MECHANISM OF SALT TOLERANCE IN WILD-RICE (ORYZA-COARCTATA-ROXB)

Oryza coarctata, a highly salt-resistant wild rice species, is commonly found on the banks of coastal rivers in India. This species can also withstand saline water (20 to 40 dSm-1 E.C) submergence for quite a long period. It was reveled that O. coarctata has some special unicellular salt hairs (trichomes) on the adaxial surface of the leaves, by which they efficiently maintain a low concentration of toxic salts in the plant tissue. Sodium and chloride were the dominant ions in the excreted material but they also excrete potassium, magnesium and calcium. With the increase in soil salinity sodium, magnesium and chloride excretion increased. O. coarctata maintained the optimum mineral concentration in its tissues. Maximum accumulation of potassium was observed in the leaves. With the increase in salt stress total biomass production and osmotic potential increased over control but there was no change in the moisture percentage of leaves.