岩溶区土著植物黄荆条和红背山麻杆水浸提液对入侵植物飞机草萌发的影响

黄荆条和红背山麻杆是广西岩溶地区常见的土著植物，在这两种土著植物较多的群落中，飞机草的入侵受到影响。本文通过分析发芽率、发芽速率和化感效应敏感指数等指标，研究了黄荆条和红背山麻杆的根、茎、叶三个部位不同浓度的水提液对飞机草种子萌发的影响，以检验这两种土著植物是否对飞机草具有化感作用。结果表明，与对照相比，红背山麻杆各部位不同浓度的水提液以及黄荆条的根、茎不同浓度的水提液对飞机草种子萌发有微弱的影响，整体表现出低促高抑的现象；但黄荆条的叶原液对飞机草种子萌发抑制作用显著，在黄荆条叶原液处理下，飞机草发芽率仅为对照的20．75％，化感效应敏感指数为-3．8191。从生态效益和经济效益考虑，黄荆条可作为岩溶地区生物替代防治飞机草的优选植物。

Effect of water extracts of Vitex negundo L.and Alchornea trewioides in karst area on the germination of invasion plant Eupatorium odoratum

Vitex negundo L. and Alchornea trewioides are common native plants in Guangxi karst area. The invasion of Eupatorium odoratum is influenced by those two aboriginal plants. In the community which they are abundant, the coverage of E. odoratum is lower. In order to test if there is the allelopathic function from the two aboriginal plants on E. odoratum, the effects of the aqueous extracts of different concentration from their root, stem and leaf on seed germination of E. odoratum are studied. The results reveal that different concentrations of aqueous extracts of the root, stem and leaf of A. trewioides and the root and stern of V. ne- gundo had faint influences on the seed germination rate and speed of E. odoratum and exhibit accelerating in low concentration and inhibiting in high concentration. The seed germination rate is 20.75% of the contrast and the index of allelopathic effect is --3. 819 1 under the treatment with leaf aqueous extracts, which proves that Vitex negundo L. has significant inhibitory effect on seed germination of Eupatorium odoratum. Taking into account ecologic and economic benefit, V. negundo should be one of the best plants to biological substitute against E. odoratum.