Acclimation of Norway spruce photosynthetic apparatus to the combined effect of high irradiance and temperature
| Autor: | Otmar Urban, Jana Podolinská, Daniel Vrábl, J. Kalina, Vladimír Špunda, Michal Štroch |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Chlorophyll
Chlorophyll a Stomatal conductance Photoinhibition Light Physiology Acclimatization Plant Science Xanthophylls Photosynthesis chemistry.chemical_compound Botany Picea chemistry.chemical_classification Photons Norway Chlorophyll A Temperature Photosystem II Protein Complex Carbon Dioxide Circadian Rhythm Horticulture chemistry Xanthophyll Photoprotection Plant Stomata Gases Agronomy and Crop Science |
| Zdroj: | Journal of Plant Physiology. 167:597-605 |
| ISSN: | 0176-1617 |
| Popis: | Diurnal courses of photosynthetic gas exchange parameters, chlorophyll a fluorescence characteristics and the de-epoxidation state of the xanthophyll cycle pigments (DEPS) were measured during the gradual acclimation of 4-year-old Norway spruce seedlings to different photosynthetic photon flux density (PPFD) and air temperature (T(air)) regimes, simulating cloudy days with moderate T(air) (LI, maximum PPFD 300 micromol m(-2)s(-1), T(air) range 15-25 degrees C), sunny days with moderate T(air) (HI, maximum PPFD 1000 micromol m(-2)s(-1), T(air) range 15-25 degrees C) and hot sunny days (HI-HT, maximum PPFD 1000 micromol m(-2)s(-1), T(air) range 20-35 degrees C). The plants were acclimated inside a growth chamber and each acclimation regime lasted for 13d. Acclimation to HI conditions led to a strong depression of the net CO(2) assimilation rates (A(N)), particularly during noon and afternoon periods. Exposure to the HI-HT regime led to a further decrease of A(N) even during the morning period. Insufficient stomatal conductance was found to be the main reason for depressed A(N) under HI and HI-HT conditions. Only slight changes of the maximum photosystem II (PSII) photochemical efficiency (F(V)/F(M)), in the range of 0.78-0.82, supported the resistance of the Norway spruce photosynthetic apparatus against PSII photoinhibition during acclimation to both HI and HI-HT conditions. The HI plants showed increased content of xanthophyll cycle pigments (VAZ) and enhanced efficiency of thermal energy dissipation within PSII (D) that closely correlated with the increased DEPS. In contrast, acclimation to the HI-HT regime resulted in a slight reduction of VAZ content and significantly diminished D and DEPS values during the entire day in comparison with HI plants. These results indicate a minor role of the xanthophyll cycle-mediated thermal dissipation in PSII photoprotection under elevated temperatures. The different contributions of the thermal dissipation and non-assimilatory electron transport pathways in PSII photoprotection during acclimation of the Norway spruce photosynthetic apparatus to excess irradiance and heat stresses are discussed. |
| Databáze: | OpenAIRE |
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