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Among-shoot variability and leaf-specific absorptance characteristics affect diel estimates of in situ electron transport of Posidonia australis
Runcie, J.W.; Durako, M.J. (2004). Among-shoot variability and leaf-specific absorptance characteristics affect diel estimates of in situ electron transport of Posidonia australis. Aquat. Bot. 80(3): 209-220. dx.doi.org/10.1016/j.aquabot.2004.08.001
In: Aquatic Botany. Elsevier Science: Tokyo; Oxford; New York; London; Amsterdam. ISSN 0304-3770, more
Peer reviewed article  

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Keywords
    Absorptance; Posidonia australis J.D.Hooker, 1858 [WoRMS]; Marine

Authors  Top 
  • Runcie, J.W.
  • Durako, M.J.

Abstract
    Electron transport rate (ETR) calculations require values of irradiance, effective quantum yield of chlorophyll fluorescence (ΔF/F′m), the distribution of energy between PSII and PSI and leaf-specific photosynthetic absorptance. We conducted virtually simultaneous replicated measurements of diel changes in ΔF/F′m of Posidonia australis in situ, and determined leaf-specific photosynthetic absorptance in vivo using integrating spheres. Leaf-specific non-photosynthetic and photosynthetic absorptance, corrected for spectral reflectance, comprised 16 and 68% of total spectral absorptance (84%); about 7% of photosynthetically active radiation incident on the leaves was reflected. Virtually simultaneous quantum-yield measurements of eight short shoots provided an estimate of among-sample variability in ΔF/F′m: generally the standard deviation was ~10% of the mean except for a few hours around midday when the variability rose to ~25% of the mean. Our results indicate that leaf-specific non-photosynthetic absorptance, spectral reflectance and shoot-to-shoot variability need to be taken into account when estimating ETR in the field

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