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Reflectance and phenolics of green and glaucous leaves of Eucalyptus urnigera


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Close, DC, Davidson, NJ, Shield, CB and Wiltshire, RJE 2007 , 'Reflectance and phenolics of green and glaucous leaves of Eucalyptus urnigera' , Australian Journal of Botany, vol. 55, no. 5 , pp. 561-567 , doi: 10.1071/BT06037.

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On MountWellington, Tasmania, Australia, there is an altitudinal cline in the juvenile leaf form of Eucalyptus
urnigera from a green phenotype at lower altitudes (from 610 m) to a glaucous phenotype at higher altitudes (up to
1050 m). The objectives of this study were to (1) quantify reflectance of ultraviolet (UV) and photosynthetically active
radiation (PAR) for the adaxial and abaxial surfaces of leaves of the glaucous and green phenotypes and (2) to investigate
seasonal adjustment in photochemical efficiency (Fv/Fm) and tannin and flavonol compounds that absorb in UV spectrum.
The following two research sites were identified: one at low altitude (at 910 m, solely green phenotype) and one at high
altitude (1004 m, solely glaucous phenotype) on the E. urnigera cline. During the experimental period, average summer
temperatureswere similar at the two sites but in winter, average temperatureswere 5–6◦C lower and minimum temperatures
0.4–0.7◦C lower at the high-altitude site occupied by the glaucous phenotype. Incident PAR was similar at the two sites.
Reflectance was higher for glaucous leaves than for green leaves across the light spectrum of UVC (190–280 nm), UVB
(280–320 nm), UVA (320–400 nm) and PAR (400–700 nm). Reflectance was significantly higher from the abaxial than
from the adaxial surface of leaves. Fv/Fm was similar for glaucous and green leaves in summer but significantly lower in
green than glaucous leaves in winter. Fv/Fm was significantly lower in winter than in summer for both leaf types. Tannins
were significantly higher in green than glaucous leaves but there was no effect of season. Flavonol concentrations were
similar for leaves of both types and did not vary with season. We conclude that high reflectance of UV radiation and PAR
may confer benefit at the cooler, high-altitude portion of the cline of E. urnigera and that low reflectance of PAR may
confer benefit at the relatively warm and densely vegetated, low-altitude portion of the cline of E. urnigera where interand
intra-specific competition for light is likely to be intense.

Item Type: Article
Authors/Creators:Close, DC and Davidson, NJ and Shield, CB and Wiltshire, RJE
Journal or Publication Title: Australian Journal of Botany
Publisher: CSIRO Publishing
ISSN: 0067-1924
DOI / ID Number: 10.1071/BT06037
Additional Information:

Copyright © 2007 CSIRO.

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