Clonal Integration of Fragaria orientalis Driven by Contrasting Water Availability between Adjacent Patches

異質生境斑塊間水分梯度對東方草莓克隆整合的影響

張運春(Yun-Chun Zhang) ； 張橋英(Qiao-Ying Zhang) ； Eshetu Yirdaw ； 羅鵬(Peng Luo) ； 吳寧(Ning Wu)

《Botanical Studies》 49卷4期 (2008/10) Pp. 373-383

摘要

生長在異質生境中的克隆植物分株間能進行物質傳遞，這種現象被稱為克隆整合。異質生境斑塊間的梯度是克隆整合的外在驅動力。我們假設克隆整合的強度隨斑塊梯度的增大而增強。文中我們用東方草莓兩個相連克隆片段的盆栽實驗驗證此假設。克隆片段被分為三組：無水分梯度組（高水分端90%田間持水量，低水分端90%田間持水量，30個克隆片段）、中等水分梯度組（高水分端90%田間持水量，低水分端60%田間持水量，60個克隆片段）、高水分梯度組（高水分端90%田間持水量，低水分端30%田間持水量，60個克隆片段）。無水分梯度組中的高水分端均為克隆片段的近端分株，中、高水分組的高水分端一半為近端分株一半為遠端分株。將以上每種處理中一半克隆片段的分株間匍匐莖切斷、一半保留。實驗中乾旱脅迫和切斷匍匐莖對克隆分株有顯著影響，並且影響隨分株間水分梯度的增加而增大，但脅迫分株來自近端或遠端多數處理下沒有顯著差異。耗－益分析表明克隆整合中乾旱脅迫端分株受益但與其相連端生長受到抑制。實驗結果表明克隆植物東方草莓能通過分株間的克隆整合抵禦土壤水分異質性，並且克隆整合隨分株間土壤水分梯度的增大而增強。克隆植物對異質水分生境的這種適應性對乾旱地區的生態恢復具有重要意義。

關鍵字

克隆植物 ； 耗－益分析 ； 乾旱脅迫 ； 東方草莓 ； 異質性環境 ； 生理整合 ； 水分傳輸

並列摘要

Experimental studies have shown that clonal plants can reciprocally translocate resources between interconnected ramets in heterogeneous environments. Resource contrast between patches in heterogeneous environments is the main external driver of integration effects. It was hypothesized that translocation of water between interconnected ramets was enhanced under higher levels of contrasts in water availability. A pot experiment with clonal fragments consisting of two interconnected ramets of F. orientalis-a stoloniferous herb widely distributed in China-was conducted. In the experiment, each of the ramets of the clonal fragments was allocated to either a high or low water treatment. The ramets in the high water treatment were maintained at 90% field capacity while those in the low water treatment were maintained at 90, 60 and 30% field capacity, respectively. The ramet developmental stage (proximal or distal from mother rosette) was accounted for by allocating either proximal or distal ramets in the contrasting patches. In order to assess the role of physiological integration among ramets, the stolon was severed for half of the clonal fragments. Stolon severing and drought stress had significant effects on plant performance, which increased with the increase of contrast. However, the directionality of stressed ramets had no influence on most treatments. Based on performance measures, a cost-benefit analysis showed that the dry ramets benefited from clonal integration at the cost of the connected wet ramets. The results indicated that this clonal species is able to withstand soil-water heterogeneity through physiological integration, which is promoted under increasing levels of water contrast. Our results suggest that clonal plants might be suitable for vegetation restoration in dry areas due to superior survival strategies.

並列關鍵字

Clonal plant ； Cost-benefit analysis ； Drought stress ； Fragaria orientalis ； Heterogeneous environment Physiological integration ； Water transport