Primary Study On Biological Characters Of Gliocladium Virens And Its Potential Of Biocontrol To Maize Sheath Blight

Rhizoctonia solani was isolated from the infected sheath of maize in suburb of Ya—an,Sichuan.The pathogen was belong to R.solani AG-1-IA.107 strains of G.virens were isolated from the different crop soil in surburb of Ya-an. According to the sites where strais were isolated, hyphal growth rate and color of the colony, 37 strains of G.virens were chosed to make further study.4 strains, named G13,G17,G25 and G33 respectively,that possessed stronger potential ability for plant disease biocontrol were screened from the 37 strains of G. virens through the hyphal growth rate, dual culture on PDA plates, effects of volatile and non-volatile metabolites.Some biological characters of 4 strains of G.virens were that the optimum conditions for hyphal growth rate of G.virens were darkness, 25℃ to 30℃, pH5 to 8 and the optimum conditions for spore sporulation were darkness, 25℃ to 35℃ and pH5 to 8 as well as the optimum conditions for conidiophore germination were light, 30℃ to 35℃ and pH5 to 8.Temperature, illumination and pH were the most important factors on hyphal growth rate and spore sporulation of G.virens.The orthogonal test of three factors,i.e.temperature,illumination and pH,was designed. The result showed that the best conditions combination of hyphal growth rate were 25℃,pH6 in darkness.And the optimum conditions for spore sporulation were 25℃, pH5 in light.The effects of G.virens on germination of maize seed showed that low concentrations fermentation liquid of G.virens made for high germinative rate,and could promote the growth of radicle and plumule of maize seed.And high concentrations fermentation liquid of G.virens reduced the germinative rate,and restrained the growth of radicle and plumule of maize seed.There was little effect on growth of maize seedling by appending bran-sand culture of G.virens into soil. There was obviously effect on maize seeding growth when appending culture of G.virens mixed with PCNB into the soil and the plant heights were much higher than other treatments. And the ratio of root/stem was smaller than other treatments.