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The Dualex is used to measure the flavonols and the chlorophyll contents of leaves.

The Dualex is an optical sensor developed by Force-A (No longer in business) for the assessment of flavonol, anthocyanin, and chlorophyll contents in leaves. The sensor is a result of technology transfer from the CNRS (National Center for Scientific Research) and University of Paris-Sud Orsay.[1][2] It allows to perform real-time and non-destructive measurements.[3] The main applications are plant science and agriculture research.

Calculated indices

The assessment of polyphenolic compounds in leaves is based on the absorbance of the leaf epidermis through the screening effect it procures to chlorophyll fluorescence. [4][5] The indices calculated by Dualex are:


Based on the four measured indices, this optical sensor is applied in the fields of research as follows:

  • Plant physiology[6][7]
  • Genetic studies[7][8]
  • Plant phenology[9]
  • Herbal selection

It is equally applied in studies related to chlorophyll[10] (nutritional chlorosis, potential photosynthesis), flavonols (UV protection,[11] leaf light environment) and anthocyanins (temperature stress, light selection).


  1. Four innovative start-ups stemming from CNRS at the European Research and Innovation Exhibition 2009
  2. ESE Presentation - Lab. Ecologie, Systématique, Evolution - Technology Transfer
  3. Zoran G. Cerovic. 2012 New proximal sensors of vegetation: towards a non destructive quantitative estimation of plant constituents Ebernburg-Workshop "Leaf Optics"
  4. Bilger, W., Veit, M., Schreiber, L., Schreiber, U., 1997. Measurement of leaf epidermal transmittance of UV radiation by chlorophyll fluorescence. Physiologia Plantarum 101, 754-763.
  5. Goulas, Y., Cerovic, Z.G., Cartelat, A., Moya, I., 2004. Dualex: A new instrument for field measurements of epidermal UV-absorbance by chlorophyll fluorescence. Appl. Opt. 43, 4488-4496.
  6. Sandrine Barthod, Zoran Cerovic and Daniel Epron. 2007 Can dual chlorophyll fluorescence excitation be used to assess the variation in the content of UV-absorbing phenolic compounds in leaves of temperate tree species along a light gradient? Journal of Experimental Botany. Volume 58. Issue 7. Pp. 1753-1760
  7. 7.0 7.1 Sajjad Hussain, Frank Curk, Claudie Dhuique-Mayer, Laurent Urban, Patrick Ollitrault, François Luro, Raphaël Morillon. 2012 Autotetraploid trifoliate orange (Poncirus trifoliata) rootstocks do not impact clementine quality but reduce fruit yields and highly modify rootstock/scion physiology Scientia Horticulturae. Volume 134. Pages 100–107
  8. Luis O. M., Riita T., Mikael B., Markku K., Anders L. and Pedro J. A. 2010 Effects of solar UV-A and UV-B radiation on gene expression and phenolic accumulation in Betula pendula leaves Tree Physiology 30, 923–934
  9. Louis, J., Meyer, S., Maunoury-Danger, F., Fresneau, C., Meudec, E., Cerovic, Z.G. 2009 Seasonal changes in optically assessed epidermal phenolic compounds and chlorophyll contents in leaves of sessile oak (Quercus petraea): towards signatures of phenological stage Functional Plant Biology, 36(8):732-741.
  10. Padillaa, F.M., Peña-Fleitasa, M.T., Gallardo, M., Thompson, R.B. 2014 Evaluation of optical sensor measurements of canopy reflectance and of leaf flavonols and chlorophyll contents to assess crop nitrogen status of muskmelon Europ. J. Agronomy 58 (2014) 39–52.
  11. Pfündel, E.E., Ben Ghozlen, N., Meyer, S., Cerovic, Z.G. 2007 Investigating UV screening in leaves by two different types of portable UV fluorimeters reveals in vivo screening by anthocyanins and carotenoids Photosynth. Res., 93:205-221.