The warm gaps during cold weather will increase the risk of freezing damage to plants. The successful winter survival of hollyhock (Alcea rosea 'nigra') can be limited by climate warming. This study exposed the cold-acclimated and non-acclimated plants to warm and cold temperatures and determined their physiological and biochemical traits. The results showed that after acclimation, cold temperature effectively delayed the chilling injury, reduced the electrolyte leakage, significantly increased the activity of SOD, APX, and CAT, inhibited the content of hydrogen peroxide (H₂O₂), and retarded the increase in malondialdehyde (MDA) content, whereas they were increased in the other treatments. When non-cold and cold-acclimated plants were exposed to warm temperatures, a rapid decrease in antioxidant activities and osmolyte regulators occurred, resulting in a plant that no longer possesses an elevated level of freezing tolerance. Cold temperatures in non-acclimated plants did not induce substantial acclimation and reduced frost resistance primarily by limiting the water-soluble sugars and proline availability. The freezing tolerance of acclimated plants maintained a lower LT₅₀ and exhibited higher net photosynthesis and stomatal conductance under freezing temperatures. Freezing tolerance in hollyhock plants (–6 °C) induced by suboptimal temperature acclimation is associated with enhanced photosynthetic adaptability, osmoregulation ability, and antioxidant activities.

寒冷天气中的温暖间隙会增加植物冻害的风险。蜀葵（ Alcea rosea 'nigra'）的成功冬季生存可能会受到气候变暖的限制。本研究将冷驯化和非驯化植物暴露于温暖和寒冷的温度下，并确定了它们的生理和生化特征。结果表明，驯化后，低温有效延缓了冷害，减少了电解质的渗漏，显着提高了SOD、APX、CAT的活性，抑制了过氧化氢（H ₂ O ₂），并延缓了丙二醛（MDA）含量的增加，而在其他处理中它们增加了。当非寒冷和寒冷适应的植物暴露在温暖的温度下时，抗氧化活性和渗透调节剂会迅速下降，导致植物不再具有较高的抗冻性水平。非驯化植物的低温不会引起实质性的驯化，并且主要通过限制水溶性糖和脯氨酸的可用性来降低抗冻性。驯化植物的耐冻性保持较低的 LT ₅₀在冰冻温度下表现出更高的净光合作用和气孔导度。由次优温度适应引起的蜀葵植物（–6°C）的耐冻性与增强的光合适应性、渗透压调节能力和抗氧化活性有关。