《植物生理学报》 2017, 53(9): 1717-1727

CO₂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

李曼¹, 董彦红¹, 崔青青¹, 张文东¹, 艾希珍^1,2, 刘彬彬^2,*, 李清明^1,2,3,*

¹山东农业大学园艺科学与工程学院, 山东泰安271018; ²作物生物学国家重点实验室, 山东泰安271018; ³农业部黄淮海设施农业工程科学观测实验站, 山东泰安271018

通信作者：刘彬彬；E-mail: lbroom@163.com; gslqm@sdau.edu.cn

摘　要：

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CO₂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CO₂浓度, 设大气CO₂浓度(400 μmol·mol^-1)和加倍CO₂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) CO₂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) CO₂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CO₂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, CO₂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) CO₂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CO₂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CO₂浓度、无干旱胁迫、高氮处理下产量最高, 其次是加倍CO₂浓度、干旱胁迫、高氮处理。在大气CO₂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CO₂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CO₂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CO₂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。

关键词：黄瓜; CO2浓度加倍; 水氮耦合; 碳氮代谢

收稿：2017-04-05   修定：2017-08-28

资助：国家自然科学基金(31471918)、山东省自然科学基金(ZR2013CM008)和山东省农业重大应用技术创新项目(鲁财农指[2016]36号)。

Effects of water-nitrogen coupling on the metabolites and key enzyme activities of carbon and nitrogen metabolism in cucumber leaves under doubled CO₂ concentration

LI Man¹, DONG Yan-Hong¹, CUI Qing-Qing¹, ZHANG Wen-Dong¹, AI Xi-Zhen^1,2, LIU Bin-Bin^2,*, LI Qing-Ming^1,2,3,*

¹College of Horticulture Science and Engineering, Shandong Agricultural University, Taian, Shandong 271018, China; ²State Key Laboratory of Crop Biology, Taian, Shandong 271018, China; ³Scientific Observing and Experimental Station of Environment Controlled Agricultural Engineering in Huang-Huai-Hai Region, Ministry of Agriculture, Taian, Shandong 271018, China

Corresponding author: LIU Bin-Bin; E-mail: lbroom@163.com; gslqm@sdau.edu.cn

Abstract:

Using three-factor split-plot design, effects of water-nitrogen coupling on the metabolites and key enzyme activities of carbon and nitrogen metabolism in cucumber (Cucumis sativus) cv. ‘Jinyou No. 35’ under doubled CO₂ concentration were investigated. The main plot factor was CO₂ concentrations: ambient CO₂ concentration (400 μmol·mol^-1) and doubled CO₂ concentration [(800±20) μmol·mol^-1]. The split plot factor was water treatments: no drought stress (95% of field capacity) and drought stress (75% of field capacity). The splitsplit plot factor was nitrogen application rate: low nitrogen (450 kg·hm^-2) and high nitrogen (900 kg·hm^-2). The results showed that: (1) Under the condition of drought stress and high nitrogen, doubled CO₂ concentration enhanced the plant height of cucumber, and no matter what kind of water condition, doubled CO₂ concentration significantly increased the leaf area under high nitrogen. (2) Doubled CO₂ concentration remarkably increased sucrose, starch and reducing sugar contents, as well as sucrose synthetase (SS) activity. Under doubled CO₂ concentration, high nitrogen remarkably increased the activities of SS and sucrose phosphate synthase (SPS), which led to accumulation of sucrose and decomposition of starch. Drought stress significantly improved SS activity, but decreased SPS activity, while doubled CO₂ concentration significantly improved the activities of SS and SPS, and contents of sucrose and reducing sugar under drought stress. High nitrogen enhanced SS and SPS activities, and sucrose content. (3) Doubled CO₂ concentration significantly improved the activity of nitrate reductase (NR), but not activities of glutamine synthetase (GS) and glutamate synthase (GOGAT). Under doubled CO₂ concentration, high nitrogen remarkably improved NR and GOGAT activities, and alleviated the decline of GS activity. (4) The yield of cucumber under doubled CO₂ concentration, no drought stress, and high nitrogen was highest, followed by under doubled CO₂ concentration, drought stress, and high nitrogen. Under the condition of ambient CO₂ concentration and drought stress, the yield of cucumber showed no significant difference between low and high nitrogen conditions, however, high nitrogen significantly improved the yield of cucumber under doubled CO₂ concentration and drought stress. In conclusion, under the condition of doubled CO₂ concentration and drought stress, high nitrogen improved photosynthate conversion in cucumber leaves, alleviated the decline of the nitrogen assimilation capacity, improved the carbon and nitrogen metabolism of cucumber leaves, and mitigated the negative effects of drought stress to some extent, therefore promoted the growth and yield of cucumber. The results of the study may provide theoretical basis and technical parameters for CO₂ fertilization and water-nitrogen management of cucumber under water deficit.

Key words: cucumber; doubled CO₂ concentration; water-nitrogen coupling; carbon and nitrogen metabolism