Abstract: 【Objective】Study the effects of reduced chemical fertilizer application on the growth and fruit quality of facility watermelon,to seek for the optimal fertilization plan.【Methods】Taking Qianli No.4 as the research object,five fertilizer gradient treatments were designed,including conventional fertilization（CK）,10% chemical fertilizer reduction（T1 treatment）,20% chemical fertilizer reduction（T2 treatment）,30% chemical fertilizer reduction（T3 treatment） and 40% chemical fertilizer reduction（T4 treatment）. During the growth period of watermelon,growth indexes such as plant extension days,pollination days,and fruit setting nodes were investigated. After fruit maturation,quality indicators such as single fruit weight, fruit longtitudinal and transverse diameter,peel thickness,and sugar content as well as the yield were measure.【Results】The pollination days of the T3 treatment were 65.67 d,significantly different with CK（P<0.05）. The edge sugar content of the T1 treatment was 9.40%. With the decrease of chemical fertilizer application,the sugar content of watermelon showed decreasing trend. The central sugar content of T2 treatment decreased significantly（P<0.05） in comparison with CK. The edge sugar content in T4 decreased to 7.87%,significantly different（P<0.05） with CK. Compared with CK,reduced chemical fertilizer application decreased the peel thickness of watermelon. T1 treatment had the highest watermelon yield of 39.98 t/hm² while T4 treatment had the lowest watermelon yield of 33.49 t/hm². The yield of the different treatment had no significant difference（P>0.05）. Fertilizer factor was positively correlated with peel thickness and edge sugar content,with correlation coefficients of 0.62 and 0.59,respectively. The higher the fertilizer application rate,the thicker the fruit peel and the higher the edge sugar content.【Conclusion】Without affecting the growth and the fruit quality of watermelon,reducing the application amount of chemical fertilizer in the base fertilizer appropriately could achieve the goal of reducing fertilizer while improving efficiency. Taking into account the growth indexes,fruit quality indicators,and yield of watermelon,10% chemical fertilizer reduction（Basal application of potassium sulfate compound fertilizer 675 kg/hm²） was optimal.

Key words: Facility watermelon, Reduced chemical fertilizer application, Growth, Fruit quality