免耕高产夏玉米田根层优化调亏滴灌制度研究

The field and pot experiment, and model simulation will be conducted together for optimizing rhizosphere deficit drip irrigation in high yield summer maize field under zero-tillage. The major research including water consumption, daily water consumption and water consumption rate of summer maize in its various growth stages under different irrigation amount and time, by which clarified the percentage of evaporation, transpiration, plant water content and deep soil water leaching. Theoretical model will be set up by the data collected to simulated maize yield and water consumption under three typical precipitation years. The water resource nonlinear dynamic optimized allocation strategy and Jensen multiplication model will also be used together with the theoretical model and soil water potential for illustrating crop water sensitive stage and water shortage degree under different precipitation year, which could be useful for drip irrigation management application, thereafter, an optimized drip irrigation management will be set up based on crop water requirement. In this study, model simulation, soil dyed and crop root collection will be applied to reveal the relationship between soil water movement, distribution and crop root growth pattern. Crop evaportranspiration will also be explored as affected by soil water dynamics with stem flow rate, leaf stoma closure, transpiration, leaf water potential and abscisic acid (ABA) content. This research will provide information for water-saving irrigation agriculture.

拟采用大田、池栽试验和数值模拟相结合的方法，开展免耕田高产夏玉米根层优化调亏滴灌制度研究。主要研究内容：不同灌水量和时期对夏玉米各生育阶段的耗水量、日耗水强度、模系数,以及棵间蒸发量、植株蒸腾量、植株含水量、深层渗漏量所占比例的影响。建立三种典型降水年型下的作物产量和耗水量之间模型。结合水资源非线性动态优化分配策略和Jensen乘法模型，以及土壤水势指标，明确三种典型降水年型下作物的水分敏感期、亏缺度、滴灌数量和滴灌周期，建立该条件下作物优化动态灌溉制度。将数值模拟、土壤染色和分层取根技术相融合，揭示土壤剖面水分时空分布和根系空间分布关系，明确该试验条件下土壤水分运移规律，通过监测茎间液流速率动态变化、叶片气孔开闭、蒸腾速率、叶片水势和叶片中脱落酸含量的变化，揭示根层土壤水分盈缺程度对植物水分散失的影响，为作物高产节水的技术提供理论支撑。

本项目针对黄淮海平原夏玉米区农业水资源匮乏限制粮食生产高产高效这一生产问题，采用作物生理生态学、农田水利学、土壤学、植物生理学、农业模型学等理论，将大田、池栽试验和数值模拟相结合的方法，开展免耕田高产夏玉米根层优化调亏滴灌水分耗散规律、高效用水规律和高效灌溉制度研究。主要结果如下：通过不同灌水模式研究，揭示出地下滴灌夏玉米总耗水量在154.8~349.5mm，阶段耗水量28.96~113.57mm，其中耗水模数高于30%以上两个阶段为拔节-大喇叭口和抽雄-成熟两个阶段耗水量较大，地下滴灌土面蒸发掉水分仅占蒸散量的8.3%~21%。夏玉米播种-拔节、拔节-大喇叭口、大喇叭口-抽雄、抽雄-成熟的水分敏感指数（λ）分别为0.0684、0.2308、0.2565、0.088，水分敏感指数最大值在大喇叭口-抽雄阶段。实验表明了地下滴灌夏玉米生长周期作物系数的变化符合高斯方程规律，夏玉米水分利用效率最高和产量最高时的蒸散量为212~288mm，对应于80%ETc灌溉处理；通过HYDRUS-2D模拟滴灌带埋深为30 cm时，在灌溉结束水分平衡3天后，土体较湿润（含水量＞75%FC）的土层范围为距地表5～55 cm，水平运移的距离分别为37 cm，湿润峰垂直和水平移动速率0.34 cm•h-1和0.51 cm•h-1；拔节期后80%ETc处理主要根系层的吸水速率一直较高，保持较高根伤流量、叶片相对含水量和光合效率，叶片中植物内源激素ABA和IAA适当升高，GA3下降；利用Pearson Ⅲ型理论分布曲线求算出试验地干旱、正常、湿润年型，夏玉米生长季节的降水量分别为359mm、456mm、569mm。依据水资源非线性动态优化分配策略，采用0-1规划方法求解夏玉米地下滴灌数量和和滴灌期，在干旱年降水年型下，在拔节-大喇叭口，大喇叭口-抽雄需灌溉3~4次，在正常降水年型下，在拔节-大喇叭口灌溉2次，在湿润年型下，在拔节-大喇叭口灌溉1~2次。研究结果为农田实时精准补灌，缓解作物根层水分短缺，确保数量上匹配、时间上同步、空间上耦合，从而实现作物高产与节水目标，具有重要科学意义。