Objective The study examines the effects of combining water-retaining agent with basal fertilizers on the growth, development, and yield formation of spring wheat in the arid regions of Xinjiang. The findings aim to provide a theoretical basis for the application of water-retaining agent in spring wheat cultivation in Xinjiang's drylands.

Methods Under the conditions of dryland field in Xinjiang, two treatments were set: 45 kg/hm² of water-retaining agent + 450 kg/hm² of diammonium phosphate (BP) and 450 kg/hm² of diammonium phosphate (CK). The study investigated the effects of different treatments on the plant traits, leaf characteristics, leaf physiological properties, and yield formation of spring wheat.

Results Compared to the application of basal fertilizer alone (CK), the combined application of water-retaining agent and basal fertilizer (BP) increased the leaf area of all leaf layers in spring wheat grown in dryland areas, lengthening the spike, and promoting more uniform development of the wheat's internodes. The application of the water-retaining agent also resulted in significant increases in the SPAD value, Pn, Tr, and g_s of the flag leaf of spring wheat, compared to application of basal fertilizer alone CK, which promoted the accumulation of dry matter. Additionally, it increased the number of fertile spikelets, reduced the number of sterile spikelets, increased the number of effective spikes and grain number per spike, and improved thousand-grain weight, thereby boosting grain yield. The highest grain yield under the BP treatment was 4817.25 kg/hm², which represented a 22.51% increase over the CK treatment.

Conclusion The one-time application of a mixture of water-retaining agent and basal fertilizer before soil preparation in Xinjiang’s dryland spring wheat can effectively improve leaf photosynthetic performance and dry matter accumulation, reduce sterile spikelets, increase the number of grains per spike and grain weight, and ultimately enhance grain yield. The research findings can provide a valuable reference for the application of water-retaining agent in spring wheat cultivation in Xinjiang's drylands.