钙对盐胁迫下棉苗离子吸收分配的影响

研究了钙对NaCl胁迫下棉花幼苗体内离子分布的影响及其与根系质膜H+-ATP酶、液泡膜H+-ATP酶和H+-PP酶活性的关系。不同器官离子含量和根系横切面X-射线微区分析结果表明,NaCl胁迫下外源钙明显减少棉花幼苗对Na+的吸收及其向茎杆、叶片的运输，增加对K+和Ca2+的吸收及其向茎杆、叶片的运输，增强棉苗体内的盐分区域化分配，提高根冠比和干物质积累，根系电解质渗漏率下降。钙明显提高盐胁迫下幼根细胞质膜H+-ATP酶、液泡膜H+-ATP酶和H+-PP酶的活性,与钙调节棉花对离子的吸收、分配相一致，说明这些酶可以为根细胞中的Na+在液泡中积累以及K+、Ca2+的选择性吸收和运输提供动力。

Effects of Ca~(2 ) on Absorption and Distribution of Ions in Salt-treated Cotton Seedlings

Regulation of calcium on ion distribution in NaCl treated cotton seedlings and relation between such regulation and H ATPase activities in plasma membrane and tonoplast and H pyrophosphatase activity in tonoplasts isolated from the young cotton roots were studied. The results of ion contents in different organs(Table 2) and X ray microanalysis(Figs.1 and 2) indicated that addition of supplemental Ca 2 to the medium decreased Na absorption and transport to the shoots and leaves, increased K and Ca 2 absorption and transport, enhanced salt regionalisation in body, increased root/shoot ratio and accumulation of dry matter(Table 1), accelerated growth in NaCl treated cotton seedlings. It is in consistent with the results that Ca 2 regulates ion absorption and distribution via its enhancement of these H ATPase and H pyrophosphatase activities(Fig.3). It suggests that these enzymes may provide driving force for accumulating of Na in the vacuoles of roots and the selective absorption and distribution of K ,Ca 2 .