水分异质性影响两种根茎型克隆植物赖草和假苇拂子茅的水分存储能力

水分在自然系统中呈异质性分布。有关水分异质性对克隆植物生长、形态和生理影响的研究已有大量的工作, 但是水分异质性对克隆植物存储能力, 尤其是水分存储能力影响的研究却十分缺乏。该文将两种根茎型克隆植物赖草(Leymus secalinus)和假苇拂子茅(Calamagrostis pseudophragmites)进行水分异质性和同质性实验处理, 探讨水分异质性对克隆植物水分存储能力、生长和形态的影响。在异质性水分处理下, 两种克隆植物的间隔子、枝和根的含水量均显著增加。两种克隆植物对水分异质性分布的适应策略有所不同, 赖草通过降低单个克隆分株的生长、提高芽的数量以应对水分异质性, 而假苇拂子茅通过增强整个分株种群的地下部分(根状茎、根和芽)生长来应对水分资源的异质性分布。水分储存能力的增强可以提高克隆植物适应水分异质性的能力。

Water heterogeneous affects water storage in two rhizomatous clonal plants Leymus secalinus and Calamagrostis pseudophragmites

Aims Essential resources for plant growth are heterogeneously distributed in natural systems, and clonal plants can efficiently use heterogeneously distributed resources. Many studies have addressed effects of heterogeneous water supply on the growth, morphology and physiology of clonal plants, but few have tested effects of water heterogeneity on the ability of clonal plants to store water.
Methods We grew ramets of two rhizomatous clonal plants Leymus secalinus and Calamagrostis pseudophragmites under both homogeneous and heterogeneous water supply. The experiment was conducted from 15 August to 14 October 2010 under a rain shelter at Ordos Sandland Ecological Station (39°29′ N, 110°11′ E). Water content and biomass of roots, shoots, spacers (rhizomes) and buds were measured.
Important findings Spacer water content, shoot water content and root water content were significantly higher under the heterogeneous water condition than under the homogeneous water condition in both species, suggesting that clonal plants could increase the ability to store water when growing in heterogeneous water conditions. Leymus secalinus decreased single ramet biomass and increased bud number to adapt to water heterogeneity, while C. pseudophragmites increased belowground biomass, including rhizome biomass, root biomass and bud biomass, to deal with water heterogeneity. Increasing water storage may increase the ability of clonal plants to adapt to unpredictable water conditions.