Photosynthetic heat tolerances and extreme leaf temperatures

Photosynthetic heat tolerances (PHTs) have several potential applications including predicting which species will be most vulnerable to climate change. Given that plants exhibit unique thermoregulatory traits that influence leaf temperatures and decouple them from ambient air temperatures, we hypothesized that PHTs should be correlated with extreme leaf temperatures as opposed to air temperatures. We measured leaf thermoregulatory traits, maximum leaf temperatures (TMO) and two metrics of PHTs (Tcrit and T50) quantified using the quantum yfield of photosystem II for 19 plant species growing in Fairchild Tropical Botanic Garden (Coral Gables, FL, USA). Thermoregulatory traits measured at the Garden and microenvironmental variables were used to parameterize a leaf energy balance model that estimated maximum in situ leaf temperatures (TMIS) across the geographic distributions of 13 species. T MO and TMIS were positively correlated with T50 but were not correlated with Tcrit. The br...光合热耐受性（Photosynthetic heat tolerances, PHTs）具备多项潜在应用场景，其中包括预测哪些物种最易受气候变化影响。鉴于植物拥有独特的体温调节性状，这些性状会影响叶片温度并使叶片温度与环境空气温度脱耦，我们提出假说：光合热耐受性应与极端叶片温度相关，而非与环境空气温度相关。 我们针对生长于美国佛罗里达州科勒尔盖布尔斯费尔柴尔德热带植物园的19种植物，测定了叶片体温调节性状、最大叶片温度（T_MO），以及通过光系统II量子产额量化得到的两种光合热耐受性（PHTs）指标：临界温度（T_crit）和半致死温度（T50）。利用在该植物园测定的体温调节性状与微环境变量，我们对叶片能量平衡模型进行参数化，以此估算13种植物地理分布范围内的原位最大叶片温度（T_MIS）。 T_MO与T_MIS均与T50呈正相关，但与T_crit无显著相关性。该研究相关内容已截断，原文为"The br..."