Peanut response to co‐inoculation of Bradyrhizobium spp. and Azospirillum brasilense and molybdenum application in sandy soil of the Brazilian Cerrado

Abstract

AbstractThe use of plant growth–promoting rhizobacteria (PGPR) associated with rhizobia may improve biological N fixation, nutrient acquisition, and grain yield of the peanut (Arachis hypogaea L.). However, few studies have reported the effect of inoculation of rhizobia and PGPR in association with Mo in tropical soil conditions. This study examined the effectiveness of (co)inoculation with Bradyrhizobium spp. and/or Azospirillum brasilense and Mo application in improving the yield response of creeping peanut crop (‘RUNNER IAC 886’). The effects of rhizobacteria and Mo on nodulation, crop growth, chlorophyll content, and yield of peanut were investigated in a moderately acidic sandy soil (pH 5.0) from the Brazilian Cerrado during the 2016–2017 and 2017–2018 growing seasons. Four seed inoculation treatments (control [uninoculated seeds], inoculation with Bradyrhizobium spp. strains SEMIA 5079 and SEMIA 5080, inoculation with Azospirillum brasilense strains Ab‐V5 and Ab‐V6, and co‐inoculation of Bradyrhizobium spp. and Azospirillum brasilense) and two Mo levels (0 and 200 mg Mo kg−1 of seed) were studied. Results showed that the effects of the interaction between rhizobacteria and Mo application were not significant (p > .05) for all crop traits. Root nodulation, dry matter accumulation, and chlorophyll content were significantly greater in Mo‐treated peanut plants than control plants in both seasons. However, the response of crop grain yield was significantly greater (17.7%) in Mo‐treated plants only in the 2017–2018 season. Therefore, the improved root nodulation, crop growth, and chlorophyll content resulting from Mo application can lead to increased pod and grain yield in peanut. Inoculation with Bradyrhizobium spp. alone or combined with A. brasilense enhanced root nodulation, chlorophyll content, and peanut grain yield. Over two harvests, average peanut grain yield increased by 25.3 and 24.0% with inoculation of Bradyrhizobium spp. alone and combined with A. brasilense, respectively, compared with noninoculated plants. Due to lower cost and higher profitability, inoculation of Bradyrhizobium spp. alone is the most efficient practice for peanut cropping in sandy soils of the Brazilian Cerrado. Together with Mo application, these agricultural practices can be recommended for Brazilian peanut farmers.