测墒补灌下不同产量层级麦田氮素高效利用的生理生态机制

The shortage of water resources and low nitrogen use efficiency in the Huang-Huai-Hai Plain are the main problems in wheat production. There are many previous studies about nitrogen absorption and utilization regular were carried out under sufficient water conditions. But now water is shortage in the area, and water-saving irrigation is imperative. Our group lasted 14 years to study the water-saving mechanism under supplemental irrigation by monitoring soil moisture, and created the "wheat water-saving cultivation techniques of supplemental irrigation by monitoring soil moisture ", which is known as the main agricultural popularize technology by Ministry of Agriculture in 2016. In this study, wheat cultivars with different yield potentials were selected and tested different nitrogen amount in different fertility wheat field under supplemental irrigation by monitoring soil moisture, to study the difference of nitrogen use efficiency, soil nitrogen supply ability, root morphological characteristics and physiological characteristics and nitrogen use and utilization of wheat under different yield-level wheat field, and to clear the physiological and ecological mechanism of efficient use of nitrogen and its limiting factor in different yield level wheat fields. The 15N tracer technique was used to study the characteristics of nitrogen fertilizer absorption, residue and loss and the response mechanism to nitrogen fertilizer in different yield levels wheat field, and explore out the theory and technology of high yield, water saving and nitrogen conservation for efficient using nitrogen, reducing environmental pollution and increasing soil fertility in different yield levels wheat field.

黄淮海麦区水资源短缺、氮素利用率低是小麦生产中存在的主要问题。前人在水分充足条件下，研究了小麦氮素吸收利用规律。但目前该区水资源紧缺，节水灌溉势在必行。本课题组历时14年研究小麦测墒补灌节水机理，创建了“小麦测墒补灌节水栽培技术”，被农业部列为2016年农业主推技术。本研究拟在测墒补灌基础上，选用不同产量潜力的小麦品种，在不同肥力麦田，设置不同施氮量试验，采用植物生理生化、同位素示踪、土壤学、酶学等方法，研究测墒补灌节水条件下不同产量层级麦田氮素利用率的差异，土壤供氮能力、根系形态特征及生理特性和小麦氮素吸收利用的差异，明确不同产量层级麦田氮素高效利用的生理生态机制及氮素高效利用的限制因子；运用15N示踪技术研究不同产量层级麦田氮肥的吸收、残留及损失的特点及其对氮肥的响应机制，探索出不同产量层级麦田小麦高效利用氮素、减少环境污染、土壤地力提升的高产节水节氮栽培理论与技术。

针对黄淮海麦区水资源短缺和氮素利用率低的问题，本项目选用不同产量潜力品种（产量潜力分别为12000、10500和9000kg hm-2的品种烟农1212、济麦22和良星99）和不同产量水平麦田（产量水平为10500、9000和7500 kg hm-2的麦田，分别用S、H 和M表示），在测墒补灌节水条件下研究各产量层级麦田氮素利用率的差异及其生理生态机制。结果表明，不同产量潜力品种比较，开花期20-60cm土层根干重密度和开花后根系活力均表现为烟农1212＞济麦22＞良星99，成熟期植株氮素积累量和营养器官贮藏氮素向籽粒的转运量以及在籽粒中的分配比例亦表现为烟农1212＞济麦22＞良星99，0-100cm土层土壤硝态氮含量为良星99＞济麦22＞烟农1212，烟农1212最终获得高产和较高的氮素吸收效率和氮素利用效率；不同产量水平麦田研究表明，0-40cm土层土壤的大团聚体含量、土壤养分含量、可溶性有机氮含量、土壤微生物量氮含量、土壤脲酶和蔗糖酶活性，以及0-100cm土层无机氮含量均表现为S＞H＞M，可见随产量水平的提高，麦田土壤具有更强的供氮能力，延缓根系衰老，有利于水分和氮素的吸收，提高了拔节至成熟期小麦植株的氮素积累量以及开花前营养器官积累氮素的转运量，获得较高的产量和氮素利用率。利用15N示踪技术设置不同施氮量研究表明，在测墒补灌节约灌溉水30%的条件下，采用微喷带水肥一体化灌溉施肥方式，可比传统施氮量减少12.5%，氮肥吸收率提高11.3%，土壤残留率提高5.2%，损失率降低31.76%，获得了较高的产量和氮肥利用率。创建的小麦高产、水氮高效利用的测墒补灌水肥一体化技术，适宜于在黄淮海麦区推广应用。