Effect of Nitrate on Nodule and Root Growth of Soybean (Glycine max (L.) Merr.)

Abstract

The application of combined nitrogen, especially nitrate, to soybean plants is known to strongly inhibit nodule formation, growth and nitrogen fixation. In the present study, we measured the effects of supplying 5 mM nitrate on the growth of nodules, primary root, and lateral roots under light at 28 °C or dark at 18 °C conditions. Photographs of the nodulated roots were periodically taken by a digital camera at 1-h intervals, and the size of the nodules was measured with newly developed computer software. Nodule growth was depressed approximately 7 h after the addition of nitrate under light conditions. The nodule growth rate under dark conditions was almost half that under light conditions, and nodule growth was further suppressed by the addition of 5 mM nitrate. Similar results were observed for the extending growth rate of the primary root as those for nodule growth supplied with 5 mM nitrate under light/dark conditions. In contrast, the growth of lateral roots was promoted by the addition of 5 mM nitrate. The 2D-PAGE profiles of nodule protein showed similar patterns between the 0 and 5 mM nitrate treatments, which suggested that metabolic integrity may be maintained with the 5 mM nitrate treatment. Further studies are required to confirm whether light or temperature condition may give the primary effect on the growth of nodules and roots.

Nitrogen Nutrition Optimization in Organic Greenhouse Tomato Through the Use of Legume Plants as Green Manure or Intercrops

“…Furthermore, the significant decrease of the %Ndfa in E3 compared to E1 in the inoculated treatments is ascribed to the notably higher soil nitrate concentrations in E3. Indeed, as shown by other researchers [44,45], high NO 3 -N concentrations in the root zone of legume plants are associated with reduced nodulation and N 2 -fixation.…”

Nitrate transporters: an overview in legumes

“…In legumes, it has been determined that nitrate is involved in the regulation of nodulation (Heath et al 2010;Saito et al 2014). Nitrate transporters are thus likely to have important roles to play during symbiosis establishment.…”

The Variation induction of Glycine max through low dose gamma irradiation produces genetic and physiological alteration as source of tolerant variants in waterlogging conditions

“…Waterlogging stress conditions caused oxygen diffusion to be inhibited. This certainly affected the formation of nodules in soybean roots as the symbiosis between nitrogen-fixing bacteria and the roots of legume plants (Saito et al 2014). The higher concentration of waterlogging stress caused the oxygen concentration to continue to decrease, causing bacterial respiration to be disrupted, so the formation of nodules decreased, conforming to the statement of Saito et al (2014).…”

“…Higher nitrogen concentration is obtained by using root nodules. Formed root nodules are the symbiosis results between Leguminosae species and Rhizobium bacteria by means of N2 tethering in the atmosphere (Saito et al 2014). Bacteria including nitrogen-fixing bacteria are Bradirhizobium japonicum, B. elkanii, and B. lianigense (Yoshiki et al 2017).…”