Groundnut grain yield responses to inoculation with Bradyrhizobium sp. and cyanobacteria

Abstract

Groundnut can obtain N from the N2 fixation in the symbiosis with rhizobia and inoculation with selected strains can improve grain yields. We report the results from four field experiments, aiming to verify if microbial inoculants may improve groundnut performance, through the effects of single inoculation with Bradyrhizobium sp. (SEMIA6144), of co-inoculation Arthrospira platensis IPR7059 or Synechocystis sp. IPR7061, and of the N fertilization with 100 kg ha− 1 of N on plant growth, nodulation, N accumulated in tissues, grain protein, and grain yield. There were no effects of inoculation treatments and N-fertilizer on shoot and root dry weights. In clayey soil, co-inoculation with Bradyrhizobium sp. and cyanobacteria increased grain productivity by an average of 19% compared to the non-inoculated control. In this clayey soil with higher P content, regardless of whether co-inoculated with Bradyrhizobium sp. and cyanobacteria or single inoculated, grain productivity was 16% higher on average compared to nitrogen fertilizer. In conclusion, it was clear that success of rhizobia inoculation in groundnut is dependent on the soil, probably due to P limitation, and weather conditions.