Abstract:In order to explore the effects of water and nitrogen coupling on the yield, quality and water and nitrogen utilization of mountain apples under different irrigation technologies, a three-factor three-level orthogonal experiment was used with a total of 9 treatments, and each treatment was repeated 3 times. The three irrigation technologies were surge-root irrigation (S), ceramic infiltration irrigation (P) and surface drip irrigation (D), the three irrigation volumes were high water (H1), medium water (H2) and low water (H3), and the three nitrogen application rates were high nitrogen (N1), medium nitrogen (N2) and low nitrogen (N3). The response of mountain apple yield and water nitrogen use efficiency to water nitrogen regulation under different irrigation technologies was analyzed. The results showed that irrigation technology had a significant effect on fruit weight, vitamin C and fruit color (p<0.05), and irrigation water volume and nitrogen application rate had significant effects on apple yield, fruit weight, fruit hardness, color, soluble solids, titratable acid, soluble sugar, vitamin C, sugar-acid ratio, nitrogen fertilizer partial productivity and irrigation water use efficiency (p<0.05). Mountain apples treated with T2 (SH2N2) had the highest yield (30 490.02 kg/hm2), T5 treatment (PH2N3) had the highest nitrogen fertilizer productivity (104.66 kg/kg), and T9 treatment (DH3N2) had the highest irrigation water use efficiency (70.81 kg/m3). The principal component analysis method showed that the optimal mode of water nitrogen coupling under different irrigation technologies was the combination of surge-root irrigation, medium irrigation volume (65%~80% θ<em>f), and medium nitrogen application rate (400 kg/hm2) (T2). The results of this study can provide scientific theoretical basis and technical support for the water and nitrogen management of apples in mountainous areas of northern Shaanxi.