根际真菌对黄瓜土传病害的抑制作用

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

为了了解根际真菌对黄瓜土传病害的影响,通过平板对峙试验和温室人工接种盆栽试验对分离自根际土的16株真菌开展了对土传病原真菌的拮抗作用和黄瓜土传病害的抑制作用研究.结果表明:有4株真菌对一种或多种供试病原真菌表现有拮抗作用,其中经鉴定为土曲霉的菌株JCL143对黄瓜枯萎病菌、立枯病菌和菌核病菌3种供试病原真菌均有较强的拮抗作用.在温室盆栽试验中,接种菌株JCL143对黄瓜3种病害的相对防效均在74%以上;而在不灭菌育苗基质的盆栽试验中,接种菌株JCL143对立枯病和菌核病的防效均在85%以上.在用自然土进行的温室盆栽试验中,接种菌株JCL143对伸蔓期黄瓜枯萎病的相对防效平均达84.1%.菌株JCL143的发酵液对3种供试病原真菌菌落生长都有不同程度的抑制作用,对菌核病菌的菌落生长抑菌率达63.3%.发酵液的抑菌活性随处理温度的升高而下降对碱性pH值比酸性pH值敏感,而对蛋白酶处理不敏感.说明土曲霉是土壤中抑制植物土传病害的重要因素,菌株JCL143的抑病效果稳定,具有潜在的生防应用价值.

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 pathogenic 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.