盐胁迫对柳树无性系SH31离子含量及光合作用的影响

以柳树无性系SH31为试材,研究了NaCl溶液半抑制浓度胁迫下根、茎、叶中Na⁺、K⁺、Ca²⁺ 的分布规律及叶片光合特性的变化。结果表明:在NaCl溶液半抑制浓度(0.6%)下,SH31耐盐性较强;在0.6% NaCl溶液胁迫下,根部在前16 d积累大量Na⁺并拦截部分Na⁺向地上部运输;盐胁迫降低了根、茎部对 K⁺ 的吸收,而叶部却保持较高的K⁺ 含量来维持离子平衡;Ca²⁺含量在根、茎、叶中与对照的相当。在NaCl溶液半抑制浓度盐胁迫下,SH31 的净光合速率前7 d降低之后保持稳定,而气孔导度、蒸腾速率、胞间CO₂先降后升,表明前7 d的蒸腾速率下降的主要原因在于气孔限制。SH31根部对Na⁺ 选择性吸收并维持K⁺、Ca²⁺的高含量及维持较高光合作用是其重要的耐盐机制。

Effect of Salt Stress on Ion Contents and Photosynthesis in Willow Clones SH31

Taking willow clones SH31 as trial material, the distribution and changes of photosynthetic characteristics of Na⁺, K⁺, Ca²⁺ in roots, stems and leaves were studied in the condition of hemi-inhibitory sodium chloride solution. The results are as follows: under the stress of 0.6% sodium chloride solution, willow clones SH31 appeared strong salt tolerance. In the condition of hemi-inhibitory sodium chloride solution, concentration of Na⁺ increased in roots during the first 16 days and part of Na⁺ was intercepted to transport to the leaves. In the condition of hemi-inhibitory sodium chloride solution, the content of K⁺ decreased in roots and stems, however it increased in leaves. It can still maintain high level K⁺ in leaves. There was no significant difference of content of Ca²⁺ in roots, stems and leaves between treatment and control. In this condition, the net photosynthetic rate of SH31 reduced during the first 7 days and then remained stable. The transpiration rate and stomatal conductance decreased during the first 7 days and then increased. However, there was no significant difference of the concentration of CO₂ between treatment and control. The root selective absorption of Na⁺ and maintaining large amount of K⁺, Ca²⁺ and high level of photosynthesis should be the important mechanism of salt tolerance in SH31.