Isolation, characterization and purification of Rhizobium strain to enrich the productivity of groundnut (Arachis hypogaea L)

Groundnut (Arachis hypogaea L.) is an important food legume in tropical and subtropical areas because of its ability to adapt to a wide range of agro-climatic regions. Groundnut is usually cultivated in nutrient-poor soil and rain-fed conditions, so average yield tends to be very low relative to potential yield. Even though the nitrogen (N) requirement of groundnut is much higher than cereals due to its high protein content, it has the capacity to meet 60-80% of N-based requirements through symbiotic N fixation via its root nodules. In its symbiotic relationship with legumes, Rhizobium fixes N, thereby positively impacting the content of this nutrient. This study aimed to isolate, characterize and purify microbial strains of Rhizobium specific to groundnut in a bid to increase this legume's productivity. The research was conducted in the AICRP-Groundnut laboratory and greenhouse of the Directorate of Research, BCKV, in Kalyani, India during October 2016 to March 2017. Two Rhizobium isolates (RhBC and NRA1) were isolated and selected from groundnut pot cultures. After 45 days, NRA1 produced higher plant biomass, longer roots and shoots, more nodules and higher nodule dry weight than RhBC. NRA1 was selected for a future field trial. The two isolated microbial strains will aid in the screening of additional local isolates to test their effectiveness when co-cultured with local groundnut cultivars to increase yield in soil with low fertility.