两个厚皮甜瓜品种不同时期的光合作用和糖分积累比较

【目的】探索厚皮甜瓜果实光合产物分配和果实糖分积累的内在生理机制，为厚皮甜瓜生产提供科学理论依据。【方法】以厚皮甜瓜品种丰蜜二号和好运52为试验材料，在授粉期至果成熟期测定叶片光合参数及果实可溶性糖含量。【结果】两个厚皮甜瓜在果实膨大初期（4月20日）蔗糖和还原糖的含量都很低，而光合速率和蒸腾速率较高，5月12日后蔗糖迅速积累，到6月5日和8日，丰蜜二号和好运52可溶性总糖含量分别达最高，分别为13．89％和10．37％，而此期厚皮甜瓜叶片光合速率和蒸腾速率呈下降趋势。【结论】丰蜜二号和好运52蔗糖积累的转折点是在授粉后22d，但随着蔗糖积累和果实的成熟，厚皮甜瓜叶片光合速率和蒸腾速率逐渐下降；丰蜜二号适宜收获期为授粉后45d左右，此时果实内可溶性总糖含量达到最高，为13．89％，风味最佳；而好运52最佳收获期在授粉后48d，其可溶性总糖达最高，为10．37％。

Comparison of photosynthesis and sugar accumulation in two melon varieties during different stages of development

Objective ]The present experiment was conducted to elucidate the physiological mechanism of sugar accumulation and changes in photosynthetic parameters in melon fruits during different growth stages in order to improve the quality fruit and its cultivation practices. Method]The leaf photosynthetic characteristics and soluble sugar content in fruits of water melon varieties Fengmi 2 and Haoyun 52 were investigated at different stages. Result]At the initial stage （April 20） of fruit enlargement, soluble sugar content and reducing sugars in both the varieties were very low, while the photosyn- thetic and transpiration rates were highest. After 22 d, the total sugar content in both the varieties increased dramatically, and the varieties Fengmi 2 and Haoyun 52 recorded maximum as 13.89 and 10.37% on 5 and 8 June, respectively, meanwhile the net photosynthetic rate and transpiration rate fell down to the minimum. Conclusion]The turning point of suerose accumulation in melon fruits was found to he 22 d after pollination, and net photosynthetic and transpiration rate decreased with the increasing sucrose accumulation and maturation of the fruits. The best harvest time for the varieties Fengmi 2 and Haoyun 52 was 45 and 48 days after pollination with 13.89 and 10.37% of highest total soluble sugar content, respectively.