[Objective] This study aims to explore the effects of irrigation quota distribution and water -phosphorus coupling on the growth regularity of alfalfa(Medicago sativa L.)under drip irrigation.[Method]Three irrigation gradient treatments were conducted:5,250 m3/hm2(W1),6,000 m3/hm2(W2),and 6,750 m3/hm2(W3),respectively.Under the irrigation amount of 6,000 m3/hm2(W2),irrigation amount were dis-tributed with three different modes:(1)35%of the total irrigation amount before mowing and 65%of the to-tal amount irrigation water after mowing(F1).(2)50% of the total irrigation amount before mowing and 50%of the total amount irrigation water after mowing(F2).(3)65% of the total irrigation amount before mowing and 35%of the total amount irrigation water after mowing(F3).Three kinds of phosphorus patterns were set up under three irrigation gradients,and the contents of P2O5were 50 kg/hm2(P1),100 kg/hm2(P2) and 150 kg/hm2(P3),respectively.[Result]In the different irrigation quota distribution conditions,the days of reaching the fastest growth rate of alfalfa plants under F 2treatment were at least 17-18 days,and the alfal-fa biomass of F1treatment had the biggest growth space,which was also the least influenced by irrigation quota distribution of different mowing.In the different water-phosphorus coupling conditions,the maximum growth rate of alfalfa plants reached at least 15-16 d at each time of W3P2treatment and the alfalfa biomass of W 1P3 and W2P3and W3P3treatments had the biggest growth space,among which,W3P3treatment was the least in-fluenced by water and phosphorus of different mowing.[Conclusion]When the alfalfa reached the maximum growth rate on 15 th to 18 th days,the effect of water fertilizer managements were the best,and the irrigation with 35%of the total irrigation amount before mowing and 65%of the total amount irrigation water after mow-ing,and effective coupling between suitable irrigation amount(6,000 m3/hm2)and phosphorus application a-mount(P2O5100 kg/hm2)were beneficial to the effective development of alfalfa growth potential under drip irrigation in the second growth year.%[目的]研究不同灌溉定额分配及水磷耦合对滴灌苜蓿(Medicago sativa L.)生长规律的影响.[方法]设3种灌溉梯度,分别为:5250 m3/hm2(W1)、6000 m3/hm2(W2)、6750 m3/hm2(W3),在灌水量为6000 m3/hm2(W2)下,设3种灌溉定额分配模式:(1)刈割前灌溉本茬次总灌水量的35%+刈割后灌溉本茬次总灌水量的65%(F1)、(2)刈割前灌溉本茬次总灌水量的50%+刈割后灌溉本茬次总灌水量的50%(F2)、(3)刈割前灌溉本茬次总灌水量的65%+刈割后灌溉本茬次总灌水量的35%(F3).在三种灌溉梯度下分别设3种施磷模式为:施P2O550 kg/hm2(P1)、100 kg/hm2(P2)、150 kg/hm2(P3).[结果]不同灌溉定额分配条件下,各茬次F2处理苜蓿植株达到最快生长速率的天数最少为17~18 d,F1处理苜蓿生物量的增长空间最大,且受灌溉定额分配的影响最小;不同水磷耦合条件下,各茬次W3P2处理苜蓿植株达到最快生长速率的天数最少为15~16 d,W1P3处理、W2P3处理、W3P3处理苜蓿生物量的增长空间最大,W3P3处理受水磷影响最小.[结论]在苜蓿达到最大生长速率15~18 d时进行水肥管理效果最佳,且刈割前灌溉本茬次总灌水量的35%,刈割后灌溉本茬次总灌水量的65%,以及适宜灌溉量(6000 m3/hm2)与施磷量(P2O5100 kg/hm2)的有效耦合,均有利于建植第二年滴灌苜蓿生长潜力的有效发挥.
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