Characterization and screening for inoculation of rhizobium and PGPR for improving growth of mash bean under axenic conditions

Abstract

Abstract Excessive use of synthetic fertilizers is a major bottleneck towards adopting microbial techniques on a large scale and poses great challenge to food security by disrupting soil properties and increasing production costs. Current research must focus on developing suitable alternatives for optimizing crop production along with reduced agricultural costs. We compared the efficacy of different rhizobial and rhizobacterial isolates for promoting growth of Vigna mungo in a growth room trial. Results revealed that among PGPR isolates, ‘Stenotrophomonas rhizophila PKA-18’ significantly enhanced shoot length (1.58 fold), root length (95%), root fresh weight (1.45 fold), shoot dry weight (6.3 fold) and SPAD value (1.35 fold) as compared to control. Among rhizobia, inoculation of ‘Rhizobium sp. RKA-47’ significantly increased shoot length (2.07 fold), root length (77%), shoot fresh weight (2.95 fold) and shoot dry weight (1.55 fold). Principal component analysis (PCA) indicated that among rhizobacteria, ‘Bacillus subtilis PKA-25’ and ‘Stenotrophomonas rhizophila PKA-18’ whereas, among rhizobia, ‘Rhizobium sp. RKA-47’ and ‘Bradyrhizobium japonicum RKA-46’ were the most efficient strains. Similarly, root parameters (root diameter, number of tips and root length) with root scanner were noted. Hence, co-inoculation of rhizobacteria and rhizobia proved to be an ideal option for improving mash bean growth under axenic conditions.