EFFECT OF Trichoderma SPECIES ON ZOOSPORE PRODUCTION OF Phytophthora sojae, DISEASE SEVERITY, AND GLUCANASE ENZYMES ACTIVITY ASSAY

In this present study the antagonistic effect of culture filtrate metabolites of twelve Trichoderma species including: Trichoderma ceramicum, T. virens, T. pseudokoningii, T. koningii, T. koningiosis, T. atroviridae, T. viridescens, T. asperellum, T. harzianum, T. orientalis., T. brevicompactum and T. spirale was studied on Phytophthora sojae zoospore production and activity rate of β-1, 3-glucanase and β-1, 4-glucanase enzymes of all species in relation to degradation of Phytophthora cell wall used in laboratory condition. In final tests, the biocontrol effect of Trichoderma species on Phytophthora root rot of soybean in greenhouse, was also studied. To analyze the effects of culture filtrates on the zoospore production at concentrations of 0. 5, 1, 5, and 10 percent the culture were used in sterile deionized distilld water. To compare the effect of two types of carbon source on production of hydrolytic enzymes by Trichoderma, activity rate of β-1, 3-glucanase and β-1, 4-glucanase enzymes of all species were evaluated in presence of glycerol and P. sojae - hyphe as the carbon source in Wiendling’s medium. The results showed that culture filtrates of all species inhibited of zoospore production. Different concentration had different inhibition effects. The most inhibition effects was obtained from T. virens and T. brevicampactom culture filtrates. The results of enzyme assays showed that using Phytophthora - hyphe in medium increased the β-1, 3-glucanase and β-1, 4-glucanase enzyme activities compared with glycerol in all Trichoderma species. The highest activity rates for both enzyme obtained from T. brevicompactum and T. virens which for β-1, 3-glucanase in glycerol treatment were 2. 31 and 1. 73 U/mg protein and in P. sojae hyphe treatment were 4. 47 and 3. 91 U/mg protein. The activity rate of β-1, 4-glucanase was 0. 66 and 0. 86 U/mg protein in glycerol treatment and 1. 72 and 1. 72 U/mg protein in P. sojae hyphe treatment. To study the biocontrol effect of Trichoderma species on the soybean root rot severity, a completely randomized design was used with 15 treatments including each Trichoderma species cultured on wheat bran plus disease agent in sterile soil, at the trifoliolate stage (v1) of soybean (Wiliams cultivar), health control and disease control in the same kind soil, with three replicates at greenhouse condition. T. orientalis، T. brevicompactum and T. spirale showed the most effects on the disease severity reduction, damping of reduction and the growing factor promotion.