青藏高原高寒植物对生长季偶发性霜冻事件表现出深度过冷却现象

Alpine plants exhibited deep supercooling upon exposed to episodic frost events during the growing season on the Qinghai-Tibet Plateau

气候变暖促进了植物的春季物候,打破了气候与植物生长之间原有的平衡。随着极端气候事件出现更加频繁,气候与植物生长之间的不匹配性会影响植物的生存、生长和繁殖。为了防止生长季节在细胞内结冰,植物会采用过冷却策略。然而,气候事件的严重程度和物候期可能会影响植物在霜冻事件后的恢复。本研究通过实验探究了4种不同严重程度的极端霜冻事件如何影响青藏高原上两种优势物种钉柱委陵菜(Potentilla saundersiana,仲夏开花)和小龙胆(Gentiana parvula,夏末开花)的过冷却点和枯黄期。探讨了物候期如何影响钉柱委陵菜对霜冻事件的反应。结果发现,两个物种在遭受霜冻损害时都表现出过冷现象。钉柱委陵菜的平均过冷却点为−6.9℃,并受最低温度、持续时间和物候期的影响,而小龙胆的平均过冷却点为−4.8℃,最低温度和持续时间对其过冷却点影响不显著。此外,两个物种在最低温度(−10℃)处理持续4小时后均快速枯黄。本研究首次探索并定量了青藏高原高寒植物的过冷却点。鉴于高寒植物遭遇霜冻事件的概率不断增加,上述结果对了解高寒植物的生长和生存如何应对极端气候的不利影响具有重要意义。

Climatic warming has advanced the spring phenology of plants and disrupted the alignment of phenology with weather patterns.Such misalignments can cause problems as extreme weather events become more frequent and thus impact the survival,growth and reproduction of plants.To prevent freezing within their cells during the growing season,plants adopt a supercooling strategy.However,the weather event severity and seasonal timing may impact the plant’s recovery after a freezing event.We conducted experiments to investigate how extreme freezing events of four different severities impacted the supercooling points and senescence of two dominant alpine plant species,Potentilla saundersiana(mid-summer fowering)and Gentiana parvula(latesummer fowering)on the Qinghai-Tibet Plateau(QTP).We also explored how the phenological stage impacted P.saundersiana’s response to freezing events.We found that both species exhibited supercooling upon exposed to frost damage.However,the average supercooling point for P.saundersiana was−6.9℃and was infuenced by minimum temperature,duration and phenological stage.Whereas,the average supercooling point for G.parvula was−4.8℃,and neither minimum temperature nor duration had an effect on the supercooling point.In addition,the minimum temperature treatment of−10℃caused death in both plants when held constant for 4 h.Our study provides the frst experimental dataset exploring the supercooling points of alpine plants on the QTP.Given the increasing probability of alpine plants encounters frost events,these results are of great signifcance for understanding the growth and survival strategies of alpine plants to cope with the adverse effects of extreme climate.