Ecological adaptability of <i>Potamogeton crispus</i> under different water depths

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Abstract

用盆栽试验方法, 将菹草石芽种植在水下0.5、1.0、1.5、2.0、2.5、3.0、3.5、4.0m的花盆内, 研究了水深梯度对菹草生长、繁殖和生物量分配的影响, 得出在不同水深条件下, 菹草的能量分配适应对策.结果表明:不同水深未影响菹草石芽的萌发, 水深0.5-4m各实验组, 菹草石芽的萌发率均达到70%以上, 各实验组之间石芽萌发率无显著性差异;菹草株高与水深显著相关, 菹草生长的适宜水深范围为0.5-2.5m, 在水深0.5m处, 菹草的生物量与单颗石芽克隆数最多, 在水深1.5m处, 菹草的植株高度最大;菹草对于不同的水深适应具有较强的表型可塑性, 菹草的株高、生物量在不同的水深中形态差异显著, 随着水深的增加、光照强度的减弱, 菹草不断将更多的能量用于增加株高以获取更多的光能, 这就导致了植株分配给生殖器官的能量逐渐减少, 最终达到耗-益的最大获取;菹草除了形成不同表型可塑性来适应光照胁迫外, 还可以改变叶绿素含量进一步应对不同水深下的光照胁迫, 在水深3.0m以下, 菹草的叶绿素显著增加, 以最大效率利用光能, 从而在快速光响应曲线上, 3.0-4.0m实验组菹草光响应能力并未低于其余各组。;Submersed macrophyte, Potamogeton crispus, was planted in water at depth of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4.0 m in pots, with the aim to study the influence of the water depths on plant adaptability in reproduction, biomass allocation and photosynthetic properties and to elicit the way of energy distribution when they are in different water depths.Results showed that the stem length of P.crispus had an evident correlation with water depth and the appropriate water depth for P.crispus growth was 0.5-2.5 m.At the depth of 0.5 and 1.5 m, Potamogeton crispus turion has the largest clones and highest biomass, and the tallest stem length, respectively.Water depth gradients do not affect the germination of P.crispus turions with germination rates > 70% from deep water 0.5 m to 4 m in the experimental group.The adaptability of P.crispus to different water depths has a strong phenotypic plasticity.Height and biomass vary with different water depths for P.crispus.With the increase of water depth and the decrease of light intensity, P.crispus distributes more energy to the growth of plant height so that it can get more luminous energy, which leads to the gradually reduction of energy to reproductive organs and eventually to a balance of energy distribution.The phe-notypic plasticity can adapt to different light stress and what' s more, it can also change the content of the chlorophyll to further re-spond to different light under stress.Below the depth of 3.0 m, the chlorophyll of P.crispus greatly increased to use of energy effi-ciently, which is illustrated by the comparable light response capacity of the experimental group from 3.0-4.0 m and is still not lower than other groups.

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