Mediterranean ecosystems are dominated by evergreen species having a substantial decrease of the photosynthetic rates in summer. Drought is the factor essentially responsible for growth and survival of the evergreen species; nevertheless, the winter period, by the combination of low air temperatures and high irradiance, is considered an important factor of the photosynthetic activity limitation. This research analyzes the adaptative response to low air temperatures of the Mediterranean maquis species: Q. ilex, P. latifolia, P. lentiscus, A. unedo, C. incanus, E. arborea, E. multiflora, and R. officinalis. The results show 20 – 40 % decrease of the photosynthetic rates in winter respect to the maximum rate. Low temperatures affect also photosynthetic pigment concentration determining a decrease of the chlorophyll content and an increase of the carotenoid/chlorophyll ratio, a stress indicator reflecting the species’ capacity to mitigate the photo – oxidative damage to the photosynthetic apparatus. Among the considered species Q. ilex is the more resistant one to winter stress factors. The study of the physiological response under winter conditions contributes to define the adaptative strategies of the Mediterranean evergreen species. The physiological responses could be followed by changes in carbon acquisition of Mediterranean ecosystems, and in the long-term by changes in species distribution conferred by the different capacity to survive under the new climatic constraints.
Influence of low air temperature on gas – exchange and pigment content of Mediterranean maquis species / Varone, Laura; Gratani, Loretta. - STAMPA. - (2006), pp. 13-13. (Intervento presentato al convegno XVI Congresso Nazionale della SItE - Cambiamenti Globali, Diversità Ecologica e Sostenibilità tenutosi a Viterbo - Civitavecchia nel 19-22 Settembre 2006).
Influence of low air temperature on gas – exchange and pigment content of Mediterranean maquis species.
VARONE, LAURA;GRATANI, Loretta
2006
Abstract
Mediterranean ecosystems are dominated by evergreen species having a substantial decrease of the photosynthetic rates in summer. Drought is the factor essentially responsible for growth and survival of the evergreen species; nevertheless, the winter period, by the combination of low air temperatures and high irradiance, is considered an important factor of the photosynthetic activity limitation. This research analyzes the adaptative response to low air temperatures of the Mediterranean maquis species: Q. ilex, P. latifolia, P. lentiscus, A. unedo, C. incanus, E. arborea, E. multiflora, and R. officinalis. The results show 20 – 40 % decrease of the photosynthetic rates in winter respect to the maximum rate. Low temperatures affect also photosynthetic pigment concentration determining a decrease of the chlorophyll content and an increase of the carotenoid/chlorophyll ratio, a stress indicator reflecting the species’ capacity to mitigate the photo – oxidative damage to the photosynthetic apparatus. Among the considered species Q. ilex is the more resistant one to winter stress factors. The study of the physiological response under winter conditions contributes to define the adaptative strategies of the Mediterranean evergreen species. The physiological responses could be followed by changes in carbon acquisition of Mediterranean ecosystems, and in the long-term by changes in species distribution conferred by the different capacity to survive under the new climatic constraints.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.