Bioassociative Effect of Rhizospheric Microorganisms on Growth, Yield, and Nutrient Uptake of Greengram

Abstract

The bioassociative effect of rhizospheric microorganisms on growth, yield, and nutrient uptake of greengram [Vigna radiata (L.) Wilczek] plant and available phosphorus (P) status of the soil was determined in a sandy clay loam soil, deficient in available P. Plant yield and nutrient [nitrogen (N) and P] uptake were significantly enhanced as a result of inoculation with Bradyrhizobium sp. (vigna) and phosphate solubilizing microorganisms (PSM), Pseudomonas striata or Penicillium variable. Plant yield and nutrient uptake were further augmented by the addition of AM fungus, Glomus fasciculatum in the combined inoculation treatment with Bradyrhizobium sp. (vigna) + P. striata. However, a negative effect occurred on all the considered parameters when G. fasciculatum was added to the combination of Bradyrhizobium sp. (vigna) and Penicillium variable. In addition, the available P status of the soil improved by the addition of P. striata with Bradyrhizobium sp. (vigna) and AM fungus. The nitrogen content of the soil did not show appreciable changes after the inoculation. The population of PSM in some treatments, percentage root infection and spore density of the AM fungus in the soil increased between 35 and 50 days of plant growth. These data suggest that if favorably interacting rhizospheric microorganisms are used as microbial inoculants, nodulation is improved as well as N and P uptake by greengram plant and hence also yield is increased. However, the applicability of this approach has to be tested in further field studies.

Keywords:

• Greengram
• N₂ fixing microorganisms
• Phosphate solubilizing microorganisms (PSM)
• Vesicular arbuscular mycorrhiza

Acknowledgments

One of the authors (Almas Zaidi) thanks Indian Agricultural Research Institute, New Delhi, India for providing specific cultures used in the study.