Selection and evaluation of native peanut nodulating isolates for their use as potential inoculants

VALETTI, L., PENA, D., VILCHEZ, L., TAURIAN, T., ANGELINI, J., FABRA, A.

Mar del Plata

Congreso; XLIII Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Argentina is one of the major producers of the legume peanut, concentrating about 96% of its production in Córdoba. Rhizobia are soil bacteria able to attach to legumes roots and induce the formation of nodules where they fix atmospheric nitrogen to the plants. The soil inoculation with nitrogen fixing bacteria is a risk-free and cost-effective alternative to the chemical fertilization. Rhizobial inoculants should contain a high number of efficient and competitive strains. The objectives of this work were (i) the identification of effective and competitive native peanut nodulating strains, (ii) the evaluation of the optimum culture medium for the production and commercialization of peanut inoculants. From 220 native isolates obtained from nodules of peanut plants (Vincent, 1970) growing in different localities of Córdoba (Argentina), we selected two (named J-81 and J-237) considering their high effectiveness (measured as shoot dry weight) and competitiveness (Somasegaran and Hoben, 1994) when compared with the reference strains Bradyrhizobium sp SEMIA 6144 and C-145. Their growth and viability were evaluated in different culture media. For both, the number of viable cell reached in a balanced medium was 1010 cfu/ml while in YEM, YLG, YG and LV this value was 109cfu/ml. Our results demonstrated the better symbiotic behavior of these isolates in microcosm assays.