Winter K, Garcia M, Virgo A
Smithsonian Tropical Research Institute, Panama City, Republic of Panama.
Photosynthetica. 2025 Feb 27;63(1):46-50. doi: 10.32615/ps.2025.004. eCollection 2025.
In heating experiments with leaves, the temperature at which dark-level F chlorophyll fluorescence begins to rise, T, is widely used as an indicator of photosystem II thermotolerance. However, little is known about how T correlates with irreversible leaf tissue damage. Young and mature leaves of the tropical tree species were heated stepwise from 30 to 55°C, at 1°C min. T was 47°C in young leaves and 49°C in mature leaves. Contrary to the higher T in mature leaves, heating to 55°C elicited greater tissue damage in mature than in young leaves. Young and mature leaves heated to their respective T or T + 2°C exhibited no or little tissue necrosis after 14 d of post-culture. It is concluded that measurements of the temperature-dependent F fluorescence rise underestimate the thermal thresholds above which significant irreversible leaf damage occurs.
在用叶片进行加热实验时，暗水平F叶绿素荧光开始上升的温度T被广泛用作光系统II耐热性的指标。然而，关于T与不可逆叶片组织损伤之间的关系却知之甚少。对该热带树种的幼叶和成熟叶以每分钟1°C的速度从30°C逐步加热至55°C。幼叶的T为47°C，成熟叶的T为49°C。与成熟叶中较高的T相反，加热到55°C时，成熟叶比幼叶受到的组织损伤更大。加热到各自的T或T + 2°C的幼叶和成熟叶在培养14天后未出现或仅有很少的组织坏死。结论是，对温度依赖性F荧光上升的测量低估了会发生显著不可逆叶片损伤的热阈值。
