Development and evaluation of a liquid peanut inoculant with native rhizobial isolates from the producing area of Cordoba

VALETTI, L.; ANGELINI, J.; CERIONI, G.; FABRA, A.

Rosario

Congreso; V Congreso Argentino de Microbiología general; 2008

A critical process for yield incresement of leguminous crops is the Biological Nitrogen Fixation (BNF). Inoculant application with nitrogen fixing bacteria is economic and environmentally friendly compared to chemical fertilization. The aim of this study was to obtain a high quality and competitive product according to stablishements for its future comercialization. From 220 native isolates obtained from peanut nodules of the producing area of Cordoba, we selected two, named J-81 and J-237, considering their high effectiveness and competiveness. 16S RNAr sequence analysis showed that these two isolates belong to Bradyrhizobium genera. Optimal bacterial growth medium and solucion estabilizadora were determined in order to obtain highest bacterial concentration and viability, respectively. Reference strains Bradyrhizobium sp. SEMIA 6144 and C-145 were used as control treatments. Two inoculants were obtained and assayed in a field situated in south-southwest of Cordoba province during 2007/08 production season. Microcosmos assays demonstrated higher symbiotic parameters when plants were inoculated with Bradyrhizobium sp. J-81 and J-237 than reference strains. For both, the number of viable cell reached in the balanced medium L1 (this work) was 1.1010 ufc/ml while in YEM (Vincent, 1970) L2, L3 and L4 (this work) mediums it was 1.109 ufc/ml. Highest viability was reached with solución estabilizadora B obtaining more than 2x108 ufc/ml after two (J-237) and six (J-81) month of storage. Field experiment indicated that inculation with both inoculants obtained in this work increased field yields compared to noninoculated treatement allthough no significant differences were found respect to commercial inoculants treatments. The results of this study demonstrate that inoculants produced are of high quality and competitive products and are according to stablishements. Supported by: SECyT-UNRC, CONICET, ANPCyT