除草剂对飞机草化感作用的影响研究

 运用野外实验和室内生物测定方法，以触杀型除草剂百草枯、传导型除草剂草甘膦和选择型除草剂稳杀得的不同质量浓度（1/4倍、 1/2倍、1倍推荐质量浓度）的药液处理飞机草，对处于胁迫下的飞机草进行动态取样，以小白菜为受体检测飞机草在不同类型除草 剂胁迫下的化感作用及变化规律。研究结果表明：①草甘膦与百草枯会引起飞机草化感作用增强，施药浓度越高化感作用越强，稳 杀得在中低施药浓度下会引起飞机草化感作用减弱，在高施药浓度下会引起较小幅度的波动；②3种除草剂引起飞机草化感作用变 化的模式不同，百草枯作用最快，在施药第10天飞机草化感作用达到最强，施草甘膦在第30天化感作用最强,施高浓度的稳杀得在第 20天飞机草化感作用最强；③3种农药的作用强度不同，同等剂量下草甘膦和百草枯接近，稳杀得较弱，只有在1倍推荐质量浓度下 才会引起飞机草化感作用强度增强；④施药飞机草的化感作用强度经过大的波动后，到第40天抑制作用都有所减弱，施药浓度越低 越容易恢复到对照水平。

Effect of Herbicide on Allelopathy of Chromolaena odoratum

The production, secretion of allelochemicals and the strength of allelopathic effect of plants largely depend on their habitat besides their inscape. Chromolaena odoratum, which was proved to have allelopathic effect, has spread throughout the agroecosystem and wildland in south China. Herbicide, as a kind of severe stress factor for most weeds, was widely used for the prevention of C.odoratum. Whether herbicide would affect secretion of allelochemicals and change the allelopathy eventually? The present research was projected to answer the question. In studies,three different types of herbicides, Paraquat, Glyphosate and Fluazifop butyl，were selected and sprayed to the C. odoratum populations in field in three different concentrations (half of recommend concentration, recommend concentration and double recommend concentration). The C.odoratum was sampled every 10 days after spray. Cabbage seeds were used to test the allelopathy trend. The results demonstrated: ① Glyphosate and Paraquat enhanced the allelopathy of C.odoratum, and the allelopathical potential improved with the herbicide concentration increasing. Fluazifop butyl, however, increased the allelopathy slightly only under high concentration, and recommend and lower concentration weakened the effect. ②Different type of herbicide resulted in different peak allelopathy time: the peak effect of Paraquat appeared on the 10th day, that of Glyphosate on the 30th day and Fluazifop butyl on the 20th.③For the intensity of three herbicides on allelopathy, Paraquat and Glyphosate were stronger than Fluazifop butyl, and no significant difference was found between Paraquat and Glyphosate.④ The phenomenon following fluctuation of allelopathy was the inhibitive effect decreased after 40 days, especially, the samples under lower concentration were easier to recover to control level. This result suggested that herbicide could strengthen the allelopathy of C. odoratum. Whether long term appliance of herbicide will induce the allelopathy varying in gene expression level need further research.