Chin J Plan Ecolo ›› 2015, Vol. 39 ›› Issue (9): 917-923.DOI: 10.17521/cjpe.2015.0088

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A new method to measure and calculate light intensity and light quality simultaneously by using portable spectrometer

FAN Da-Yong, FU Zeng-Juan, XU Wen-Ting, XIE Zong-Qiang*()   

  1. State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
  • Received:2015-04-28 Accepted:2015-08-13 Online:2015-09-03 Published:2015-09-23
  • Contact: Zong-Qiang XIE
  • About author:

    # Co-first authors

Abstract:

The influence of light intensity and light quality on plants is highly concerned in the field of plant physiology and ecology. However, the calibrated quantum meter for measurement of light intensity cannot measure light quality, and vice versa. Here we developed an empirical formula to convert light energy to photon flux density, based on the measurement conditions of spectrometer. Under the guide of the formula, a portable spectrometer (AvaSpec-ULS2048×64) was calibrated by using four narrowband light emitting diode (LEDs) in combination with a calibrated quantum meter (LI-190SB). After calibration of the spectrometer, we can calculate photosynthetic photon flux density (PPFD or PAR) and measure spectrum of radiation flux simultaneously. Under natural light conditions, the errors between measured and calculated PPFDs are in the range from -2% to 5%, indicating the reliability of the method. With this new approach, the application of portable spectrometer can be greatly broadened: 1) the light intensity and quality of light source and plant growth light environment can be obtained simultaneously, 2) PPFD can be obtained within any specified wavelength range, and 3) there is no need to use standard light source to obtain the absolute light/radiation flux of a spectrum measured by spectrometer. In conclusion, this method has potential applications for the study of plant physiology and ecology.

Key words: spectrometer, photosynthetic photon flux density, empirical formula to convert light energy to photon flux density, LED light