Accumulation of free amino acids and distribution of Na⁺, Cl⁻ and K⁺ in rice varieties exposed to NaCl stress

The effect of 100 mM NaCl concentration in the nutrient solution on length, dry matter production and levels of Na⁺, Cl⁻, K⁺ and free amino acids in shoots and roots of five rice varieties was studied in a hydroponic experiment. The CSC 1 and CSC 2 avoided the Na⁺ toxicity by maintaining the high level of K⁺. TKM 4, TKM 9 and CO 43 appear less able to maintain a basal K⁺ level in the presence of Na⁺, Varieties TKM 9 and CO 43 accumulated high levels of sodium and exhibited less reduction of vegetative growth and efficient mechanism of maintaining high levels of free proline and protein-bound proline in their shoots and roots under saline conditions.