盐胁迫下大白菜吸收转运45Ca2＋的变化

CHANGES OF 45 Ca 2+ UPTAKE AND TRANSLOCATION IN CHINESE CABBAGE ( Brassica pekinensis) AT SALT STRESS

在５ｍＳｃｍ－１和１０ｍＳｃｍ－１ＮａＣｌ胁迫过程中，大白菜幼苗根系膜透性、ＴＴＣ还原能力和丙二醛含量的变化显示根受到不同程度伤害。盐胁迫处理下，根系对钙的吸收速率在〔Ｃａ２＋〕＞０７５ｍｍｏｌ／Ｌ时明显受到抑制。根系对４５Ｃａ２＋的积累能力分别在５ｍＳｃｍ－１ＮａＣｌ胁迫５ｈ和１０ｍＳｃｍ－１ＮａＣｌ胁迫３ｈ后受到抑制，而且大白菜各器官（根、茎、叶）对４５Ｃａ２＋的吸收、转运能力在盐胁迫下发生不同程度下降，其中叶对盐胁迫反应最敏感。盐胁迫条件下，叶片各部位４５Ｃａ２＋积累明显减少，其中叶缘反应最为敏感。

Seedlings of Chinese cabbage were grown in the greenhouse at 0,5 and 10 mS/cm NaCl. Membrane leakage,TTC reduction activity and MDA content of the roots were determined from one hour to ten hours after treatment as the index of root injury. Ca 2+ uptake rate as a function of external [Ca 2+ ]at 5 mS/cm and 10 mS/cm NaCl was much lower than that of control when the external Ca 2+ was more than 0.75 mmol/L. 45 Ca 2+ uptake was significantly inhibited 3 hours after exposed to 10 mS/cm and 5 hours after exposed to 5 mS/cm,respectively. Distribution of 45 Ca 2+ in roots,stems and leaves reveals that young leaves are the most sensitive part to salt stress in terms of the absorption of Ca 2+ , thus Ca deficiency occurs in young leaf margin when exposed to salt stress.