Antagonistic Bacillus spp. reduce blast incidence on rice and increase grain yield under field conditions

Rice blast is a severe threat for agricultural production. Plant growth promoting rhizobacteria could be suitable biocontrol agents to reduce the disease incidence. In this study, Bacillus spp. KFP-5, KFP-7, KFP-17 significantly reduced disease severity by 40-52% with grain yield of 3.2-3.9 t ha−1 in two rice varieties i.e., basmati super and basmati 385. Bacillus spp. significantly colonized the rice rhizosphere with a cell population of 2.40E+06-5.6E+07CFU. Rice plants treated with antagonistic bacterial suspension followed by challenge inoculation with P. oryzae were found to have higher activities of antioxidant enzymes such as superoxide dismutase (308-266 Ug−1 FW), peroxidase (change in absorbance (ΔA) = 0.20-0.71 min−1 g−1 FW), polyphenol oxidase (ΔA = 0.29-0.58 min−1 g−1 FW) and phenylalanine ammonia lyase (ΔA = 0.32-0.59 min−1 g−1 FW). A consistency in the performance of strains was observed in the consecutive years 2013-2014. These findings suggest that indigenous Bacillus spp. could be a potential bio-inoculum for rice to control blast diseases and enhance yield.