不同光周期对黄瓜幼苗抗冷性的影响

为了探讨光周期对低温胁迫下黄瓜幼苗膜脂过氧化水平和抗氧化酶活性等生理指标的影响。以25℃和10℃ 2种温度处理黑夜补光0，3，6，9，12 h的黄瓜幼苗，研究不同光周期对黄瓜幼苗生理指标的影响。结果表明，2种温度处理条件下，黄瓜幼苗叶片中叶绿体色素含量、可溶性糖和可溶性蛋白含量、CAT和POD活性都是随补光时间的延长而升高，而电解质相对渗漏率和MDA含量随补光时间的延长而下降。与25℃相比较，低温（10℃）处理降低黄瓜幼苗叶绿体色素含量，提高电解质相对渗漏率，MDA、可溶性糖和可溶性蛋白含量，CAT和POD活性；其中，光周期越长，黄瓜幼苗叶片叶绿体色素含量，电解质相对渗漏率和MDA含量的变化幅度越小，可溶性糖和可溶性蛋白含量，CAT和POD活性的变化幅度越大。延长光照时间可通过促进低温胁迫下黄瓜幼苗叶片可溶性蛋白、可溶性糖的大量积累和抗氧化酶活性的提高，来降低膜脂过氧化水平，从而增强黄瓜幼苗的抗冷性。

Effect of Different Photoperiod on Cold Resistance of Cucumber Seedlings

The aim was to study the effects of photoperiod on membrane lipid peroxidation, antioxidant enzyme activities and other physiological indices in cucumber seedlings. The cucumber seedlings filled light 0, 3, 6, 9, 12 h at night were treated by 25℃ and 10℃ in order to study the effect of different photoperiod on cold resistance of cucumber seedlings. The results showed that： the chloroplast pigments content, soluble sugar and soluble protein content, CAT and POD activity in leaves of cucumber seedlings treated by 25℃ and 10℃, were increased with the fill light extension, but relative electrolytic leakage and MDA content decreased. Compared with 25℃, low temperature stress （10℃） reduced cucumber chloroplast pigment content, but increased relative electrolytic leakage, MDA, soluble sugar and soluble protein content, CAT and POD activity. The longer the photoperiod, the smaller the change ratio of chloroplast pigment content, relative electrolytic leakage and MDA content, the greater the change ratio of soluble sugar and soluble protein content, CAT and POD activity. Extending the illumination time could promote the accumulation of soluble protein and sugar, raise the activities of antioxidant enzymes, decrease the membrane lipid peroxidation and improve the cold resistance of cucumber seedlings.