| In order to elucidate the effects of different nitrogen (N) application rates and N:K ratios on soil salinity dynamics, yield, and fruit quality in labor-saving, high-density fragrant pear orchards under drip irrigation. A two-year field experiment was conducted including four N application rates (N1: 100 kg hm-2, N2: 200 kg hm-2, N3: 300 kg hm-2, and N4: 400 kg hm-2) and two N:K ratios (N1: 1:1 and 2:1; N2: 2:1 and 4:1; N3: 3:1 and 6:1; N4: 4:1 and 8:1) under each N application rate treatment. An entropy-weight method was employed to objectively assign weights and construct a comprehensive fruit-quality evaluation index, and a structural equation model (SEM) was used to quantitatively identify the key drivers affecting yield and quality of Korla fragrant pear (Pyrus sinkiangensis). The optimal N:K ratio for orchard fertilization management was proposed to provide technical support for scientific fertilization in Korla fragrant pear production. The results showed that both N application rate and N:K ratio significantly affected soil salt accumulation in the 0~100 cm soil profile across different phenological stages (P<0.05). Appropriate N application rate and N:K ratio reduced soil salt accumulation during the fruit-expansion stage. As N application rate and N:K ratio increased, soil salt accumulation exhibited a decreasing-then-increasing trend. Among all treatments, N3 reduced salt accumulation by 43.84%~99.58% compared with other treatments in 2022 and 2023. The lowest salt accumulation was observed at an N:K ratio of 3:1, which was 19.32%~142.27% lower than that under the other ratios. In addition, N application rate and N:K ratio significantly influenced pear yield and fruit quality (P<0.05). Both yield and the comprehensive quality index increased initially and then declined with increasing N rate and N:K ratio. Compared with other treatments, N3 increased yield and the comprehensive quality index by 4.81%~23.73% and 36.69%~152.00%, respectively, in 2022 and 2023. The N:K ratio of 3:1 achieved the best performance, improving yield and quality by 1.35%~3.46% and 38.18%~79.59%%, respectively, compared with other ratios. SEM analysis indicated that the N:K ratio was the primary factor governing both yield and quality. Therefore, for labor-saving fragrant pear orchards under drip irrigation in saline-affected regions, an N application rate of 300 kg·hm-2 combined with an N:K ratio of 3:1 can synergistically enhance yield and fruit quality while reducing the risk of soil salinization. |