Induction of Resistance Related Responses of Phaseolus vulgaris to Rhizoctonia solani by Bio-fungicides

Damping-off is one of the major diseases of Phaseolus vulgaris in different parts of the country. Because damping-off agents are soil-borne, the use of chemical methods had not satisfactory results, therefore, in recent years much attention has been paid to the biological struggle, especially the use of Trichoderma fungi. One of the Trichoderma mechanism is the induction of the plant's defense system. In this research, five spices of Trichoderma harzaianum, T. viride, T. Konigi, T. atroviride, T. virense were used to induce resistance of bean plant (Phaseolus vulgaris) against Rhizoctonia solani. In order to investigate the effect of mutation induction in the Trichoderma genome on the rate of plant resistance induction, five superior mutants (from each Trichoderma spices) were used for treatment of plants. The experiments were carried out in a completely randomized design with four replications. Yield, malondialdehyde, proline, chlorophyll a and b, carotenoids and protein concentration in treated plants in greenhouse condition were evaluated. The data from the evaluations showed that the mutants of these Trichoderma species decrease the diseases incidence more than the same wild type Trichoderma species, which lead to increase the bio control potential of mutant based bio-fungicides in competitive with wild type based or chemical compounds. The amount of soluble protein, enzymes activity, chlorophyll a and b and carotenoids increased in Trichoderma treatments compared to control (pathogen treatment). The results of these experiments showed that seed coating formulations (mutant and wild) had better efficiency than other formulations for controlling damping-off disease and resistance induction in bean plant.