RESEARCH REPORTS FROM INSTITUTE FOR AGRO-MICROBIOLOGY, Vol. 3, 1999 p.87-94
Copyright © Institute for Agro-Microbiology. All Rights Reserved.

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GRANT REPORT

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8.Evaluation of Non-Pathogenic Pythium spp. as Biocontrol Agents Against Pythium Root Rot Enhanced by the Incorporation of Green Manure

-Population Changes of Pythium spp. in Soil by Incorporation of Green Manure-

Motoaki Tojo, Kayoko Nakayama and Hiroko Mimura (College of Agriculture, Osaka Prefecture University)

Population changes of Pythium spp. in soil by incorporation of green manure were investigated to obtain non-pathogenic Pythium isolates as biocontrol agents against Pythium root rot enhanced by the decomposition of green manure. Oat and red clover were used as green manure crops. Field experiments were performed at Ebetsu, Hokkaido and Sakai, Osaka. Population densities of Pythium spp. increased at 0 to 20 days and significantly declined at 20 to 30 days after incorporation of green manure into soils. Maximum densities of the increased populations of Pythium spp. were higher in soil incorporated with red clover than in soil incorporated with oat. These population changes of Pythium spp. in soil were observed at both of Ebetsu and Sakai. Ten pathogenic Pythium spp. which including P. ultimum, P. spinosum, Pythium 'group HS', P. irregulare and unidentified Pythium spp. were increased by green manure incorporation into soils. P. oligandrum, which was non-pathogenic to cucumber seedlings and indicated mycoparasitism to P. ultimum, was found in soils before and after incorporation of green manure at both of Ebetsu and Sakai.

キーワード／Keywords
生物防除資材／biocontrol agents、緑肥分解／decomposition of green manure、菌間寄生性／mycoparasitism、非病原性Pythium属菌／non-pathogenic Pythium spp、病原性Pythium属菌／pathogenic Pythium spp.