BIOLOGICAL NITROGEN FIXATION AND ITS EFFECTS ON THE PHYSIOLOGICAL POTENTIAL OF COMMON BEAN SEEDS 156 BIOLOGICAL NITROGEN FIXATION AND ITS EFFECTS ON THE PHYSIOLOGICAL POTENTIAL OF COMMON BEAN SEEDS Vitor Henrique Vaz Mondo 1 , Enderson Petrônio de Brito Ferreira 1 , Nand Kumar Fageria 1 ; Marco Túlio Machado Costa 2 1 Embrapa Rice and Beans –E-mail: vitor.mondo@embrapa.br, enderson.ferreira@embrapa.br, nand.fageria@embrapa.br 2 Universidade Federal de Goiás, E-mail: marcotulio_suk@hotmail.com ABSTRACT The aim of this study was to evaluate the effects of biological nitrogen fixation and its association with mineral sources of nitrogen in common bean seed physiological potential. Therefore, a field experiment was conducted from April to August 2012, using three common bean varieties (‘BRS Requinte’, ‘BRS Notável’ and ‘Aporé’), which were grown and subjected t o the following treatments: non-inoculated seeds, inoculated seeds, inoculated seeds + 50 kg.ha -1 of N and non-inoculated seed +120 kg.ha -1 of N. The seeds were evaluated in Embrapa Rice and Beans seed analysis laboratory, by physiological tests of germination and seed vigor (first count of germination, accelerated aging, seedling length and electrical conductivity). It was concluded that the mineral nitrogen fertilization, for common bean crop, when associated with biological nitrogen fixation, may be reduced from high (120 kg.ha-1 of N) to low doses (50 kg.ha-1 of N). Such reduction does not affect seed physiological potential. Keywords: Biological fixation, Rhizobium tropici, seed quality, Phaseolus vulgaris FIXAÇÃO BIOLÓGICA DE NITROGÊNIO E EFEITOS SOBRE O POTENCIAL FISIOLÓGICO DE SEMENTES DE FEIJÃO-COMUM RESUMO O objetivo deste estudo foi avaliar os efeitos da fixação biológica de nitrogênio e sua associação com fontes minerais de nitrogênio no potencial fisiológico de sementes de feijão- comum. Para tanto, um experimento de campo foi realizado utilizando-se três cultivares de feijão, as quais foram semeadas e submetidas aos seguintes tratamentos: sementes não-inoculadas; sementes inoculadas; sementes inoculadas + 50 kg.ha-1 de N e; sementes não-inoculadas + 120 kg.ha-1 de N. As sementes colhidas foram avaliadas por meio de testes fisiológicos de germinação e vigor das sementes (primeira contagem de germinação, envelhecimento acelerado, comprimento