Effect of Low and High Temperatures on the Photosynthetic Performance of Lantana camara L. Leaves in Darkness

Abstract

Low and high temperatures are known as most important factors influencing plant performance and distribution. Plants of Lantana camara L. coming from two distinct geographical populations (Iberian Peninsula and Galápagos Islands) were cultivated in a common garden experiment, and their leaves were subjected to thermal treatments (from +20.0 to –7.5°C during the winter and from +20.0 to +50.0°C during the summer) in a programmable water bath in darkness. Their photosynthetic performance and their recovery capacity after the thermal treatment were evaluated by measuring chlorophyll fluorescence, net photosynthe sis rate, and leaf necrosis. In general, L. camara photosynthetic apparatus showed a wide range of tempera ture tolerance in darkness, showing optimal functioning of its photosystem II just after exposure to tempera tures between –2.5 and +35.0°C for the Iberian population and between +10.0 and +25.0°C for the Galápa gos population. Just after exposure to low and high temperatures, gradual cold and heatinduced photoinhibition was recorded for both populations. After 24 h, leaves of L. camara demonstrated a great recovery capacity from –2.5 to +42.5°C. However, leaves of the treatments from –5.0°C down and +47.50°C up showed permanent damages to the photosynthetic apparatus and to the leaf tissues. Slight inter population differences were found only at extreme temperatures. Keyw