中文摘要：

选择安徽地区主栽品种”早甜一号”为试材，幼苗3叶l心时移人光强为100μmol／（m2·s）的光照培养箱内，每天光照12h，研究昼夜低温（5℃，5℃（昼／夜））处理8d中甜瓜幼苗叶片代谢产物含量的变化。结果表明：5℃，5℃低温胁迫下随着时间的延长H202先增加后减少．叶片膜脂过氧化产物丙二醛（MDA）的含量呈波动性增加，可溶性糖及可溶性蛋白质等代谢产物与对照相比也增加．导致这种结果的原因可能是低温胁迫影响酶的活性，随着低温处理时间延长甜瓜有受冻害的可能，从而引起代谢产物含量的变化。经过低温锻炼，测定主要代谢产物含量的变化来研究植物的生理特性，可为选育耐低温品种及设施栽培提供理论依据。

英文摘要：

In this study, Zaotian No.l, a major melon cultivar in Anhui Province, was used as the test material. At the three-leaf stage, the seedlings of Zaotian No.1 were transferred into a light incubator at day/night temperature of 5 ℃（3/5 ℃. The photoperiod was 12 L：12 D, and the light intensity was 100 iJmoV（rn=.s）. The incu- bation lasted for 8 d. After the incubation, the changes in metabolite contents in melon seedling leaves were studied. The results showed that with the proceeding of low temperature stress, the H~ content was increased first and then decreased; the MDA content was increased in overall; the soluble sugar content and soluble protein content were also increased compared with those in the control group. It was speculated that low temperature stress affected activities of enzymes in melon seedling leaves, and long-term low temperature stress caused cold damage to melon seedlings, leading changes in metabolite contents in melon seedling leaves. Under low temperature stress, the physiological characteristics of plant can be studied by investigating changes in contents of main metabolites. This will provide a theo- retical basis for breeding of cold resistant cultivars, as well as facility cultivation.