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

Research Project

Project/Area Number	62480053
Research Category	Grant-in-Aid for General Scientific Research (B)
Allocation Type	Single-year Grants
Research Field	土壌・肥料
Research Institution	Kyushu University
Principal Investigator	KAWAGUCHI Sadao Kyushu University, Faculty of Agriculture Associate Professor, 農学部, 助教授 (20091366)
Co-Investigator(Kenkyū-buntansha)	WADA Shinichiro Kyushu University, Faculty of Agriculture Assistant Professor, 農学部, 助手 (60108678) IKEDA Motoki Kyushu University, Faculty of Agriculture Associate Professor, 農学部, 助教授 (00038283)
Project Period (FY)	1987 – 1989
Project Status	Completed (Fiscal Year 1989)
Budget Amount *help	¥5,400,000 (Direct Cost: ¥5,400,000) Fiscal Year 1989: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1988: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1987: ¥4,400,000 (Direct Cost: ¥4,400,000)
Keywords	Replant Failure / Antagonistic Microorganism / Biological Control / Phytophthora blight / Red Pepper / Fungilytic Action / Suppressive Soil / beta-Glucanase / Cellulase / Phytophthora capsici / トウガラシ / βーグルカナ-ゼ / Phytophthora capsici / 土壌酵素 / 疫病 / 溶菌活性 / 遊走子のう / 発病抑止
Research Abstract	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.