Journal Article

PreJuSER-8362

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Leaf photosynthetic and solar-tracking responses of mallow, Malva parviflora, to photon flux density

Greer, D. H. ; Thorpe, M. R.FZJ*

2009
Elsevier Science Amsterdam [u.a.]

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Please use a persistent id in citations: doi:10.1016/j.plaphy.2009.06.002

Abstract: Malva parviflora L. (mallow) is a species that occupies high-light habitats as a weedy invader in orchards and vineyards. Species of the Malvaceae are known to solar track and anecdotal evidence suggests this species may also. How M. parviflora responds physiologically to light in comparison with other species within the Malvaceae remains unknown. Tracking and photosynthetic responses to photon flux density (PFD) were evaluated on plants grown in greenhouse conditions. Tracking ability was assessed in the growth conditions and by exposing leaves to specific light intensities and measuring changes in the angle of the leaf plane. Light responses were also determined by photosynthesis and chlorophyll fluorescence. Leaves followed a heliotropic response which was highly PFD-dependent, with tracking rates increasing in a curvilinear pattern. Maximum tracking rates were up to 20 degrees h(-1) and saturated for light above 1,300 micromol (photons) m(-2) s(-1). This high-light saturation, both for tracking (much higher than the other species), and for photosynthesis, confirmed mallow as a high-light demanding species. Further, because there was no photoinhibition, the leaves could capture the potential of an increased carbon gain in higher irradiance by resorting to solar tracking. Modelling suggested the tracking response could increase the annual carbon gain by as much as 25% compared with leaves that do not track the sun. The various leaf attributes associated with solar tracking, therefore, help to account for the success of this species as a weed in many locations worldwide.

Keyword(s): Carbon: metabolism (MeSH) ; Chlorophyll: chemistry (MeSH) ; Chlorophyll: metabolism (MeSH) ; Ecosystem (MeSH) ; Fluorescence (MeSH) ; Malva: metabolism (MeSH) ; Malva: physiology (MeSH) ; Models, Biological (MeSH) ; Photons (MeSH) ; Photosynthesis: radiation effects (MeSH) ; Plant Leaves: metabolism (MeSH) ; Plant Leaves: physiology (MeSH) ; Seasons (MeSH) ; Sunlight (MeSH) ; Time Factors (MeSH) ; Chlorophyll ; Carbon ; J ; Malva parviflora (auto) ; Carbon gain (auto) ; Chlorophyll fluorescence (auto) ; Light response (auto) ; Leaf angle (auto) ; Photosynthesis (auto) ; Sun tracking (auto)

Note: We thank Wayne Scott for technical assistance for this project. The study was also technically supported by Evert Van Thoor while on an Internship from Wageningen University and Research Centre for a Masters degree in Agricultural Engineering. We also thank SAS Australia for their generous support to the senior author for supplying software.

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Research Program(s):

1. Terrestrische Umwelt (P24)

Appears in the scientific report 2009
Notes: Nachtrag

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Database coverage:
; JCR ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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