Photosynthetic response of <Emphasis Type="Italic">Fragaria orientalis</Emphasis> in different water contrast clonal integration |
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Authors: | Yunchun Zhang Qiaoying Zhang Peng Luo Ning Wu |
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Institution: | (1) Chengdu Institute of Biology, Chinese Academy of Sciences, No. 9 Section 4, Renmin Nan Road, 610041 Chengdu, Sichuan, People’s Republic of China;(2) Shandong Institute of Light Industry, 250353 Jinan, Shandong, People’s Republic of China;(3) State Key Laboratory of Biocontrol, Sun Yat-Sen University, 510275 Guangzhou, Guangdong, People’s Republic of China |
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Abstract: | The capacity to exchange resources and non-resource agents is one of the most outstanding features of clonal plants. Contrast
between patches in a heterogeneous environment is the main external driving force behind integration effects. It was hypothesized,
on the basis of the source–sink hypothesis, that assimilate demand from drought-stressed ramets will result in enhancement
of the photosynthesis of well-watered ramets by a mechanism of feedback regulation, that the negative effect of drought on
the photosynthesis of drought-stressed ramets will be ameliorated by physiological integration, and that these effects will
be enhanced by increasing contrast. A pot experiment was conducted with clonal fragments consisting of two interconnected
ramets of Fragaria orientalis. In the experiment, both the connected and the disconnected clonal fragments were divided into three water contrast groups:
(1) homogeneous (no contrast) group; (2) low-contrast group; (3) high-contrast group. The photosynthesis and stress tolerance
of drought-stressed ramets did not decrease under the support of well-watered ramets when they were connected, allowing clones
to maintain their performance in less favorable environments. But the photosynthesis and stress tolerance of drought-stressed
ramets decreased with increasing drought-stress when stolons were disconnected. With a feedback regulation process, the photosynthesis
of well-watered ramets connected to drought-stressed ramets was enhanced by the latter, which can compensate, at least partially,
for the cost of maintaining the stressed ramets. Drought-stressed ramets gained more benefits in a high-contrast environment
than in a lower-contrast environment; this can enhance the survival of drought-stressed ramets in unfavorable habitats, especially
stressed patches that would otherwise be unexploitable by independent ramets. But photosynthesis of well-watered ramets did
not increase with increasing water availability contrast. It can be concluded that photosynthesis and stress tolerance of
F. orientalis was affected by clonal integration and by contrasts of water availability. |
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Keywords: | Clonal plant Physiological integration Drought Heterogeneous environment |
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