CHARACTERIZATION OF SOIL TRICHODERMA ISOLATES FOR POTENTIAL BIOCONTROL OF PLANT PATHOGENS

Abstract

Various fungal strains belonging to genus Trichoderma act as biological control agents for soil born plant pathogens. Two new strains of Trichoderma harzianum (T.h.) and Trichoderma viride (T.v.) were isolated from forest soils in Ilfov county and their morphological aspects, enzymatic and antagonistic activity were examined. Current chemical fungicides had constantly, in time, less influence on pathogens due to their diversity, adaptability and increasing resistance. The paper present the morphological characterization of two strains of Trichoderma isolated from forest soils. Growth rate was higher in strain T.v.SP456 (0,675mm/h) than in strain T.h.P8 (0,505mm/h) when fungi were grown on Czapek culture medium. Morphological description is completed with photographs of colonies in Petri plates and microscopical aspects of fungal structures belonging to Trichoderma strains SP456 and P8. Comparative aspects concerning the level of main enzymes released by T.h. isolate P8 and T.v.SP456 in liquid culture media showed differences as a function of genetic structure of each fungal isolate. The optimum culture media for inducing peroxidase, polyphenol-oxidase, β-1,3-glucanase activity in T.v.SP456 isolate was Czapek and PDA for phenil-alanin-ammonium-oxidase and chitinase. T.v.SP456 was more efficient than T.h.P8 concerning enzymes activity. The interaction between Trichoderma fungal strains SP456 and P8 and strawberry plant pathogen strains, three belonging to Botrytis cinerea (S1, P1, P2) and one to Phytophtora spp. were examined, also. Both Trichoderma strains act as mycoparasites for plant pathogens. The inhibition percent of radial growth was higher for T.v.SP456 when compared with T.h.P8 for almost all pathogenic isolates.