Does coinoculation with bradyrhizobia and cyanobacteria improve groundnut growth and yield?

Groundnut plants can obtain N from N2 fixation via symbiosis with rhizobia, and inoculation with selected strains can improve grain yields. We report the results of four field experiments carried out under subtropical conditions to confirm whether microbial inoculants can improve groundnut performance through the effects of single inoculation with Bradyrhizobium arachidis (SEMIA6144), coinoculation with Arthrospira platensis (IPR7059) or Synechocystis sp. (IPR7061), or N fertilization with 100 kg ha-1 N on plant growth, nodulation, N accumulation in tissues, grain protein concentration (GPC), and grain yield. There were no effects of inoculation treatment or N fertilizer on shoot or root dry weight. In clayey soil, coinoculation with B. arachidis and cyanobacteria increased grain productivity by an average of 19% compared to that in the noninoculated control. In this clayey soil with a higher P content, regardless of whether coinoculated with B. arachidis or cyanobacteria or single inoculated, grain productivity was 16% greater on average than that resulting from N fertilizer addition. In conclusion, the success of rhizobial inoculation in groundnuts is dependent on the soil, probably due to P limitation and weather conditions.