Isolation, characterization and evaluation of efficient rhizobia suitable for production of biofertilizers for important arid legumes

The study carried out to isolate and evaluate efficient Rhizbium cultures from guar and moth bean plants grown at farmers’ fields in arid districts of western Rajasthan showed that the GBR-2 and GBK-21-2 cultures from guar and MBR-8 and MBK-15 from moth bean grew fast and developed wet and gummy colonies on YEMA plates within 2448 hrs. Cultures of GBR-2 and GBK-21-2 also exhibited better plant biomass in nursery and 15-18 per cent higher yield and nodulation over the uninoculated control under field conditions. MBR-8 and MBK-15 also exhibited higher plant biomass in nursery and higher yield (up to 19 %) and nodulation over the uninoculated control under field conditions. MBR-8 was used for studying the shelf life of the liquid bioformulations for later use as bioinoculant. The liquid bioformulations having polyethylene glycol (0.5%) or gum arabic (0.5%) as cell protectants or top layer of castor oil retained viable cell density (e” 10¹⁰ cfu ml^-1) up to 180d after storage.