Low concentrations of nitrate and ammonium stimulate nodulation and N₂fixation while inhibiting specific nodulation (nodule DW g^-1root dry weight) and specific N₂fixation (N₂fixed g^-1root dry weight) in soybean

Relationship between photosynthetic capacity, nitrogen assimilation and nodule metabolism in alfalfa (Medicago sativa) grown with sewage sludge

“…Although some authors have observed that sludge application can diminish plant nodulation ability [19], it was also observed that sludge addition caused no negative effects on the formation of nodules [18,56] contrary to the common view that nodulation is suppressed in soil high in N. Currie et al [57] hypothesize that sludge N do not repress N 2 fixation for two reasons: firstly, sludge N may not be evenly distributed within the rooting zone of plants, and secondly, sludge N is made available to the plant over the entire growing period, not just the early period when nodules are being formed. Also, it has been shown that a small dose of N can stimulate seedling growth and early nodulation such that N 2 fixation and yield are enhanced [58].…”

Mineral Nitrogen Associated Changes in Growth and Xylem-N Compounds in Amazonian Legume Tree

“…In this case, products of photosynthesis may regulate root and nodule ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 5 activity. Moreover, NO 3 -assimilation is more energy demanding than ammonium (Gloser et al, 1996;Gan et al, 2004). Large amounts of assimilates are needed since high reductant production is required to meet the demand of NO 3 -assimilation (Schulze, 2004).…”

Nitrate inhibits soybean nodulation by regulating expression of CLE genes

“…Although the degree of nodulation inhibition is variable, the effects are clear when the concentration of nitrate is high. Application of high concentrations of nitrogen, either as nitrate, ammonium, or ammonium nitrate, significantly suppressed the number, dry weight, and N 2 fixation activity of root nodules [4,[14][15][16]. In addition, nitrogen form, treatment period, placement, temperature, pH in the root zone, plant species, and the titer of inoculating bacteria can affect its effect on nodulation and nodule growth [2,15,[17][18][19][20].…”