土壤水分对外来入侵植物五爪金龙植株表型可塑性和化感作用的影响

摘要

The invasive alien plant Ipomoea cairica has caused serious damage to ecosystems. Invasive plants usually have broad ecological amplitudes, and hence can increase the invasiveness of this species. The objective of this study is to research the germination rate, morphological plasticity and allelopathic potential of I. cairica under different water conditions (10%, 20% and 30%). The result showed that:(1) The seed germination rates of I. cairica were 15.2%, 36.4%and 33.6%under 10%, 20%and 30%soil-water conditions, respectively. Germination rate of I. cairica was significant increased with the increasing soil-water condition, especially at the high soil-water condition (30%);(2) Total biomass of I. cairica were 0.88 g, 2.26 g and 2.42 g under 10%, 20%and 30% soil-water conditions, respectively. Compared with the low soil-water condition (10%), total biomasses of I. cairica were increased by 156.8%and 175.0%under the medium soil-water condition (20%) and high soil-water condition (30%), respectively. Increasing water conditions significantly increased the leave area, leaf mass ratio, shoot length and specific leaf area. The root mass ratio and R/S were significantly decreased with the increased of water conditions. Stem mass ratio has no significantly changed during the treatment;(3) The allelopathic potential of aqueous leachates of I. cairica on the seeding growth of Lactuca sativa and Raphanus sativus at the same concentration were increased under lower soil-water conditions. These results indicated that I. cairica can active adapt to drought stress environment by changing the biomass pattern and the allelopathic potential of it.%外来入侵植物五爪金龙（Ipomoea cairica）对华南地区的生态环境造成严重危害，表型可塑性可增强外来物种的入侵能力。本文通过盆栽试验研究土壤含水量为10%、20%和30%对外来入侵植物五爪金龙种子萌发、植株表型可塑性和化感作用的影响，探讨五爪金龙对土壤水分变化的响应机理，为进一步了解五爪金龙的入侵机理和提高对入侵种的预警和控制能力提供理论依据。结果表明，（1）在土壤含水量为10%，20%和30%条件下，五爪金龙种子的萌发率分别为15.2%、36.4%和33.6%。五爪金龙种子的萌发率随土壤含水量的增加而增加，尤其是在土壤含水量为30%时，五爪金龙种子萌发率最高。（2）土壤含水量为10%、20%和30%时，五爪金龙植株的总生物量分别为0.88、2.26和2.42 g。与土壤含水量为10%相比，土壤含水量为20%和30%条件下五爪金龙的总生物量分别增加了156.8%和175.0%，表明土壤水分增加显著增加了五爪金龙的总生物量。土壤含水量增加显著增加了五爪金龙的叶面积、叶生物量比、比叶面积和茎长，同时减少了根生物量比和根冠比，而对茎生物量比无显著影响。（3）相同浓度的五爪金龙水浸提液对受体植物莴苣（Lactuca sativa）和萝卜（Raphanus sativus）根长和苗高生长的化感抑制作用随着土壤含水量的减少而增强。研究表明：五爪金龙通过改变生物量分配模式和化感潜力对土壤水分变化有一定的适应能力。