摘要： 以5年生大金星山楂品种为试材，对其开花结果期叶片光合速率作了研究，结果表明，山植结果新梢叶片在展叶后15d时即有大量的光合产物输出，展叶后48d时光合速率达到第2次高峰。在不同生育期、天气状况下，叶片的光合速率变化较大，阴天时明显降低。树冠外、中、内各层结果新梢叶片光合速率依次降低。盛花期喷布赤霉素，可提高叶片的光合速率。外围营养枝和结果新梢叶片的光合速率无显著差异。

关键词: 山楂, 叶片, 光合作用, 幼树

Abstract: The photosynthetic rate of leaves in young haw trees at blooming and fruit setting stages was studied taking the 5-year-old Dajinxing haw trees as test materials. The results showed that the leaves on the new shoots could produce a lot of photosynthetic products on the 15th day alter spreading leaves,and the photosynthetic rate reached the second high peak on the 48th day. The photosynthetic rate could markedly vary at different growth stages and under different weather conditions,and it would significantly go down in cloudy days. It was also found that the photosynthetic rate of leaves on the new shoots gradually decreased in this order;outer (0-10cm) ,inner (10-50cm from the outer) and center (>50cm from the outer) canopies. The photosynthetic rate could be increased by spraying GA at full bloom stage. There was no clear difference in photosynthetic rate of leaves on both the nutritive shoots ana fruit shoots.

Key words: Haw, Leaf, Photosynthesis