Effect of different microbial inoculants on soil properties, nutrient acquisition and growth of pomegranate (Punica granatum)

Abstract

An experiment was conducted during 2007 and 2008 to evaluate the effectiveness of various microbial inoculants in pomegranate saplings prepared from air layers. The present study demonstrates the beneficial effect of seven microbial inoculants, viz. Gluconaetobacter diazotrophicus, Pseudomonas striata, Trichoderma viride, P. fluorescens, Azospirillum brasilense, pink pigmented facultative methylotrophs (PPFM) isolated from pomegranate and cotton, as a sole inoculant or in combination, on nutrient acquisition and plant growth under semi-arid agro-climatic condition. Inoculation with T. viride recorded highest content of available N, P and DTPA extractable Zn content of the soil. This was followed by A. brasilense and G. diazotrophicus inoculation for nitrogen content while P. fluorescence and P. striata for phosphorus content. Among various microbial inoculants, P. fluorescence was found efficient in promoting photosynthesis and transpiration rate of the plant. Dual inoculation with N2-fixing A. brasilense and P-solubilizing P. striata was most effective in promoting uptake of most of the major and micronutrients through beneficial interaction. A significant improvement in plant height and shoot biomass was also recorded in this treatment while root biomass was highest with P. striata inoculation. Microbial inoculants under study benefited the growth of saplings by improving the soil properties, fertility status, physiological parameters and nutrient uptake. Hence using these microbial inoculants in potting mixture for air layers may facilitate their better establishment and growth under field condition