Vol. 16, issue 12, article # 13

Abstract:

We have studied how the sunlight energy is converted in polymer films doped with europium photoluminophores that are widely used as greenhouse polymer films. From the transmission spectra of various light films, the contribution of luminescence is quantitatively determined, in the regions of natural luminescent emission and absorption of plant phytochromes. The enhancement of electromagnetic radiation in the red spectral region due to luminescence at propagation through the films is found to be less than 1% of the sunlight intensity in the same spectral region, or 0.001-0.01 W/m². Uncontrolled change in the transmission of electromagnetic radiation by high-pressure polyethylene films in the same spectral region due to reflection by the polymer matrix is two to three orders of magnitude greater than that due to photoluminescence. The determined indices of change in the spectral composition of the electromagnetic radiation transmitted through the films do not confirm the hypotheses explaining faster growth and development of plants under such films (polysvetan effect) by currently known mechanisms of photoregulation of the plant growth. The explanation of the polysvetan effect as an example of the low-energy photoluminescent biostimulation similar to the low-energy light-induced biostimulation under the exposure to LED luminescent radiation and low-energy laser radiation is discussed.