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Suppression of three soil-borne diseases of cucumber by a rhizosphere fungal strain.

LYU Heng1,2, NIU Yong-chun2, DENG Hui2, LIN Xiao-min1, JIN Chun-li2   

  1. (1Department of Forestry, Henan University of Science and Technology, Luoyang 471003, China; 2Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences / Key Laboratory of Microbial Resources, Ministry of Agriculture, Beijing 100081, China)
  • Online:2015-12-18 Published:2015-12-18

Abstract: To understand the effect of rhizosphere fungi on soilborne diseases of cucumber, 16 fungal strains from rhizosphere soil were investigated for the antagonistic activity to three soilborne pathogenic fungi with dual culture method and for suppression of cucumber diseases caused by the pathogens in pot experiments. Four strains showed antagonism to one or more pathogenic fungi tested. The strain JCL143, identified as Aspergillus terreus, showed strong antagonistic activity to the three pathogenic fungi Fusarium oxysporum f. sp. cucumerinum, Rhizoctonia solani and Sclerotinia sclerotiorum. In greenhouse pot experiments, inoculation with strain JCL143 provided 74% or more of relative control effect to all the three diseases of cucumber seedling caused by the above three pathogenic fungi, and provided 85% or more of relative control effect to Rhizoctonia root rot and Sclerotinia root and stem rot in pot experiment with nonsterilized substrate. In pot experiment with natural soil as substrate, inoculation with strain JCL143 provided average 84.1% of relative control effect to Fusarium wilt of cucumber at vine elongation stage. The fermentation broth of strain JCL143 showed inhibitory effect in different degrees on the colonial growth of the three pathogenic fungi tested, and reached 63.3% of inhibitory rate of colonial growth to S. sclerotiorum. The inhibitory activity of the fermentation broth decreased with increasing treatment temperature, was liable to decrease to alkaline pH than acid pH, and stable to protease treatment. The results indicated that A. terreus is an important factor in suppression of plant soil-borne diseases, and strain JCL143 with stable disease suppression is potential in biocontrol application.