classified as salt sensitive with IR85, PH127 and IR86 as least salt tolerant respectively. 14 genotypes were classified as salt tolerant with Nona Bokra, CT182, IRRI 154 and FED473 as high salt tolerant genotypes respectively. Root traits were found more important in studying and identifying salt tolerant genotypes during the seedling establishment stages in rice. The genotypes identified as salt tolerant based on morphological parameters, further need to be confirmed by molecular analysis and can be used as a valuable resource in rice breeding programs to develop new genotypes best suited for salt stress conditions.