Abstract: The absorption of Na⁺ and function of plasma membrane ATPase from rice roots exposed to salt stress were investigated using two varieties, 80-85 (salt-tolerant) and 83-51 (susceptible). The rice seedlings were grown in Espino culture solution containing different NaCl concentrations. Na⁺ content in the whole plants (including root and shoot) increased with increasing external NaCl concentration and prolonging the treatment. There was a apparent varietal difference in Na⁺ absortion of the root. For the salt-tolerant variety, with low total Na⁺ uptake by the root and high K⁺ / Na⁺ ratio in tha whole plant, the Na⁺ uptake rate was lower and selectivity for K⁺ uptake over Na⁺ uptake (S_K:Na) was higher at 10 mmol/l ion concentration than that of the salt susceptible variety. It was observed that low NaCl (0. 2% or 34 mmol/l) caused a slight increase in the plasma membrane ATPase activity from rice roots. However, the ATPase activity was inhibited obviously by high Na⁺ (above 0. 5% or 86 mmol/l), especially for the susceptible. The define of the enzyme activity was accompanied by accumulation of Na⁺ and decrease of K⁺ uptake in the roots. The results suggest that K⁺ and Na⁺ uptake might be controlled by the plasma membrane ATPase.

Key words: Ion selectivity, Sodium ion uptake, Plasma membrane ATPase, Salt tolerance

摘要： 以两个不同耐盐力水稻品种80-85 (耐盐) 和83-51(不耐盐)为材料进行研究。根系Na⁺总吸收随盐胁迫的加重而增高，耐盐品种始终具有较低的Na⁺总吸收和较高的整株K⁺／Na⁺比；在10 mmol／L NaCl浓度下显示出根系具有较低的Na⁺吸收速率和较强的对K⁺选择性，低盐浓度(0.2% NaCl) 对根质膜ATP酶活性略有提高；在高盐浓度(0.5% NaCl以上)下，质膜ATP酶活性受到明显抑制，而耐盐品种受抑程度更大．ATP酶活性的下降与根部Na⁺积累以及K⁺吸收的减少相伴随，推测根系K⁺、Na⁺吸收与质膜ATP酶有关

关键词: 钠吸收, 质膜ATP酶, 耐盐性