油菜素内酯对NaCl胁迫下棉花幼苗生理特性的影响

Cotton physiology affected by brassinosteroid under NaCl stress

该试验采用水培方法,探讨外施油菜素内酯对NaCl胁迫下棉花幼苗叶片光合速率、根系活力、叶片和根系抗氧化酶活性等生理指标的影响。结果显示:NaCl胁迫下棉花幼苗叶片光合速率下降、MDA含量上升、抗氧化酶(SOD、POD、CAT)活性降低,外施油菜素内酯可提高NaCl胁迫下棉花叶片中抗氧化酶活性、降低MDA含量、增强叶片光合能力;NaCl胁迫下棉花根系活力降低、MDA含量上升、SOD和CAT活性升高,外施油菜素内酯对根系活力、MDA含量、内源保护酶活性则影响较小。表明,油菜素内酯通过提高叶片抗氧化酶活性,减轻叶片膜脂过氧化程度,提高叶片光合性能,从而有效缓解盐胁迫对棉花叶片的伤害。

Salt stress is one of the environmental factors affecting plant growth and development.Brassinosteroid,a plant hormone,plays a significant role in growth and development and stress tolerance.In order to evaluate the effect of brassinosteroid on cotton under NaCl stress,exogenous brassinosteroid was applied on NaCl-stressed cotton,and the photosynthesis,root activity and antioxidant enzyme activity of two cotton cultivars（K638 and 86-1）were determined.The results showed that,under NaCl stress,cotton photosynthetic rate decreased,MDA content of cotton leaf increased,and the activities of endogenous protective enzymes（SOD,POD,CAT） declined.Exogenous brassinosteroid enhanced the antioxidant capacity of cotton leaf.Compared to NaCl stress treatment alone,SOD,POD and CAT in the cotton leaves increased in the treatment of exogenous brassinosteroid application after NaCl stress.Under NaCl stress,root activity decreased,MDA content,and the activities of SOD and CAT in cotton root increased,but exogenous brassinosteroid did not show much influence on root physiological parameters.It was indicated that exogenous brassinosteroid enhanced the resistance of cotton to NaCl stress through increasing the activity of endogenous protective enzymes in cotton leaf and alleviating the peroxidation of membrane lipid of leaf,therefore improving the photosynthesis of leaves.