Elevated atmospheric CO2 concentration (e[CO2]) and varied nitrogen (N) fertilization levels may mediate the different responses of C4 crops to progressive soil drought. In this study, the effects of reduced N (N1, 0.8 g pot−1) and adequate N (N2, 1.6 g pot−1) supply on leaf physiology, plant growth and water use efficiency (WUE) of maize (C4 crop) exposed to progressive soil drought grown at ambient CO2 (a[CO2], 400 ppm) and elevated CO2 (e[CO2], 800 ppm) concentration were investigated. The results indicated that compared with a[CO2], net photosynthetic rate (An) and leaf water potential (Ψl) at e[CO2] were maintained in maize leaves, while stomatal conductance (gs), transpiration rate and leaf hydraulic conductance were decreased, leading to enhanced WUE from stomatal to leaf scale. Despite An and Ψl of e[CO2] plants were more sensitive to progressive soil drought under both N fertilization levels, e[CO2] would increase leaf ABA concentration ([ABA]leaf) but decline the gs response to [ABA]leaf under N1 supply. e[CO2] coupled with N1 fertilization was conducive to enlarging leaf area, promoting specific leaf area, root and total dry mass, whereas reduced stomatal aperture and plant water use under progressive drought stress, contributing to an improvement in plant WUE, implying a better modulation of maize leaf stomata and water status under reduced N supply combined with e[CO2] responding to progressive soil drought. These findings in the current study would provide valuable advice for N management on maize (C4) crop efficient water use in a drier and CO2‐enriched environment.

中文翻译：

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二氧化碳浓度升高和氮肥供应调节玉米叶片生理、作物生长和水分利用效率，以应对土壤逐渐干旱

大气中二氧化碳浓度升高2专注 （e[一氧化碳2]）和不同的氮（N）施肥水平可能介导C的不同反应4农作物导致土壤逐渐干旱。在这项研究中，减少氮的影响（N1，0.8克罐−1）和充足的氮气（N2，1.6克罐−1）对玉米叶片生理、植物生长和水分利用效率（WUE）的供应（C4暴露于土壤逐渐干旱的作物）在环境二氧化碳下生长2（A[一氧化碳2], 400 ppm) 和 CO 升高2（e[一氧化碳2]，800 ppm）浓度进行了研究。结果表明，与A[一氧化碳2]、净光合速率（An）和叶水势（Ψ我） 在e[一氧化碳2] 在玉米叶片中保持不变，而气孔导度（Gs），蒸腾速率和叶片导度降低，导致从气孔到叶片尺度的WUE增加。尽管An和Ψ我的e[一氧化碳2] 在两种施氮水平下，植物对渐进的土壤干旱更加敏感，e[一氧化碳2] 会增加叶片 ABA 浓度（[ABA]叶子）但拒绝Gs对[ABA]的回应叶子在N1供应下。e[一氧化碳2] 与 N1 施肥相结合，有利于扩大叶面积，提高比叶面积、根系和总干质量，而在渐进性干旱胁迫下减少气孔孔径和植物水分利用，有助于改善植物 WUE，这意味着更好地调节玉米氮供应减少与叶片气孔和水分状况相结合e[一氧化碳2] 应对逐渐发生的土壤干旱。本研究的这些结果将为玉米的氮肥管理提供宝贵的建议（C4) 干燥机和二氧化碳中作物高效用水2‐丰富的环境。