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水淹作为陆生植物遭受的环境胁迫之一,与干旱、盐碱等环境因子一样,对陆生植物的生长、存活及地理分布等会产生重要影响[1].在目前全球气候变化引发的降水异常、洪涝灾害频发[2],以及因能源短缺而筑坝开发水电日益盛行的背景下,陆生植物是否能够耐受水淹胁迫已成为影响农、林生产的重要因素[3];同时,也特别成为影响水滨陆地生态系统或低洼地带陆地生态系统结构和功能的重要因素[4-5].因此,关于陆生植物对水淹逆境的响应及适应机制研究具有重要的理论及实际意义.
陆生植物遭受水淹胁迫,特别是大型水库(例如三峡水库)修建导致的长时间、大深度的水淹时,不仅光照、溶氧及CO2浓度等环境因子会发生显著变化[6-7],植物所承受的压力也会发生明显变化.但是,当前有关水压对陆生植物影响或是植物对水压变化适应的相关研究却鲜见报道.水淹环境下水压如何影响陆生植物生长和存活,或陆生植物会如何适应水压的变化,目前对此还并不十分清楚.为了探究水压对陆生耐淹植物存活能力的影响,张小萍等提出植物在大深度、完全水淹时,光照和CO2浓度严重不足,植株无法通过光合作用生产碳水化合物[8],因此,植株体内碳水化合物储备量的多少及其消耗速率的快慢对植株抵御水淹胁迫具有重要的作用[9-10].本文提出如下科学假说,植株体内储备的碳水化合物量越多,代谢需求越低(也即消耗速率越低),则植株可能死亡越慢,抵抗水淹的能力也越强.已有研究表明[11-13],当O2分压过低形成低氧胁迫时,压力增加可能会促进植物的无氧呼吸代谢强度进而促进乙烯的产生和释放.本文推测,耐淹植物遭受水淹时,随着水淹深度的增加,水压亦增大,植株可能增强其无氧呼吸代谢水平,加大其贮备碳水化合物的消耗速率,进而其主茎死亡速率也会增加.
为了验证上述科学假说,本文以长江三峡水库消落区典型陆生耐淹植物狗牙根(Cynodon dactylon)、牛鞭草(Hemarthria altissima)及瘦瘠野古草(Arundinella anomala Steud.)为研究对象,进行了变量控制实验设计.本研究主要回答如下科学问题:
1) 是否随着水淹深度的加深、水压的增加,植株主茎死亡的速率会逐渐增加?2)是否不同种类或耐淹能力不同的植株在抵抗水压胁迫时,其主茎死亡过程会表现出不同?
通过本研究,有助于了解陆生植物对水淹环境下水压胁迫的响应机制,进而丰富和发展关于陆生植物对水淹逆境的响应及适应机制研究的理论和方法.
Effect of High Hydrostatic Pressure on Main Stem Death of Three Typical Flooding-Tolerant Species
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摘要: 陆生植物遭受水淹胁迫,特别是大型水库修建导致的长时间、大深度的水淹,不仅导致光照、溶氧及CO2浓度等环境因子发生显著变化,也导致植物所承受的压力发生明显变化,但是目前关于水压对陆生植物影响的研究鲜见报道.以长江三峡水库消落区典型陆生耐淹植物狗牙根、牛鞭草及瘦瘠野古草为研究对象,进行变量控制实验设计,探究了水压对典型耐淹植物主茎死亡特征的影响.结果表明:1)水压对典型耐淹植株主茎的死亡过程有着显著的促进作用(即表现为正效应);2)不同种类(或耐淹能力不同)的植株在抵抗水压胁迫时,其主茎死亡过程表现出显著差异,并且随着水淹深度的增加继而水压亦增加,这种差异表现得越来越明显.通过本研究,有助于了解陆生植物对水淹环境下水压胁迫的响应机制,并且丰富和发展了关于陆生植物对水淹逆境的响应及适应机制研究的理论和方法.Abstract: The construction of large reservoirs often results in long-time and deep flooding of terrestrial plants in the riparian zones, and illumination, dissolved oxygen (DO) and CO2 concentration undergo great changes. But the effects of such environmental stress on terrestrial plants are now poorly documented. In order to have a better understanding of the response and adaptation mechanism of flooding-tolerant terrestrial plants to flooding stress, a variable-controlling experiment was made with three typical riparian plant species (Cynodon dactylon, Hemarthria altissima and Arundinella anomala Steud.) to study the effects of flooding on the death of their main stem. Three submergence level treatments (2m, 5m and 10m water depth), and three flooding duration treatments (0, 25 and 50 days) were set. We measured total stem length and total stem biomass of the three plants before and after they were submerged. It was found in the experiment that high hydrostatic pressure significantly accelerated the death rate of the main stem of the three plant species, and that different plant species performed differently in main stem death process under submergence. At the early stage of submergence (0-25 d), main stem death rate of A. anomala was higher than that of C. dactylon and H. altissima and the reverse was true at the late stage of submergence (26-50 d).
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Key words:
- Cynodon dactylon /
- Hemarthria altissima /
- Arundinella anomala Steud. /
- main stem death /
- hydrostatic pressure /
- response .
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表 1 水淹实验设计
物种名 水淹深度/m 水淹时间/d 狗牙根 2 0,25,50 5 0,25,50 10 0,25,50 牛鞭草 2 0,25,50 5 0,25,50 10 0,25,50 瘦瘠野古草 2 0,25,50 5 0,25,50 10 0,25,50 表 2 物种、水淹时间及水淹深度对植株主茎长度的影响
类别 自由度 均方 F P 物种 2,371 47 759.517 9 290.685 <0.001 水淹深度 2,371 432.714 84.176 <0.001 水淹时间 2,371 498.679 97.008 <0.001 物种*水淹深度 4,371 52.666 10.245 <0.001 物种*水淹时间 4,371 60.843 11.836 <0.001 水淹深度*水淹时间 4,371 169.662 33.004 <0.001 物种*水淹深度*水淹时间 8,371 26.898 5.232 <0.001 注:p<0.05表示差异有统计学意义. 表 3 物种、水淹时间及水淹深度对植株主茎生物量的影响
类别 自由度 均方 F P 物种 2,375 16.363 617.998 <0.001 水淹深度 2,375 0.130 4.914 0.008 水淹时间 2,375 1.589 60.029 <0.001 物种*水淹深度 4,375 0.071 2.681 0.031 物种*水淹时间 4,375 0.582 21.971 <0.001 水淹深度*水淹时间 4,375 0.144 5.430 <0.001 物种*水淹深度*水淹时间 8,375 0.153 5.782 <0.001 注:p<0.05表示差异有统计学意义. -
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