钙提高水稻耐盐性的研究

The Study on Increasing Salt Resistance of Rice by Calcium

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。

Salt stress is the main constrains for rice production in coast low areas. This study was conducted to determine whether exogenous Ca ameliorated the harmful effects of NaCl (0.5% or 86mmol / L) on Na+, K+ contents and growth of two rice varieties, 80-85 (salt tolerant) and 83-51 (salt sensitive). The seedlings were grown in the greenhouse for 15 days and then stressed with cultural solutions containing various Na / Ca ratios. The addition of CaCl2 to NaCl solutions significantly minimized Na+ content in the plants and the rate of Na+net transport from root to shoot, and increased relative growth rate. However, K+ content wasn't significantly affected by exogenous Ca2+. Ameliorative effects of calcium varied with external Na/Ca ratios. Higher ratio (1000) and lower ratio (5) both aggravated the salinity injury. The optimum Na/Ca ratios which reduced the damage were 20 and 50. In addition, the presence of Ca2+ in low NaCl concentration (10 mmol/ L) decresed apparently the rate of Na+ uptake by rice roots. Supplemental Ca2+ in saline mediums significantly reduced membrane permeability of the roots and leaves, and enhanced plasmalemma ATPase activity of the rpots. The results suggested that Ca2+ could.protect the integration of membrane structure and function under salt stress.