Parameters of illumination including the spectra, intensity, and photoperiod play an important role in the cultivation of plants under greenhouse conditions, especially for vegetables such as lettuce. We previously showed that illumination by a combination of red, blue, and white LEDs with a high red light intensity, was optimal for lettuce cultivation; however, the effect of the photoperiod on lettuce cultivation was not investigated. In the current work, we investigated the influence of photoperiod on production (total biomass and dry weight) and parameters of photosynthesis, respiration rate, and relative chlorophyll content in lettuce plants. A 16 h (light):8 h (dark) illumination regime was used as the control. In this work, we investigated the effect of photoperiod on total biomass and dry weight production in lettuce plants as well as on photosynthesis, respiration rate and chlorophyll content. A lighting regime 16:8 h (light:dark) was used as control. A shorter photoperiod (8 h) decreased total biomass and dry weight in lettuce, and this effect was related to the suppression of the linear electron flow caused by the decreasing content of chlorophylls and, therefore, light absorption. A longer photoperiod (24 h) increased the total biomass and dry weight, nevertheless an increase in photosynthetic processes, light absorption by leaves and chlorophyll content was not recorded, nor were differences in respiration rate, thus indicating that changes in photosynthesis and respiration are not necessary conditions for stimulating plant production. A simple model to predict plant production was also developed to address the question of whether increasing the duration of illumination stimulates plant production without inducing changes in photosynthesis and respiration. Our results indicate that increasing the duration of illumination can stimulate dry weight accumulation and that this effect can also be induced using the equal total light integrals for day (i.e., this stimulation can be also caused by increasing the light period while decreasing light intensity). Increasing the duration of illumination is therefore an effective approach to stimulating lettuce production under artificial lighting.

Investigation is devoted to the optimization of light spectrum and intensity used for red mustard growing. Notably, most of the studies devoted to red mustard growing were conducted on micro-greens, which is not enough for the development of methods and recommendations for making the right choices about the irradiation parameters for full-cycle cultivation. In this study, we tested four models of LED with different ratios of blue, green red and far red radiation intensity: 12:20:63:5; 15:30:49:6; 30:1:68:1, in two values of photon flux density (PFD)—120 and 180 µmol m⁻² s⁻¹—to determine the most effective combination for red mustard growing. The study was conducted in a container-type climate chamber, where the red leaf mustard was cultivated in hydroponics. On the 30th day of cultivation, the plant’s morphological, biochemical and chlorophyll fluorescence parameters, and reflection coefficients were recorded. The results indicated that the PFD 120 µmol m⁻² s⁻¹ had a worse effect on both mustard leaf biomass accumulation and nitrate concentration (13–30% higher) in the plants. The best lighting option for growing red mustard was the blue–red spectrum, as the most efficient in terms of converting electricity into biomass (77 Wth/g). This light spectrum contributes to plant development with a larger leaf area (60%) and a fresh mass (54%) compared with the control, which has a maximum similarity in spectrum percentage to the sunlight spectrum. The presence of green and far red radiation with the blue–red light spectrum in various proportions at the same level of PFD had a negative effect on plant fresh mass, leaf surface area and photosynthetic activity. The obtained results could be useful for lighting parameters’ optimization when growing red mustard in urban farms.

The present study has been carried out to determine the effects of four different illuminators with red, far-red, blue, and white light-emitting diodes (LEDs) on the growth, morphology, pigment composition, and chlorophyll fluorescence of spinach (Spinacia oleracea L.) of the ‘Zhirnolistny’ cultivar. We investigated these variants in two photon flux densities, 400–800 nm (PFD) 120 µmol m⁻² s⁻¹ and 180 µmol m⁻² s⁻¹. The studies were carried out in a climate chamber. Plant measurements were carried out on the 30th and 45th days of cultivation. The results showed that during the period of active growth, on the 30th day, spinach plants accumulated 2.6 and 2.4 times more fresh weight in the variant with a higher PFD (180 µmol m⁻² s⁻¹). At the end of the growing season, only a decrease in PFD had an effect on the fresh and dry weight of plants. The highest concentration of chlorophyll on both the 30th and 45th days of vegetation was found when spinach plants were grown under red-blue (RB) LEDs in a spectrum proportion of R70:B30. It was found that the variants had a higher proportion of green radiation in the spectrum of illuminators with PFD 180 µmol m⁻² s⁻¹, and the nitrate content in spinach was slightly lower than in other variants.

The oscillation synchronization analysis in biological systems will expand our knowledge about the response of living systems to changes in environmental conditions. This knowledge can be used in medicine (diagnosis, therapy, monitoring) and agriculture (increasing productivity, resistance to adverse effects). Currently, the search is underway for an informative, accurate and sensitive method for analyzing the synchronization of oscillatory processes in cell biology. It is especially pronounced in analyzing the concentration oscillations of intracellular signaling molecules in electrically nonexcitable cells. The bispectral analysis method could be applied to assess the characteristics of synchronized oscillations of intracellular mediators. We chose endothelial cells from mouse microvessels as model cells. Concentrations of well-studied calcium and nitric oxide (NO) were selected for study in control conditions and well-described stress: heating to 40 °C and hyperglycemia. The bispectral analysis allows us to accurately evaluate the proportion of synchronized cells, their synchronization degree, and the amplitude and frequency of synchronized calcium and NO oscillations. Heating to 40 °C increased cell synchronization for calcium but decreased for NO oscillations. Hyperglycemia abolished this effect. Heating to 40 °C changed the frequencies and increased the amplitudes of synchronized oscillations of calcium concentration and the NO synthesis rate. The first part of this paper describes the principles of the bispectral analysis method and equations and modifications of the method we propose. In the second part of this paper, specific examples of the application of bispectral analysis to assess the synchronization of living cells in vitro are presented. The discussion compares the capabilities of bispectral analysis with other analytical methods in this field.

Spring rapeseed is one of the most important oilseed crops worldwide. Currently, one rapeseed development cycle takes about five to six months. Shortening the growing season can significantly reduce the growing period and speed up the realization of breeding and research projects. This could allow up to four generations of rapeseed instead of two or three under greenhouse conditions. Our research was conducted in 2023–2024 in a two-section climatic chamber developed at Federal Scientific Agroengineering Center VIM. The aim of the study was to study the effect of accelerating the growing season of rape by increasing the photoperiod and using different spectral composition of light. The experiment was conducted in 4 variants: Variant 1(22/2 RB) — photoperiod 22 h day / 2 h night and spectral composition R:40/B:60 (red-blue spectrum only); Variant 2 (22/2 FS) — photoperiod 22 h day / 2 h night and full spectrum FS (UV0.5: B37: G6.5: Y3: R49: FR4); Variant 3 (16/8 RB) — photoperiod 16 h / 8 h night and spectral composition R:40/B:60 (red-blue spectrum only); Variant 4 (16/8 FS) (control) — photoperiod 16 h day / 8 h night and full spectrum (UV0.5: B37: G6.5: Y3: R49: FR4). We achieved a reduction in growing season by 14 days using an extended photoperiod (22-hour daylight hours) and full spectrum radiation (UV0.5: B37: G6.5: Y3: R49: FR4). It was found that variants 1 and 2 used in the experiment could be used to obtain rape seeds of proper quality. The best was variant 2–22/2 FS using 22 hour daylight hours and full spectrum radiation (UV0.5: B37: G6.5: Y3: R49: FR4).

Особенности стрессовых реакций однодольных и двудольных растений в присутствии биодоступных соединений свинца на примере салата посевного ( Lactuca sativa L.) и пшеницы яровой ( Triticum aestivum L.)