Identify The Substances In Root Exudates Of Soybean And Study On Allelopathy

Soybean was one of the most important food and oil crops in China. Common soybean was full of protein and fat, and the comprehensive utilization was high. Therefore, soybean was one indispensable crop. However, the contradiction between limited land and market supply all year long resulted in the phenomenon that continuous cropping obstacles became more and more common and serious.Studies had shown that allelopathy effect was one of the most important factors of continuous cropping obstacles. The root of crops could secrete large amounts of allelochemicals, and they could do some allelopathy with those crops. In order to understand the allelopathy of root exudates on soybean, this experiment was to the crop root exudates as an object of study. Identification of root exudates components was used of GC-MS. The identification results showed that the more appropriate collection methods and extraction reagents. Analysis and comparison with the different composition of root exudates among soybean, corn and wheat; Analysis and comparison with the different composition of soybean root exudates among the first crop, one year and two years of continuous cropping; It made biological detection for seed germination and seedling growth of allelopathy of soybean, corn, wheat and sorghum with soybean root exudates in three different levels of concentration. The main results were as follow:1. The experiments were used of three kinds of reagents that dichloromethane, ethyl acetate, ethyl ether and three kinds of methods to collect root exudates that solution collection method, in situ soil solution sampler, rhizosphere soil collection method. The results showed that the root exudates that in situ soil solution sampler collected was closest to the actual situation of the natural. Dichloromethane were able to extract more compounds or allelochemicals.2. The root exudates of soybean, corn, and wheat contained major compounds that hydrocarbons, alcohols, acids, esters, phenols, aldehydes, benzene, naphthalene and naphthylamine. However, the root exudates of soybean were more than corn and wheat's. And it could detect a wider range of allelopathic substances in the root exudates of soybean, while corn and wheat did not have.3. The main compounds in soybean root exudates of the first crop, one year and two years of continuous cropping were basically the same category that contained hydrocarbons, alcohols, acids, esters, phenols, aldehydes, ketones, benzene, naphthalene and other compounds. However, the compounds of one year and two years of continuous cropping were more than the first crop. And the more years of continuous cropping, allelochemicals of root secreted by the more.4. In this experiment, soybean, corn, wheat and sorghum crops, as subjects, and exerted their seeds and seedlings with soybean root exudates of different concentrations.It did seed germination experiments and seedling fresh weight, plant height, root length, chlorophyll content and root activity. The results show that four kinds crops seed germination were allelopathic inhibition of different levels. And the greater the concentration of soybean root exudates, the stronger the inhibition; However, soybean root exudates were played promote the role of allelopathy for wheat seedling growth and development; Corn and sorghum seedlings showed weak inhibition of the allelopathic. Soybean seedlings showed a significant inhibition of the allelopathic, and the greater the concentration of soybean root exudates, the stronger the inhibition.