Three cultivars of Cucumis melo L. Were used to study the effects of light density on sugar accumulation of melon fruits. The results indicated that the glucose and fructose of melon increased quickly at early stages of fruit de-velopment , while sucrose rapid accumulation took place at later stage. When maturing, the sugar content of Yujinxiang (136.63 mg/g) was significantly higher than that of Yindi (119.9 mg/g) , and that in Yindi was clearly higher than that in Huanghemi (108.14 mg/g) . The sugar contents at different fruit points in ripen melon was blossom end > central flesh > stem end. Under shading conditions, the soluble sugars (mainly sucrose) accumulated in melon fruits decreased and the rapid accumulation of sucrose was delayed, whlie the accumulation mode of fruit sugar was not significantly affected. The sugar content reduction in large fruited cv. Huanghemi was higher than those in middle fruited cv. Yindi and small fruited cv. Yujinxiang. These results imply that the sugar content of melon fruits depends on the supply level of assimila-tion .%以3个果实大小不同的品种为材料,研究光照强度对甜瓜果实糖分积累的影响.结果表明:果实定个前(玉金香花后14 d,银帝和黄河蜜花后28 d),果实中糖分积累以葡萄糖和果糖为主,蔗糖次之,可溶性总糖含量较低.果实定个后,蔗糖开始快速积累,并持续至果实成熟.果实成熟时,三品种含糖量为玉金香(136.63 mg/g)＞银帝(119.9 mg/g)＞黄河蜜(108.14 mg/g),果实3个部位的含糖量为脐部＞中部＞蒂部.遮阴对甜瓜果实糖分积累模式影响不显著,但使蔗糖开始大量积累的时间推迟、果实最终糖分积累量显著下降,表明甜瓜果实糖分积累量依赖于同化产物供应水平.果实生育期糖分积累动态表明:玉金香耐弱光性较强,银帝能够逐渐适应弱光,黄河蜜对弱光最敏感.遮阴后甜瓜果实糖分积累量降幅具有品种依赖性:大果型品种黄河蜜＞中果型品种银帝＞小果型品种玉金香.
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