Effects of pH on the Growth and Activities of Antioxidative Enzymes of Hydrilla verticillata under two Nutritional Conditions

摘要

By means of laboratory simulation, this article studied the effects of different pH 7,8,9,10 on the growth, chlorophyll contents, antioxidative enzymes and malondiadhyde(MDA) contents of Hydrilla verticillata under two different nutritional conditions: mesotrophic(TN:0.60mg/L;TP:0.04mg/L) and eutrophic(TN:4.20 mg/L;TP:0.28mg/L). The results showed that after culture of 21days plant growth was obviously inhibited at pH10 , particularly under eutrophic condition. Chlorophyll contents increased by eutrophic condition at pH7 and pH8, but the chlorophyll contents of Hydrilla verticillata under eutrophic condition were lower than that under mesotrophic condition at pH10. POD and SOD activities significantly increased at pH8 and were inhibited at pH9 under eutrophic condition, but the activities of two enzymes increased at pH up to 9 under mesotrophic condition. CAT activities significantly increased at pH9 under both nutritional conditions and were obviously inhibited at pH10 under eutrophic condition. MDA contents increased linearly with pH from 7 to 9 under eutrophic condition. Plants under eutrophic condition had significantly higher MDA contents than those under mesotrophic condition with pH from 7 to 9, and the difference was the most significant at pH9. It can be indicated that the influence of pH on Hydrilla verticillata was relevant to nutritional conditions. There is stress to Hydrilla verticillata above pH 9 under both nutritional conditions and the effect is aggravated by eutrophic condition.