Influence of composite inoculations of phosphate solubilizing organisms and an arbuscular mycorrhizal fungus on yield, grain protein and phosphorus and nitrogen uptake by greengram

Abstract

The agronomic efficiency of nitrogen (N) fixing and phosphate solubilizing microorganisms and an arbuscular mycorrhizal (AM) fungus on vigour, photosynthetic pigments, seed yield, grain protein and nutrient uptake of greengram plants, were assessed in soils, deficient in phosphorous (P). The tripartite inoculation of Glomus fasciculatum + Bradyrhizobium sp. (vigna) + Bacillus subtilis, significantly increased dry matter, chlorophyll content and nutrient uptake of greengram plants. Generally, the number of nodules formed per plant was more at flowering stage, which decreased at podfill stage of plant growth. Seed yield increased significantly by 27% due to inoculation with Bradyrhizobium sp. (vigna) + B. subtilis + G. fasciculatum, relative to the control. Grain protein ranged from 17% (P. variabile) to 28% (Bradyrhizobium sp. (vigna) + B. subtilis + G. fasciculatum) in inoculated greengram. A negative effect occurred on some of the measured parameters when P. variabile was used alone or in combination treatments. The N and P contents in measured plant parts (e.g., roots, shoots, straw and grain) differed considerably among treatments. The populations of PSM, percentage of root infection and density of the AM fungal spore improved in some of the treatments.