Evaluation of Pseudomonas mosselii PR5 as a biocontrol agent for controlling rice blast compared to Bacillus amyloliquefaciens-based biopesticide

Rice blast is a globally destructive disease that significantly impairs rice production and poses a serious threat to food security. While Pseudomonas mosselii has shown biocontrol potential against blast, its field-level efficacy remains underexplored. This study evaluated a native isolate, P. mosselii PR5, in three rice varieties susceptible to blast comparing its performance with a commercial biopesticide. Seven treatments were used: absolute control, negative control (Magnaporthe oryzae), positive control (commercial biopesticide), seedling priming (SeP), and SeP combined with bacterial cell filtrate (BCF) applied as one (BCF1), two (BCF2), or three (BCF3) foliar sprays. PR5 inoculation reduced blast severity following artificial inoculation with M. oryzae, with enhanced disease suppression observed in SeP + BCF3. At 21 days after inoculation, SeP + BCF3 lowered the disease indices from 33.55 to 17.03% in US2, 29.4–17.04% in BINA dhan18, and 32.22–16.26% in BRRI dhan28. PR5 treatments outperformed the commercial biopesticide in suppressing disease severity. In BRRI dhan28, SeP + BCF3 led to highest accumulation of most of the nutrients while SeP + BCF2 resulted highest accumulation of few grain nutrients. PR5 inoculation also improved agronomic traits, yield and grain proximate composition. SeP + BCF3 resulted highest grain yields in US2 and BINA dhan18, while in BRRI dhan28, SeP + BCF2 resulted the maximum, which was statistically similar to SeP + BCF3.These findings suggest that PR5 seedling priming combined with 2–3 foliar sprays offers an optimal strategy to manage rice blast effectively and boost the overall production of nutrient-rich rice.