EFFECTS OF ISO-OSMOTIC CA(NO₃)₂ AND NACL STRESS ON IONIC CONTENTS IN DIFFERENT ORGANS OF CUCUMBER SEEDLINGS

A hydroponic experiment was applied to investigate the effects of iso-osmotic Ca(NO₃)₂ and NaCl stresses on content and distribution of mineral in cucumber seedlings (Cucumis sativus L. ‘Jinchun No.2’). The results showed that under NaCl stress (84 mmol/L) K⁺ and Mg²⁺ contents decreased significantly while Na⁺ content increased significantly in roots, stems and leaves, the Ca²⁺ content decreased in leaves while accumulated substantially in roots and stems. But under Ca(NO₃)₂ (56 mmol/L) stress, Ca²⁺ content increased while K⁺ and Mg²⁺ contents decreased in the roots, stems and leaves, and the decreased degree of Mg²⁺ content was greater than that of K⁺ content. In terms of trace elements, NaCl stress aggravated the accumulation of Fe²⁺, Cu²⁺ and Zn²⁺ in roots, while inhibited the absorption of Mn²⁺ in roots; Ca(NO₃)₂ stress promoted the accumulation of Mn²⁺ and Zn²⁺ in roots but inhibited Cu²⁺ absorption. These results suggested that plant growth was inhibited by NaCl stress through increasing the Na⁺ content and decreasing the K⁺, Ca²⁺ contents of leaves, while isotonic Ca(NO₃)₂ stress inhibited plant growth mainly through increasing the Ca²⁺ content and decreasing the Mg²⁺ content of leaves.