leaf reflectance & absorption. “pimple” savanna forms from termite mounds in innundated...
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LeafLeaf Reflectance & Absorption Reflectance & Absorption
““Pimple” SavannaPimple” Savannaforms from termite mounds in forms from termite mounds in innundated tropical grasslandsinnundated tropical grasslands
LeafLeaf Reflectance & Absorption Reflectance & Absorption
Beltsville winter wheatBeltsville winter wheat
True & False Color PhotosTrue & False Color PhotosIn true-color, grass and astroturf look similar; in the near-infrared, grass is more reflective
grass
astroturf
astroturfastroturf
grass
TrueTrue colorcolor filmfilm
ColorColor infraredinfrared filmfilm
Plant PigmentsPlant PigmentsSo, what absorbs in functioning leaves?So, what absorbs in functioning leaves?
None of the key pigments absorbs green light; instead it is reflected to our eyes, which makes plants look green to us.
Liquid Water AbsorptionLiquid Water Absorption
Liquid water in Liquid water in plant leaves plant leaves completes the completes the absorption absorption picture: leaves picture: leaves must be must be hydrated for hydrated for photosynthesisphotosynthesis
Green LeafGreen Leaf StructureStructure
Dicot and Conifer LeavesDicot and Conifer Leaves
Bean leaf x420Bean leaf x420 Pine needle x370
Maple & Pine reflectanceMaple & Pine reflectance
maple
pine
Similar in visible light, different in the near-IR
LeafLeaf Reflectance & Absorption Reflectance & AbsorptionReflectance = 1.0 - Absorption
Banana x1400 Cucumber x490
Leaf PhotosynthesisLeaf PhotosynthesisPhotosynthesis Determines Optical Properties
Bean leaf x4200
Leaf PhotosynthesisLeaf PhotosynthesisPhotosynthesis Determines Optical Properties
Must capture photons to drive Must capture photons to drive chemical reactions (energy input)chemical reactions (energy input)
Must be in presence of H2OMust be in presence of H2O
Must be in presence of CO2Must be in presence of CO2
Must get rid of O2 (poisonous)Must get rid of O2 (poisonous)
Must live in hostile setting…Must live in hostile setting…
Internal Leaf StructureInternal Leaf Structure
ChloroplastsIntercellular air labyrinth CO2 in & O2 out
LeafLeaf Reflectance & Absorption Reflectance & AbsorptionPhotosynthesis requires CO2 from atmosphere to be in contact with the plant cell surfaces. The intercellular labyrinth allows movement of CO2 into leaves and O2 out. Part of the “deal” is H2O is lost
LeafLeaf Photosynthesis Photosynthesis
Stomata regulate gas exchange and water loss CO2 in/O2 out
LeafLeaf Photosynthesis Photosynthesis Piers Seller’s PAR DiagramPiers Seller’s PAR Diagram
Photosynthesis Action SpectrumPhotosynthesis Action Spectrum