The study looked at different types of winter wheat to see how well they use nitrogen. They tested 20 types of wheat in France with and without nitrogen fertilizer. Some wheat types did better with added nitrogen, while others did well without it. The number of kernels on each ear of wheat was the biggest factor in how much grain the plants produced. The way the plants took up nitrogen from the soil also affected how efficiently they used it. This information can help breeders create wheat varieties that work well in farming systems with less nitrogen.