SALT TOLERANCE POTENTIAL OF UPLAND AND LOWLAND RICE IN PHYSIOLOGICAL PERSPECTIVES

Studies were conducted to evaluate upland (UR) and lowland (LR) types of rice for their salt tolerance potential at early seedling stage under controlled laboratory conditions. The treatment of salinity (100 mM NaCl) along with non saline control was imposed for the period of two weeks. Shoot and root growth of all genotypes reduced with varying intensity under salinity. All UR types were more sensitive except UR-74 and UR-60 and exhibited comparatively less reduction in growth. These studies have revealed significant differential responses of UR and LR at physiological level. LR types of rice were remarkably different from UR types in their shoot sodium concentrations. LR types have exhibited comparatively low concentration of sodium and also found distinctly different in their proline production. Tolerant LR types have exhibited less relative increase in Na and better K: Na ratio in their shoot. Significant positive correlation (r = 0.93) was observed between sodium and proline concentrations in shoot. While, significant negative correlation (r = -0.84) was observed between sodium and potassium sodium ratios in shoot. Tolerant varieties of both types of rice exhibited more sucrose and total soluble sugars under salinity stress indicating its protective role. These findings suggest that LR types of rice have better capability for selective uptake and osmotic adjustment in comparison to UR types under salinity stress.