Revista Chilena de Historia Natural 81 (3): 321-333, 2008
RESEARCH ARTICLE
Effects of low temperature acclimation on photosynthesis in three Chilean
Proteaceae
Embothrium coccineum, Gevuina avellana, and Lomatia
ferruginea grow in habitats contrasting in temperature and light intensity. Embothrium coccineum is a pioneer
species that establishes itself in open sites completely exposed to variable sunlight and temperature. Gevuina avellana is
usually found in more protected sites. Lomatia ferruginea regenerates under the canopy in sites with low thermal
oscillations and high humidity. In order to establish an association of their habitats with functional attributes of each species, we studied
their photosynthetic responses to temperature and light intensity. We expected that E. coccineum, which grows at full
sun, is able to acclimate much better its photosynthetic apparatus to different temperatures than the shade tolerant L. ferruginea
and the semi-shade tolerant G. avellana. One group of plants of each species containing six individuals each was
subjected to 4 ºC (cold-acclimated plants). Another group with the same number of individuals was subjected to 20 ºC (non-acclimated
plants). In non-acclimated plants of E. coccineum, the photosynthetic rate as measured by
O<sub>2</sub> evolution presented its maximum at 30 ºC (16.5 µmol O<sub>2</sub> m<sup>-
2</sup>s<sup>-1</sup>) with an optimum between 20 and 35 °C, while in G. avellana and L.
ferruginea the highest photosynthetic rate (~13 µmol O<sub>2</sub> m<sup>-2</sup>s<sup>-
1</sup>) was obtained at 25 ºC. Cold acclimation significantly reduced the photosynthetic rates of the investigated species. The
Q<sub>10</sub> for O<sub>2</sub> evolution decreased significantly in coldacclimated E. coccineum
and G. avellana but not in L. ferruginea. The fluorescence parameters of PSII showed that E.
coccineum presents a higher effective quantum yield (F<sub>PSII</sub>) at both growth temperatures. Photochemical quenching (qP) was
more affected by the photosynthetic photon flux density (PPFD) in L. ferruginea than in the other species.
Lomatia ferruginea presented the highest non-photochemical quenching (NPQ) at lower PPFD. Thus, the photosynthetic
apparatus of each species presents functional differences according to the characteristics of light availability and temperature changes
of their habitats.
Key words:
Proteaceae, cold
acclimation, photosynthetic oxygen evolution, photochemical efficiency of PSII
