免耕宽幅精播麦田水分利用效率及其碳水平衡调控机制研究

North China Plain is the main winter wheat production area in China; however, water resources are limited; hence, increasing water use efficiency (WUE) is the key measure to develop sustainable winter wheat production in this region. No tillage could increase WUE in field, but decrease winter wheat grain yield. WUE is the result of coupling effect of carbon adsorption and evapotranspiration, and there are balances between them. Through carbon adsorption and evapotranspiraiton balance, the quantitative characteristics of WUE could be revealed in essence. This project discusses the question from a point on the effect of wide-precision planting pattern on canpoy structure of winter wheat in no tillage, adopting physiological plant ecology, isotopic labeling, and structure model, to research carbon adsorption, evapotranspiration, and coupling effect between them. Exploring the tillers number dynamics, canopy structure regulation, driving mechanism of photosynthetic carbon assimilation process, and carbon adsorption amount, to reveal the regulate and control mechanisms of carbon adsorption in wide-precision planting pattern under zero tillage; Exploring the heat balance conditions above the groundsurface, water potential energy and resistance in soil-plant-atmosphere continuum, and soil evaporation and leaves transpiration during the winter wheat growing seasons, etc, to clarify the regulate and control mechanism of evapotranspiration in wide-precision planting pattern under no tillage; Constructing models on the coupling effect of carbon adsorption and evapotranspiration, discussing the balance point between them, revealing the mechanism of carbon adsorption and evapotranspiration balance in WUE. Clearing the above questions, not only exploring whether wide-precision planting pattern could overcome the shortcomings in no tillage and increase the winter wheat grain yield, but also discuss the regulation and control mechanisms of carbon and water balance in WUE in essence. This study could provide theoretical basis and technical support of the development of saving water agriculture and conservation tillage in the North China Plain.

我国北方冬麦区水资源短缺，提高水分利用效率(WUE)是农业可持续发展的关键。免耕可调控农田水分利用，但降低冬小麦产量。农田WUE是碳吸收和水分散失耦合的结果，碳水平衡可从本质上揭示WUE的数量特征。本研究以激发免耕宽幅精播麦田群体调节能力为切入点，采用同位素示踪等方法进行农田碳吸收、水分散失和WUE研究。探索冬小麦群体结构调控、地上部光合碳同化过程驱动机制、碳吸收量和产量等，揭示免耕宽幅精播麦田碳吸收调控机制和产量损失补偿效应；研究近地面热量平衡状况、土壤-植物-大气连续体水分传输势能和阻力等，探索农田蒸散及水分传输的影响机理；以气孔导度为节点，构建碳水耦合模型，求取碳水耦合平衡点，揭示该平衡点在产量形成和WUE中的作用机理。明确上述问题，不仅可探索宽幅精播对免耕冬小麦产量损失的补偿效应，而且可从本质上揭示免耕宽幅精播麦田WUE的数量特征。本研究可为北方冬麦区发展节水农业提供理论依据。

我国北方冬麦区水资源短缺，提高水分利用效率（WUE）是农业可持续发展的关键。农田WUE是碳吸收和水分散失耦合的结果。免耕可调控农田水分利用和碳排放，但由于显著降低穗数而影响冬小麦产量。因此，如何在不显著降低冬小麦产量前提下提高WUE是免耕冬小麦发展的关键。本项目以激发免耕条件下宽幅精播麦田群体调节能力为切入点，系统研究了免耕宽幅精播麦田产量损失补偿效应、农田耗水、碳排放特征和碳水耦合等，主要结果如下：. 1. 和常规耕作相比，免耕覆盖显著降低了冬小麦穗数和千粒重，产量显著降低了6.8-12.0%。但是，在免耕条件下，宽幅精播显著提高了穗数，从而对免耕产量损失有补偿作用。而且，由拔节期灌溉推迟至拔节后10d灌溉，可进一步减少分蘖消亡，显著提高穗数。. 2. 在灌浆期，免耕处理的蒸腾速率比常规耕作处理显著提高，免耕和泰农18号均显著提高冬小麦旗叶的气孔导度。免耕和泰农18号均显著降低了冬小麦整个生育期的耗水量。2017-2018生长季，宽幅精播种植模式的耗水量比常规种植模式降低了5.5%，拔节后10d灌溉处理比拔节期灌溉处理的耗水量降低了5.0%。结果说明，宽幅精播种植模式和拔节后10d灌溉相结合可降低冬小麦整个生育期耗水量。. 3. 和常规种植模式与常规耕作相比，宽幅精播和免耕均显著降低了碳排放速率和CO2-C累积排放量。宽幅精播和泰农18对免耕产量损失有补偿作用。因此，在免耕条件下，推迟拔节期灌溉，宽幅精播与泰农18相结合可显著提高冬小麦产量碳利用效率和WUE，并显著降低单位耗水碳排放。. 项目研究结果已被Science of the Total Environment、Agricultural Water Management和排灌机械工程学报等国内外学术期刊发表或接受。已累计发表和接受期刊论文12篇，其中，SCI收录8篇，EI收录1篇，国内核心期刊论文3篇。授权实用新型专利2项。获农业农村部全国农牧渔业丰收奖二等奖1项（第三位）、山东省农牧渔业丰收奖二等奖1项（第三位）和山东省高等学校科学技术奖三等奖1项（首位）。1篇论文获2019年度山东省优秀硕士学位论文。本项目圆满完成了各项任务，达到了预期目标。