Studies on the Synergism among Rhizobium, Phosphate Solubilizing Bacteria and Plant Growth-Promoting Rhizobacteria and their Effect on the Blackgram (Vigna mungo L.)

Field experiments were conducted to study the synergistic effect among Rhizobium with phosphate solubilizing bacteria (PSB) and plant growthpromoting rhizobacteria (PGPR) and their effect on the growth and yield of blackgram. Seeds of blackgram variety VBN(Bg)-5 were treatedwiththe inoculants individually, dually andin combination with each other and sown in the Kharif seasons of the year 2012–13 and 2013–14. The results revealed that inoculation of Rhizobium sp., PSB and PGPR individually increased the root length, shoot length and numberof nodules perplant over the uninoculated control. However, the composite inoculation of all inoculants resulted in an increased growth attributes and nodulation. A similar response to combined inoculation of Rhizobium + PSB + PGPR was noticed in terms of plant biomass and grain yield for both the years under study. It registered higher mean grain yield of 1106.2 kg/ha, whereas the uninoculated control recorded only 892.9 kg/ha. From this study it is evident that synergism was found amongst Rhizobium, PSB and PGPR which resulted in an increased growth and yield in blackgram.