Distribution of leaf characteristics in relation to orientation within the canopy of woody species |
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| Institution: | 1. Institute of Natural Resources and Agrobiology of Salamanca, IRNASA-CSIC, Cordel de Merinas 40, E-37008 Salamanca, Spain;2. IRTA (Institute for Food and Agricultural Research and Technology), Field Crops, Av. Alcalde Rovira i Roure, 191, E-25198 Lérida, Spain;1. Faculty of Agriculture, University of Peradeniya, Peradeniya 20400, Sri Lanka;2. School of Plant Biology, and Institute of Agriculture, The University of Western Australia, 35 Stirling Hwy, Crawley, Perth, Western Australia 6009, Australia;1. Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, New Mexico;2. Department of Cell Biology and Physiology, School of Medicine, University of New Mexico, Albuquerque, New Mexico;4. Department of Pathology, School of Medicine, University of New Mexico, Albuquerque, New Mexico;3. Department of Internal Medicine, Division of Molecular Medicine, School of Medicine, University of New Mexico, Albuquerque, New Mexico;1. Biosystems Engineering, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran;2. Plant Pathology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran;3. Electrical Engineering, Faculty of Electrical and Computer Engineering, Shahid Beheshti University, Tehran, Iran;1. Department of Oncology, First Affiliated Hospital of Anhui Medical University, Hefei, China;2. Department of Pathology, Basic Medical School of Anhui Medical University, Hefei, China;3. Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, California |
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| Abstract: | Over the last few decades considerable effort has been devoted to research of leaf adaptations to environmental conditions. Many studies have reported strong differences in leaf mass per unit area (LMA) within a single tree depending on the photosynthetic photon flux density (PPFD) incident on different locations in the crown. There are fewer studies, however, of the effects of differences in the timing of light incidence during the day on different crown orientations.Leaves from isolated trees of Quercus suber and Quercus ilex in a cold Mediterranean climate were sampled to analyze differences in LMA and other leaf traits among different crown orientations. Gas-exchange rates, leaf water potentials, leaf temperatures and PPFD incident on leaf surfaces in different crown orientations were also measured throughout one entire summer day for each species.Mean daily PPFD values were similar for the leaves from the eastern and western sides of the canopy. On the western side, PPFD reached maximum values during the afternoon. Maximum leaf temperatures were approximately 10–20% higher on the west side, whereas minimum leaf water potentials were between 10 and 24% higher on the east side. Maximum transpiration rates were approximately 22% greater on the west, because of the greater leaf-to-air vapor pressure deficits (LAVPD). Mean individual leaf area was around 10% larger on the east than on the west side of the trees. In contrast, there were no significant differences in LMA between east and west sides of the crown.Contrary to our expectations, more severe water stress on the west side did not result in increases in LMA, although it was associated with lower individual leaf area. We conclude that increases in LMA measured by other authors along gradients of water stress would be due to differences in light intensity between dry and humid sites. |
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