Isolation and biochemical characterization of rhizobium from pea crop at Swabi

Abstract

Microorganisms like Rhizobium are symbiotic bacteria forming nitrogen fixing nodules on legumes. Nodule inducing bacteria are capable of colonizing the roots of legumes to fix nitrogen and to produce phosphorus, phytohormones, siderophores and HCN. To study the important characters of Rhizobium was the main objective of this study which will help for growth and improvement of Pea. Nitrogen (N) and Phosphorus (P) are the foremost limiting nutrients in agricultural soils of Pakistan. Through the enhancement of these microorganisms the deficiency of these major plant nutrients can be control. From diverse areas of Swabi pea samples were collected. Rhizobium strains were isolated from nodules on Yeast-Manitol Agar medium (YMA) and were characterized bio-chemically for Nitrogenase activity, phytohormone production, phosphate solubalization, siderophores and HCN production. Nitrogenase was determined through calorimetrically. The production of ethylene by the Rhizobium strains were ranges from 20.7 µ moles C2H2/hr to 38.4 µ moles C2H2/hr. Phytohormone (IAA) was measured through Electro-Spectrophotometer. The qualitative assessment of phosphorus solubalization was made by size of halo zones around the colonies on Pikovskaya agar medium. Rhizobium strains produced IAA (ranging from 14.25-13.65 µg/ml), Phosphorus solubilized (18-24µg ml-1) and four Rhizobium strains were siderophores positive. Out of seven Rhizobium strains only five strains were able to produce hydrogen cyanide (HCN). Furthermore, biozotes (Biofertilizer) were prepared from inoculation of these Rhizobium strains and were applied in pot experiment to check their effects on pea. All the inoculants showed positive effect on growth and development of peas and significantly increased root shoot length, dry and fresh weight