The researchers studied how shading affects the photosynthesis of winter wheat leaves and overall grain yield. They shaded two wheat varieties to see how different levels of low light affected the top three leaves. They found that as shading increased, the overall photosynthesis of the wheat plants decreased. The main leaf (flag leaf) had a significant drop in photosynthesis, but the third leaf compensated by increasing its photosynthesis. However, this compensation was not enough to maintain overall photosynthesis levels, leading to a decrease in grain yield. This study provides important information for wheat production in certain regions.