土壤水分对薇甘菊不同繁殖体单位存活能力和植株表型可塑性影响

Effect of Soil-Water Conditions on Survival Rate and Morphological Plasticity of Clonal Plant Mikania micrantha H.B. Kunth

【目的】研究土壤水分对入侵性植物薇甘菊(Mikania micrantha H.B.Kunth)的克隆繁殖和植株形态特征的可塑性,提高对该物种的预警能力和控制能力。【方法】在人工气候箱内通过模拟干旱和淹水条件,研究土壤水分对薇甘菊不同繁殖单位存活能力的影响;通过温室水分控制试验研究低、中、高土壤水分和水深1 cm条件下,薇甘菊植株的表型可塑性。【结果】除节间和不定根外,土壤水分对薇甘菊其它营养繁殖体单位的存活率具有显著影响,且不同营养繁殖体单位在同等土壤水分条件下的存活率存在差异。当土壤含水量为12.5%时,薇甘菊地下营养繁殖体不定根+节点、不定根+根状茎+节点的存活率显著大于其它营养繁殖单位,而叶片则不能存活;随着土壤含水量的增加,各营养繁殖单位的存活率逐渐增大;当处于淹水状态时,在水深1 cm条件下,营养繁殖体节间、节点、不定根、不定根+节点不能存活,而其它营养繁殖体的存活率均超过80%;但水深为6 cm时,各营养繁殖体均不能存活。薇甘菊的主茎长、总分枝长、叶面积和主茎节间长均随着土壤含水量的增加而增大;分枝数则在高土壤水分含量下达到最大,且各土壤水分处理间差异显著;茎节数在中土壤水分含量下达到最大,后随着土壤含水量的增加而减小。薇甘菊的地上生物量、茎生物量、叶生物量以及地上生物量分配和叶生物量分配均随着土壤水分的增加而增大;而茎生物量分配在中等土壤水分含量下最大;地下生物量在高土壤含水量时达到最大,后在淹水状态下减小,而地下生物量分配则随着土壤含水量增加而减小。【结论】薇甘菊的克隆繁殖和植株形态随土壤水分变化具有很强的可塑性,在干旱(土壤含水量为12.5%)和淹水(水深1 cm)条件下,均可通过营养繁殖体克隆繁殖并生长,而在水深6 cm则不能存活。

【Objective】The objective of this study is to research the morphological plasticity on clonal reproduction and plant morphologic characters under different water conditions of Mikania micrantha H.B.Kunth which is considered one of the most invasive and destructive species in the world,and to strengthen capability in early warning and control.【Method】Soil-water conditions on drought and flood were simulated in the artificial climate box,and the survival rate on different phytomers of clonal plant M.micrantha were tested,then in a greenhouse,four types of soil-water conditions of low,medium,high and flood were simulated,respectively,and morphological characteristics,biomass accumulation and biomass allocation patterns were measured.【Result】In addition to the internode and adventitious roots,soil water content had a significant effect on survival rate of vegetative phytomers of M.micrantha,and the survival rate of different vegetative phytomers was different at the same soil water content.When the soil water content was 12.5%,the survival rate of adventitious root ＋ node,adventitious root ＋ root stock ＋ node was significantly higher than others,while the leaf could not live.Then as the soil-water content increased,clonal reproducibility of vegetative phytomers of M.micrantha was gradually strengthened.At the drowned conditions,when the water depth at 1cm,the internode,node,adventitious root,adventitious root＋ node could not live,but the survival rate of other phytomers was more than 80%.All the vegetative phytomers of M.micrantha couldn’t survive at the water depth 6 cm.As the soil water content increased,the main stem length,total branch length,leaf area and internode length of M.micrantha increased.Branch number reached peak in high soil water content,but no significant difference with other treatments.In medium soil water content,stem node reached maximum,then gradually decreased with soil water content increase.Biomass accumulations and allocation of above-ground,stem and leaf increased with soil water content increase.In medium soil water content,biomass allocation of stem reached the maximum.Underground biomass reached maximum in the highest soil water content,but decrease in the drowned conditions,but the allocation of underground biomass decreased with soil moisture content increase.【Conclusion】 Soil-water conditions had an obvious effect on clonal reproduction ability and morphological plasticity characteristics of M.micrantha,and it could clonal reproduction and growth in the drought（12.5% water content of the soil） and flood（the water depth at 1 cm） conditions,but it could not survive in the water depth 6 cm.