Natural abundance of 15N of N derived from the atmosphere by different strains of Bradyrhizobium in symbiosis with soybean plants

Abstract

To quantify the BNF contribution to legumes using the 15N natural abundance technique, it is important to know the abundance of 15N of the plants grown entirely dependent on BNF (value ‘B’). The aim of the study was to determine the 15N natural abundance of N2 fixed by different Bradyrhizobium strains in symbiosis with one soybean cultivar. Treatments consisted of soybean plants cultivated with and without inoculation with ten Bradyrhizobium strains, in five replicates planted in Leonard jars in a sand/vermiculite mixture. Plants were harvested after 46 days. The ‘B’ values of the aerial tissue (‘Bs’) ranged from -2.6 to -3.9 ‰. There was a tendency for the ‘Bs’ values of plants inoculated with strains of B. elkanii to be more negative than plants inoculated with other strains. All ‘B’ values of the whole plant were less than 1 unit of δ15N (‰) different from zero, suggesting that the symbioses have little tendency to show significant isotopic fractionation during N2 fixation, but there is considerable depletion in 15N of the N translocated to the shoot tissue.

DIVERSITY OF NITROGEN-FIXING BACTERIA IN COFFEE CROPS (Coffea arabica L.)

“…This genus was also considered the core microbione among the diazotrophs of different Chinese soil and responsible for the interaction with other diazotrophs (HAN et al, 2019). It has been the species used as inoculants in legumes (PEREIRA et al, 2010;ULZEN et al, 2016), such as soybean where in the nodules Bradyrhizobium is able fixes a large part of the N used by the plant (ARAUJO et al, 2019).…”