Nitrogen fixation(N-15 dilution) with soybeans under Thai field conditions. III. Effects of Bradyrhizobium japonicum strains and herbicides in northeast Thailand.

Abstract

In the infertile sandy soils of northeast Thailand, field experiments were conducted to evaluate the effects on rates of biological nitrogen fixation (BNF) of inoculating soybeans with selected strains of Bradyrhizobium japonicum and adding herbicides. Inoculating soybean seeds with effective B. japonicum strains increased the acetylene reduction by nodulated root systems, and increased the nodule numbers and dry weights associated with soybean roots. The amounts of Nz fixed, as measured by N-15 isotope dilution methods, were also increased by adding the B. japonicum. Inoculation of soybeans with a nif -strain of B. japonicum resulted in increased nodule weights and numbers, but did not increase the acetylene reduction rates or the amounts of Nz fixed. There was a significant straincultivar interaction. Application of metolachlor, alachlor, fluazifop butyl or sethoxydim did not reduce the levels of Nz fixed by B. japonicum in association with soybeans, but paraquat did significantly reduce the Nz fixed by the inoculated plants.

Application of the Cropping System Model (CSM)‐CROPGRO‐Soybean for Determining Optimum Management Strategies for Soybean in Tropical Environments

“…2002). In addition, supplemental nitrogen fertilizer could be applied as starter N, which results in supporting N 2 fixation as well as increasing plant growth and seed yield (Kucey et al. 1989, Tewari et al.…”

“…It has been reported that there is a strong interaction between genotype, soil type and inoculate on nitrogen fixation (Van Jaarsveld et al 2002). In addition, supplemental nitrogen fertilizer could be applied as starter N, which results in supporting N 2 fixation as well as increasing plant growth and seed yield (Kucey et al 1989, Tewari et al 2004). Jefing et al (1992) and Yinbo et al (1997) reported that application of the minimum starter N at a rate of 25 kg N ha )1 has been found to enhance the yield of soybean.…”

Evaluation of effective MyanmarBradyrhizobiumstrains isolated from Myanmar soybean and effects of coinoculation withStreptomyces griseoflavusP4 for nitrogen fixation

“…It is thus extremely important to match symbionts prudently for maximum N fixation (FAO 1984). Since rhizobial strains within a species vary in their effectiveness, the first step in manufacturing inoculants is to obtain highly effective N-fixing strains of rhizobia for the legumes to be inoculated (Kucey et al 1988). Several studies also reported significant increase in soybean growth parameters and yield due to the inoculation of bradyrhizobial isolates (Purcino et al 2000;Pant and Prasad 2004;Soe et al 2010).…”

“…It is thus extremely important to match symbionts prudently for maximum N fixation (FAO 1984). The first step in manufacturing inoculants is to obtain highly effective N-fixing strains of rhizobia for the legume to be inoculated, since rhizobial strains within a species vary in their effectiveness (Boonkerd et al 1978;Kucey et al 1988). A strain of rhizobia which is effective on one legume cultivated may not be highly effective on others (Boonkerd and Singleton 2002).…”

Rhizobium -Legume Symbiosis and Nitrogen Fixation under Severe Conditions and in an Arid Climate

“…In most published studies, herbicides varied in the extent of their effect on N 2 fixation. Consequently, the effect of herbicides on N 2 fixation in soybeans must eventually be determined under field conditions, and if the results are to be relevant, the effect must be studied in the area where they are to be used (184). Fungicides are also dangerous to the Rhizobium-legume symbiosis.…”