Microbial dynamics in rhizosphere at different growth stages of rice (Oryza sativa L.) based on plant growth promoting functions.

Abstract

In the present study 101 bacterial isolates were obtained from rhizosphere of rice plants (Oryza sativa L.) cv PR-118 and PRH-10 cultivated in a field at ICAR-Indian Institute of Seed Science, Mau Nath Bhanjan, Uttar Pradesh, India at different stages of growth seedling stage [37 days old after transplantation (RI stage)], booting stage [80 days old after transplantation (RII stage)], Maturating stage [100 days old after transplantation (RIII stage)]. The bacterial isolates were tested for various nutrient mobilizing properties as well as plant growth promotion activities including siderphore production, ammonia production and P solublization in in-vitro conditions. Seventy nine bacterial isolates were found to be siderophore producers, 78 were ammonia producers and 39 were Psolublizers with varying potentials in different activities. It was observed that siderophore producers declined in number as the plant ages but simultaneously the efficiency of siderophore production among them increased with the age of plant. The number of ammonia producers increased from seedling stage to booting stage and declined at maturity stage and the same trend at different growth stages of plant was observed in the ammonia production capability of the isolates. Similar trend was observed for the number of P solublizers and their P solublization capability which in both the cases was found to be maximum at booting stage. The present study reveals that the rhizospheric microbial population and functions changes with the physiological requirement of plants during its developmental growth stages as well as nutritional status of soil.