Co-inoculation Effects of Phosphate Solubilizing Microorganisms and Glomus fasciculatum on Green Gram-Bradyrhizobium Symbiosis

Authors: ALMAS ZAIDI, MOHAMMAD SAGHIR KHAN

Abstract: Experiments were conducted to evaluate the effects of nitrogen fixing (Bradyrhizobium sp. (Vigna)), phosphate solubilizing bacterium (Bacillus subtilis), phosphate solubilizing fungus (Aspergillus awamori) and AM fungus (Glomus fasciculatum) on the growth, chlorophyll content, seed yield, nodulation, grain protein, and N and P uptake of green gram plants grown in phosphorus-deficient soils. The triple inoculation of AM fungus, Bradyrhizobium sp. (Vigna) and B. subtilis significantly increased dry matter yield, chlorophyll content in foliage and N and P uptake of green gram plants. Seed yield was enhanced by 24% following triple inoculation of Bradyrhizobium + G. fasciculatum + B. subtilis, relative to the control. Nodule occupancy, determined by indirect enzyme linked immunosorbent assay (ELISA), ranged between 77% (Bradyrhizobium + A. awamori) and 96% (Bradyrhizobium + G. fasciculatum + B. subtilis) at flowering (45 DAS), decreasing at the pod-fill (60 DAS) stage with each treatment. Replica immunoblot assay (RIBA) revealed a greater variation in the rhizobial populations within nodules and the correlation between nodule occupancy and immunoblot counts was highly significant at 45 (r = 0.95) and at 60 DAS (r = 0.96). There was a negative effect on some of the measured parameters when A. awamori was used alone or added to the combination treatments. The present findings showed that rhizospheric microorganisms can interact positively in promoting plant growth, as well as N and P uptake of green gram plants, leading to improved yield.

Keywords: AM fungi, ELISA, green gram, N uptake

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