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通过对敞口山楂叶片光合速率（Pn）的研究表明：（1）Pn年周期变化为双峰曲线，峰值分别出现在6月中下旬和9月下旬。（2）不同类型枝叶片的Pn值有明显差异，但其Pn的年变化曲线均为三峰型，并且结果枝的光合能力强于营养枝。营养技类型中以剪口芽新梢的Pn变化最为剧烈。腋芽果枝叶片的Pn第一高峰较顶芽果枝早，但总体水平较低。（3）不同节位叶片的光合速率有明显差异。年周期变化中，营养枝中部9位叶具有相对稳定的高Pn值，随着季节的推进，光合能力最强的部位逐步向外转移。果枝不同节位叶片的卜变化受果实发育的影响。（4）树冠不同受光部位的光照强度、叶片中叶绿素的含量与Pn间均无显著的相关性。
The study on the photosynthetic rate (Pn) of hawthorn leaves showed that: (1) The annual variation of Pn was a bimodal curve with the peaks appearing in the middle and late June and late September respectively. (2) The Pn values of different types of branches and leaves were significantly different, but the annual variation curves of Pn were all three peaks, and the photosynthetic ability of the branches was stronger than that of vegetative branches. Nutritional techniques in the type of shoots bud shoots change Pn most intense. The first peak of Pn in axillary buds was earlier than that in the top buds, but the overall level was lower. (3) There were significant differences in photosynthetic rate among different node leaves. In the annual cycle, nine leaves in the middle of vegetative shoots had a relatively high Pn value. As the seasons progressed, the strongest photosynthetic sites gradually shifted outward. The changes of the leaves in different nodes of fruiting branches are affected by the development of fruits. (4) There was no significant correlation between the light intensity of chlorophyll and chlorophyll content in different light-receiving parts of canopy.