CRESCIMENTO E TROCAS GASOSAS NO PERÍODO VEGETATIVO DA SOJA INOCULADA COM BACTÉRIAS DIAZOTRÓFICAS

Objetivou-se estudar o crescimento e as trocas gasosas em diferentes estadios fenologicos da soja no periodo vegetativo quando inoculada e/ou co-inoculada. O experimento foi conduzido em Marechal Cândido Rondon, Parana, em condicoes de casa de vegetacao. Os tratamentos foram: controle; inoculacao de sementes com Bradyrhizobium japonicum ; inoculacao com Azospirillum brasilense ; co-inoculacao com B. japonicum via semente + A. brasilense via sulco e co-inoculacao com B. japonicum via sulco + A. brasilense via semente. Avaliacoes foram realizadas nos estadios fenologicos V2; V4; V6 e V8, e as seguintes caracteristicas foram determinadas, o numero de nodulos, percentagem de nodulos viaveis, area foliar e massa seca de parte aerea, a taxa de assimilacao liquida de CO 2 , transpiracao, condutância estomatica, concentracao interna de CO 2 , eficiencia do uso da agua, eficiencia intrinseca do uso da agua e eficiencia de carboxilacao. A inoculacao ou co-inoculacao com A. brasilense eleva a nodulacao, a viabilidade, a area foliar e a massa seca de parte aerea, porem nao interfere na atividade fotossintetica e transpiratoria da soja. Entretanto, o uso de A. brasilense torna a planta mais eficiente no uso do CO 2 , sendo notado que a nodulacao ocasionada por B. japonicum causa um maior requerimento de CO 2 , durante os estadios iniciais. Palavras-chave : Glycine max, Bradyrhizobium japonicum, Azospirillum brasilense, co-inoculacao. GROWTH AND GAS EXCHANGE IN THE VEGETATIVE PERIOD OF SOY INOCULATED WITH BACTERIA DIAZOTROPHIC ABSTRACT Aimed to study the growth and gas exchange at different growth stages of soybean in the growing season when inoculated and /or co-inoculated. The experiment was conducted in Marechal Cândido Rondon, Parana, Brazil, under greenhouse conditions. The treatments were: control; inoculating seeds with Bradyrhizobium japonicum ; inoculation with Azospirillum brasilense ; co-inoculation with B. japonicum via seed + A. brasilense via groove and co-inoculation with B. japonicum via groove + A. brasilense via seed. Evaluations were performed at the phenological stages V2; V4; V6 and V8, and the following characteristics were determined, the number of nodules, percentage of viable nodules, leaf area and dry mass of shoots, net assimilation rate of CO 2 , transpiration, stomatal  conductance, internal CO 2 concentration, efficiency water use, intrinsic efficiency of water use and carboxylation efficiency. Inoculation or co-inoculation with A. brasilense increases nodulation, viability, leaf area and shoot dry weight, but does not interfere with photosynthetic activity and soybean transpiration. However, the use of A. brasilense makes the plant more efficient in the use of CO 2  being noted that nodulation caused by B. japonicum  causes a greater application of CO 2  during the initial stages. Keywords : Glycine max , Bradyrhizobium japonicum , Azospirillum brasilense , co-inoculation. DOI: http://dx.doi.org/10.14583/2318-7670.v04n05a03