The study looked at how changing the amount and timing of nitrogen fertilizer application affected the quality and yield of a wheat variety called Guinong-19. By reducing the amount of nitrogen fertilizer used, the quality of the wheat improved significantly, while the yield only decreased slightly. Specifically, when the nitrogen fertilizer amount was reduced from 225 kg·hm-2 to 165 kg·hm-2, the quality of the wheat improved, and the yield only decreased by 4.2 kg·hm-2.