作 者 ：朱丹婷,李铭红*,乔宁宁
期 刊 ：生态学报 2010年 30卷 23期 页码：6451~6459
Keywords:light intensity, temperature, total nitrogen concentration, interaction, orthogonal test, Vallisneria natans,
摘 要 ：苦草(Vallisneria natans)，是我国长江中下游淡水水体中常见的沉水植物种类。通过室内模拟正交试验的方法，研究不同光照强度、温度和总氮浓度(3光照×3温度×3总氮浓度)对苦草生长的影响。结果表明：(1)苦草在5320lx光照强度、10℃、2—4mg/L水体总氮浓度的条件下生长良好。实验所设100%(12000lx)和50%(5320lx)光照条件下苦草均可正常生长；但对于30℃的高温胁迫耐受性较差；苦草在总氮浓度为4mg/L的水体中各生长指标达到最大值，2mg/L或8mg/L的总氮浓度均会抑制其生长。(2) 5320lx的光照强度和10℃的温度对苦草光合色素的合成较为有利;而单纯总氮浓度的变化对苦草光合色素的合成影响不大。(3)苦草的生理活性在高于12000lx或低于1025lx的光强、高于30℃的温度以及8mg/L的总氮浓度下均会受到一定程度的抑制。(4)方差分析结果显示，苦草生长发育的过程中，光照强度和温度是主效环境因子；上述3个环境因子对苦草光合色素的合成均有极显著的影响，并且光强与温度的交互作用对其也有显著影响；光照强度、温度以及这两个环境因子的交互作用为影响苦草生理活性的主效因子。苦草作为不能形成冠层的基生叶莲座型沉水植物，对光强要求不高，对低温的耐受性较好，但较不耐高营养盐浓度， 因此，在得到一定修复的富营养化水体中，可以作为秋、冬季水生植物恢复和重建的关键物种。
Abstract:With the strengthening of freshwater eutrophication, the original aquatic vegetation gradually reduced and even disappeared, resulting in the well-functional grass type water degraded to algae-based water. Submerged plant is a key factor for the construction of stable and well-functioning freshwater ecosystems. Therefore, restoration and reconstruction of submerged plants is very important for prevention and control of eutrophication. The growth and development, decline and extinction of submerged plants are closely related with environmental factors due to their aquatic characteristics. In this study, we aim to explore the effects of light intensity, temperature, total nitrogen concentration and their interactions on the growth and development of submerged plants. Our study can shed new light on the mechanism of decline of submerged plants in the eutrophic water, and supply a theoretical basis for species selection in the process of the restoration and reconstruction of eutrophic water. Vallisneria natans is a common submerged plant species in fresh water of the middle-lower reaches of the Yangtze River in China. The effects of light intensities, temperatures and total nitrogen concentrations, 3(light) 3(temperature)×3(nutrient), on the growth of V. natans were investigated with orthogonal design methods in the laboratory. The experimental results showed that (1) light intensity and temperature, as well as their interaction significantly affect the growth of V. natans, V. natans grew well under the conditions of the light intensity in 5320lx, water temperature at 10 ℃, and total nitrogen concentration in 24 mg/L. In addition, V. natans can grow normally when the light intensity were 12000lx and 5320lx, and all of growth parameters were largest when total nitrogen concentration was 4mg/L. However, 2mg/L or 8mg/L total nitrogen concentration as well as 30 ℃, the growth of V. natans was inhibited. (2)The concentration of photosynthetic pigment was highest under the conditions of the light intensity in 5320lx, water temperature at 10 C than other conditions, however, the effect of total nitrogen concentration on the synthesis of photosynthetic pigment of V. natans was little. (3)The physiological activity of V. natans was inhibited under the conditions of the light intensity more than 12000lx or less than 1025lx, or temperature more than 30 ℃, or total nitrogen concentration in 8mg/L. (4) The results of analysis of variance indicated that, in the process of the growth of V. natans, the light intensity and temperature were main factors. Light intensity, temperature, total nitrogen concentration, as well as all the interaction of light intensity and temperature all had significant impact on the synthesis of photosynthetic pigment of V. natans. In addition, light intensity, temperature and the interaction of them were main factors for physiological activity of V. natans. In conclusion, V. natans, as a basal leaves and rosette-type of submerged plant species which can not form canopy, can grow well under the environment of low light intensity and low temperature, however, it can′t endure high nitrogen concentration. Therefore, for the eutrophic water restored for some extent, V. natans can be used as a key species for restoration and reconstruction of aquatic plants in autumn and winter.
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