Benefits of biological nitrification inhibition of Leymus chinensis under alkaline stress: the regulatory function of ammonium-N exceeds its nutritional function

The production of root exudates with biological nitrification inhibition (BNI) effects is a strategy adopted by ammonium-N ( ) tolerant plant species that occur in N-limited environments. Most knowledge on BNI comes from plant species that occur in acidic soils. Here, combining field sampling and laboratory culture, we assessed the BNI-capacity of , a dominant grass species in alkaline grasslands in eastern Asia, and explored why has BNI ability. The results showed that has strong BNI-capacity. At a concentration of 1 mg mL , ' root exudates inhibited nitrification in soils influenced by by 72.44%, while DCD only inhibited it by 68.29%. The nitrification potential of the soil of community was only 53% of the or 41% of the community. We also showed that the supply of driven by ' BNI can meet its requirements . In addition, can enhance plant adaptation to alkaline stress by regulating pH, and in turn, the uptake of nitrate-N ( ). We further demonstrated that the regulatory function of is greater than its nutritional function in alkaline environment. The results offer novel insights into how adapts to high pH and nutrient deficiency stress by secreting BNIs, and reveal, for the first time, differences in the functional roles of and in growth and adaptation under alkaline conditions in a grass species.