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High resolution monitoring of sun-flecks: Sun-fleck intensity drives both increases and decreases in non-photochemical quenching in shade leaves

Conference Paper


Abstract


  • Many inner canopy leaves and understory plants derive the majority of actinic light from transient flecks

    of light (sun-flecks). However, until recently, studying photosynthesis under rapid sun-flecks has been

    limited by the temporal resolution of photosynthesis-measuring instruments. In this study, we use a noninvasive

    active fluorescence technique (Light Induced Fluorescence Transient; LIFT), to remotely

    measure photosynthesis in leaves during sun-flecks at a high time resolution (<10 seconds). Using the

    LIFT approach and micro quantum light sensors attached to leaves, photosynthesis during sun-flecks

    was monitored in both inner canopy (shade) and outer canopy (sun) leaves of Persea americana

    (avocado) over 16 days. Analysis of sun-fleck observations (n = 136) identified four different regulatory

    mechanisms based upon leaf type, sun-fleck duration and sun-fleck light intensity. In shade leaves, sunfleck

    intensity was found to be most important, with shade leaves showing a decrease in nonphotochemical

    quenching (YNPQ) with sun-fleck light intensities <150 μmol photons·m-2·s-1 and increases

    with sun-fleck light intensities >150 μmol photons·m-2·s-1. In contrast, sun leaves were predominantly

    found to respond to sun-fleck duration and showed novel intra-sun-fleck interactions in photosynthetic

    parameters. Sun-flecks <6 minutes in length were found to lead to increases in YNPQ and electron

    transport rates (ETR). However, in sun-flecks longer than 6 minutes, the initial increase in ETR was

    followed by a decrease to low levels following a sustained increase in YNPQ. This study emphasizes the

    importance of leaf acclimation to light environments in determining sun-fleck responses, which may be

    important in modelling plant productivities.

Authors


  •   Wyber, Rhys (external author)
  •   Osmond, Barry B. (external author)
  •   Malenovky, Zbynek (external author)
  •   Robinson, Sharon

Publication Date


  • 2016

Citation


  • Wyber, R., Osmond, B., Malenovky, Z. & Robinson, S. (2016). High resolution monitoring of sun-flecks: Sun-fleck intensity drives both increases and decreases in non-photochemical quenching in shade leaves. The 17th International Congress on Photosynthesis Research Photosynthesis in a Changing World (pp. 312-312).

Start Page


  • 312

End Page


  • 312

Abstract


  • Many inner canopy leaves and understory plants derive the majority of actinic light from transient flecks

    of light (sun-flecks). However, until recently, studying photosynthesis under rapid sun-flecks has been

    limited by the temporal resolution of photosynthesis-measuring instruments. In this study, we use a noninvasive

    active fluorescence technique (Light Induced Fluorescence Transient; LIFT), to remotely

    measure photosynthesis in leaves during sun-flecks at a high time resolution (<10 seconds). Using the

    LIFT approach and micro quantum light sensors attached to leaves, photosynthesis during sun-flecks

    was monitored in both inner canopy (shade) and outer canopy (sun) leaves of Persea americana

    (avocado) over 16 days. Analysis of sun-fleck observations (n = 136) identified four different regulatory

    mechanisms based upon leaf type, sun-fleck duration and sun-fleck light intensity. In shade leaves, sunfleck

    intensity was found to be most important, with shade leaves showing a decrease in nonphotochemical

    quenching (YNPQ) with sun-fleck light intensities <150 μmol photons·m-2·s-1 and increases

    with sun-fleck light intensities >150 μmol photons·m-2·s-1. In contrast, sun leaves were predominantly

    found to respond to sun-fleck duration and showed novel intra-sun-fleck interactions in photosynthetic

    parameters. Sun-flecks <6 minutes in length were found to lead to increases in YNPQ and electron

    transport rates (ETR). However, in sun-flecks longer than 6 minutes, the initial increase in ETR was

    followed by a decrease to low levels following a sustained increase in YNPQ. This study emphasizes the

    importance of leaf acclimation to light environments in determining sun-fleck responses, which may be

    important in modelling plant productivities.

Authors


  •   Wyber, Rhys (external author)
  •   Osmond, Barry B. (external author)
  •   Malenovky, Zbynek (external author)
  •   Robinson, Sharon

Publication Date


  • 2016

Citation


  • Wyber, R., Osmond, B., Malenovky, Z. & Robinson, S. (2016). High resolution monitoring of sun-flecks: Sun-fleck intensity drives both increases and decreases in non-photochemical quenching in shade leaves. The 17th International Congress on Photosynthesis Research Photosynthesis in a Changing World (pp. 312-312).

Start Page


  • 312

End Page


  • 312