The researchers studied how different types of winter wheat and levels of nitrogen fertilizer affected the quality of the grain. They tested two wheat varieties, 'Bussard' and 'Zentos', with four levels of nitrogen application. They found that both the wheat variety and the amount of nitrogen used had a significant impact on the protein content, wet gluten, and sedimentation value of the grain. After storing the grain for 60-120 days, they observed changes in these quality traits, such as a decrease in sedimentation values and an improvement in gluten quality. They also discovered strong correlations between protein content, gluten content, and sedimentation value for both wheat varieties.