Selection of Rhizobium leguminosarum strains via symbiotic and production variables in Pisum sativum L.

Field pea (Pisum sativum L.) is a winter symbiotic legume that associates with Rhizobium leguminosarum sv viciae. This work aimed to evaluate strains of R. leguminosarum for their infective ability and early-plant growth, BNF contribution, biomass and grain yield. Seventy-eight specific strains and four pea cultivars were evaluated in a growth chamber, five strains and three cultivars were evaluated in a greenhouse, and three strains and two cultivars were evaluated in a field experiment. Only 44-55% of all evaluated strains were infective in the four cultivars. In the greenhouse, D70 and D156 strains showed the best nodulation variables as well as higher N content and yield. The field experiment showed D156 and D70 yielded a similar behavior for N content in canopy biomass and individual nodule biomass, whereas D191 had a higher nodule number per plant, aerial biomass and grain yields. D70 provided good nodulation, N content in biomass, and yield in the growth chamber, greenhouse, and field experiments, whereas D156 had a like or superior behavior in the greenhouse and field experiments. Therefore, D156 could constitute a good candidate for bacterial single-strain inoculants, as well as for formulating microbial consortia. Highlights: • Only 44-55% of all the strains tested presented nodules in the four commercial cultivars. • The isolates from the genus Lathyrus had a higher proportion of infective and effective nodules (60%), whereas the isolates from Pisum had only 8%. • The D156 strain exhibited similar or better behavior than the reference strain D70 in chamber growth, greenhouse, and field experiments. • The D156 strain could be a good candidate for bacterial single-strain inoculants, as well as for a microbial consortium with D70 for Pisum sativum (L).