| Abstract: In order to explore the optimal irrigation strategy for the cultivation of watermelons in facilities, three treatments of alternate partial root-zone irrigation (APRI, the upper limit of irrigation was 70%, 80% and 90% fi eld moisture capacity, respectively) were set up under the cultivation mode of plastic greenhouse in early spring, taking conventional drip irrigation as the control and watermelon 'Zaojia 8424' as material. The effects of different irrigation modes on the growth, yield, quality, nutrient absorption and water use effi ciency of watermelon were studied. The results showed that the APRI treatment (the upper limit and lower limit of irrigation were 90% and 60% fi eld moisture capacity, respectively) had the best comprehensive characteristics, and the main vine length, SPAD value, average fruit weight, yield, central soluble solid content, total nitrogen content and total potassium content signifi cantly increased compared with the control. The theoretical yield was 48 217.5 kg/hm2, and the water use effi ciency was 78.21 kg/m3, which increased by 11.09% and 35.50% compared with the control, respectively, and could save water by 33.01%, which had obvious water saving effect and higher water use effi ciency. This treatment could not only promote the growth, quality and nutrient absorption of watermelon, but also achieve purposes of high yield and water saving, and effectively improving irrigation water use effi ciency. |