Maize (Zea mays L.) is one of the most important crops worldwide. However, low temperature limits seed germination and seedling growth of maize, which can in turn affect grain yield. The calcium ion (Ca²⁺) is the second messenger involved in the response to environmental-stimuli-induced signal transduction networks. The underlying physiological mechanisms related to the effects of exogenous Ca²⁺ treatment of different maize cultivars under low temperature are unclear. We selected two inbred lines, cold-sensitive cv. C546 and cold-tolerant cv. Y478, for studying the effects of Ca²⁺ on seed germination, photosynthesis, antioxidant enzymes and the osmotic regulation of seedling resistance to low temperature. The optimal concentration of CaCl₂ was 80 mmol L^–1, which significantly improved the germination percentage at temperatures <10°C. Application of CaCl₂ at this concentration under cold stress mitigated the degree of membrane injury and improved the antioxidant enzyme system through reduced relative electrolyte conductivity and malondialdehyde content, increased the soluble protein content, and enhanced superoxide dismutase and peroxidase activity. CaCl₂ also significantly increased chlorophyll fluorescence indicators (F_v/F_o, F_v/F_m) and the photosynthetic rate. We conclude that exogenous CaCl₂ at a concentration of 80 mmol L^–1 protects the function and structure of the membrane and photosystems, improves antioxidant enzyme activity and increases osmotic regulatory substances under cold stress. These results improve our understanding of the mechanisms of Ca²⁺ and contribute to the development of cold-tolerant maize varieties.

玉米（Zea mays L.）是世界上最重要的农作物之一。然而，低温限制了玉米的种子发芽和幼苗生长，这反过来又会影响谷物的产量。钙离子（Ca ²⁺）是参与环境刺激诱导的信号转导网络响应的第二信使。低温下外源Ca ²⁺处理不同玉米品种的相关生理机制尚不清楚。我们选择了两个自交系，即冷敏感简历。C546和耐寒简历。Y478，用于研究Ca ²⁺的作用对种子萌发，光合作用，抗氧化酶和渗透调节幼苗对低温的抗性。CaCl ₂的最佳浓度为80 mmol L ^–1，这显着提高了<10°C温度下的发芽率。在冷胁迫下以该浓度施用CaCl ₂可以减轻膜损伤的程度，并通过降低相对电解质电导率和丙二醛含量来改善抗氧化酶系统，增加可溶性蛋白质含量，并增强超氧化物歧化酶和过氧化物酶活性。CaCl ₂还显着增加了叶绿素荧光指示剂（F _v / F _o，F _v / F_m）和光合速率。我们得出的结论是，浓度为80 mmol L ^–1的外源CaCl ₂保护膜和光系统的功能和结构，提高抗氧化酶的活性并增加冷胁迫下的渗透调节物质。这些结果增进了我们对Ca ²⁺机理的理解，并有助于开发耐寒玉米品种。