摘要
Pholidota chinensis 是一种兼具药用和观赏价值的兰花。由于过度采挖和自然繁殖能力有限，其野生种群数量急剧下降。尽管无菌播种可实现大规模繁殖，但气候驱动的极端高温对种苗生产构成威胁。然而，P. chinensis 组培苗在热胁迫下的生理响应和繁殖潜力仍知之甚少。本研究考察了六个月龄的离体培养组培苗在四种温度（34 °C、36 °C、38 °C、40 °C）下长达 96 h 的表现。采用常规 0 h 测量值作为处理前基线，未设置平行的时间匹配 25 °C 对照。光合色素特征采用 UV-Vis 光谱法评估，PSII 光化学效率采用叶绿素荧光（Fv/Fm）评估。色素估算结果显示，在四种培养箱温度条件和不同暴露时长之间呈非单调变化。在 34 °C 下，总叶绿素浓度从常规 0 h 处理前基线约 6.9 mg L−1 降至 96 h 时的约 5.5 mg L−1，相当于初始值的约 80%。在 36–40 °C 条件下，总叶绿素浓度表现出显著的时间波动，而非随温度升高或暴露时间延长而持续下降。相比之下，Fv/Fm 在 96 h 终点时于四种培养箱-温度条件下表现出更明显的数值下降。所选光谱吸光度变量在各处理间表现出显著的正协变（r = 0.708–0.983，所有原始 p
Pholidota chinensis is an orchid with both medicinal and ornamental value. Due to overharvesting and limited natural reproduction, its wild populations have declined sharply. Although aseptic sowing enables large-scale propagation, climate-driven extreme heat poses a threat to seedling production. However, the physiological responses and propagation potential of P. chinensis plantlets under heat stress remain poorly understood. This study examined six-month-old in vitro-grown plantlets under four temperatures (34 °C, 36 °C, 38 °C, 40 °C) for up to 96 h. The common 0 h measurements were used as a pre-treatment baseline, and no parallel time-matched 25 °C control was included. Photosynthetic pigment characteristics were assessed using UV-Vis spectroscopy, while PSII photochemical efficiency was evaluated using chlorophyll fluorescence (Fv/Fm). Pigment estimates showed non-monotonic variation among the four chamber-temperature conditions and exposure durations. At 34 °C, total chlorophyll concentration decreased from the common 0 h pre-treatment baseline of approximately 6.9 mg L−1 to approximately 5.5 mg L−1 at 96 h, corresponding to approximately 80% of the initial value. Under the 36–40 °C conditions, total chlorophyll concentrations exhibited substantial temporal fluctuations rather than a consistent decline with increasing temperature or exposure duration. In contrast, Fv/Fm showed a clearer numerical decline across the four chamber–temperature conditions at the 96 h endpoint. Selected spectral absorbance variables showed significant positive covariation across treatments (r = 0.708–0.983, all raw p