罗布麻对不同浓度盐胁迫的生理响应

利用网室盆栽实验,研究不同浓度的NaCl（100-400mmol·L^-1）胁迫对罗布麻（Apocynum venetum）生长及生理特性的影响。结果表明,100mmol·L^-1NaCl处理显著降低了罗布麻植株的鲜重,但对其干重影响不大;随着盐浓度继续增加,罗布麻鲜重和干重显著下降。在盐胁迫下,罗布麻叶片内的丙二醛含量、电解质渗漏率、根部和地上部Na^＋的含量明显增加,K^＋的含量随着盐离子浓度的增加而降低。盐胁迫显著降低了地上部Ca^2＋的含量,而对根部Ca^2＋的含量没有影响。植株K^＋/Na^＋和Ca^2＋/Na^＋比值随着盐胁迫强度的增加而降低。盐胁迫显著促进了罗布麻根部对K^＋和Ca^2＋的选择性吸收及对K^＋的选择性运输。当NaCl浓度小于或等于200mmol·L^-1时,随着盐离子浓度的增加,罗布麻叶片内的脯氨酸和可溶性糖积累显著增加,而当NaCl浓度大于200mmol·L^-1时,这2种有机溶质含量显著下降。总体上,罗布麻通过积累无机离子、合成有机溶质及维持较高的K^＋、Ca^2＋选择性吸收和运输来适应一定浓度（≤200mmol·L^-1NaCl）的盐胁迫。

Physiological Responses of Apocynum venetum to Different Levels of Salt Stress

To understand the responses of Apocynum venetum to various levels of salt stress, we conducted the experiment. The pot experiments were in a net room to study the effects of NaCl at different concentrations （100-400 mmol·L^-1） on plant growth and several physiological characteristics of A. venetum. An amount of 100 mmol·L^-1 NaCl reduced the plant fresh weight significantly but did not affect plant dry weight. The fresh weight and dry weight of A. venetum decreased with increasing NaCI concentrations. Leaf malondialdehyde content, electrolyte leakage percentage and Na^＋ content in root and shoot were all elevated. K^＋ content in root and shoot and Ca^2＋ content in shoot decreased significantly. However, Ca2＋ content in roots grown under all NaCI stresses was unaffected. Ratios of K^＋/Na^＋ and Ca^2＋/Na^＋ in plant decreased with increasing NaCI concentration. Salt stress markedly promoted the selective absorption of K^＋ and Ca^2＋ in root and selective transportation of K^＋. Contents of proline and soluble sugar increased with increasing NaCI concentration （≤200 mmoI·L^-1NaCl）. Nevertheless, contents of proline and soluble sugar gradually decreased with stresses increasing （〉200 mmol·L^-1NaCl）. In general, adaptation to salinity （≤200 mmol· L^-1 NaCl） in A. venetum was mainly caused by inorganic ion accumulation, organic solute synthesis, strong K^＋, Ca^2＋ selective absorption and transportation.