Comparative field study of Quercus ilex and Phillyrea latifolia: Photosynthetic response to experimental drought conditions

Romà Ogaya, Josep Peñuelas

    Research output: Contribution to journalArticleResearchpeer-review

    174 Citations (Scopus)

    Abstract

    Quercus ilex and Phillyrea latifolia growing in a holm oak forest in Prades mountains (NE Spain) were subjected to experimental drought conditions. Soil water availability was reduced about 15% by plastic strips and funnels that partially excluded rain throughfall and by ditch exclusion of water runoff. Diurnal courses of maximum photochemical efficiency of PSII (Fv/Fm), apparent photosynthetic electron transport rate (ETR), net photosynthetic rate (A), transpiration rate (E) and water use efficiency (WUE) were measured in sunlit and shade leaves of both species during 2 years. Moreover, the responses of photosynthetic rates to PPFD and CO2 concentrations were also measured. Q. ilex experienced lower E rates and higher A rates and WUE than P. latifolia throughout the experimental period, but during summer drought these differences disappeared. Q. ilex exhibited a less cold sensitive behavior whereas P. latifolia showed a more heat-drought resistant behavior. Under severe summer drought conditions none of the two species was able to reach a positive carbon gain. Drought treatment produced a slight decrease in Fv/Fm values of Q. ilex plants and a strong decrease in Fv/Fm values of P. latifolia only in winter 2000, when drought stress coincided with cold stress. Drought treatment produced also a slight decrease in ETR values of both species. During midday, A and E rates decreased in drought plots in both species associated to lower photochemical efficiencies. In those drought plots, only P. latifolia was able to increase WUE by reducing transpiration losses during midday. Both species tended to present higher A rates for a given soil humidity in drought than in control plots. However, whereas Q. ilex A rates increased with soil humidity, P. latifolia A rates did not increase above 17% soil humidity, showing no water availability response above such threshold. It is very likely that mesic species such as Q. ilex lose competitive advantage in the drier environment forecasted for next decades than the more xeric P. latifolia. © 2003 Elsevier Science B.V. All rights reserved.
    Original languageEnglish
    Pages (from-to)137-148
    JournalEnvironmental and Experimental Botany
    Volume50
    Issue number2
    DOIs
    Publication statusPublished - 1 Jan 2003

    Keywords

    • Carbon sequestration
    • Chlorophyll fluorescence
    • Climate change
    • Electron transport rate
    • Photochemical efficiency
    • Photoinhibition
    • Photosynthetic rates
    • Stomatal conductance

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