Evaluation of antagonistic properties of Trichoderma harzianum mutants against some plant pathogenic fungi in vitro

Soilborne fungal plant pathogens which cause damping-off، root and crown rot and reduce the seed germination lead to crop loss. The biocontrol fungus Trichoderma species is known as the most important antagonists against soilborne fungal diseases. In this study، to improve the efficiency of biological control of antagonists، mutation induction by gamma irradiation was conducted in Gamacell with optimized dose of 250 Gy per second (rate of 0. 23 Gy)، and 24 mutants of Trichoderma harzianum 65 (wild type) isolate were selected. The study of antagonistic properties against Macrophomina phaseolina، Rhizoctonia solani AG4، Sclerotinia sclerotiorum and Fusarium graminearum was done in dual culture، volatile metabolites and extracellular extracts tests in a completely randomized design with three replications.، Th15، Th11، Th5، Th1، Th4 and Th 22 mutants showed the maximum growth inhibition and was inroduced as superior mutants. These mutants have capaibility of evaluation in greenhouse biocontrol tests.