A Higher Stomatal Aperture is Associated with the Growth Promotion of Centipedegrass (Eremochloa ophiuroides (Munro) Hack.) Under High Concentrations of Ammonium

The key to improving the efficiency by which acid-soil-growing plants utilize nitrogen is to improve their efficiency of utilizing ammonium. The carbon deficiency is recognized as the main cause of the failure to increase ammonium efficiency by simply strengthening the ammonium absorption capacity of the roots. Whether increasing carbon input by manipulating the stomatal aperture can enhance the utilization of ammonium in plants that receive high-intensity ammonium absorption in roots is our goal. We use a high ammonium treatment to mimic the excessive ammonium uptake condition and manipulate the stomata by spraying potassium or potassium uptake inhibitors through a foliar method. This was performed to investigate the effect of manipulating the stomatal aperture on the ammonium utilization capacity of centipedegrass, a typical acid soil-growing excellent turf grass, under the root excessive ammonium uptake condition. Once a high-ammonium root environment is encountered, the stomatal aperture rapidly decreases. Leaf potassium supply, rather than sodium ion supply, increases the stomatal aperture. Under hydroponic conditions, foliar application of potassium solution alleviates the inhibition of stomatal opening, restores photosynthetic capacity, and thus increases plant tolerance to high ammonium levels. When additional potassium absorption inhibitor Cs is added, the plant loses the relieving effect caused by foliar potassium spraying. Foliar spraying of potassium solution improves the high ammonium tolerance of centipedegrass by increasing the stomatal aperture. Co-reinforcing the leaf stomatal opening process and the root ammonium absorption capacity process is a feasible strategy to achieve the high efficiency of ammonium.