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Photosynthetic responses of two heliotropic legumes from contrasting habitats
Author(s) -
PRICHARD J. M.,
FORSETH I. N.
Publication year - 1988
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1988.tb01801.x
Subject(s) - transpiration , photosynthesis , canopy , deciduous , nitrogen , botany , specific leaf area , photosynthetic capacity , environmental science , agronomy , biology , chemistry , organic chemistry
Photosynthetic responses to light, temperature and leaf‐to‐air water vapour concentration deficit for Strophostyles helvola (L.) Ell. in an open beach site, and Amphicarpa bracteata (L.) Ell. in two deciduous forest sites were quantified. Photosaturated rates of net CO 2 assimilation were 52.1 ± 4.6, 11.0 ± 1.6 and 4.1 ± 0.3 μmol m −2 s −2 for plants in beach, roadside and closed canopy sites, respectively. In terms of photosynthesis, plants in the beach site were more tolerant of higher leaf temperatures and water vapour concentration deficits than were plants in forested sites. Heliotropic leaf movements in the beach site reduced calculated total daily transpiration by 2%, increased total daily carbon gain by 8% and reduced the transpiration ratio by 9% relative to an horizontal leaf. During long‐term sunflecks in forested sites, heliotropism reduced transpiration by 15%, increased carbon gain by 71% and reduced the transpiration ratio by 50% relative to an horizontal leaf. We hypothesize that heliotropic leaf movements in mesic, high‐light, low‐nitrogen habitats may increase carbon return on nitrogen investment in photosynthesis, while heliotropism in canopy gaps may represent a morphological mechanism to reduce damage to low‐light acclimated photosynthetic systems during long‐term sunflecks.