Combined Application of Fungicide Tolerant Pseudomonas fluorescens and Reduced Dosage of Azoxystrobin for the Management of Rice Blast

摘要

Twenty isolates of P. fluorescens were isolated and identified based on morphology and amplification of ITS region.Ten foliar fungicides and twenty P. fluorescens isolates were evaluated for the inhibitory action against P. oryzae and among these azoxystrobin and P. fluorescens PF9 exerted maximum inhibition. Further, fungicide azoxystrobin was compatible with/! fluorescens PF9. The interaction between azoxystrobin andP fluorescens for arresting the growth and sporulation of P. oryzae was found to be synergistic. Inaddition, Gas Chromatography Mass Spectrum (GCMS) analysis of the effective isolate of P. fluorescens PF9 revealed seven antimicrobial biomolecules. Increased activity ofthe enzymes viz., peroxidase, polyphenol oxidase, catalase, phenylalanine ammonia - lyase, pM, 3-glucanase and phenol content were observed in the rice seedlings when treated with the azoxystrobin 125 g a.i. ha'in combination of P. fluorescens against rice blast disease. Further, native PAGE analysis ofthe rice seedlings treated with azoxystrobin 125 g a.i. ha'in combination of P. fluorescens revealed an additional isoforms. The efficacy of azoxystrobin at different dosages in combination with P. fluorescens was tested under field conditions using two most susceptible varieties Co39 and ASD 19 at two locations and was observed that the treatment azoxystrobin 125 g a.i. ha"1 plus P. fluorescens (0.2 %) recorded the least incidence of leaf and neck blast disease. The interaction of azoxystrobin and P. fluorescens for suppressing leaf and neck blast was categorised as additive in both the locations. Further, yield was also increased in the above treatment.