This study explores and compares the limits for photosynthesis in subzero temperatures of six Antarctic lichens: , , , and combining linear cooling and chlorophyll fluorescence methods. The results revealed triphasic S-curves in the temperature response of the maximum quantum yield () and effective quantum yield of photosystem II () for all species. All investigated species showed a high level of cryoresistance with critical temperatures () below −20 °C. However, record low temperatures have been discovered for (−54 °C for and −40 °C for ) and (−52 °C for and −38 °C for ). Additionally, the yield differentials ( − ) in functions of temperature revealed one or two peaks, with the larger one occurring for temperatures below −20 °C for the above-mentioned species. Finally, Kautsky kinetics were measured and compared at different temperatures (20 °C, 10 °C, 0 °C and −10 °C and then −10 °C after 1 h of incubation). This research serves as a foundation for further developing investigations into the biophysical mechanisms by which photosynthesis is carried out at subzero temperatures.

中文翻译：

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通过叶绿素荧光评估冰冻温度对南极地衣光系统 II 的影响

本研究探索并比较了六种南极地衣在零下温度下光合作用的极限： 、 、 、 以及结合线性冷却和叶绿素荧光方法。结果揭示了所有物种的最大量子产率 () 和光系统 II 的有效量子产率 () 的温度响应的三相 S 曲线。所有研究的物种都表现出高水平的耐低温性，临界温度 () 低于 -20 °C。然而，已发现创纪录的低温（-54 °C 和 -40 °C ）和（-52 °C 和 -38 °C ）。此外，温度函数的产量差异 (−) 揭示了一个或两个峰值，对于上述物种，较大的峰值出现在温度低于 -20 °C 的情况下。最后，在不同温度（20℃、10℃、0℃和-10℃，以及孵育1小时后-10℃）下测量和比较考茨基动力学。这项研究为进一步研究在零下温度下进行光合作用的生物物理机制奠定了基础。