不同生长环境下黄顶菊浸提液对多年生黑麦草萌发与生长的影响

为阐明黄顶菊入侵机制,本文在调查不同生境下黄顶菊居群特征的基础上,进一步采用植株浸提液生物测试的方法研究了不同生境、生长密度及替代植被下黄顶菊对多年生黑麦草的化感潜力。结果表明:黄顶菊的化感作用强弱与其入侵能力存在一定相关性,黄顶菊浸提液的化感潜力随浓度升高而增强;不同植株组织浸提液的化感潜力存在显著差异,表现为地下部分明显低于地上部分;不同生境下黄顶菊浸提液的化感潜力顺序为水边>果园>路边,50 g.L 1茎叶浸提液对多年生黑麦草发芽率化感效应敏感指数分别为2.83(水边)、1.31(果园)和0.71(路边);不同密度黄顶菊的茎叶化感潜力顺序为高、中密度区显著大于低密度区,50g.L 1浓度浸提液对多年生黑麦草发芽率化感效应敏感指数分别为3.91(高密度)、4.89(中密度)和0.29(低密度);根部浸提液的化感潜力顺序则相反。不同替代植被下茎叶浸提液的化感效应为混种>单种,而根系浸提液的化感效应敏感指数则差别不大。因此,黄顶菊不同组织器官化感活性物质分配不同,同时其化感效力能够适应环境条件而发生变化,这可能是造成黄顶菊在不同环境中入侵效果差异的原因之一。

Effect of extracts of Flaveria bidentis in different growth habitats onLolium perenne germination and seedling growth

A new exotic weed invader, Flaveria bidentis, is spreading rapidly in central China. Aqueous extracts of F. bidentis plants growing in different habitats, and with different densities, and in vegetations with different replacement plants were used to evaluate the allelopathic effects of the plant on seed germination and seedling growth of Lolium perenne. The primary aim of the study was to clarify the invasion mechanism of F. bidentis. The results showed some degree of correlation between allelopathy and environmental factors. Inhibition effects on seed germination and seedling growth of L. perenne increased with increasing extract concentration. Significant differences were noted among different habitats and plant parts. Inhibition effects among different habitats were in the order of waterside > orchard > roadside with response indexes of allelopathy of ?2.83, ?1.31 and ?0.71 of 50 g·L^?1 leaf and stem aqueous extracts of F. bidentis on L. perenne seed germination rate, respectively. The inhibition effects of 50 g·L^?1 leaf and stem aqueous extracts of F. bidentis from wasteland plants with different community density were in the order of medium density > high density > low density, and with response indexes of allelopathy of ?4.89, ?3.91 and ?0.29 on L. perenne seed germination rate, respectively. The reverse was the trend for root extracts. In vegetations with different replacement plants, the inhibition effects of leaf and stem aqueous extracts of F. bidentis were in the order of mixture with replacement plants > mono-culture. A similar inhibition pattern was observed for root extracts, regardless of the pattern of the replacement plants. The findings suggested that allelopathic active component distribution in different plant organs was changed and associated efficacies varied with environmental conditions. This was a critical factor that influenced the invasion mechanism of F. bidentis.