Characteristics of photosynthetic function in different leaf ages of 'Tieton' sweet cherry in a greenhouse

To clarify the stages of leaf growth and development, the young leaf stage was identified at 0-20 d after emergence (DAE). The functional stage was at 20-100 DAE, with the highest functional point at 80 DAE. The leaf aging stage occurred at 100-220 DAE. During the functional stage of leaf development, optimal photosynthetic parameters and anatomical structures were achieved; the leaf area (LA) was at its largest, and the thickening rate of the palisade parenchyma was the fastest. The palisade parenchyma and LA were closely related to photosynthetic characteristics. Stomatal opening and closing, and stomatal density were greater in the functional stage than in the early stage. Both decreased during the aging stage, and the net photosynthetic rate decreased.