Seed Coating Formulations for Improving Rhizobia Survival, Growth, and Grain Yield of Common Bean

Coating legume seeds with Rhizobia have met a little success because of the difficulty in supporting bacterial survival on the seed coating agent. Accordingly, these studies aimed (i) to determine the best seed coating formulations to maintain the survival of Rhizobium phaseoli population on the surface of coated bean seed over a storage period of 0, 24, and 48 hours at 400C for laboratory trial, and (ii) to evaluate the best formulations for common bean growth and yield for field trial. Twelve seed coating formulations (SCFs) were used to coat garden bean seeds for the two studies. The results showed that four SCFs were the best for R. phaseoli  survival throughout the storage period. They contained combinations of gum arabic and peat moss (100%), gum arabic and peat moss+biochar (25%:75%), carboxymethyl cellulose and peat moss (100%), and carboxymethyl cellulose and peat moss+biochar (25%:75%). These four Rhizobia seed-coating formulations also promoted the best common bean growth and yield based on nodule number, plant dry weight, and grain yield indicators. Overall, these studies suggest that the four SCFs promoted the highest increase in nodulation, plant biomass production, and grain yield due to their ability to maintain the highest survival of R. phaseoli population on the surface of coated bean seed.