低温弱光下外源褪黑素对黄瓜幼苗生长及抗氧化系统的影响

Effects of Exogenous Melatonin on Growth and Antioxidant System of Leaves in Cucumber Seedlings under Low Temperature and Weak Light Stress

以黄瓜品种‘津优4号’为材料,利用人工气候箱进行低温弱光处理(昼/夜,18℃/10℃),研究外源褪黑素(MT)对低温胁迫下黄瓜幼苗生长和抗氧化系统等生理指标的影响。结果显示:低温弱光下,与对照相比,外源褪黑素处理显著提高了黄瓜幼苗株高、茎粗、植株鲜重和干重,叶绿素和根系活力分别显著提高了13.3%和18.8%,抗氧化物质GSH及ASA的含量分别显著增加了39.3%和24.7%,保护酶SOD、POD、CAT、APX活性均显著升高;同时,外源褪黑素处理还显著提高了黄瓜叶片质膜及液泡膜H+-ATP酶的活性,从而使黄瓜幼苗叶片MDA含量和电解质渗漏率分别显著降低了28.7%和29.7%。研究表明,低温弱光下外源褪黑素可通过提高黄瓜幼苗保护酶活性、抗氧化物质的含量、细胞膜ATP酶活性等来降低质膜过氧化水平,保持细胞膜的完整性和功能,从而增强黄瓜幼苗对低温弱光的适应性,维持其正常生长,并以200μmol·L-1褪黑素处理效果较好。

Cucumber cultivar‘Jinyou 4＇was subjected to low temperature treatment of 18℃/10℃（day/night）in the artificial climate chamber.The effects of exogenous melatonin（MT）on the growth and antioxidant system of leaves in cucumber under low temperature and weak light stress were investigated.The results showed that：compared with the control treatment,exogenous MT treatment could significantly promote the increment of plant height,wall thickness,flesh weight,dry weight;the chlorophyll content and root activity increased by 13.3% and 18.8%,GSH content and ASA content by 39.3%and 24.7%,respectively and increased SOD,POD,CAT,APX,membrane H＋-ATP activities,while reduced MDA content and electrolyte leakage by 28.7% and 29.7%in cucumber seedlings leaves under low temperature and weak light stress.So we can conclude that exogenous MT treatment could raise the activities of antioxidant enzymes and matter,membrane H＋-ATP activities,decrease the membrane lipid peroxidation,maintain membrane integrity and function,and improve the adaptability of cucumber seedlings under low temperature and weak light stress,the 200μmol·L-1 MT treatment was better.