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Energy dissipation in drought-avoiding and drought-tolerant tree species at midday during the Mediterranean summer

AuthorsMartínez-Ferri, E.; Balaguer, L.; Valladares Ros, Fernando ; Chico, J.M.; Manrique, Esteban
KeywordsChlorophyll fluorescence
Juniperus phoenicea
Midday depression
Pinus halepensis
Quercus coccifera
Quercus ilex
Xanthophyll cycle
Issue DateJan-2000
PublisherHeron Publishing
CitationTree Physiology 20: 131-138 (2000)
AbstractPhotosynthetic performance was monitored during two consecutive summers in four co-occurring evergreen Mediterranean tree species growing on a south-facing rocky slope. In response to midday water stress, the drought-avoiding species Pinus halepensis Mill. exhibited marked stomatal closure (gs) but no changes in stem water potential (Ψs), whereas the drought-tolerant species Quercus coccifera L., Q. ilex ssp. ballota (Desf.) Samp. and Juniperus phoenicea L. displayed declines in midday gs and Ψs. The higher resistance to CO2 influx in needles of P. halepensis compared with the other species did not result in either a proportional increase in non-radiative dissipation of excess energy or photo-inactivation of photosystem II (PSII). No significant differences were found among species either in the de-epoxidation state of the xanthophyll cycle (DPS) or in the pool of its components on a total chlorophyll basis (VAZ). Despite contrasting midday assimilation rates, the three drought-tolerant species all exhibited a pronounced drop in photochemical efficiency at midday that was characterized by a decrease in the excitation capture efficiency of the open PSII centers. Although photoinhibition was not fully reversed before dawn, it apparently did not result in cumulative photo-damage. Thus, the drought-avoiding and drought-tolerant species employed different mechanisms for coping with excess light during the midday depression in photosynthesis that involved contrasting midday photochemical efficiencies of PSII and different degrees of dynamic photoinhibition as a photo-protective mechanism. These behaviors may be related to the different mechanisms employed by drought-avoiding and drought-tolerant species to withstand water deficit.
Description8 páginas, 6 figuras . En la sección "Acknowledgments" se incluye la siguiente mención "The authors are grateful to I. Barrera, M. Gil, A. Lobillo, J. Navarro, M.E. Orejas, A. Pintado, B. Rábago, E. Seriñá and E. Zuazua for their hard work at the field site and for their helpful comments."
Publisher version (URL)http://dx.doi.org/10.1093/treephys/20.2.131
Appears in Collections:(CCMA) Artículos
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