de Kroon Hans, Fransen Bart, van Rheenen Jan W A, van Dijk Arnold, Kreulen Rob
Department of Plant Ecology and Evolutionary Biology, University of Utrecht, PO Box 800.84, NL-3508 TB, Utrecht, The Netherlands.
Department of Geochemistry, University of Utrecht, Budapestlaan 4, NL-3584 CD, Utrecht, The Netherlands.
Oecologia. 1996 Apr;106(1):73-84. doi: 10.1007/BF00334409.
We studied water trnaslocation between interconnected mother and daughter ramets in two rhizomatous Carex species, using a newly developed quantitative method based on deuterium tracing. Under homogeneous conditions, in which both ramets were subjected either to wet or dry soil, little water was exchanged between the ramets. When the ramet pair was exposed to a heterogeneous water supply, water translocation became unidirectional and strongly increased to a level at which 30-60% of the water acquired by the wet ramet was exported towards the dry ramet. The quantity of water translocated was unrelated to the difference in water potential between the ramets, but highly correlated to the difference in leaf area. In both species, the transpiration of the entire plant was similar under heterogeneous and homogeneous wet conditions. This was a direct result of an increase in water uptake by the wet ramet in response to the dry conditions experienced by the interconnected ramet. In C. hirta, the costs and benefits of integration in terms of ramet biomass paralleled the responses of water consumption. This species achieved a similar whole-plant biomass in heterogeneous and homogeneous wet treatments, and water translocation was equally effective in the acropetal and basipetal directions. In C. flacca, responses of biomass and water consumption did not match and, under some conditions, water translocation imposed costs rather than benefits to the plants of this species. It is concluded that enhanced resource acquisition by donor ramets may be of critical importance for the net benefits of physiological integration in clonal plants.
我们使用一种基于氘示踪的新开发定量方法，研究了两种具根状茎的苔草属物种中相互连接的母株和子株分株之间的水分转运。在均匀条件下，即两个分株都处于湿润或干燥土壤中时，分株之间几乎没有水分交换。当分株对暴露于异质水分供应时，水分转运变得单向且大幅增加，达到湿润分株获取的水分中有30 - 60%向干燥分株输出的水平。转运的水量与分株之间的水势差异无关，但与叶面积差异高度相关。在这两个物种中，在异质和均匀湿润条件下，整株植物的蒸腾作用相似。这是湿润分株因相连分株经历的干燥条件而增加水分吸收的直接结果。在硬苔草中，就分株生物量而言，整合的成本和收益与水分消耗的响应平行。该物种在异质和均匀湿润处理中实现了相似的整株生物量，并且水分在向顶和向基方向的转运同样有效。在曲芒苔草中，生物量和水分消耗的响应不匹配，并且在某些条件下，水分转运给该物种的植物带来的是成本而非收益。得出的结论是，供体分株增强的资源获取对于克隆植物生理整合的净收益可能至关重要。
