Song Yu-Zhi, Wang Jin-Qi, Gao Yong-Xia, Xie Xue-Jian
International Center for Ecology, Meteorology and Environment (IceMe), School of Applied Meteorology, Nanjing University of Information Science & Technology, No.219, Ningliu Road, Nanjing, 210044, Jiangsu, China,
Environ Sci Pollut Res Int. 2015 Jun;22(11):8480-7. doi: 10.1007/s11356-014-3998-x. Epub 2014 Dec 30.
To reveal the mechanism of submerged plants decline in progressively eutrophicated freshwaters, physiological responses of Vallisneria natans to epiphytic algae were studied in simulation lab by measuring plant physiological indexes of chlorophyll content, malondialdehyde (MDA) content, and superoxide dismutase (SOD) activity based on a 2 × 4 factorial design with two epiphytic conditions (with epiphytic algae and without) and four levels of N and P concentrations in water (N-P[mg.L(-1)]: 0.5, 0.05; 2.5, 0.25; 4.5, 0.45; 12.5, 1.25). Compared with control (non-presence of epiphytic algae), chlorophyll contents of V. natans were significantly decreased (p < 0.01) for the presence of epiphytic algae under any concentrations of N and P in water bodies. While the presence of epiphytic algae induced peroxidation of membrane lipids, MDA contents of V. natans had significantly increased (p < 0.05) by comparing with control. SOD activity significantly enhanced (p < 0.05) with the presence of epiphytic algae in the treatments of T2 and T3 in the whole culture process by comparing with control, sometimes reaching an extremely significant level (p < 0.01). However, in the treatments of T1 and T4, SOD activity had no obvious change with the presence of epiphytic algae (p < 0.05) by comparing with control. At the end of the experiment, the effects of epiphytic algae on chlorophyll content and SOD activity in the leaves of V. natans were increased at first and then decreased with the concentrations of N and P in water, and MDA content became higher with the increase of N and P. concentrations. Repeated measurement data testing showed that the effects of epiphytic algae on the chlorophyll content and MDA content and SOD activity were significant, respectively (p < 0.001), the effects of epiphytic algae were combining with effects of concentrations of N and P (p < 0.001), respectively, and their interaction (p < 0.001). Our observations confirmed that this prediction: the growth of epiphytic algae directly produced adverse effects on physiology of V. natans and epiphytic algal biomass were positively correlated with nutrient available in the water column.
为揭示富营养化程度不断加剧的淡水水体中沉水植物衰退的机制，在模拟实验室中，基于2×4析因设计，通过测量苦草的叶绿素含量、丙二醛（MDA）含量和超氧化物歧化酶（SOD）活性等植物生理指标，研究了苦草对附生藻类的生理响应。该设计包含两种附生条件（有附生藻类和无附生藻类）以及水体中四种氮磷浓度水平（氮-磷[mg·L⁻¹]：0.5，0.05；2.5，0.25；4.5，0.45；12.5，1.25）。与对照（无附生藻类）相比，在水体中任何氮磷浓度下，有附生藻类时苦草的叶绿素含量均显著降低（p＜0.01）。同时，附生藻类的存在诱导了膜脂过氧化，与对照相比，苦草的MDA含量显著增加（p＜0.05）。在整个培养过程中，与对照相比，在T2和T3处理中有附生藻类时SOD活性显著增强（p＜0.05），有时达到极显著水平（p＜0.01）。然而，在T1和T4处理中，与对照相比，有附生藻类时SOD活性无明显变化（p＜0.05）。在实验结束时，附生藻类对苦草叶片叶绿素含量和SOD活性的影响随水体中氮磷浓度的升高先增加后降低，但MDA含量随氮磷浓度的升高而升高。重复测量数据检验表明，附生藻类对叶绿素含量、MDA含量和SOD活性的影响均显著（p＜0.001），附生藻类的影响分别与氮磷浓度的影响存在联合作用（p＜0.001），且二者存在交互作用（p＜0.001）。我们的观察结果证实了这一预测：附生藻类的生长直接对苦草的生理产生不利影响，且附生藻类生物量与水体中可利用养分呈正相关。
