## 3 Results
To understand the cause of the acceleration in tomato growth under the photoconversion films, we examined the impact of photoconversion films on the plant photochemistry. For this aim, we analyzed the development of changes in the maximum quantum yield of plant photochemistry (which provides information about the general state of the photosynthetic apparatus). This parameter reflects the utilization of excitation energy (Figure 4). The level of photochemical activity recorded in the plants did not decrease during the experiment, which may indicate similar and stable overall states of the photosynthetic apparatus in both groups of plants (Figure 4A). Illumination of plants led to formation of exited states of pigments of photosynthetic antenna. Part of this energy is used for photosynthesis. The proportion of excited energy routed to photosynthesis is reflected in the level of effective Y(II) (quantum yield of photosystem II photochemistry). Under the unfavorable conditions, the plant can change the proportion of energy directed to photosynthesis and activate mechanisms aimed at the quenching of excitation energy via heat dissipation: so-called processes of regulated and non-regulated heat dissipation. Activity of these processes correlate well with levels of non-photochemical quenching of  
Figure 2: Scanning electron microscopy image for Sr\({}_{0.955}\)Yb\({}_{0.020}\)Er\({}_{0.025}\)F\({}_{2.045}\) (**A**) and particle number as a function of their diameter (**B**). fluorescence (NPQ), and non-regulated heat dissipation and fluorescence emission (NO), respectively. The installation of the coating over the plants and the appearance of ultraviolet light in the growth spectrum induce the changes in ChlF parameters. These changes had similar trends in both control and experimental groups. The Y(II) decreases within the first 6-7 days from approximately 0.3 to 0.1 (Figure 4B), which indicates some suppression of photosynthesis in the plants. The reduction of Y(II) is accompanied by an increase in Y(NPQ) (Figure 4C) and Y(NO) (Figure 4D) in both control and experiment plants. The amplitude of Y(II) reduction was equal to the sums of growth of Y(NPQ) and Y(NO). However, the changes described above were reversible: the photochemistry parameters gradually reached initial values. The rate of relaxation of Y(NO) and Y(II) values in plants growing under PCF was relatively fast (initial levels were observed within 3-5 days and did not change later). In control plants, Y(II) and Y(NO) relaxed slowly (achievement of initial levels were observed in only three weeks). Note that the kinetics of Y(NPQ) in both control and experimental plants were practically identical. The above-mentioned data reflect a reversible decrease in efficiency of photosynthesis at the first week of the experiment. The different capacities of the photosynthetic electron-transport chain, and the activity of enzymes during the dark stage of photosynthesis, show that electron transport and, concurrently the redistribution of excitation energy, changes in plants growing under different conditions, as a result of changes in light intensity. We studied the dependence of Y(II), Y(NPQ) and ETR (the rate of linear electron transport through photosystem II) on light intensity (Figure 5). Figure 3: (**A**) Photoluminescence (**1**) of the nanoparticles in acetone in PAR range, which was excited by a semiconductor laser (**2**). (**B**) Difference spectrum (“light spectrum under photoconversion film” minus “light spectrum under common film”), showing changes in the spectrum of growth light. In figure (**A**), green and red colors indicate the luminescence in the green and red regions of the spectrum, respectively. The Y(II) and Y(NPQ) in leaves of plants growing under PCF were relatively stable at weak light (up to 100 \(\upmu\)mol photons s\({}^{-1}\) m\({}^{-2}\)) (Figure 5A,B). When Y(II) was relatively high (about 0.72-0.73), the Y(NPQ) value close to zero.