Formulations of Pseudomonas fluorescens and Burkholderia pyrrocinia control rice blast of upland rice cultivated under no-tillage system

Abstract

Leaf blast caused by Magnaporthe oryzae is among the major diseases that limit rice productivity in the world, and control of the disease occurs, basically, through the application of fungicides. Control methods such as the application of growth promoting rhizobacteria could be inserted in the integrated management of rice blast. The objective of this work was to evaluate the potential of four liquid formulations containing Pseudomonas fluorescens (BRM 32111) and Burkholderia pyrrocina (BRM 32113) to suppress leaf blast, under field conditions. The trials were conducted at Embrapa Rice and Beans, between December 2018 and April 2019. The experiments were performed in a randomized block containing 7 treatments, 4 replicates. The treatments consisted of microbiolized seeds and sprays at 14 and 21 days after planting with: Formulation 11 + BRM 32,113 (T1); Formulation 32 + BRM 32,113 (T2); Formulation 11 + BRM 32,111 (T3): Formulation 20 + BRM 32,111 (T4); BRM 32,111 (T5); BRM 32,113 (T6) and Absolute control (water – T7). Severity of leaf blast and panicle, gas exchange and grain yield were evaluated. Plants treated with P. fluorescens (T3, T4 and T5) or B. pyrrocinia (T1, T2 and T6) presented 49%, 39%, 60%, 15% increase in the assimilation rate of CO2 (A), transpiration (E), stomatal conductance (gs) and internal CO2 concentration (Ci), respectively. All treatments were efficient in suppressing leaf and panicle blast and in promoting biomass increase in 55%. The yields of T1, T4, T5 and T6 treatments increased 481, 424, 688 and 427 kg ha−1, respectively. Our results indicate that the formulated rhizobacteria have the potential to be included in the integrated management for blast control in rice fields.