Isolation of Rhizobium from root nodules of Pisum Sativum and its use as biofertilizer

Abstract

Biofertilizers are substances which contain living microorganisms which when applied to a soil promote the growth by increasing the supply or availability of primary nutrients to the host plant. Biofertilizers are usually prepared as a carrier based inoculants containing effective microorganism which would show a good relationship with the host plant. This makes it easy to handle with wide range of acceptance by the host. Rhizobia are a special type of bacteria which live in root nodules in symbiotic association and fix atmospheric free nitrogen and make it available to the plants. In this study Rhizobium is isolated and cultured from the root nodules of Pisum sativum (pea plant) in a selective media i.e. YEMA (Yeast Extract Mannitol Agar medium with Congo Red). The isolate was found with poor absorption of congo red and appeared as whitish gummy colony which was biochemically tested. The isolated strain was then mixed with carrier and applied on pea. Uninoculated soil was used as control. The growth of plants was observed at regular time intervals. The growth parameters observed were germination of seed, shoot initiation, root initiation, root length and shoot length. The seed started to germinate by day 2. After 20 days the plant with the biofertilizer showed a shoot length of 11.5cm and root length of 18cm while control showed 7cm and 9cm respectively. This report showed that application of isolated rhizobial strain enhanced the growth of plant. The isolated strain can be used as biofertilizer.