盐胁迫对桑树幼苗生长、叶片水分状况和离子分布的影响

以黑龙江省两个桑树品种（秋雨桑和泰来桑）为试验材料,研究了不同盐浓度下桑树幼苗生长、叶片水分关系和不同器官中离子的分布.结果表明：盐胁迫明显降低了桑树幼苗的植株高度和每株干物质量,且对新生叶片干质量的影响大于老叶片.随着盐胁迫的加重,两个品种桑树的叶片水势、渗透势、压力势和相对含水量明显下降,根、茎中Na⁺浓度明显增加,当外界NaCl浓度达到或超过150 mmol·L^-1时,各器官中Na⁺浓度达到饱和.盐胁迫明显降低了两个品种桑树根、茎和叶片中K⁺ 和 Ca²⁺浓度,以及茎和叶片中Mg²⁺浓度，而对根中Mg²⁺浓度影响不大.Na⁺在根、茎和老叶中的区域化分布是两个品种桑树生长过程中表现出耐盐性的机理之一,而盐胁迫使叶片中的Ca²⁺、K⁺和Mg²⁺浓度降低，导致植株体内的离子亏缺,从而限制了植株的生长.

Effects of salt stress on mulberry seedlings growth, leaf water status, and ion distribution in various organs.

Taking the seedlings of mulberry (Morus alba) varieties Qiuyu and Tailai from Heilongjiang Province as test materials, this paper studied their growth, leaf water relations, and ion distribution in various organs under the stress of different salt concentration. The results showed that salt stress decreased the plant height and dry mass of the seedlings obviously, and the dry mass of young leaves was more affected than that of old leaves. With increasing salt stress, leaf water potential, osmotic potential, pressure potential, and relative water content decreased markedly, while the Na+ concentration in root and stem had an obvious increase. When the soil NaCl concentration was 150 mmol·L-1 or higher, the Na+ concentration in leaf, stem, and root reached saturated. Salt stress markedly decreased the K+ and Ca2+ concentrations in leaf, stem, and root as well as the Mg2+ concentration in leaf and stem, but had lesser effects on the Mg2+ concentration in root. The decrease of leaf Ca2+, K+, and Mg2+ concentrations under salt stress caused the ion deficiency in plant and limited plant growth, while the regionalized distribution of Na+ in root, stem, and older leaf could be one of the salt tolerance mechanisms of test varieties.