Abstract: To explore the suitable irrigation techniques for Alfalfa in Haihe Plain, six irrigation treatments were set up to study the effects of different irrigation treatments on the yield, agronomic traits and water use efficiency of one-year and two-year Alfalfa from 2015 to 2017. The results showed that alfalfa yield increased slightly with increasing irrigation amount in Haihe Plain, but had no significant difference among six treatments. Compared with the treatment without irrigation, the cumulative increment of alfalfa yield in three years was only 6.13 t·hm^-2. The water use efficiency of Alfalfa significantly decreased gradually with the increase of irrigation amount (P<0.01). It suggested that the alfalfa was not irrigated in Haihe Plain where was extreme shortage of water resources, but when the annual rainfall was less, especially in winter and spring, alfalfa should be irrigated overwintering water once and the irrigation amount was 75 mm, which could improve the alfalfa yield and the sustainable production capacity of alfalfa.

Key words: Alfalfa, Irrigation period, Irrigation amount, Yield, Water use efficiency

摘要： 为了探讨紫花苜蓿（Medicago sativa L.）在海河平原区适宜的灌溉技术，2015-2017年选用1龄苜蓿和2龄苜蓿为试验材料，设置6种灌溉处理，研究不同灌水处理对苜蓿产草量、农艺性状、水分利用效率的影响。试验结果显示：在海河平原区，苜蓿产草量随着灌水量增加略有升高，但差异不显著。年增加灌水量225 mm处理与不灌水处理相比，苜蓿3年累计增产仅为6.13 t·hm^-2，并且随着灌水量的增加，苜蓿水分利用效率逐渐降低，且差异极显著（P<0.01）。综合分析显示，在海河平原区水资源极度紧缺情况下苜蓿种植一般无需灌溉，但在年度降雨量较少，特别是冬春季节降雨较少的年份，建议对苜蓿进行1次补灌，选择灌冻水，灌水量75 mm，可能对提高苜蓿当年生物产量以及提高苜蓿持续生产能力具有一定促进作用。

关键词: 紫花苜蓿, 灌溉时期, 灌水量, 产草量, 水分利用效率