Dynamic changes in flag leaf angle contribute to high photosynthetic capacity

Abstract

Dynamic changes in flag leaf angle, anatomy, photosynthesis, chlorophyll content, population photosynthesis, and light transmission are investigated in three wheat cultivars: Xiaoyan 81 (Xy 81) in which flag leaf angle changes from erect to draped, Xiaoyan 41 (Xy 41) in which flag leaf angle changes from erect to half draped (middle type), and Xiaoyan 6 (Xy 6) in which the flag leaf remains erect from the flowering to the grain-filling stage. No obvious differences in leaf thickness, leaf area, mesophyll morphology, granal stacking, photosynthesis, or chlorophyll content are found among the three cultivars. It is of interest to find that the flag leaf angle of Xy 81 changes from erect to draped during the grain — filling stage, but there are no obvious changes in chlorophyll content or photosynthetic capacity during this period, indicating that changes in flag leaf angle do not result from senescence. Moreover, the study shows that levels of population photosynthesis and light transmission in Xy 81 are higher than in Xy 41 and Xy 6. Taken together, these results demonstrate that dynamic changes in Xy 81 flag leaf angle enhance population photosynthesis and thus may improve wheat yield.