Melatonin is effective in modulating plant metabolism under stress conditions whereas nitrogen (N) is essential for plant growth. To explore the effects of melatonin and N applications on early growth, associated physiological and biochemical traits, and cadmium (Cd) uptake in maize under Cd stress, a pot experiment was conducted. Two melatonin levels, i.e., 0 and 200 μM, and two N levels, i.e., 1/4 N and full N dose of Kimura nutrient solution, were employed on two widely cultivated maize varieties, i.e., Yuecainuo 2 and Yuebaitiannuo 7, under Cd stress (150 μM). Results showed that melatonin application improved plant biomass and seedling growth, especially in low N treatment which further activated antioxidant defense system in terms of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) while melatonin application variably affected activities of antioxidants under Cd stress. In addition, melatonin application and low N treatment activated enzymes involved in N metabolism in Yuecainuo 2 as well as resulted in higher Cd concentration in shoot and root of maize seedlings in both maize varieties. Overall, short-term low N treatment showed marginal decrease in early growth of maize with higher Cd accumulation, while melatonin application could accelerate the growth of maize seedlings and further improve the Cd absorption in maize seedlings.

褪黑素可有效调节胁迫条件下的植物代谢，而氮（N）对于植物生长至关重要。为了研究褪黑激素和氮肥施用对镉胁迫下玉米早期生长，相关的生理和生化特性以及镉（Cd）吸收的影响，进行了盆栽试验。在镉下，两个广泛栽培的玉米品种Yuecainuo 2和Yuebaitiannuo 7分别采用两种褪黑激素水平，即0和200μM，以及两种氮水平，即1/4 N和全氮剂量的木村营养液。应力（150μM）。结果表明，褪黑激素的施用改善了植物的生物量和幼苗的生长，特别是在低氮处理中，这进一步激活了抗氧化防御系统的超氧化物歧化酶（SOD），过氧化物酶（POD），和过氧化氢酶（CAT），而褪黑素的施用会在镉胁迫下影响抗氧化剂的活性。此外，在两个品种的玉米中，褪黑素的施用和低氮处理激活了参与氮素代谢的酶，并导致较高的镉浓度。总体而言，短期低氮处理显示玉米早期生长略有减少，镉积累量较高，而褪黑激素的施用可以促进玉米幼苗的生长并进一步提高玉米幼苗对镉的吸收。