Bradyrhizobium strain and the 15N natural abundance quantification of biological N2 fixation in soybean

Scientia Agricola

Ana Paula Guimarães²  Rafael Fiusa De Morais¹  Segundo Urquiaga¹  Robert Michael Boddey¹  Bruno José Rodrigues Alves¹ 

[1] ,UENF CCTA Depto. de Produção VegetalCampos dos Goytacazes RJ ,Brasil

关键词: Bradyrhizobium elkanii;    Bradyrhizobium japonicum;    Glycine max;    'B' value;    Bradyrhizobium elkanii;    Bradyrhizobium japonicum;    Glycine max;    valor de 'B';   

DOI  :  10.1590/S0103-90162008000500011

来源: SciELO

【 摘 要 】

In commercial plantations of soybean in both the Southern and the Cerrado regions, contributions from biological nitrogen fixation (BNF) are generally proportionately high. When using the 15N natural abundance technique to quantify BNF inputs, it is essential to determine, with accuracy, the 15N abundance of the N derived from BNF (the 'B' value). This study aimed to determine the effect of four recommended strains of Bradyrhizobium spp. (two B. japonicum and two B. elkanii) on the 'B' value of soybean grown in pots in an open field using an equation based on the determination of δ15N natural abundance in a non-labelled soil, and estimate of the contribution of BNF derived from the use of 15N-isotope dilution in soils enriched with 15N. To evaluate N2 fixation by soybean, three non-N2-fixing reference crops were grown under the same conditions. Regardless of Bradyrhizobium strain, no differences were observed in dry matter, nodule weight and total N between labelled and non-labelled soil. The N2 fixation of the soybeans grown in the two soil conditions were similar. The mean 'B' values of the soybeans inoculated with the B. japonicum strains were -1.84 ‰ and -0.50 ‰, while those inoculated with B. elkanii were -3.67 ‰ and -1.0 ‰, for the shoot tissue and the whole plant, respectively. Finally, the 'B' value for the soybean crop varied considerably in function of the inoculated Bradyrhizobium strain, being most important when only the shoot tissue was utilised to estimate the proportion of N in the plant derived from N2 fixation.

【 授权许可】

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