Integrated Effect of Rhizobium and Azotobacter Cultures on the Leguminous Crop Black Gram (Vigna mungo)

Abstract

A pot experiment was performed to evaluate the integrated effect of Rhizobium and Azotobacter sp. on the plant growth, nodule appearance, no of leaf, shoot length, root length, chlorophyll contents and carbohydrate content in black gram during 2016 growing period at the Department of Microbiology, Dr. Ram Manohar Lohia Avadh University Faizabad, UP, India. Different treatments viz., T1: Control (Sterile soil+Seeds without culture treatment), T2: Sterile Soil and Seeds both are treated with Azotobacter sp., T3: Sterile Soil and Seeds both are treated with Rhizobium sp., T4: Sterile Soil and Seeds both are treated with mixed culture of Azotobacter sp. and Rhizobium sp., T5: Sterile Soil+Seeds treated with Azotobacter sp., T6: Sterile Soil + Seeds treated with Rhizobium sp., T7: Sterile Soil+Seeds treated with mixed culture of Azotobacter sp. and Rhizobium sp. All experiments were carried out in triplicate set. The T4 treatment showed maximum shoot length (51.6 cm), root length (17.3 cm), fresh and dry shoot biomass (12.99 and 3.21 g), fresh and dry root biomass (3.54 and 0.99 g), no. of leafs (20.4), root nodules per plant (18.2) and chlorophyll content (1.3 mg/g) and reducing (867.4 μg/g) and non-reducing sugar (1905.5 μg/g) content per plant biomass respectively. The Azotobacter and Rhizobium sp. have friendly associations and they have different physiology and habitat. Therefore, they help plant growth promotion by them own system. Therefore, such combination can be recommended for field application for sustainable agriculture. Excessive application of chemical fertilizers causes environmental and economic problems; hence the use of PGPR and Rhizobium bacteria can be acceptable due to cut contribution expenditure, increase in grain yield and environmental friendly.