Rhizobia Unique Plant Growth Promoting Rhizobacteria: A Review

Rhizobia are well known nitrogen fixing bacteria. On the basis of generation time rhizobia is classify into slow (Bradyrhizobium) and fast growing Rhizobia (Rhizobium). Chemical fertilizer reduces the soil fertility and biofertilizer improve soil ecology. Rhizobia have some unique quality to fix nitrogen, produce plant growth hormones, Siderophore production, HCN production and good colonizer. Such activity directly or indirectly increases the plant growth and productivity. Co-inoculation of Rhizobia with other microorganism can also improve the plant growth and productivity. Biologiocal control activity enhances its important as PGPR. Few Rhizobia can tolerate few extend of salt, acidic environment, and low water content in soil. All above activity clearly indicate that Rhizobia are unique plant growth promoting rhizobacteria.