盐胁迫对柳树无性系SH31离子含量及光合作用的影响

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

以柳树无性系SH31为试材,研究了Na Cl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Na Cl溶液半抑制浓度(0.6%)下,SH31耐盐性较强;在0.6%Na Cl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Na Cl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。

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 solu- tion. 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 bemi-in- hibitory 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 photosyn- thesis should he the important mechanism of salt tolerance in SH31.