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The impacts of leaf shape and arrangement on light interception and potential photosynthesis in southern beech (Nothofagus cunninghamii)

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Kern, SO and Hovenden, MJ and Jordan, GJ (2004) The impacts of leaf shape and arrangement on light interception and potential photosynthesis in southern beech (Nothofagus cunninghamii). Functional Plant Biology, 31 (5). pp. 471-480.

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Abstract

The impact of differences in leaf shape, size and arrangement on the efficiency of light interception, and in particular the avoidance of photoinhibition, are poorly understood. We therefore estimated light exposure of branches in the cool temperate rainforest tree, Nothofagus cunninghamii (Hook.) Oerst., in which leaf shape, size and arrangement vary systematically with altitude and geographic origin. Measurements of incident photosynthetic photon flux density (PPFD) were made in the laboratory at solar angles corresponding to noon at summer solstice, winter solstice and equinox on branches collected from a common garden experiment. Tasmanian plants showed more self-shading than Victorian plants in summer and equinox. This was related to branch angle, leaf arrangement and leaf shape. Using a modelled light response-curve, we estimated the carbon assimilation rate and the flux density of excess photons at different incident PPFD. Victorian plants had higher predicted assimilation rates than Tasmanian plants in summer and equinox, but were exposed to substantially greater levels of excess photons. Because of the shape of the light-response curve, self-shading appears to reduce the plant's exposure to excess photons, thus providing photoprotection, without substantially reducing the carbon assimilation rate. This is dependent on both regional origin and season.

Item Type: Article
Keywords: assimilation, leaf morphology, photoprotection, phyllotaxy, self-shading
Journal or Publication Title: Functional Plant Biology
Page Range: pp. 471-480
Identification Number - DOI: 10.1071/FP03211
Additional Information: The definitive version is available online at http://www.publish.csiro.au/nid/102.htm
Date Deposited: 03 Sep 2007
Last Modified: 18 Nov 2014 03:21
URI: http://eprints.utas.edu.au/id/eprint/1795
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