As global temperatures continue to rise, heat stress and its severity are projected to advance as a major abiotic stress, seriously limiting the growth and production of herbaceous peony (Paeonia lactiflora Pall.), especially in low-latitude areas. Therefore, determining the ravaging effects of heat stress on the growth and development of herbaceous peony has become a prerequisite for expanding the cultivation area of this world-renowned ornamental crop. Comprehensive research on physiological and biochemical responses to summer heat stress was conducted between low-latitude and midlatitude herbaceous peony cultivars at low latitudes. Field observations showed that the stay-green (SG) duration varied among the cultivars from different latitudes and had a direct correlation with the level of heat damage. As the heat stress intensified, chlorophyll (Chl) contents and Chl fluorescence were decreased in the six cultivars. On the contrary, the relative electrical conductivity (REC) increased sharply, with the low-latitude ‘Hang Baishao’ presenting the lowest REC among the six cultivars before August 15 (with the highest temperatures). Photosynthetic curves showed more sustained photosynthesis in ‘Hang Baishao’, ‘Meiju’ and ‘Bo Baishao’. Based on principal component analysis (PCA) and subordinate function value analysis, ‘Hang Baishao’ was deduced as the most heat-tolerant cultivar, whereas ‘Zhuguang’ as a most heat-sensitive cultivar out of the six cultivars. The oxidative stress analysis between the two cultivars indicated an over-accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) with lower antioxidant enzyme activity in ‘Zhuguang’ than ‘Hang Baishao’. The results imply that heat-tolerant ‘Hang Baisao’ exhibited minimal heat damage and a delayed SG duration based on its enhanced antioxidant enzyme activity and heat acclimation under high-temperature stress. This study could provide insights into the responses and adaptions of peonies to heat stress and aid in the breeding of excellent peonies with improved heat resistance under ever-changing climatic conditions.

随着全球气温持续上升，预计热应激及其严重程度将成为主要的非生物胁迫，严重限制草本牡丹（芍药）的生长和生产。Pall.)，尤其是在低纬度地区。因此，确定热胁迫对芍药生长发育的破坏作用已成为扩大这一世界著名观赏作物种植面积的前提。综合研究低纬度低纬度和中纬度芍药品种对夏季热胁迫的生理生化反应。实地观察表明，不同纬度的品种之间的保持绿色（SG）持续时间不同，并且与热害程度直接相关。随着热应激的加剧，六个品种的叶绿素（Chl）含量和Chl荧光降低。相反，相对电导率（REC）急剧增加，8 月 15 日之前的 6 个品种中，低纬度“杭白芍”的 REC 最低（气温最高）。光合曲线显示'行百少'、'美居'和'薄百少'的光合作用更持久。基于主成分分析（PCA）和从属函数值分析，在六个品种中，'杭白芍'被推断为最耐热的品种，而'竹光'是最耐热的品种。这 而'珠光'是六个品种中对热敏感度最高的品种。这 而'珠光'是六个品种中对热敏感度最高的品种。这两个品种之间的氧化应激分析表明，'竹光'中的活性氧（ROS）和丙二醛（MDA）过度积累，抗氧化酶活性低于'杭白芍'。结果表明，耐热的'杭白骚'基于其增强的抗氧化酶活性和高温胁迫下的热适应，表现出最小的热损伤和延迟的SG持续时间。这项研究可以深入了解牡丹对热应激的反应和适应，并有助于在不断变化的气候条件下培育出耐热性更高的优秀牡丹。