Heat stress hinders the growth and productivity of sweetpotato plants, predominantly through oxidative damage to cellular membranes. Therefore, the development of efficient approaches for mitigating heat-related impairments is essential for the long-term production of sweetpotatoes. Melatonin has been recognised for its capacity to assist plants in dealing with abiotic stress conditions. This research aimed to investigate how different doses of exogenous melatonin influence heat damage in sweetpotato plants. Heat stress drastically affected shoot and root fresh weight by 31.8 and 44.5%, respectively. This reduction resulted in oxidative stress characterised by increased formation of hydrogen peroxide (HO) by 804.4%, superoxide ion (O) by 211.5% and malondialdehyde (MDA) by 234.2%. Heat stress also reduced chlorophyll concentration, photosystem II efficiency (/) by 15.3% and gaseous exchange. However, pre-treatment with 100 μmol L melatonin increased growth and reduced oxidative damage to sweetpotato plants under heat stress. In particular, melatonin decreased HO, O and MDA by 64.8%, 42.7% and 38.2%, respectively. Melatonin also mitigated the decline in chlorophyll levels and improved stomatal traits, gaseous exchange and / (13%). Results suggested that the favorable outcomes of melatonin treatment can be associated with elevated antioxidant enzyme activity and an increase in non-enzymatic antioxidants and osmo-protectants. Overall, these findings indicate that exogenous melatonin can improve heat stress tolerance in sweetpotatoes. This study will assist researchers in further investigating how melatonin makes sweetpotatoes more resistant to heat stress.

中文翻译：

---

外源褪黑素通过调节抗氧化防御系统、渗透稳态和气孔特性增强甘薯的热应激耐受性


热应激主要通过细胞膜的氧化损伤来阻碍甘薯植物的生长和生产力。因此，开发减轻热相关损害的有效方法对于甘薯的长期生产至关重要。褪黑激素因其帮助植物应对非生物胁迫条件的能力而得到认可。本研究旨在探讨不同剂量的外源褪黑激素如何影响甘薯植物的热损伤。热应激对地上部和根部鲜重的影响分别为 31.8% 和 44.5%。这种减少导致了氧化应激，其特征是过氧化氢 (H2O) 的形成增加了 804.4%，超氧离子 (O) 的形成增加了 211.5%，丙二醛 (MDA) 的形成增加了 234.2%。热应激还降低了叶绿素浓度、光系统 II 效率 (/) 15.3% 和气体交换。然而，用 100 μmol L 褪黑激素预处理可促进热胁迫下甘薯植物的生长并减少氧化损伤。特别是，褪黑激素使 HO、O 和 MDA 分别降低 64.8%、42.7% 和 38.2%。褪黑素还可以缓解叶绿素水平的下降并改善气孔性状、气体交换和/（13%）。结果表明，褪黑激素治疗的良好结果可能与抗氧化酶活性的升高以及非酶抗氧化剂和渗透保护剂的增加有关。总的来说，这些发现表明外源褪黑激素可以提高甘薯的热应激耐受性。这项研究将帮助研究人员进一步研究褪黑激素如何使甘薯更能抵抗热应激。