Abstract

In this study the in vitro potential of six selected Iranian isolates of three species of Trichoderma (Trichoderma hamatum T614, T. hamatum T612, Trichoderma harzianum T447, T. harzianum T969, Trichoderma virens T523 andTrichoderma sp. T) were evaluated against five isolates of soil borne phytopathogenic fungi (Fusarium graminearum, Rhizoctonia solani (AG4 and AG5), Macrophomina phaseoli and Phytophtora cacturum) in dual culture techniques and through production of volatile and non-volatile inhibitors, and the pH and temperature effects on Trichoderma mycelial growth were also evaluated. All Trichoderma isolates had a marked statistical inhibitory effect on mycelial growth of the pathogens in dual culture compared with controls. Maximum inhibitions occurred in F. graminearum-T. hamatum T614 interaction. Significant pathogen colony growth inhibitions were observed when exposed to the trapped atmosphere from culture of the Trichoderma. F. graminearum was most susceptible to the volatile inhibitors produced by T. hamatum T612 (%inhibition = 48.65). Medium filtrate obtained the Trichoderma isolate culture also were effected on the pathogen species significantly. Maximum growth inhibition was observed in radial growth of F. graminearum by T. hamatum T612 non volatile metabolites (%inhibition = 38.3). Evaluation of pH and temperature effects on Trichoderma isolates mycelial growth showed that Trichodermastrains were found to be able to display activities under a wider range of pH values. Also, Trichoderma strains are mesophilic.

Key words: Trichoderma spp., biological potantial, soil borne phytopathogenic fungi, Iran.