Rhododendrons (Rhododendron) are ornamental plants that exhibit poor thermotolerance. To provide a theoretical basis for the production and application of Rhododendron in summer, effects of high temperature and low light stress on the growth, physiological characteristics (including photosynthesis), and leaf structure of Rhododendron were explored. Two Rhododendron cultivars, Rh. ‘Fen Zhenzhu’ and Rh. ‘Zhuangyuan Hong’, were selected. Rhododendron plants were subjected to stress in 6-day intervals in an artificial climate box with 37.5, 75, 112.5, and 150 μmol m−2 s−1 photosynthetic photon flux at 38 °C. The leaf anatomical parameters and physiological indexes, including gas exchange parameters, relative water content, relative conductivity, chlorophyll and osmotic substance contents, malondialdehyde and hydrogen peroxide levels, and enzyme activity, of Rhododendron under high temperature and different low light levels were measured. The results showed that the combined stressors of high temperature and low light caused damage to leaves, such as loss of water, cell membrane damage, decreased net photosynthetic rate, and changes in leaf structure. Additionally, with the decreased light intensity caused more damage, and different damage mechanisms were found in different cultivars and treatments.

中文翻译：

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两种杜鹃花品种对高温弱光的生理和微观结构响应

杜鹃花（Rhododendron）是耐热性较差的观赏植物。研究高温低光胁迫对杜鹃花生长、生理特性（包括光合作用）和叶片结构的影响，为夏季杜鹃花的生产和应用提供理论依据。两个杜鹃花品种，Rh。'粉珍珠'和Rh。'状元香'，入选。杜鹃花植物在人工气候箱中以 6 天为间隔经受胁迫，在 38 °C 下具有 37.5、75、112.5 和 150 μmol m-2 s-1 光合光子通量。叶片解剖参数和生理指标，包括气体交换参数、相对水分含量、相对电导率、叶绿素和渗透物质含量、丙二醛和过氧化氢含量，测定了杜鹃花在高温和不同弱光条件下的酶活性。结果表明，高温弱光联合胁迫对叶片造成损害，如失水、细胞膜损伤、净光合速率降低、叶片结构改变等。此外，随着光照强度的降低，造成更多的损害，并且在不同的栽培品种和处理中发现了不同的损害机制。