Stomatal conductance drives variations of yield and water use of maize under water and nitrogen stress

Water and nitrogen (N) supply are the two main factors limiting crops productivity. However, physiological mechanisms of crop responses to water and nitrogen stress remain to be elucidated. We examined stomatal conductance (g(s)), water use (ET), yield, and water productivity (WPs) of maize and analyzed the relationships between g(s) with ET, growth and yield under three growth stage-based deficit irrigation (mild, moderate and severe) and two nitrogen supplies (high and low nitrogen). Drought reduced g(s) as exacerbated by nitrogen stress. Coordination of g(s) by soil water content (SWC) and vapor pressure deficit (VPD) was affected by nitrogen supply. Controlling of transpiration by stomata was intensified by nitrogen stress in drought conditions. Yield was indirectly driven by gs through ET and aboveground biomass and directly by harvest index, but excessive water consumption did not result in higher yield instead reduced WPc. Field management optimization based on g(s) can promote the efficient use of water and fertilizer and the sustainable development of agriculture.