Pigeon pea is the most important leguminous crop of rainfed agriculture. It used as both a food crop and fodder crop with some important amino acids like Methionine, Lysine and Tryptophan. Pigeon pea is multipurpose plant, grains are eaten as dal; Green pods are used as vegetable; Leaves of Pigeon pea used for rearing silkworm; Husk, green leaves and tops are used as fodder and also has green manure. Pigeon pea is also used for medicinal purpose as it is indicated in the relief of pain in traditional Chinese medicine and as a sedative. Rhizobium is beneficial to legume, as the nitrogen fixation can increases crop yield. The nodulation process is a series of events in which Rhizobium interact with the roots of legume plant to form a specialized structure called root nodule.