Revista Chilena de Historia Natural 82 (3): 387-402, 2009
RESEARCH ARTICLE
Photochemical efficiency of PSII and photoprotective pigments in seedlings and adults of two
Proteaceae with different shade tolerance from the Chilean temperate rain forest
MIREN ALBERDI, MARJORIE REYES-DÍAZ, RAFAEL ZÚÑIGA, SUSAN HESS, LEÓN A. BRAVO & LUIS J.
The seasonal variation in energy quenching parameters of photosystem II and
photoprotective pigments were studied in seedlings and adults of two Proteaceae: a shade-intolerant species (Embotrium
coccineum J.R. et G. Forster) and a shade-tolerant species (Lomatia ferruginea (Cav.) R. Br.). We postulate that
the shade intolerant species favors photochemical energy driven processes (mainly CO<sub>2</sub> assimilation) while the
shade tolerant species exhibits higher non-photochemical energy dissipation under unfavorable conditions. Moreover, the shade
tolerant species presents lower seasonal variations in these parameters that the shade intolerant species. Differences in energy
dissipation should be more evident in seedlings than adults because of their contrasting light environments and temperatures are more
evident at this stage. Their maximal photochemical efficiency (Fv/Fm) was in the range 0.70-0.83. The effective photochemical
efficiency (FPSII), photochemical quenching (qP), and electron transport rate (ETR) were higher in
seedlings of E. coccineum than in seedlings of L. ferruginea. Adults showed higher
photochemical energy quenching parameters than seedlings. Nonphotochemical quenching (NPQ) was frequently similar between
daily periods, seasons, species, and developmental stages, with the exception of the lowest non-photochemical quenching in
seedlings of E. coccineum in summer. Seedlings and adults showed a larger xanthophyll cycle pool content
at midday in summer than in winter, while the pool of antheraxanthin + zeaxanthin was always higher at midday. Lutein increased the
most during summer. Thus, E. coccineum seedlings and adults maintained high photosynthesis, a higher fraction of open
reaction centres, and higher ETR than the shade tolerant species. These differences are consistent with the ecological functions of
both species: a pioneer character, higher growth rate, and wide altitudinal and latitudinal distribution of E. coccineum
compared to L. ferruginea.
chlorophyll
fluorescence, lutein, photosynthesis, photoprotective pigments, xanthophylls cycle
