完全水淹环境中光照和溶氧对喜旱莲子草表型可塑性的影响  

Effects of light and dissolved oxygen on the phenotypic plasticity of Alternanthera philoxeroides in submergence conditions

作　　者：许建平[1] 张小萍[1] 曾波[1] 袁慎鸿[1] 刘建辉[1] 刘明智[1] 

机构地区：[1]三峡库区生态环境教育部重点实验室,重庆市三峡库区植物生态与资源重点实验室,西南大学生命科学学院,重庆400715

出　　处：《生态学报》2014年第2期258-268,共11页Acta Ecologica Sinica

基　　金：国家自然科学基金资助项目(31070474;31370443);教育部高校博士点基金课题资助项目(20100182110022);中央高校基本科研业务费专项资金资助项目项目(XDJK2013A003);国家重点基础研究发展计划资助项目(2012CB723205)

摘　　要：光照和溶氧是水环境和陆地环境间差异显著的两个环境因子,对水淹植物的生长和存活具有重要的意义。以三峡库区常见外来入侵植物喜旱莲子草(Alternanthera philoxeroides)为研究对象,考察了水体中的光照(L)和溶氧(DO)对完全水淹环境中喜旱莲子草的形态特征和生物量分配等表型可塑性的影响。实验设置水淹和非水淹对照两组处理,对水淹组的光照和溶氧两个环境因子再分别设置有(+)、无(-)以及高(+)、低(-)两种水平,共计4个处理。实验结果表明:(1)水淹可促进喜旱莲子草主茎和叶片发生可塑性反应,引发伸长生长。水淹后,其细长的主茎以及长而薄的直立叶更有利于植株早日出露水面。(2)完全水淹条件下,喜旱莲子草主茎和叶片的表型可塑性受光照和溶氧的复合影响,其中主茎的伸长生长主要受溶氧的影响,而叶片的形态变化则主要受光照影响。高溶氧处理下喜旱莲子草的主茎伸长生长显著(P<0.05)。在相同光照条件下,高溶氧处理下喜旱莲子草的主茎长、节间数、节间长以及主茎长/主茎直径均明显高于低溶氧处理。不论有光还是无光,高溶氧处理下喜旱莲子草主茎长以及节间数的平均增长率均处于最高水平,分别为61.8%、34.2%。喜旱莲子草叶片的形态变化在有光处理下表现得尤为显著,其平均叶片长宽比、比叶面积以及叶倾角分别较水淹前增加了39.65%、28.3%、45.9°。(3)光照和溶氧对于喜旱莲子草不定根和分枝的发生及发展存在影响差异。有光条件下可促进植株抽枝,而高溶氧处理时更有利于植株生根。这些形态变化有助于喜旱莲子草扩大株型占据有利生境,进一步提高植株的水下存活能力。Plants show phenotypic plasticity in response to changing environments via variations of morphological and ecophysiological traits, and the plasticity of plants can increase markedly the capability of survival, growth, establishment, recruitment and distribution. In the real world, terrestrial plants suffer multiple stresses when they are submerged, such as oxygen deficiency and shading due to the lower gas diffusion and light intensity in water. Light climate and dissolved oxygen availability are strikingly different in aquatic environments from that in terrestrial habitats. It has been reported in many studies that most flooding-tolerant plants adapt to flooding through high phenotypic plasticity. However, few studies have investigated the effect of both light and dissolved oxygen levels on functional response in morphological plasticity of plants under submergence condition. To reveal the effects of light （L） and dissolved oxygen （DO） in water on the morphology andgrowth of Alternanthera philoxeroides, one of the common invasive plant species in the Three Gorges reservoir region, an experiment was conducted and the morphological traits and biomass allocation of A. philoxeroides were analyzed in the ecological garden of Southwest University. Flooded groups and non-flooded control group were set in the experiment, A. philoxeroides were put to grow in water with light （＋） or dark （-） and high （＋） or low （-） levels of dissolved oxygen. Flooded groups included L＋DO＋, L＋DO-, L-DO＋ and L-DO- four treatments. The following parameters were measured before flooding ： stem length, internode number, internode length, stem diameter, leaf number, leaf length, leaf width, leaf thickness, leaf angle. At the end of the experiment, we harvested the whole plant, including above-ground parts and below-ground parts, and measured the same parameters above mentioned and some new parameters, such as leaf disk area, adventitious root number, adventitious root length, shoot number and shoot length.

关 键 词：完全水淹 光照 溶氧 表型可塑性 喜旱莲子草 

分 类 号：S451[农业科学—植物保护]