Journal Article

Acclimation of shade-developed leaves on saplings exposed to late-season canopy gaps

Shawna L. Naidu and Evan H. DeLucia

in Tree Physiology

Volume 17, issue 6, pages 367-376
Published in print June 1997 | ISSN: 0829-318X
Published online June 1997 | e-ISSN: 1758-4469 | DOI:
Acclimation of shade-developed leaves on saplings exposed to late-season canopy gaps

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We hypothesized that photoinhibition of shade-developed leaves of deciduous hardwood saplings would limit their ability to acclimate photosynthetically to increased irradiance, and we predicted that shade-tolerant sugar maple (Acer saccharum Marsh.) would be more susceptible to photoinhibition than intermediately shade-tolerant red oak (Quercus rubra L.). After four weeks in a canopy gap, photosynthetic rates of shade-developed leaves of both species had increased in response to the increase in irradiance, although final acclimation was more complete in red oak. However, photoinhibition occurred in both species, as indicated by short-term reductions in maximum rates of net photosynthesis and the quantum yield of oxygen evolution, and longer-term reductions in the efficiency of excitation energy capture by open photosystem II (PSII) reaction centers (dark-adapted Fv/Fm) and the quantum yield of PSII in the light (φPSII). The magnitude and duration of this decrease were greater in sugar maple than in red oak, suggesting greater susceptibility to photoinhibition in sugar maple. Photoinhibition may have resulted from photodamage, but it may also have involved sustained rates of photoprotective energy dissipation (especially in red oak). Photosynthetic acclimation also appeared to be linked to an ability to increase leaf nitrogen content. Limited photosynthetic acclimation in shade-developed sugar maple leaves may reflect a trade-off between shade-tolerance and rapid acclimation to a canopy gap.

Keywords: Acer saccharum; carbon gain; chlorophyll fluorescence; gap; irradiance; leaf absorptance; leaf nitrogen content; photoinhibition; Quercus rubra; red oak; sugar maple

Journal Article.  0 words. 

Subjects: Plant Sciences and Forestry

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