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.
