亚适宜温光下黄瓜氮吸收与代谢的生理与分子机制研究

Yield and quality of cucumber cultured in greenhouses in winter and spring in northern China were declined by long-term stress of suboptimal temperature and photon flux density. Our previous studies found that nitrogen content in cucumber leaves and biomass of cucumber were significantly declined by stress of suboptimal temperature and photon flux density. This decline may be induced by the decrease of nitrogen absorption, transportation and metabolism. In the project, artificial climate chambers would be used to imitate suboptimal stress, the cucumber growth, nitrogen content, activities and expression of enzymes related to nitrogen absorption,transportation and metabolism under conditions of different temperature, photon flux intensity, quantities of nitrogen fertilizer and ratio of nitrate to ammonia would be studied. The aim of this project is to clarify the physiological and molecular mechanisms of nitrogen absorption, transportation and metabolism and the law and amount of nitrogen uptake of cucumber under suboptimal temperature and photon flux density condition and to provide a scientific basis for reasonable application of nitrogen fertilizer to improve yields and quality of cucumber cultured in greenhouses in winter and spring in northern China.

长期亚适宜温光环境是引起我国冬春季节设施黄瓜产量和品质下降的主要因素。我们的前期研究发现，亚适宜温光处理使黄瓜叶片氮含量明显降低，生物量显著减少。亚适宜温光环境可能通过影响黄瓜氮的吸收、转运与代谢从而降低了黄瓜的产量与品质。本项目以人工气候室模拟亚适宜温光环境，研究温度、光照强度、氮肥施用量与硝铵比等对黄瓜生长、氮含量、氮吸收、转运与代谢相关酶活性及其基因表达的影响，阐明亚适宜温光环境影响黄瓜氮吸收、转运与代谢的生理与分子机制，弄清亚适宜温光环境下黄瓜氮吸收规律和需氮量，为合理施用氮肥提高冬春季节设施黄瓜产量，改善设施黄瓜品质提供科学依据。

长期亚适宜温光环境是引起我国冬春季节设施黄瓜产量和品质下降的主要因素。氮（N）是植物生长发育和品质形成所必需的营养元素。本项目以人工气候室模拟亚适宜温光环境，研究温度、光照强度、氮肥施用量与硝铵比等对黄瓜生长、氮含量、氮吸收、转运与代谢相关酶活性及其基因表达的影响。发现亚适宜温光降低 N 运转蛋白基因的表达，抑制了 N 的吸收，降低 N 含量，进而抑制了黄瓜生长。亚适宜温光环境下，增施2倍氮素水平内可使N转运蛋白基因上调，进而促进了黄瓜幼苗对氮的吸收与代谢；结果期增施1倍氮肥黄瓜株高、茎粗、产量和品质均最高。增施1倍氮肥、硝铵比调整为21:7的处理能提高黄瓜根系活力，调节其根系构型，增加H+-ATPaseNR、GS、GOGAT等的活性，提高NRT与AMT基因表达量，从而提高根系的氮吸收能力，增加黄瓜中氮含量，促进黄瓜生长，并显著提高了黄瓜产量。GA3可以有效缓解亚适宜温光对黄瓜幼苗生长的抑制作用，黄瓜幼苗根施GA3的最适浓度为5μmol•L-1，而结果期喷施GA3的最适浓度为50mg•L-1。GA通过刺激生长，增强N需求，降低组织N营养水平，解除反馈抑制的间接方式调控根区亚低温下黄瓜的NO3-吸收。另一方面，根施GA3可以通过增强光能捕获和CO2同化能力，调节N、C代谢平衡，增加向N代谢方向的能量和C骨架供应，促进根区亚低温下黄瓜对N的吸收与代谢。项目的实施基本阐明亚适宜温光环境影响黄瓜氮吸收、转运与代谢的生理与分子机制及此过程中赤霉素的作用机理，弄清亚适宜温光环境下黄瓜氮吸收规律和需氮量及适宜的赤霉素调控浓度，为合理施用氮肥和其他化学物质促进冬春季节设施黄瓜生长、提高其产量提供了科学依据。培养硕士研究生4人，博士研究生1人，发表6篇，其中SCI论文2篇，中文核心期刊论文4篇。圆满完成了计划任务和考核指标。