title: Remote sensing of the xanthophyll cycle and chlorophyll fluorescence in sunflower leaves and canopies.
abstract: Sudden illumination of sunflower (Helianthus annuus L. cv. CGL 208) leaves and canopies led to excess absorbed PFD and induced apparent reflectance changes in the green, red and near-infrared detectable with a remote spectroradiometer. The green shift, centered near 531 nm, was caused by reflectance changes associated with the de-epoxidation of violaxanthin to zeaxanthin via antheraxanthin and with the chloroplast thylakoid pH gradient. The red (685 nm) and near-infrared (738 nm) signals were due to quenching of chlorophyll fluorescence. Remote sensing of shifts in these spectral regions provides non-destructive information on in situ photosynthetic performance and could lead to improved techniques for remote sensing of canopy photosynthesis.
authors.affiliation: Department of Plant Biology, Carnegie Institution of Washington, 290 Panama Street, 94305, Stanford, CA, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Gamon
authors.affiliation: Department of Plant Biology, Carnegie Institution of Washington, 290 Panama Street, 94305, Stanford, CA, USA.
authors.forename: C B
authors.initials: CB
authors.lastname: Field
authors.affiliation: Department of Plant Biology, Carnegie Institution of Washington, 290 Panama Street, 94305, Stanford, CA, USA.
authors.forename: W
authors.initials: W
authors.lastname: Bilger
authors.affiliation: Department of Plant Biology, Carnegie Institution of Washington, 290 Panama Street, 94305, Stanford, CA, USA.
authors.forename: O
authors.initials: O
authors.lastname: Björkman
authors.affiliation: Department of Plant Biology, Carnegie Institution of Washington, 290 Panama Street, 94305, Stanford, CA, USA.
authors.forename: A L
authors.initials: AL
authors.lastname: Fredeen
authors.affiliation: Department of Plant Biology, Carnegie Institution of Washington, 290 Panama Street, 94305, Stanford, CA, USA.
authors.forename: J
authors.initials: J
authors.lastname: Peñuelas
keywords: Chlorophyll fluorescence; Photosynthesis; Remote sensing; Sunflower (Helianthus annuus); Xanthophyll cycle