作物获得最佳产量的亏缺灌溉及其实施策略

要想减少对灌溉水量的相对需求，必须尽可能降低或防止不必要的水分损失，同时可通过亏缺灌溉使有限供水得到强化利用。作者在总结前人工作的基础上，提出实施亏缺灌溉的七条原则来优化管理有限水分资源，使作物产量降低较小的同时获得最大水分利用效率。它们是：（１）使用抗旱能力较强的作物；（２）考虑水分亏缺发生时的作物生长发育阶段；（３）增加降雨对作物水分需求的贡献；（４）播前灌溉的需要性；（５）应用于深层土壤具有中等程度以上持水性能的土地；（６）管理地面灌溉系统以降低水分渗漏和径流；（７）改进作物栽培措施。

DEFICIT IRRIGATION AND RULES FOR OPTIMIZING YIELDS OF CROPS

Water is a key limited factor to the development of agriculture.As the amount of water available for irrigation diminishes to a extent in which crop's demand for water can not be fully met,it becomes essential to prevent or minimize all unnecessary losses of water such as deep drainage,runoff,evaporation,and weed transpiration.There have been many new concepts and research work on water-saving and yield-increasing.The main purpose of irrigation is to provide crops with nearly optimum supply of soil water so as to minimize such injury.Seven rules for deficit irrigation that are expected as guides to management of irrigation water so as to minimize yield reductions and maximize water use efficiency are :(1)use drought resistant crops;(2)consider the growth stage at which irrigation deficits are imposed;(3)Increase the contribution of precipitation to crop;(4)consider the necessity for irrigation;before sowing;(5)practice deficit irrigation only on relatively deep soils with moderately high water holding capacities;(6)manage surface irrigation systems to reduce water infiltration rates and runoff;(7)improve cultivation practices,for example,conservation fillage ,flexible planting dates,modification of the irrigation system,use of tuanspiration inhibitions and so on.