Heat emission as a protective mechanism against high-irradiance stress in sugar maple leaves

K. Veeranjaneyulu, R. M. Leblanc

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

High-irradiance (HI) induced changes in heat emission, fluorescence, and photosynthetic energy storage (ES(T)) of shade grown sugar maple (Acer saccharum Marsh.) saplings were followed using modulated photoacoustic and fluorescence spectroscopic techniques. HI-treatment at 900-4400 μmol m-2 s-1 for 15 min caused an increase in heat emission and a decrease in ES(T). In some leaves, HI-treatment of 900 μmol m-2 s-1 for 1 min induced a rapid increase in heat emission with a marginal decrease in ES(T). Parallel to the increase in heat emission, there was a decrease in fluorescence, and this phenomenon was reversible in darkness. Quenching of thermal energy dissipation and a recovery in ES(T) were observed during the first 15 min after the HI-treatment. This down-regulation of photochemical activity and its recovery may be one of the photoprotective mechanisms in shade grown sugar maple plants. The increase in thermal energy dissipation was greater in the red absorbing long wavelength (640-700 nm) region than in the blue absorbing short wavelength region of photosynthetically active excitation radiation. The photochemical activity was affected more in short wavelengths (400-520 nm) than in the long wavelength region of the spectrum. This can be due to the migration of light-harvesting chlorophyll (Chl) a/b protein complex from photosystem (PS) 2 to PS1 and/or to the disconnection of carotenoid pool from Chls in the pigment bed of photosynthetic apparatus.

Original languageEnglish (US)
Pages (from-to)191-203
Number of pages13
JournalPhotosynthetica
Volume35
Issue number2
DOIs
StatePublished - Dec 1 1998

Keywords

  • Acer saccharum
  • Fluorescence
  • Photoacoustic spectroscopy
  • Photoinhibition
  • Photoprotection
  • Photosystems

ASJC Scopus subject areas

  • Plant Science

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