Chilling stress is a type of low temperature stress that occurs when plants are exposed to temperatures below optimum but above 0 °C. It determines the geographical distribution of crop species that are of tropic and sub-tropic origin and causes huge losses every year. Thus, besides developing stress tolerant crop varieties, the use of various substances has become an important way of alleviating the adverse effects of abiotic stress conditions and melatonin has gained huge attention lately due to its proven anti-oxidative nature. The objective of the present study was to explore if exogenous application of melatonin through soil drench would mitigate the damage caused by chilling stress in pepper at seedling and flowering stages. Pepper seedlings and flowering plants were treated with melatonin after which they were subjected to chilling stress at 5 °C/10 °C (night/day) for 3 days. The results indicated that melatonin application resulted in reduced visual damage but increased leaf area and shoot mass in pepper seedlings. Melatonin treatment also improwed water relations, photosynthetic parameters and the activities of antioxidant enzymes while lowering malondialdehyde (MDA) and H₂O₂ contents and membrane permeability. When applied at flowering stage, melatonin doubled the early yield but caused slight increase in the final yield. Thus, the results of this research indicate that treatment of pepper plants with 5 µM melatonin through soil drench could be used to improve plant growth and early yield potential under chilling stress conditions.

寒冷胁迫是一种低温胁迫，当植物暴露在低于最佳温度但高于 0 °C 的温度下时会发生这种胁迫。它决定了热带和亚热带作物物种的地理分布，每年造成巨大损失。因此，除了开发抗逆作物品种外，使用各种物质已成为缓解非生物胁迫条件不利影响的重要途径，而褪黑激素因其已被证明具有抗氧化性而近来备受关注。本研究的目的是探索通过土壤浸透外源性施用褪黑激素是否能减轻辣椒在幼苗和开花阶段的低温胁迫造成的损害。辣椒幼苗和开花植物用褪黑激素处理，然后在 5°C/10°C（夜/天）下经受 3 天的低温胁迫。结果表明，褪黑激素的施用导致辣椒幼苗的视觉损伤减少，但叶面积和枝条质量增加。褪黑激素处理还改善了水分关系、光合参数和抗氧化酶的活性，同时降低了丙二醛 (MDA) 和 H₂ O ₂含量和膜渗透性。在开花期施用褪黑激素可使早期产量增加一倍，但最终产量略有增加。因此，这项研究的结果表明，通过土壤浸透用 5 µM 褪黑激素处理辣椒植物可用于改善低温胁迫条件下的植物生长和早期产量潜力。