# Cultivation of _Solanum Lycopersicum_ under Glass Coated with Nanosized Upconversion Luminophore
## 3 Results  
It was previously shown that illumination of SrF\({}_{2}\) doped with Er\({}^{3+}\) and Yb\({}^{3+}\) single crystals with infrared light induces luminescence in red and green spectral regions [21; 23; 50; 51; 52; 53]. Similar spectra in these regions were obtained in the present work (Figure 1A, curve 1). Infrared (975 nm) excitation of Sr\({}_{0.910}\)Yb\({}_{0.075}\)Er\({}_{0.015}\)F\({}_{2.090}\) (UCL) led to photoluminescence with typical emission bands of the ion pair Er\({}^{3+}\)/Yb\({}^{3+}\). 1.87 eV (about 660 nm), 2.27 eV (545 nm) and 2.36 eV (525 nm). Thus, the obtained results allow us to assume that the selected luminescence nanoparticles have sufficient potential to improve light for plant growth and may be used in photoconversion covers to increase the PAR intensity due to IR conversion into red and green light. Figure 1B shows a typical X-ray pattern diffraction for a Sr\({}_{0.910}\)Yb\({}_{0.075}\)Er\({}_{0.015}\)F\({}_{2.090}\) solid solution dried at 45 \({}^{\circ}\)C in air (curve 1) and treated at 600 \({}^{\circ}\)C in a platinum crucible (curve 2). The synthesis of the solid solution Sr\({}_{1\text{-}xy}\)Yb\({}_{x}\)Er\({}_{y}\)F\({}_{2\text{+}xy}\) leads to the formation of a single-phase powder with a fluorite structure (JCPDS #06\(-\)0262, \(a\) = 5.800 A) (compare curve 1, curve 2 and curve 3). As it can be seen from the figure, the powder dried in air at 45 \({}^{\circ}\)C (curve 1) has broadened peaks that indicate a small particle size. Heat treatment at 600 \({}^{\circ}\)C led to narrowing of the peaks (curve 2) due to the agglomeration of particles. The unit cell parameters were \(a\) = 5.7944(2) and \(a\) = 5.7722(1) for the 45 \({}^{\circ}\)C and 600 \({}^{\circ}\)C thermal treatment stages, respectively. The scanning electron microscopy image of the samples shows that heat treatment led to the formation of rounded particles with a 68 and 350 nm mean size (Figure 1C), which is consistent with the XRD data. The dynamic light scattering method confirmed that the powder contained two pools of particles: primary particles with an average nanoparticle size from 55 to 85 nm, and agglomerates of primary particles (Figure 1D). Note that most of the particles are presented in the form of agglomerates. The real composition of the solid solution powder was determined using energy-dispersive X-ray spectroscopy on Sr\({}_{0.897}\)Yb\({}_{0.088}\)Er\({}_{0.015}\)F\({}_{2.103}\). Our measurements show that the average solar lighting on a cloudy day in the Moscow region reached a PPFD (400-700 nm) intensity of approximately 70-80 umol photon s\({}^{-1}\) m\({}^{-2}\). To simulate natural light conditions, all of the plants were grown under 70 umol photon s\({}^{-1}\) m\({}^{-2}\) (provided by an incandescent light bulb). At the seventh leaf stage, both experiment and control plants were placed under glass coated with a fluorplate polymer with or without photoconversion nanoparticles. A UVA component (\(\lambda\) = 370 nm, PFD = 10 umol photon s\({}^{-1}\) m\({}^{-2}\)) was added to the illumination spectrum. The spectral composition of light can influence plant morphology, physiology and development, including photosynthesis [54; 55; 56]. It is known that light energy absorbed by plants' photosynthetic antenna complexes and transformed into excitation energy can be utilized via three processes: (1) photosynthesis, (2) regulated heat dissipation and (3) non-regulated heat dissipation and fluorescence emission (NO). The partitioning of absorbed light energy was determined by the analysis of the light-induced changes in the ChIP. The efficiency of photosynthesis correlates well with the effective quantum yield of photosystem 2 photochemistry (Y(II)), or so-called photochemical quenching of fluorescence (q\({}_{\rm P}\)). Regulated heat dissipation is reflected in the non-photochemical quenching of fluorescence (NPQ). Figure 2A,B show that the proportion of absorbed light energy used for photosynthesis before the start of the experiment was about 30%.