The researchers studied how different amounts of nitrogen and planting density affect the grain yield and nitrogen use efficiency of winter wheat. They found that both planting density and nitrogen levels have a big impact on the wheat's yield. By adjusting the nitrogen rate and planting density, farmers can increase the grain yield and use nitrogen more efficiently. For one type of wheat, the best planting density was 102 kg/ha with 180 kg/ha of nitrogen, while for another type it was 83 kg/ha with the same amount of nitrogen. Adjusting these factors can help farmers get more wheat while using nitrogen effectively.