| In order to solve the problem of insufficient irrigation water resources and low utilization rate of fertilizer resources in the sorghum production in northern Shaanxi region, this study aims to analyze the response of sorghum dry matter accumulation and yield to different fertilizer application rates and basal-topdressing ratio under supplementary irrigation in northern Shaanxi province, so as to provide a theoretical basis for determining water-saving and fertilizer reduction, developing sustainable agriculture in this region. In 2023, conducting a field experiment with two factors of fertilizer application rates and basal-topdressing ratios in Yulin, Shaanxi. The study investigated the effects of three fertilizer application rates (standard fertilizer application rate, Z100; 80% standard fertilizer application rate, Z80; 60% standard fertilizer application rate, Z60) combined with three basal-topdressing ratio (base fertilizer: jointing fertilizer: flowering fertilizer =8:1:1, F82; Base fertilizer: jointing fertilizer: flowering fertilizer =6:2:2, F64; base fertilizer: jointing fertilizer: flowering fertilizer =4:3:3, F46) on dynamic dry matter accumulation and yield of sorghum. The fertilizer application rate and basal-topdressing ratio had a significant effect on dry matter accumulation, water use efficiency and yield of sorghum (p<0.05). The dry matter accumulation increased initially and then decreased as the application of fertilizer was reduced after the jointing stage. The dry matter accumulation increased with the increase of topdressing proportion under the application of Z80 fertilizer. Z80F46 treatment significantly increased the maximum and average accumulation rates of dry matter, delayed the time required to reach the maximum dry matter accumulation rate, and significantly increased the dry matter accumulation at maturity by 23.47% and 11.01% compared with Z80F82 and Z80F64 treatments, respectively. At the same time, Z80F46 treatment significantly increased the allocation proportion of dry matter in grain, promoted dry matter transport before flowering and assimilation after flowering. Under the same fertilizer application, the dry matter remobilization efficiency of pre-flowering nutrient organs and post-flowering dry matter assimilation of Z80F46 treatment were 81.82% and 101.71% higher, respectively, than Z80F82 and Z80F64 treatments. In addition, compared with the same basal-topdressing ratio treatment with Z100 and Z60 fertilizer application rates, the grain yield increased by 28.25%~54.35% and 42.49%~81.50%, respectively, under the application of Z80 fertilizer. Under the same fertilizer application, the water use efficiency of Z80F46 treatment was 25.35% higher than that of Z80F82 and Z80F64 treatments. Under supplementary irrigation conditions, reducing fertilizer application by 20% and increasing the topdressing proportion can promote dry matter accumulation, allocation and transport in sorghum, significantly improving water use efficiency and yield. Therefore, the recommended drip irrigation fertilization scheme for sorghum cultivation in northern Shaanxi region is to reduce the standard fertilization amount by 20%， with the base fertilizer : jointing fertilizer : flowering fertilizer adjusted to 4:3:3. |