油菜苗期对盐碱胁迫的离子响应机制

Ion Response Mechanism of Canola Seedlings to Saline-alkali Stress

为探究油菜苗期不同生长阶段(苗前期与苗后期)体内离子吸收及分配对复合盐碱胁迫的响应机制,以‘华油杂62号’为材料,采用盆栽方法,分析复合盐碱胁迫下离子(Na+、K+、Ca2+、Mg2+)在油菜苗期不同器官吸收及分布的变化。结果表明,油菜苗前期在中度、重度盐碱处理下,根冠比较轻度处理分别增加16.47%、48.83%,而苗后期分别降低9.06%、45.49%;随盐碱程度的增加,油菜苗期各部位Na+含量均呈增加趋势,重度盐碱处理下Na+含量均显著高于轻度和中度处理,且苗前期Na+主要积累于茎叶,苗后期主要积累于根部;根中Na+含量在苗后期显著大于苗前期,分别增加1.80(轻度)、1.80(中度)和1.17倍(重度);K+主要积累于根部,苗后期根中的K+含量显著低于苗前期,分别降低65.7%(轻度)、83.1%(中度)和67.3%(重度);选择性运输系数SCa2+,Na+表现为苗前期>苗后期,而SK+,Na+和SMg2+,Na+表现为苗前期<苗后期。由此可见,油菜苗前期与苗后期的离子平衡耐盐碱机制可能不同;苗前期根中Na+含量小于茎叶,优先促进根系生长发育,同时增加根部向茎叶选择性运输Ca2+以缓解盐碱胁迫;而苗后期根中Na+含量大于茎叶,茎叶Na+含量减少,同时增加根部对K+、Ca2+吸收以及根部向茎叶选择性运输K+、Mg2+,以提高其耐盐性,为油菜在盐碱地的种植提供理论依据。

To study the mechanisms of ion distribution and uptake in canola seedlings under combined saline stress at different growth stages(early-seedling stage and late-seedling stage),‘Huayouza 62’was as material.The changes of dry weight and the contents ions(Na+,K+,Ca2+,Mg2+)in root and stem-leaf of canola seedlings at different stages under different degrees of combined salinity stress were determined by a pot experiment.The results showed that the root/shoot ratio under moderate and high stress increased by 16.47%and 48.83%in the early-seedling stage compared with the low stress,and decreased by 9.06%and 45.49%in the late-seedling stage.The Na+contents in the stem-leaves and roots of canola seedling increased with the increase of salinity stress,and the Na+content under high stress was significantly higher than other treatments,and Na+accumulated mainly in stems and leaves in the early-seedling stage while in roots in the late-seedling stage.Compared with that in the early-seedling stage,the Na+content of root in the late-seedling stage increased significantly by 1.80(low stress),1.80(moderate stress)and 1.17-fold(high stress).K+was mainly accumulated in roots,and the K+content of root in the late-seedling stage was significantly lower than that in the early-seedling stage,with a reduction of 65.7%(low stress),83.1%(moderate stress)and 67.3%(high stress).The selective transport coefficient(SCa2+,Na+)in early-seedling stage was higher than that in late-seedling stage,and SK+,Na+,SMg2+,Na+in early-seedling stage were lower than those in late-seedling stage.Salt tolerance mechanisms of ion homeostasis in early-seedling and late-seedling stages of canola were different under combined salt stress.In the early-seedling stage,Na+accumulated mainly in the stem and leaves,which preferentially promoted root growth and development and increased the selective transport of Ca2+from the roots to the stem and leaves to alleviate salinity stress.In the late-seedling stage,salt tolerance was improved by accumulating more Na+in the roots and reducing Na+accumulation in the stem and leaves,and increasing root uptake of K+and Ca2+and the selective transport of K+and Mg2+from the roots to the stem and leaves.Above results provided a theoretical basis for rapeseed planting in saline-alkali land.