NaCl胁迫对侧柏幼苗生长及矿质离子吸收和分配的影响

Effects of NaCl stress on growth and mineral ions absorption and distribution of Platycladus orientalis seedlings

【目的】探讨侧柏幼苗对盐生环境的适应性及耐盐机制。【方法】以当年生侧柏幼苗为材料,通过温室土培模拟盐分不同梯度胁迫试验,研究不同浓度(0,100,200mmol/L)NaCl胁迫对侧柏幼苗生物量积累及其不同器官(根、茎、叶)K^+、Na^+、Ca^(2+)、Mg^(2+)吸收、运输与分配的影响。【结果】(1)盐胁迫不同程度地促进了侧柏幼苗根系生长,但显著抑制了幼苗生物量的积累。(2)随着NaCl浓度的升高,侧柏幼苗各器官中Na^+含量增加,且Na^+含量在不同浓度盐胁迫下具有相同的分配规律,即根>叶>茎;随着Na^+含量的升高,各器官中K+含量显著减少,Ca2+含量在根和叶中显著升高。(3)各器官中K^+/Na^+、Ca2+/Na+和Mg2+/Na+总体随NaCl胁迫浓度的升高呈下降趋势,叶片和茎部离子比值始终高于根部。(4)随着NaCl胁迫浓度的增加,根部到茎部的离子选择性运输系数SK,Na、SCa,Na、SMg,Na逐渐降低;而茎部到叶部的SK,Na、SCa,Na、SMg,Na在低浓度盐胁迫时显著升高,在高浓度盐胁迫下受到抑制。【结论】侧柏幼苗对NaCl胁迫具有一定的耐受性,这与根系对Na+的聚积和限制作用以及低浓度盐胁迫下地上部对K+、Ca2+、Mg2+选择性运输能力的提高有关。

【Objective】This study aimed to understand the growth adaptability and salt tolerance mechanism of Platycladus orientalis seedlings under NaCl stress.【Method】A potting experiment was conducted in a greenhouse to study the biomass accumulation as well as absorption,transportation and allocation of mineral ions including K+,Na+,Ca 2+and Mg 2+in different plant organs(roots,stems and leaves)of raw P.orientalis seedlings under NaCl stress with different concentrations(0,100 and 200 mmol/L).【Result】1)The roots growth of P.orientalis seedlings was stimulated by NaCl stress,while the biomass accumulation was significantly inhibited.2)The contents of Na+in roots,stems and leaves were significantly increased with the increase of NaCl stress and the distribution was in the order of roots>stems>leaves.With the increase of Na+,K+were significantly decreased,while Ca 2+in roots and leaves were significantly increased.3)With the increase of NaCl stress,the ratios of K+/Na+,Ca 2+/Na+and Mg 2+/Na+in all organs decreased,and the ratios of leaf and stem were always higher than that of roots.4)The selective transport coefficients,S K,Na,S Ca,Na and S Mg,Na,from roots to stems decreased with the increase of NaCl stress;while those from steams to leaves were enhanced at low NaCl stress but were inhibited at high NaCl stress.【Conclusion】P.orientalis seedlings had certain tolerance to NaCl stress,which was mainly related to the accumulation and restriction of Na+in roots and increased selective transport ability of K+,Ca 2+and Mg 2+in shoots under low salt stress.