本试验以抗旱玉米自交系郑58和旱敏感自交系E28为材料，研究干旱胁迫下外源褪黑素对玉米幼苗根系生长及生理生化特性的影响。结果表明：与干旱胁迫相比，干旱胁迫下外施75μmol/L的褪黑素能显著促进玉米幼苗根系的生长。郑58总根长、根尖数、根体积和根表面积分别显著增加47.22％、12.69％、39.29％和18.9％。E28总根长、根尖数、根体积和根表面积分别显著增加51.06％、54.78％、44.74％和81.44％。外施75μmol/L的褪黑素能显著缓解干旱胁迫带来的损伤，郑58的SOD、POD、CAT、APX酶活性、可溶性蛋白、可溶性糖和脯氨酸含量分别增加了72.94％、22.43％、110.52％、79.77％、10.94％、13.63％、19.35％；E28的SOD、POD、CAT、APX酶活性、可溶性蛋白、可溶性糖和脯氨酸含量分别增加了66.82％、13.25％、81.25％、51.82％、7.25％、34.10％、33.22％；且两玉米自交系的膜脂过氧化程度降低，抗氧化酶基因SOD、POD和CAT的表达量也显著上调。表明褪黑素可以减少干旱胁迫对玉米带来的损伤，提高玉米的抗旱性。

This experiment used drought resistant maize inbred line Zheng 58 and drought sensitive inbred line E28 as materials to study the effects of exogenous melatonin on the root growth and physiological and biochemical characteristics of maize seedlings under drought stress. The results showed that compared to drought stress, applying 75μmol/L of melatonin external fertilizer under drought stress can significantly promote the growth of maize seedling roots. The total root length, number of root tips, root volume, and root surface area of Zheng 58 significantly increased by 47.22%, 12.69%, 39.29%, and 18.9%, respectively. The total root length, number of root tips, root volume, and root surface area of E28 significantly increased by 51.06%, 54.78%, 44.74%, and 81.44%, respectively. External application 75μmol/L of melatonin can significantly alleviate the damage caused by drought stress. The activities of SOD, POD, CAT, APX enzymes, soluble protein, soluble sugar, and proline in Zheng 58 increased by 72.94%, 22.43%, 110.52%, 79.77%, 10.94%, 13.63%, and 19.35%, respectively; The SOD, POD, CAT, APX enzyme activity, soluble protein, soluble sugar, and proline content of E28 increased by 66.82%, 13.25%, 81.25%, 51.82%, 7.25%, 34.10%, and 33.22%, respectively; Moreover, the degree of membrane lipid peroxidation in the two maize inbred lines decreased, and the expression levels of antioxidant enzyme genes SOD,POD and CAT were significantly upregulated. This indicates that melatonin can reduce the damage caused by drought stress on maize and improve its drought resistance.

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甘肃省自然科学基金重点项目(23JRRA1405)；国家自然科学基金地区科学(32060487)；甘肃省教育厅产业支撑计划项目(2021CYZC-12)；中央引导地方科技发展资金项目（23ZYQA0322）