Objectives Investigating the regulatory impact of phosphorus (P) and potassium (K) application patterns on grain yield and quality of medium and strong-gluten wheat can offer technological support for high-quality, high-yield cultivation of wheat in a rice-wheat system.

Methods A wheat field experiment was conducted in Jiangdu District, Jiangsu Province during 2022−2023. The cultivation system was rice-wheat rotation, with all the rice and wheat straw being consistently returned to the field. Yangmai 39, a medium-strong gluten variety, was utilized as the experimental material. The nine treatments of P and K fertilizers were composed of single application, combined application, basal and top-dressing application, single nutrient fertilizers and compound fertilizer (N−P₂O₅−K₂O₂ 15%−15%−15%). Before and after anthesis stage, plant samples were collected for determination of N, P and K contents and accumulation. At harvest, the yield and yield components were investigated, and the grain nutrition and procession quality were measured.

Results Application of P and K fertilizers significantly improved grain yield, quality, and nutrient accumulation, and significant differences were observed among the treatments. Compared to the control without P and K fertilizers, the split application of total amount of P and K fertilizers (120 kg/hm² for both) half as the basal and half as topdressing were recorded the highest grain yield, with the yield increase of 61% by applying single fertilizer and 65% by applying compound fertilizer. Total amount of P and K fertilizer in basal application were recorded the second high yield levels, while total K in base application alone was recorded the lowest yield effect. Split application of total PK fertilizers also increased grain total protein content, and the ratio of gluten to alcohol-soluble gluten, thereby improved the procession quality indexes like wet-gluten content, hardness, and sedimentation value. Like yield results, compound fertilizer showed better effect than the single fertilizers at the same application amount and method. The split application of PK fertilizers stimulated the N, P and K accumulation before and after anthesis stage, and the transportation of N and P accumulated before anthesis.

Conclusions High amount of P and K fertilizers applied half in base and half as topdressing is most conducive to enhancing the absorption and translocation of nitrogen, phosphorus, and potassium nutrients in wheat, elevating grain yield and total protein content. The method also increase the ratio of glutenin and gliadin, thereby improving the wet gluten content, hardness, and sedimentation value of the flour. With the same amount and method of fertilizer application, compound fertilizers are more effective than single-nutrient fertilizers. Basal applying potassium fertilizer only increases potassium absorption in wheat but does not enhance yield or quality.