Inoculation method influences competitiveness and effectiveness of biological nitrogen fixation in the interaction peanut-rhizobia.

BOGINO P., NIEVAS, F., BANCHIO, E., GIORDANO, W.

Carlos Paz, Córdoba

Congreso; VI congreso Argentino de Microbiología General (SAMIGE); 2009

Inoculation of legume plants with effective rhizobial strains constitutes a beneficial alternative in order to increase the productivity in these crops. Introduction of viable rhizobia into the agricultural ecosystems can be achieve by means of seed inoculation or by direct application into the soil, technology termed in furrow inoculation .The inoculation of the seedbed present several advantages with respect to the inoculation of the seed because it favors the survival and competitiveness of introduced strain. Arachis hypogaea L. (peanut) is one of the most important legume crop cultivated in the central area of Argentine. Inoculation of peanut is a practice which is under discussion because nodulation by native bacteria is usually assumed to be sufficient. By using a lab model which makes possible to represent the application of seed inoculation or in furrow inoculation, we evaluated the effect that these technologies have on the efficiency of nitrogen fixation and competitiveness between a recommended as inoculant C-145 strain and indigenous strains. In furrow inoculation was found better than seed inoculation for the majority of the parameters of efficiency studied. It significantly increased weight and number of nodules, nitrogenase activity and shoot dry weight respect to seed inoculation. Competitiveness assays for nodule occupancy clearly showed the interference caused by native strains on the ability of a recommended strain to nodulate the legume independently of the inoculation method applied. The effect was more marked for seed inoculation, C-145 strain inoculated on the seed was incapable of competing with native established strains which occupied nearly the totality of nodules (∼) 90 %) independently of their ubication on principal or lateral roots. For in furrow inoculation nodule occupancy by C-145 strain was slightly increased when it rise in the inoculum. Results obtained for efficiency and competitiveness according the technique of inoculation applied, supports the superior benefits that in furrow inoculation provides to an introduced recommended strain and finally to the legume crop.