Seasonal changes in the photosynthetic performance of two evergreen Nothofagus species in south central Chile

Abstract

The evergreen Nothofagus dombeyi and Nothofagus nitida are important members of the temperate Chilean rainforest. They seldom grow together in nature. Nothofagus nitida is more susceptible to excess light and drought than N. dombeyi. We postulate that the different properties of the photosynthetic apparatus under common garden conditions of these species could explain their contrasting habitat preferences. The two species growing in a common garden in south central Chile were studied. The optimal photochemical efficiency (Fv/Fm) of both species remained within normal values (≈ 0.8) with the exception of a decrease in N. dombeyi at midday in summer, suggesting reversible reduction in photochemical efficiency of photosystem II (PSII). During summer the effective photochemical efficiency (Φ PSII ), photochemical quenching (qP), photosynthesis (A max ), stomatal conductance (gs) and transpiration rates (E) in N. dombeyi were higher than in N. nitida. The highest increments in photoprotective pigments (zeaxanthin + antheraxanthin and lutein) contents between predawn and midday were obtained in summer in N. dombeyi. In N. nitida a nocturnal retention of dissipative pigments, without a decrease in Fv/Fm, was found in winter. The results suggest that N. dombeyi showed a better photosynthetic performance than N. nitida under high light, high temperature, and drier conditions. These data support are consistent with the pioneer character of N. dombeyi and the semitolerant shade properties and more restricted distribution of N. nitida. These photosynthetic characteristics, along with their freezing and flooding resistance differences, may result from their habitat separation.Key words: chlorophyll fluorescence, photosynthesis, Nothofagus dombeyi, Nothofagus nitida, xanthophyll cycle. RESUMENLas siempreverdes, Nothofagus dombeyi y Nothofagus nitida, representantes importantes de los bosques lluviosos templados de Chile, raramente crecen juntos en forma natural. Nothofagus nitida es más sensible al exceso de luz y déficit de agua que N. dombeyi. Se postula que diferentes propiedades del aparato fotosintético bajo condiciones de jardín común de estas especies podrían explicar sus contrastantes preferencias de hábitat. Se estudian algunas de estas propiedades en estas dos especies creciendo en un jardín común en el centro sur de Chile. La eficiencia fotoquímica máxima (Fv/Fm) de ambas especies permanece en el rango de los valores normales (≈ 0,8) con excepción de un decrecimiento al mediodía y en verano en N. dombeyi, que sugiere una reducción reversible de la eficiencia fotoquímica máxima del fotosistema II (PSII). Durante el verano, la eficiencia fotoquímica efectiva del PSII (Φ PSII ), el apagamiento fotoquímico (qP), la fotosíntesis (A max ), conductancia estomática (gs) y las tasas de transpiración (E) en N. dombeyi fueron mayores que en N. nitida. Los mayores incrementos en los contenidos de pigmentos fotoprotectores (zeaxantina + anteraxantina y luteína) entre prealba y mediodía se obtuvieron en verano en N. domb...

Photochemical efficiency of PSII and photoprotective pigments in seedlings and adults of two Proteaceae with different shade tolerance from the Chilean temperate rain forest

“…(Mohammed et al, 2003) and therefore it can not be interpreted as photodamage, but as a regulatory adjustment of PSII efficiency (Huner et al 2002). In contrast, the evergreen Nothofagus dombeyi from the Chilean temperate rainforest showed a decrease in Fv/Fm in summer at the highest irradiances (midday) (Zúñiga et al 2006), but not in winter as was found in our study for L. ferruginea and E. coccineum. Because this decline was reversed in the afternoon in N. dombeyi, these authors suggested a photoprotective down regulation of the PSII mediated by Z, thus preventing the damage of the photosynthetic system as reported by other authors (Adams & Demmig-Adams 1994, Krause & Winter 1996.…”

“…There appears to be a high proportion of nocturnal retention of A+Z in these two Proteaceae, similar as has been found in N. nitida, a species from the Chilean temperate rainforest (Zúñiga et al 2006). Sustained retention of large amounts of A+Z appears to be a common response to low temperature stress under field conditions in plants (Adams & Demmig-Adams 1994, Adams & Barker 1998, Verhoeven et al 1999.…”

“…The climate of this area is temperate and strongly humid with oceanic influence (Reyes-Díaz et al 2005, Zúñiga et al 2006. Seedlings (2-3 year old plants) and adults (reproductive plants) of these species were considered in this study.…”

“…A second aliquot was used for xanthophyll analyses. They were separated and quantified by HPLC (Hewlett Packard 1100, Agilent Technologies Inc., San Jose, CA, USA) according to the method described by Gilmore & Yamamoto (1991) with minor modifications (Zúñiga et al 2006). 50 μL of the extract were injected in a Zorbax Rx-C18 reversed phase HPLC column (250 x 4.6 mm ID, 5 μm particle size) protected by a Zorbax Rx-C18 guard column (12.5 x 4.6 mm ID, 5 μm).…”

Above- And Below-Ground Nutrient Tissue Concentration and Leaf Pigment Changes in Patagonian Woody Seedlings Grown Under Light and Soil Moisture Gradients

“…This capability could refer to changes in photosynthetic performance, in biomass compartmentalization, in gas exchange, in leaf morphology and in water capture (Sun et al, 1995;Evans and Poorter, 2001;Damesin, 2003;Reynolds and Frochot, 2003;Sardans et al, 2006;Lencinas et al, 2007;Martínez Pastur et al, 2007). These physiological adjustments could also modify nutrient tissue concentration and their requirements (Sardans et al, 2006), as well as leaf pigment changes in the seedlings (Valladares et al, 2000;Damesin, 2003;Larcher, 2003;Zúñiga et al, 2006;Lichtenthaler et al, 2007) according to the new micro-environmental conditions.…”