a.s mohamadi - Biotechnology Department, Faculty of Agriculture, Pyam e Noor University, Alborz, Iran
s shahbazi - Radiation Application Research School,Nuclear Science and Technology Research Institute(NSTRI) Atomic Energy organization of IRAN (AEOI)Alborz, Iran
h askari - Radiation Application Research School,Nuclear Science and Technology Research Institute(NSTRI) Atomic Energy organization of IRAN (AEOI)Alborz, Iran

Trichoderma viride was isolated from soil and its spore suspensions were irradiated in different dose of γ-radiation (0-400 Gy) for induced mutation. Dose of 250 Gy γ-radiation approximately results in 43.4% the inhibition of spore germination and this dose selected for optimum dose of induced mutation in Trichoderma. The T. viride mutants were selected based on potential growth on selective medium and their morphological characteristics and antagonistic activity against pathogenic fungi of Rhizoctonia solani have been evaluated. The results showed that γ-radiation could change the morphological characteristics like: colonies shape, color, sporolation and mycelia growth rate. Trichoderma mutants of T. v M12, T. v M11 and T. v M21 maintained higher ability to restrict R. solani. The study clearly showed the possibility of improving the antagonistic capability of Trichoderma for biological control of plant diseases through mutation with γ-radiation

γ-radiation; Trichoderma viride; R.solani; bio-control; mutation