Inoculation with selected microbial consortia not only enhances growth and yield of French bean but also reduces fertilizer application under field condition

French bean is an important vegetable crop. An earlier pot culture study brought out that Paenibacillus polymyxa (Pp) and Pantoea agglomerans (Pa) to be the best PGPR (both being equally good) and Funneliformis mosseae (Fm) to be the best arbuscular mycorrhizal (AM) fungus for inoculating French bean. In the present investigation, a pot culture experiment was conducted in a polyethylene house to study the effect of soil inoculation with Pp, Pa and Fmsingly and in combination on the growth of French bean. Plant growth, nutrition, yield, mycorrhizal root colonization and alkaline phosphatase activity in the root zone soil were found to be higher when Fm was co-inoculated with both the PGPR Pp + Pacompared to inoculation with individual organisms and the uninoculated treatment. The percent increase in fruit yield over control was 108% when inoculated with all the three organisms. It was concluded that the inoculated organisms interact synergistically and a microbial consortia consisting of all the three organisms is the best for inoculating French bean. This pot culture trial was followed by a field experiment to validate the results of the pot culture trial and to find out the possibility of reducing the amount of chemical fertilizer application through the application of the selected microbial consortia. The six treatments for the field experiment were (i) control (ii) microbial consortia (MC) consisting of Fm+Pp+Pa(iii) MC + 100NPK (100% recommended NPK fertilizer by the University of Agricultural Sciences in the region) (iv) MC + 75NPK (75% recommended fertilizer) (v) MC +50NPK (50% recommended fertilizer) and (vi) 100NPK. The result brought out that plant height, stem girth, shoot dry biomass and fruit yield are higher in the treatment MC + 75NPK and is statistically on par with the treatment 100NPK, suggesting that application of chemical fertilizers for French bean cultivation can be reduced by 25% through treatment with microbial consortia. The increase in fruit yield was 41% and 32.5% in MC+ 75NPK and 100NPK treatments respectively over control, thus 7% more in MC+ 75 NPK treatment compared to the treatment with recommended chemical fertilizer. (C) 2015 Elsevier B.V. All rights reserved.