© 2007 Heron Publishing—Victoria, Canada
Acclimation of leaves to contrasting irradiance in juvenile trees differing in shade tolerance
Tomasz Wyka (1, 2), Piotr Robakowski (3) and Roma Zytkowiak (4)
1. Adam Mickiewicz University, Biology Department, Laboratory of General Botany, ul. Umultowska 89, 61-614 Poznañ, Poland / 2. Corresponding author (twyka@amu.edu.pl) / 3. August Cieszkowski Agricultural University of Poznañ, Department of Forestry, ul. Wojska Polskiego 69, 60-625 Poznañ, Poland / 4. Institute of Dendrology, Polish Academy of Sciences, Unit of Ecology, ul. Parkowa 5, 62-035 Kórnik, Poland / Received August 4, 2006; accepted November 14, 2006; published online June 1, 2007
Summary
Leaves developing in different irradiances undergo structural and functional acclimation, although the extent of trait plasticity
is species specific. We tested the hypothesis that irradiance-induced plasticity of photosynthetic and anatomical traits is
lower in highly shade-tolerant species than in moderately shade-tolerant species. Seedlings of two evergreen conifers, shade-tolerant
Abies alba Mill. and moderately shade-tolerant Picea abies Karst., and two deciduous angiosperm species, highly shade-tolerant Fagus sylvatica L. and moderately shade-tolerant Acer pseudoplatanus L., were grown in deep shade (LL, 5% of full irradiance) or in full solar irradiance (HL) during 2003 and 2004. Steady state
responses of quantum yield of PSII (φPSII), apparent electron transport rate (ETR), nonphotochemical quenching (NPQ) and photochemical quenching (qP) were generally
modified by the light environment, with slower declines in φPSII and qP and greater maximal ETR and NPQ values in HL plants in at least one season; however, no link between quantitative
measures of plasticity of these traits and shade tolerance was found. Plasticity of nine anatomical traits (including palisade
cell length, which was reduced in LL) showed no relationship with shade tolerance, but was less in conifers than in deciduous
trees, suggesting that leaf life span may be a significant correlate of plasticity. When LL-acclimated plants were exposed
to HL conditions, the degree and duration of photoinhibition (measured as a decline in maximum quantum yield) was greatest
in F. sylvatica, much lower in P. abies and A. alba, and lowest in A. pseudoplatanus. Thus, as with the other traits studied, vulnerability to photoinhibition showed no relationship with shade tolerance.
Keywords:
Abies alba, Acer pseudoplatanus, chlorophyll a fluorescence, Fagus sylvatica, Picea abies, shade acclimation, sun and shade leaves.
