Fluorescence as a biological feedback signal for energy optimising spectra for greenhouse LED-illumination
Licentiate thesis, 2018
Furthermore, we have investigated different methods of evaluating how much the different diodes in the armature enhance the fluorescence and short term photosynthetic rate. At different background light, one LED colour at a time was changed, and the consequent change in fluorescence was measured. We refer to the fluorescence gain, for the specific LED colour, as the change in fluorescence divided by the change in photon flux, caused by the specific LED colour. When comparing the fluorescence gains for the different LED colours, the mutual relation was constant for a given plant species, independent of the background light spectra. Hence, if implementing the suggested controller for a predefined intensity, aiming to find the optimal spectra for maximised plant growth, the controller will maximise the intensity input to the most efficient LED colour and minimise the intensity to all other LEDs.
When evaluating the performance of the different LED colours, as a function of different intensity levels, changes were noticed in the mutual relations of the fluorescence gains. For cucumber, we found that when passing the light level where the photosynthesis saturate, no further changes in the mutual relation of the fluorescence gains were noticed. This opens up for using our method, i.e. comparing the fluorescence gains caused by excitation of light of different colours, to determine the light level where light saturation occurs.
Chalmers, Electrical Engineering, Systems and control, Automatic Control
Using chlorophyll a fluorescence gains to optimize LED light spectrum for short term photosynthesis
Computers and Electronics in Agriculture,; Vol. 142(2017)p. 224-234
LED spectrum optimisation using steady-state fluorescence gains
Acta Horticulturae,; Vol. 1134(2016)p. 367-374
Ahlman, L., Bånkestad, D., Wik, T. The correlation between changes in photosynthetic rate and changes in canopy level chlorophyll fluorescence in various background light and excitation of different LED colours
The Swedish Foundation for Strategic Environmental Research (Mistra), 2012-01-01 -- 2015-12-31.
Areas of Advance
Technical report - School of Electrical Engineering, Chalmers University of Technology, Göteborg, Sweden: R012/2018
Chalmers University of Technology
Opponent: Dr. Rikard Fristedt, Department of Biology and Biological Engineering, Chalmers University of Technology