以‘津优35号’黄瓜(Cucumis sativus)为试材,采用三裂式裂区试验设计,研究了CO_2浓度加倍下水氮耦合对黄瓜叶片碳、氮代谢及其关键酶活性的影响。主区因素为CO_2浓度,设大气CO_2浓度(400μmol·mol~(-1))和加倍CO_2浓度[(800±20)μmol·mol~(-1)]两个水平;裂区因素为水分处理,设无干旱胁迫(灌水上限为田间持水量的95%)和干旱胁迫(灌水上限为田间持水量的75%)两个水平;再裂区因素为施氮量,设施氮量450 kg·hm-2(低氮)和900 kg·hm~(-2)(高氮)两个水平。结果表明:(1)CO_2浓度加倍提高了干旱和高氮条件下黄瓜的株高,且使高氮下的叶面积显著增加。(2)CO_2浓度加倍显著提高了黄瓜叶片蔗糖、淀粉、还原糖含量,蔗糖合成酶(SS)的活性显著增加;高氮显著增加了CO_2浓度加倍条件下SS和蔗糖磷酸合成酶(SPS)活性,促进蔗糖积累和淀粉分解。干旱胁迫使SS活性显著增加,SPS活性显著降低,CO_2浓度加倍显著提高了干旱胁迫下SS和SPS活性以及蔗糖和还原糖含量,且SS和SPS活性以及蔗糖含量随氮素的增加而显著增加。(3)CO_2浓度加倍显著提高了硝酸还原酶(NR)活性,但是谷氨酰胺合成酶(GS)和谷氨酸合酶(GOGAT)活性并未同步增加。在CO_2浓度加倍条件下,高氮使干旱胁迫的黄瓜叶片NR和GOGAT活性显著提高,GS活性的降低得到缓解。(4)加倍CO_2浓度、无干旱胁迫、高氮处理下产量最高,其次是加倍CO_2浓度、干旱胁迫、高氮处理。在大气CO_2浓度和干旱条件下,低氮处理产量最大,继续增施氮肥产量无显著差异,而在CO_2浓度加倍和干旱条件下,增施氮肥黄瓜产量则显著上升。因此,在CO_2浓度加倍条件下高氮促进了干旱胁迫的光合产物转化,使氮同化能力的降低得到缓解或改变,促进干旱胁迫下黄瓜叶片的碳氮代谢,能在一定程度上缓解干旱胁迫造成的不利影响,从而提高黄瓜生长量和产量,可为设施黄瓜CO_2施肥及水分亏缺等逆境下水氮科学管理提供理论依据和技术参数。 Cucumber (Cucumis sativus) was used as experimental material to study the effect of water and nitrogen coupling on the carbon and nitrogen metabolism and its key enzyme activities in cucumber leaves under doubled CO2 concentration. The main factors of CO 2 concentration are atmospheric CO 2 concentration (400 μmol · mol -1) and double CO 2 concentration (800 ± 20 μmol · mol -1) , With no drought stress (upper limit of irrigation is 95% of the field capacity) and drought stress (upper limit of irrigation is 75% of the field capacity). The factors of the secondary cracking zone are nitrogen application rate, 450 kg · hm -2 (low nitrogen) and 900 kg · hm -2 (high nitrogen). The results showed that: (1) doubling CO 2 concentration increased the plant height of cucumber under drought and high nitrogen conditions, and significantly increased the leaf area under high nitrogen stress. (2) Doubled CO 2 significantly increased the content of sucrose, starch and reducing sugar in cucumber leaves, and the activity of sucrose synthase (SS) increased significantly. High nitrogen increased the activities of SS and sucrose phosphate synthase (SPS) , Promote sucrose accumulation and starch decomposition. Drought stress increased SS activity and SPS activity significantly. Doubled CO 2 concentration significantly increased SS and SPS activities and sucrose and reducing sugar content under drought stress. SS and SPS activity and sucrose content increased significantly with the increase of nitrogen. (3) The doubling of CO 2 concentration significantly increased nitrate reductase (NR) activity, but the activity of glutamine synthetase (GS) and glutamate synthase (GOGAT) did not increase synchronously. Under the doubled CO 2 concentration, high nitrogen increased the activity of NR and GOGAT in cucumber leaves under drought stress, and the reduction of GS activity was alleviated. (4) Doubling CO2 concentration, no drought stress, the highest yield under high nitrogen treatment, followed by double CO 2 concentration, drought stress and high nitrogen treatment. Under the condition of CO_2 concentration and drought in the atmosphere, the yield of low N treatment was the highest, and the yield of N fertilizer continued to increase without significant difference. However, under the condition of doubling CO 2 concentration and drought, the yield of cucumber increased significantly. Therefore, under the condition of doubling CO2 concentration, high N promoted the transformation of photosynthetic products under drought stress, and alleviated or reduced the reduction of nitrogen assimilation ability, promoted the carbon and nitrogen metabolism of cucumber leaves under drought stress and alleviated the drought stress to a certain extent , Which can improve cucumber growth and yield, which can provide theoretical basis and technical parameters for scientific management of water and nitrogen under the adverse conditions of CO_2 fertilization and water deficit in cucumber.