Fracionamento isotópico do 15N na fixação biológica de nitrogênio na soja em função da intensidade de luz e estirpe de Bradyrhizobium spp. Inoculada

Abstract

ARAUJO, Karla Emanuelle Campos. Isotopic fractionation of 15N in nitrogen fixation in soybean due to light intensity and Bradyrhizobium spp. strain inoculated. 2014. 40f. Dissertation (Master in Plant Science). Institute of Agronomy, Department of Plant Science, Federal Rural University of Rio de Janeiro, Seropédica, RJ, 2014. This work aimed to study the isotopic fractionation of N from BNF in stems function and light intensity in soybean plant symbiosis with Bradyrhizobium. The 'B' value was evaluated for ten Bradyrhizobium strains, as well as their interaction with the soybean plant (Glycine max L.). The experiment was conducted at Embrapa greenhouse Agrobiologia, Seropédica, RJ. The soybean plants inoculated with the different strains of Bradyrhizobium and a control not inoculated, were grown under conditions similar to Leonard vessels using substrate of sand and vermiculite in a 2: 1 (v / v). In the second experiment to assess the value 'B' of the resulting symbiosis BNF among cultivars (cv) of soybean BRS 133, BRS 184, MONSOY9144 nine Bradyrhizobium. Soybean plants in all the treatments, were grown under the same conditions, the soybean cultivation was performed in vessels Leonard with sand and perlite substrate in the proportion 1: 1 (v / v). In both experiments after 47 days of planting the plants were harvested and calculated the value 'B'. In the third experiment evaluated the effect of different strains of Bradyrhizobium and the reduction in the intensity of light on natural abundance of 15N N2 fixed by the strains in symbiosis with soybean cv BRS 133. An experiment was conducted in the experimental field of Embrapa Agrobiology. The soybean plants inoculated with 11 Bradyrhizobium and treatment uninoculated were grown under similar conditions in plastic pots with sand substrate and pearlite in the proportion 1: 1 (v / v) .After 75 days after planting the plants were collected and calculated the value 'B'.No experiment 1, the values of ‘Bpa’ ranged between -2 and -4 ‰, according to the strain used. In experiment 2, the values of ‘Bpa’ showed no difference between the soybean cultivars inoculated with Bradyrhizobium as the isotopic abundance of 15N in plants grown entirely dependent on FBN. There was a tendency for the abundance of 15N values in ‘Bpa’ treatment of plants inoculated with strains of B. elkanii to be less negative than in the case of plants inoculated with B. japonicum. In experiment 3 the values of ‘B’PA showed natural 15N abundance values significantly more negative than the shaded plants. There was a tendency for the abundance of 15N in the shoot (and values of ‘Bpa’) treatment of the plants inoculated with B. japonicum strains to be less negative than in the case of plants inoculated with B. elkanii. For the determination of the 'B' value, the plants should be in the same stage of maturity that being used to sample the plants in the field, to assess the value 'B' in low light intensity conditions (green house) can lead to the result of a 'B' value less negative than that given in full sun and so probably less appropriate uses it to calculate the contribution of BNF in legume under field conditions.