SORGHUM GENOTYPES RESPONSE TO INOCULATION WITH PHOSPHATE SOLUBILIZING BACTERIA

Abstract

Sorghum bicolor adapts to phosphorus (P) deficient soils through mechanisms that contribute to its absorption and solubilization, including the association with microorganisms. The direct application of rock phosphate (RP) and the inoculation with phosphate solubilizing bacteria (PSB) is a sustainable alternative for P supply to the crops. The aim of this study was to evaluate the effect of PSB inoculation of two sorghum genotypes with different P responses (BR007 - efficient and responsive and SC283 - efficient and non-responsive), cultivated in soil fertilized with RP and triple superphosphate (TSP), in greenhouse and field experiments. The sorghum genotypes were inoculated separately with the Bacillus strains that are efficient in P solubilization, B116 and B70, and cultivated under different P fertilization sources (TSP, RP, ½TSP + ½RP). The results suggest that the inoculation response was dependent on sorghum genotype, P source and microbial strain. Inoculation of the genotype BR007 significantly increased root biomass and grain P content under greenhouse conditions, as well as yield and grain P content in field experiments, but no effect was observed on genotype SC283. The use of PSB as bioinoculants, in combination with RP, is a promising alternative to reduce the use of synthetic fertilizers, contributing to the sustainable sorghum production.