Survival of Bradyrhizobium sp. in cowpea seeds treated with carbendazin and inoculants formulated with the carboxymethylcellulose polymer

Abstract

Fungicides associated with inoculants can reduce the survival of rhizobia in seeds. The objective was to evaluate the survival of Bradyrhizobium sp. in cowpea seeds treated with carbendazin and inoculants formulated with carboxymethylcellulose (CMC). Seeds were inoculated with a Bradyrhizobium strain. CMC was used in ten concentrations. Strain survival was evaluated at 0, 1, 2, 3, 4, 12, 24, 96, 192 and 768 h of storage of seeds treated with these products. The number of viable cells was obtained by counting the colony-forming units, using the serial dilution method. Concentrations such as 0.25 and 0.75 g/L of CMC were able to maintain cell viability for 768 h after treatment with carbendazin. Even without a growth pattern, the combination of the inoculant conveyed by the CMC with carbendazim allows the rhizobia to survive, in many of the polymer concentrations and in some of the seed storage periods.