Mechanism of biological suppression of replant failure and the utilization of antagonistic microorganisms against Phytophthora blight of red pepper.

由于红辣椒易受辣椒疫霉病的影响，再植失败一直是制约红辣椒连作的重要因素。本研究旨在阐明栽培土壤中微生物对红辣椒连作危害的抑制作用，为拮抗微生物的合理应用奠定基础。本文的研究结果表明：1。对比土壤对红辣椒疫霉的抑制和促进作用，抑制力的大小与土壤微生物特性的关系比与土壤理化性质的关系更密切。施用一些有机质对辣椒粉侵染红辣椒的抑制作用呈减弱趋势，其中秸秆改进剂在秋季温度期的抑制作用最强。从抑制土壤中分离出的拮抗微生物中，绿木霉和黑曲霉对辣椒粉的侵染效果最好。对疫霉的抑制力与土壤的真菌作用密切相关，使病原菌数量显著减少。土壤的真菌降解作用也与灌剂和土壤中β -葡聚糖酶和纤维素酶的活性密切相关。而几丁质酶活性与真菌降解作用无关。辣椒菌丝细胞壁主要由β -葡聚糖和纤维素组成，并含有少量的几丁质，表明其抗疫作用的机制是通过两种酶的活性来水解细胞壁成分。

Replant failure has been a serious limitation for a continuous cropping of red pepper because it is susceptible of phytophthora blight Phytophthora capsici Leonian.This study has been performed to clarify the microbiological suppression of the cultivated soils against the injury by continuous cropping of red pepper and establish the rational use of antagonistic microorganisms for the biological control. The results presented here show that:1. Comparing the soils suppressive and conducive to phytophthora blight of red pepper, the magnitude of suppressive force is more closely related to soil microbiological characters than physical and chemical properties of soils.2. Suppression of the infection of red pepper by P. capsici with application of some organic matters can be rendered decreased in the severity, among of which rice straw amendment was most suppressive during the mild temperature season at autumn.3. Among antagonistic microorganisms isolated from suppressive soils, Trichoderma viride and Aspergillus niger led the most effectively to lessen infection of red pepper by P. capsici.4. Suppressive force against Phytophthora blight was closely related to fungilytic action of soils so that the population of the pathogen remarkably decreased.5. The fungilytic action of soils also well correlated with the activities of both beta-glucanase and cellulase in inculants and soils. chitinase activities however,had no connection with fungilytic action.6. The hyphal cell wall of P.capsici is primarily made up of beta-glucan and cellulose and contained a few amount of chitin, which suggested that mechanism of fungilytic action against phytopthora blight was attributed to two enzyme activities, hydrolysing the cell wall components.