【Objective】The aim of this study was to understand the variations of grain nitrogen (N) content and its relationships with yield formation as well as uptake, transfer and partitioning of nitrogen, phosphorus, and potassium (NPK) within high-yielding wheat cultivars, which was of great significance for screening and breeding superior wheat cultivars with high yield and grain N content, and for nutrient management in green production of wheat with high yield and high quality in drylands.【Method】Field experiments were carried out, and 14 high-yielding wheat cultivars of similar yields and different grain N content were cultivated on the typical dryland area of the Loess Plateau from 2017 to 2022. Differences in grain N contents of high-yielding wheat cultivars and its relation to yields, yield components as well as N, P and K content in different organs were analyzed. Meanwhile, biomass accumulation and yield formation as well as uptake, transfer and partitioning of NPK in response to fertilization were investigated.【Result】Significant positive correlation was found between the grain N content and 1000-grain weight of wheat cultivars, and for each 1.0 g increase of the 1000-grain weight, the grain N content increased by 0.3 g·kg-1. The grain N content showed significant differences in the tested wheat cultivars, with the mean of high-N group being 24.9 g·kg-1, and 16% higher than that of the low-N group (21.5 g·kg-1), respectively, while the average yields were not significantly different from each other of the two groups. The yield, biomass and spike number of high-N group exhibited higher response to N and P fertilizer application. The grain P content and straw K content of the high-N group were higher than the low-N group under different fertilization conditions, and the increases of N, P and K uptake in grain and shoot were larger than that of low-N group after N and P application. The abilities of N transfer from glumes to grains in the high-N group was greater than that in the low-N group, but the capacities of K transfer from straws to grains and glumes was lower than that in low-N cultivars. The abilities of K transfer from straws to other organs decreased significantly after N application. Application of N, P and K was conducive to increase the partitioning of K from shoots to straws of the high-N group.【Conclusion】The high-yielding wheat cultivars exhibited significant differences in the grain N content. The 1000-grain weight and grain P content of high-N cultivars were higher, its straw K content was also higher, but its capacities of K transfer from straws to grains and glumes was lower. The N, P and K uptake of the high-N group in grains and shoots increased extremely after N and P application. Therefore, to screen and breed superior wheat cultivars with high grain N content on the basis of high yield, the attention should be paid to select the cultivars with high grain 1000-grain weight as well as the strong transferring and partitioning abilities of P to grains and K to straws. The efforts should be also made to cooperate the supply of P, K and N in wheat production, with the purpose to increase the grain N content.
