Combined Effect of Vam-Fungi and Rhizobium for Increasing Growth and Yield of Soybean

Abstract

Significant increase of VAM-spores population in the rhizosphere region was observed on cultivation of soybean plants as compared to the population before sowing. Higher population of VAM-spores was observed in the rhixospheric region of soybean var. NARC-I than the other 2 soybean vars. NARC-11 and William-82 at harvesting stage. a significant increase in the percentage of validity of VAM-spores from rhixospheric soil was founded from sowing upto the harvesting stage of soybean whereas there was a non-significant increase in the validity if VAM-spores in non-rhizospheric regions. VAM-infection percentage in soybean roots varied in the soybean valid and the initial VAM-infection was established within 15 days in root of all 3 soybean vars. Followed by an exponical increase upto the stage of maturity. A higher frequency of of VAN-infection was observed in NARC-1 followed by NARC-11 and William-82 respectively. Inoculation with axenic rhizobase VAM-inocula of different VAM-fungi separately in soil pots sown with soybean seeds opf 2 Vars. Resulted in significant increase in VAM-infection %, fresh and dry weights and seed weight per plant as against the control. of the six VAM-species inoculated in soil pots and plots, glomus macrocarpum showed a higher increase in fresh weight (28.2%) dry weight ( 25.3%) and seed weight (33.3%) per plant whereas acaulospora gerdemanii shoed least increase in fresh weight (18.0%) dry weight (16.6%) as compared to the control. The effect of seed inoculation of soybean seed with two strains of nitrogen fixing bacteria viz. Rhizobium japonicum strain KUBFH-145 and phizo-bium japonicum strain KUBFH-146 produced more nodulation, VAM-infection, growth and yield of soybean plants as compared to the control. Of the two nitrogen fixing bacteria, Rhizobium japonicum strain-145 produced increasing number of nodules, nodule weight, fresh weight (22.9%), dry weight (23.2%) and seed weight (22.9%) per plant with inoculated seeds in experimental plots than without inoculation. On combined inoculation of the nitrogen fixing bacterium, Rhizobium japonicum strain KUBFH-145, either with the VAM-fungus Glomus macrocarpum or Glomus warcupii produced better growth response than on inoculation either either with the bacterium or VAM-fungus cultures separately. Of the two VAM-fungi, Glomus macrocarpum in combination with Rhizobium japonicum strain KUBFH-1345 produced increase fresh (30.2%) dry (31.5%) weight / plant (34.0) which was highly significant thsn when inoculated with Glomus warcupi combination with Rhizobium japonicum strain KUBFH-145. In general on combined inoculation both in pots and lots there was a significant increase in the number and weight of nodules, VAM-infection, fresh and dry weights, and seed weight /plant of soybean. It was thus found that on combined inoculation of an efficient strain of a VAM-fungus and Rhizobium improved growth and yield of soybean plants took place than on separate inoculation of a VAM-fungus or a strain of rhizbium.