Effects of lanthanum on the plant growth and leaf anti-oxidative enzyme activities of cucumber seedlings under nitrate stress.
镧对硝酸盐胁迫下黄瓜幼苗生长及叶片抗氧化酶活性的影响

The study with water culture showed that nitrate stress had significant inhibitory effects on the plant growth, especially the shoot growth of cucumber seedlings. On the 7th day under nitrate stress, the shoot fresh mass per plant decreased by 12.77 g, leaf SOD, POD and CAT activities increased, while leaf APX, DHAR and GR activities decreased significantly, compared with the control. The addition of low concentration (0.05 mmol L(-1)) LaCl3 increased the shoot fresh mass per plant by 35%, enhanced the leaf thermally stable protein content and SOD, POD, CAT, APX, DHAR and GR activities, and decreased the leaf MDA content and electrolytic leakage, resulting in a definite alleviation of the inhibitory effects of nitrate. However, an addition of high concentration (0.5 mmol L(-1)) LaCl3 had no obvious alleviation effect. It was concluded that the addition of certain concentration LaCl3 could alleviate the nitrate stress on cucumber via increasing anti-oxidative enzymes activities and thermally stable protein content.