Effects of low temperature acclimation on photosynthesis in three chilean proteaceae

Abstract

Embothrium coccineum, Gevuina avellana, and Lomaría ferruginea grow in habitats contrasting in temperature light intensity. Embothrium coccineum is a pioneer species that establishes itself in open sites completely to variable sunlight and temperature. Gevuina avellana is usually found in more protected sites.Lomaría ferruginea regenerates under the canopy in sites with low thermal oscillations and high humidity. In to establish an association of their habitats with functional attributes of each species, we studied their responses to temperature and light intensity. We expected that E. coccineum, which grows at full , is able to acclimate much better its photosynthetic apparatus to different temperatures than the shade L. ferruginea and the semi-shade tolerant G. avellana. One group of plants of each species containing individuals each was subjected to 4 °C (cold-acclimated plants). Another group with the same number of was subjected to 20 °C (non-acclimated plants). In non-acclimated plants of E. coccineum, the rate as measured by 0 2 evolution presented its maximum at 30 °C (16.5 ̂mol 0 2 m"2 s"1) with optimum between 20 and 35 °C, while in G. avellana and L. ferruginea the highest photosynthetic rate (̃13 mol 0 2 m"2 s") was obtained at 25 °C. Cold acclimation significantly reduced the photosynthetic rates of the species. The Q 10 for 0 2 evolution decreased significantly in cold-acclimated E. coccineum and G. but not in L. ferruginea. The fluorescence parameters of PSII showed that E. coccineum presents a effective quantum yield (cPPSII) at both growth temperatures. Photochemical quenching (qP) was more by the photosynthetic photon flux density (PPFD) in L. ferruginea than in the other species. Lomaríaferruginea presented the highest non-photochemical quenching (NPQ) at lower PPFD. Thus, the photosynthetic of each species presents functional differences according to the characteristics of light availability and changes of their habitats.