在0.5％NaCl盐胁迫下,适当增加外界Ca~(2+)浓度,可显著降低水稻体内Na~+含量,减少Na~+由根向地上部的净运输率,并提高植株相对生长率。但Ca~(2+)作用大小受介质中Na~+与Ca~(2+)两者之比值的制约,最适Na/Ca比值为20和50。Ca~(2+)的减少（即Na/Ca比值=1000）或过多（即Na/Ca比值=5）都导致了水稻盐害进一步加剧。钙还可以明显降低叶片和根系的质膜透性,并提高根质膜ATPase的活性。推测,Ca~（2+）对水稻耐盐性的提高很可能是通过保护细胞膜结构和功能的完整性来实现的。 Under the condition of 0.5% NaCl stress, increasing Ca 2+ concentration in the external environment could significantly decrease Na + content in rice, decrease net transport rate of Na + from root to shoot and increase relative growth rate of plants. However, the size of Ca2 + is restricted by the ratio of Na ~ + and Ca ~ (2+) in the medium, and the optimum Na / Ca ratios are 20 and 50. The reduction of Ca 2+ (ie Na / Ca ratio = 1000) or excess (ie Na / Ca ratio = 5) all contributed to further aggravating salt damage in rice. Calcium could also significantly reduce the plasma membrane permeability of the leaves and roots and increase the ATPase activity of the root plasma membrane. It is speculated that the enhancement of salt tolerance by Ca 2+ may be achieved by protecting the integrity of cell membrane structure and function.