Lichens are symbiotic organisms that are well adapted to desiccation/rehydration cycles. Over the last decades, the physiological background of their photosynthetic response—specifically activation of the protective mechanism during desiccation—has been studied at the level of photosystem II of the lichen photobiont by means of several biophysical methods. In our study, the effects of desiccation and low temperatures on chlorophyll fluorescence and spectral reflectance parameters were investigated in Antarctic chlorolichen Dermatocarpon polyphyllizum. Lichen thalli were collected from James Ross Island, Antarctica, and following transfer to a laboratory, samples were fully hydrated and exposed to desiccation at temperatures of 18, 10, and 4 °C. During the desiccation process, the relative water content (RWC) was measured gravimetrically and photosynthetic parameters related to the fast transient of chlorophyll fluorescence (OJIP) were measured repeatedly. Similarly, the change in spectral reflectance parameters (e.g., NDVI, PRI, G, NPCI) was monitored during thallus dehydration. The dehydration-response curves showed a decrease in a majority of the OJIP-derived parameters (e.g., maximum quantum yield of photosystem II photochemistry: F_V/F_M, and performance index: PI in D. polyphyllizum, which were more apparent at RWCs below 20%. The activation of protective mechanisms in severely dehydrated thalli was documented by increased thermal dissipation (DI₀/RC) and its quantum yield (Phi_D₀). Low temperature accelerated these processes. An analysis of the OJIP shape reveals the presence of K-bands (300 μs), and L-bands (80 μs), which can be attributed to dehydration-induced stress. Spectral reflectance indices decreased in a majority of cases with an RWC decrease and were positively related to the OJIP-derived parameters: F_V/F_M (capacity of photosynthetic processes in PSII), Phi_E₀ (effectiveness of electron transport), and PI_tot (total performance index), which was more apparent in NDVI. A negative relation was found for NPCI. These indices could be used in follow-up ecophysiological photosynthetic studies of lichens that are undergoing rehydration/dehydration cycles.

地衣是共生生物，非常适合干燥/补水循环。在过去的几十年中，已经通过多种生物物理方法在地衣光生物体的光系统II水平上研究了其光合作用的生理背景（特别是在干燥过程中保护机制的激活）。在我们的研究中，研究了干燥和低温对南极叶绿素地皮果皮中叶绿素荧光和光谱反射率参数的影响。从南极洲的詹姆斯·罗斯岛（James Ross Island）收集地衣thalli，并将其转移到实验室后，将样品充分水合并在18、10和4°C的温度下干燥。在干燥过程中，通过重量分析法测量相对含水量（RWC），并重复测量与叶绿素荧光快速瞬变有关的光合参数。类似地，在th失水脱水期间监测光谱反射率参数（例如NDVI，PRI，G，NPCI）的变化。脱水-响应曲线表明：在大部分OJIP衍生参数（的降低例如，光系统II光化学最大量子产率：˚F _V / ˚F_中号，并且性能指数：PI在D. polyphyllizum，在RWC低于20％时更为明显。通过增加的热耗散（DI ₀ / RC）及其量子产率（Phi_D ₀）证明了严重脱水的塔利中保护机制的激活。低温加速了这些过程。对OJIP形状的分析揭示了K波段（300μs）和L波段（80μs）的存在，这可以归因于脱水引起的应力。在大多数情况下，随着RWC的降低，光谱反射率指数降低，并且与OJIP衍生的参数呈正相关：F _V / F _M（PSII中光合作用的能力），Phi_E ₀（电子传输的有效性）和PI_tot（总性能指标），这在NDVI中更为明显。发现与NPCI呈负相关。这些指数可用于进行补液/脱水循环的地衣的后续生态生理光合研究。