Light and nutrient availability are critical factors of plant growth and development, particularly at the early stages, where they significantly influence the establishment and survival of young seedlings. The morphological parameters and the biomass accumulation of soybean were measured in a hydroponic vertical farm in the first 14 days of seedling growth in two successive experiments under two types of lighting environments and at three nutrient concentration levels. The lighting conditions were set by two parallel variable-spectrum linear luminaires positioned above the lower and upper edges of the cultivation trays. In the first lighting environment, seedlings were exposed to a constant photosynthetic photon flux density (PPFD) with red and blue photon irradiance ratio (R/B) varying in broad range from the lower to the upper end of the cultivation trays. In the second environment, the spatial R/B distribution was uniform, and the PPFD varied between two maxima at the edges and a minimum in the middle of the trays. The R/B ratio within the 0.6–6 interval had little or no effect on plant development. We report the dependence of growth traits as a function of PPFD in the range of 30–290 µmol m⁻² s⁻¹ in full-strength, half-strength, and blank nutrient solutions. The light response for shoot height and the first internode length was mainly influenced by blue light. We observed a rapid decline in growth between 6–20 µmol m⁻² s⁻¹ blue photon irradiance. The shoot height and first internode length did not change significantly at higher blue light intensities. The lengths of the first internode and the root dry mass did depend on the nutrient solution strength. All other growth traits, including stem diameter, leaf size, shoot mass, root mass, and SPAD readings, showed a linear correlation with PPFD and electrical conductivity. The leaf mass and root mass ratios indicated that soybeans adopt a nutrient search strategy by giving preference for root growth while increasing shoot height at the expense of the shoot diameter in conditions of low nutrient availability and low light intensity. The functional relationships determined in the experiments provide valuable inputs to plant growth models. The methodology we employed could also be used to study other plant species and to investigate the interactive effects of specific nutrients and lighting conditions.

Light and nutrient availability are critical factors of plant growth and development, particularly at the early stages, where they significantly influence the establishment and survival of young seed-lings. The morphological parameters and the biomass accumulation of soybean were measured in a hydroponic vertical farm in the first 14 days of seedling growth in two successive experiments under two types of lighting environments and at three nutrient concentration levels. The lighting condi-tions were set by two parallel variable-spectrum linear luminaires positioned above the lower and upper edges of the cultivation trays. In the first lighting environment, seedlings were exposed to a constant photosynthetic photon flux density (PPFD) with red and blue photon irradiance ratio (R/B) varying in broad range from the lower to the upper end of the cultivation trays. In the second en-vironment, the spatial R/B distribution was uniform, and the PPFD varied between two maxima at the edges and a minimum in the middle of the trays. The R/B ratio within the 0.6-6 interval had little or no effect on plant development. We report the dependence of growth traits as a function of PPFD in the range of 30-290 µmol m⁻² s⁻¹ in full-strength, half-strength, and blank nutrient solutions. The light response for shoot height and the first internode length was mainly influenced by blue light. We observed a rapid decline in growth between 6-20 µmol m⁻² s⁻¹ blue photon irradiance. The shoot height and first internode length did not change significantly at higher blue light intensities. The lengths of the first internode and the root dry mass did depend on the nutrient solution strength. All other growth traits, including stem diameter, leaf size, shoot mass, root mass, and SPAD readings, showed a linear correlation with PPFD and electrical conductivity. The leaf mass and root mass ratios indicated that soybeans adopt a nutrient search strategy by giving preference for root growth while increasing shoot height at the expense of the shoot diameter in conditions of low nutrient availability and low light intensity. The functional relationships determined in the experiments provide valuable inputs to plant growth models. The methodology we employed could also be used to study other plant species and to investigate the interactive effects of specific nutrients and lighting conditions.

Integrated nutrient management reduces reliance on chemical fertilizers by combining organic and inorganic inputs. A field experiment was conducted under rainfed conditions in Hungary from 2022 to 2024 to evaluate organic, inorganic and biological fertilizers applied to the high-oleic sunflower hybrid ES Emeric. Seven treatments were compared, namely, an unfertilized control, potassium (K), combined organic and inorganic nitrogen (GOIM), effective microorganisms (EM-1), and the combinations K+GOIM, K+EM-1 and GOIM+EM-1. Seed oil, crude protein and moisture content were determined, together with the fatty acid profile of the oil. Growing season influenced every measured variable far more strongly than fertilization, and all treatment responses were expressed as year-by-treatment interactions. Mean oleic acid content was 69.9% in the dry season of 2022 and 85.3% in 2024, but only 28.9% in the cooler and wetter season of 2023, when linoleic acid reached 59.8%. In 2022, K and K+EM-1 gave the numerically highest oil contents, 48.7% and 48.0%, less than one percentage point above the control, while GOIM+EM-1, GOIM and K+GOIM gave significantly higher protein contents than the remaining treatments. In the same season, EM-1 and K+GOIM raised linoleic and alpha-linolenic acids and, therefore, total polyunsaturated fatty acids, whereas GOIM+EM-1 and K increased oleic acid and total monounsaturated fatty acids. Integrated fertilization can therefore be used to shift the balance between monounsaturated and polyunsaturated fatty acids in sunflower oil, but the size and direction of the shift are governed by the conditions of the growing season.