胜红蓟化感作用研究 Ⅸ.主要化感物质在土壤中的转化

Allelopathy of Ageratum conyzoides Ⅸ. Transformation of Main Allelochemical in the Soil

在田间条件下 ,胜红蓟挥发油能抑制花生的出苗和生长发育。进一步用高效液相色谱 (HPLC)研究证实 :胜红蓟挥发油中的主要化感物质胜红蓟素在土壤中的转化与土壤的有机质和营养元素水平显著相关。在高有机质和营养元素水平的土壤中 ,胜红蓟素先聚合形成二聚体 ,2 6d后又解聚成胜红蓟素 ,然后逐步降解成苯甲酸类 ,2 -甲基丙酸和乙酸等小分子。而在低有机质和营养元素水平的土壤中 ,胜红蓟素不经过二聚化过程 ,而是直接降解成小分子。经液质 (LC/MS)和核磁共振 (NMR)等技术分离鉴定了胜红蓟素二聚体的结构。生物测定表明

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.