Abstract: This study was conducted to determine effect of external K⁺ on rice salt tolerances under NaCl (0.5% or 86 mmol/L) stress. The rice seedlings were grown in the greenhouse for 15 days and then stressed with cultural solutions containing Na/K ratios of 5, 10, 50, 100, 369, and 0.5% KCl. The dry weight was decreased more under 0.5% KCl than under 0.5% NaCl. The addition of KCl to 0.5% NaCl solutions significantly minimized Na⁺ content in the plants, the total amount of (Na⁺+K⁺) in the shoots, as well as the net rate of Na⁺ transport from root to shoot, and increased K⁺ in saline mediums significantly reduced membrane premeability of the roots and leaves, and enhanced plasmalemma ATPase activity of the roots. The results indicated that high external K⁺ level can improve salt tolerance of rice seedling. However, ameliorative effects of potassium were related with external Na/K ratio. Lower ratio aggravated the salinity injury. The optimum Na/K ratios which enhance s4lt tolerance were 10 and 50.

Key words: Rice seedling, Salt tolerance, Potassium

关键词: 水稻, 耐盐性, 钾