SALT STRESS TOLERANCE POTENTIAL OF SELECTED RICE CULTIVARS OF PAKISTAN

Ten local rice varieties (Sarshar, Pakhal, Sada Hayat, Jajai-77, NIR-9, RI-DR-92, JP-5, Shaheen Basmati, Shadab-31 and TN-1) were evaluated for salinity stress (0, 50, 75 and 100 mM of NaCl) tolerance at seedling stage, in Completely Randomized Design (CRD). On an average the root length, shoot length and the relative growth rate of all rice varieties decreased linearly with increased levels of salinity. Based on the individual results of all the parameters studied, Pakhal was found to be the most salt tolerant variety. The germination rate of the varieties RI-DR-92 and TN-1 was better at higher levels of salinity (75 and 100 mM NaCl) among all the tested varieties. While, considerable reduction in germination rate was recorded for Jajai-77. The varieties RI-DR-92 and TN-1 that were more affected showing more reduction in shoot length (4.2 cm and 4.4 cm), root length (2.9 and 3.2 cm) and relative growth rate (0.22 and 0.14 g/gday), grown at 75 and 100 mM NaCl respectively. The variety Pakhal showed less reduction in shoot length (1.5 and 2.7 cm), root length (0.95 and 1.0 cm) and relative growth rate (0.073 and 0.075 g/gday), grown at 75 and 100 mM NaCl, respectively as compared to control. However, according to Stress Susceptibility Index (SSI), TN-1 was observed to be the most tolerant and Jajai-77 was the most susceptible variety to salt stress. The most tolerant rice varieties differentiated in the current study could be used to produce higher yields under saline conditions.