新疆滴灌小麦水分高效利用原理与调控机理研究

According to the demand of efficient use technology of water and fertilizer in arid area of Xinjiang, the field, potted and soil column culture experiments will be designed to investigate the relationship between soil water dynamics and water consumption features in drip-irrigated wheat field, the effects of various root zone moisture and nitrogen to root configuration and coordinated growth characteristics between root and canopy organs, the photosynthetic source-sink characteristics in yield forming under drip irrigation,and compensatory effects of synergically improving yield and water use efficiency. To carry out the trial, we will reveal water physiological mechanism responsible for the high-yield in drip-irrigated wheat field,look for the optimal pattern of drip irrigation and regulatory pathways with trickle irrigation of moisture and fertilizer integrated, draw up the reasonable drip-irrigated regime that would provede the basis for the production practices.Furthermore,the performance of this experiment will be conducived to clarifying the regulatory mechanism of improving coordinately the yield and water use efficiency and nitrogen uptake rate,to ascertaining the features of assimilate transportation and distribution in the high yield of wheat under water-saving conditions, which could provide evidence for confirming the theory of redundancy and broad sense compensation of crop. Therefore,it will has important theoretical and practical significance in supplementing the water-saving cultivation theory and drip irrigation technology of dense-planted crop.

针对新疆干旱区气候条件下节水节肥技术的需求，开展滴灌麦田土壤水分动态与麦田耗水关系、根区水分和氮素变化对根系构型与生长特征及对地上部器官生长与生理特征的调节效应、滴灌条件下产量形成的光合源和穗库特性的关系等的研究，探讨滴灌麦田耗水特征、小麦根冠协调生长与土壤水分和养分变化的关系，及水分调节下小麦生长特性与产量形成的补偿效应，揭示滴灌小麦水分高效利用特征与高产形成的生理机理，找寻小麦优化滴灌模式、"以肥调水"的水氮一体化调控途径，提出适宜于新疆干旱区生态条件下小麦节水、高产、高效的滴灌制度，为生产实践提供依据。另外，开展本项目研究，有助于从理论上认识滴灌小麦产量和水氮利用效率协同提高的调控机制及小麦高产、节水、高效生产的根冠光合同化物积累与优化分配特征，为证实作物生长冗余理论及广义补偿理论提供依据，对补充干旱区密植作物节水节肥高产栽培新理论具有重要意义。

为了探讨滴灌小麦水分高效利用原理与调控途径，开展了滴灌小麦产量和水氮利用效率协同提高的调控机制的研究。结果表明：（1）滴灌水分在土壤中的垂直运移距离缩短，水分调节的层次上移，上层土壤（0-60cm）水分变化差异减小。滴灌入渗最大深度为60cm左右，最大扩展宽度为40cm左右，灌后10天左右土壤水分含量达到生长下限。10~30 cm土层是滴灌小麦的主要耗水层，其耗水量占58.4%；（2）高水、中水、低水和漫灌处理的春小麦生育期蒸散量分别为459.19mm、400.10mm、274.23mm和686.58mm，平均蒸散强度为4.32 mm/d、4.05 mm/d、2.65mm/d和5.75mm/d。耗水量、水分利用效率与产量间呈极显著的对数关系和直线关系，耗水量、水分利用效率和产量间达到一个合理的阈值，才能实现高产与节水的统一；（3）水、氮对小麦根冠生长和产量性状具有明显的协同补偿效应，并以根系性状的“以氮调水”效应较大，冠部的“以水调氮”效应较大水氮处理中，水分是主控因素，其调控效益是供氮效应的1.93倍。水氮在小麦产量与水分利用上具有耦合补偿效应，其对产量的贡献率达16.61%，这为适宜的水氮调控提供依据；（4）干旱对小麦光合性能的影响具有累加效应，造成光合速率（Pn）、气孔导度（Co）、WUE和群体光合速率（CAP）降低，光合 “午休”现象明显；过量灌溉生育延迟，群体LAI过大，Pn、CAP、CR、叶源量（CLSC）在小麦生育后期下降快，倒伏加重。适宜滴灌在灌浆期能较长时间保持高的Pn、WUE、CAP、CR和CLSC，保证了籽粒发育和灌浆养分需求；（5）春小麦阶段受旱引起的生长负效应可通过其他阶段充分供水而得到补偿，这为生产中受旱后及时补水、调节生长以获得较高产量提供理论依据；（6）与漫灌相比，滴灌麦田的ET较低而WUEi较高，南疆滴灌春小麦生育期内ET为547.57mm，平均阶段耗水强度为6.08mm/d，孕穗-扬花耗水强度最大，达13.96mm/d，扬花-乳熟耗水量最多，占全部耗水量的40.05%，作物系数（Kc）分别为：初期生长期Kcini =0.71，生长中期Kcmid =1.15，成熟期Kcend=0.48， WUE在13.75-15.21kg/（mm•hm2）之间。