In Antarctica, multiple stresses (low temperatures, drought and excessive irradiance) hamper photosynthesis even in summer. We hypothesize that controlled inactivation of PSII reaction centres, a mechanism widely studied by pioneer work of Fred Chow and co-workers, may effectively guarantee functional photosynthesis under these conditions. Thus, we analysed the energy partitioning through photosystems in response to temperature in 15 bryophyte species presenting different worldwide distributions but all growing in Livingston Island, under controlled and field conditions. We additionally tested their tolerance to desiccation and freezing and compared those with their capability for sexual reproduction in Antarctica (as a proxy to overall fitness). Under field conditions, when irradiance rules air temperature by the warming of shoots (up to 20 °C under sunny days), a predominance of sustained photoinhibition beyond dynamic heat dissipation was observed at low temperatures. Antarctic endemic and polar species showed the largest increases of photoinhibition at low temperatures. On the contrary, the variation of thermal dissipation with temperature was not linked to species distribution. Instead, maximum non-photochemical quenching at 20 °C was related (strongly and positively) with desiccation tolerance, which also correlated with fertility in Antarctica, but not with freezing tolerance. Although all the analysed species tolerated − 20 °C when dry, the tolerance to freezing in hydrated state ranged from the exceptional ability of Schistidium rivulare (that survived for 14 months at − 80 °C) to the susceptibility of Bryum pseudotriquetrum (that died after 1 day at − 20 °C unless being desiccated before freezing).

在南极洲，即使在夏季，多重压力（低温、干旱和过度辐照）也会阻碍光合作用。我们假设 PSII 反应中心的受控失活，这是 Fred Chow 及其同事的先驱工作广泛研究的一种机制，可以有效地保证在这些条件下进行功能性光合作用。因此，我们分析了通过光系统响应温度的能量分配，这些苔藓植物具有不同的全球分布，但都在受控和野外条件下生长在利文斯顿岛。我们还测试了它们对干燥和冷冻的耐受性，并将它们与它们在南极洲的有性生殖能力（作为整体健康状况的代表）进行了比较。在田间条件下，当辐照度通过使枝条变暖（晴天下高达 20°C）来控制气温时，在低温下观察到持续光抑制超出动态散热的优势。南极特有和极地物种在低温下表现出最大的光抑制增加。相反，热耗散随温度的变化与物种分布无关。相反，20 °C 下的最大非光化学淬灭与耐旱性（强烈且正相关）相关，这也与南极洲的肥力相关，但与耐寒性无关。尽管所有分析的物种在干燥时都能耐受 - 20 °C，但在水合状态下对冷冻的耐受性不等 在低温下观察到持续光抑制超出动态散热的优势。南极特有和极地物种在低温下表现出最大的光抑制增加。相反，热耗散随温度的变化与物种分布无关。相反，20 °C 下的最大非光化学淬灭与耐旱性（强烈且正相关）相关，这也与南极洲的肥力相关，但与耐寒性无关。尽管所有分析的物种在干燥时都能耐受 - 20 °C，但在水合状态下对冷冻的耐受性不等 在低温下观察到持续光抑制超出动态散热的优势。南极特有和极地物种在低温下表现出最大的光抑制增加。相反，热耗散随温度的变化与物种分布无关。相反，20 °C 下的最大非光化学淬灭与耐旱性（强烈且正相关）相关，这也与南极洲的肥力相关，但与耐寒性无关。尽管所有分析的物种在干燥时都能耐受 - 20 °C，但在水合状态下对冷冻的耐受性不等 热耗散随温度的变化与物种分布无关。相反，20 °C 下的最大非光化学淬灭与耐旱性（强烈且正相关）相关，这也与南极洲的肥力相关，但与耐寒性无关。尽管所有分析的物种在干燥时都能耐受 - 20 °C，但在水合状态下对冷冻的耐受性不等 热耗散随温度的变化与物种分布无关。相反，20 °C 下的最大非光化学淬灭与耐旱性（强烈且正相关）相关，这也与南极洲的肥力相关，但与耐寒性无关。尽管所有分析的物种在干燥时都能耐受 - 20 °C，但在水合状态下对冷冻的耐受性不等Schistidium rivulare（在 − 80 °C 下存活 14 个月）对Bryum pseudotriquetrum（除非在冷冻前干燥，否则在 − 20 °C 下 1 天后死亡）的易感性。