Rice blast, caused by Pyricularia grisea, is a highly destructive fungal disease that affects rice crops worldwide, annually inflicting significant damage on this crop and leading to a reduction in its yield. Considering that the use of chemical pesticides has become widespread for controlling this disease, and that these chemicals can have destructive effects on the environment, the present study was conducted with the aim of investigating the potential of Bacillus subtilis and Trichoderma harzianum for the biocontrol of this disease in the Hashemi rice cultivar. In this study, the effects of T. harzianum and B.subtilis, individually or in combination, were investigated using three methods: seed coating, seedling impregnation, and irrigation. The results showed that for all growth parameters examined, including shoot fresh weight, dry weight and length, root fresh weight, dry weight and length, as well as disease indices such as percentage of leaf surface infection, disease severity and percentage of disease reduction, the use of B. subtilis alone or in combination with T. harzianum as a seed treatment showed the best performance. Therefore, the application of the B. subtilis alone or in combination with T. harzianum, especially when applied by seed coating, has the greatest impact on reducing and controlling rice blast and improving the growth parameters of this crop. Consequently, it can be used by farmers as a practical method for the biocontrol of this disease.
