Allelopathy of Ageratum conyzoides Ⅸ. Transformation of Main Allelochemical in the Soil
胜红蓟化感作用研究 Ⅸ.主要化感物质在土壤中的转化

Under treatment condition of volatile oil from Ageratum conyzoides , the germination rate, fatty and protein enzymes, soluble protein of seed, root length, shoot height, chlorophyll content, the number of nodule of seedling and the number of branch, peg and pod as well as flowering period of peanut were tested and determined. All items and indexes demonstrated that the germination, growth and development of peanut were inhibited by volatile oil from A. conyzoides in the field. Obviously, allelopathic effects of volatile oil from A. conyzoides on peanut correlated with effective concentrations and active status of allelochemicals from volatile oil in the soil. Further research results by HPLC revealed that ageratochromene of main allelochemical from volatile oil firstly polymerized into dimers and depolymerized after 26 days under high organic matter and the fertility of soil, and then degraded gradually into benzoic acid and its derivatives, 2 methyl propanoic acid and acetic acid after 34 days. However, ageratochromene had no polymerization and directly degraded into benzoic acid and its derivatives, 2 methyl propanoic acid and acetic acid under low organic matter and the fertility of soil within 18 days. The results showed that transformation of ageratochromene in the soil were different and correlated significantly with organic matter and the fertility of soil. Dimers of transformation from ageratochromene in the soil were isolated and identified by means of LC/MS and NMR. Bioassay of ageratochromene and its transformation compounds in the soil on peanut and ryegrass showed that ageratochromene, benzoic acid and its derivatives inhibited significantly the growth of seedlings. However, dimers of ageratochromene had no inhibitory activities on the growth of peanut and ryegrass.