Nitrate is a major source of the inorganic nitrogen taken up by the roots of plants. Nitrate sources are generally derived from inorganic minerals by an energy-consuming chemical process; as a result, the price of chemical fertilizers is gradually increasing year by year. NO₃-N, generated from N₂ using the plasma technique, is an alternative method of producing nitrate from the air. Therefore, in this research, we aimed to determine the efficiency of generating NO₃-N using plasma-activated water (PAW) to replace nitrates from chemical fertilizer in a nutrient solution. Green oak lettuce (Lactuca sativa L.) was grown in a hydroponics system using the double-pot technique. The plants were supplied with three different nutrient solutions (based on Hoagland’s solution), i.e., T1, no nitrate in the nutrient solution (NO₃⁻ = 0); T2, using nitrate sourced from a commercial chemical fertilizer (normal nitrate); and T3, using a nitrate source generated using the pinhole plasma jet technique (plasma nitrate). The other macronutrients and micronutrients in each treatment were equally supplied. The results show that, at the harvested stage (21 days after the plants received treatment), the no-nitrate (T1) treatment provided lower growth and yields. Moreover, compared with the normal nitrate (T2) and plasma nitrate (T3), the results indicate that most growth and yields showed no statistical differences. In terms of nitrate accumulation within plants, it was found that the normal nitrate treatment (T2) had the highest levels of nitrate accumulation, in both the underground and aboveground parts of green oak lettuce. These results confirmed that plasma nitrate could be an alternative source of nitrate N which provided a safer way for the environment and human health in terms of nitrate accumulation. In addition, data related to the chemical analysis of free amino acid concentrations in each treatment are discussed in this research.

This study examines the effects of different LED light spectra and intensities on the growth, photosynthetic performance, and biochemical composition of the ‘Daruma’ cultivar of wasabi (Eutrema japonicum). The primary objective is to enhance the efficiency of indoor cultivation techniques for this economically significant crop. Wasabi seedlings were cultivated under LED lighting with four light intensities (35, 60, 90, and 140 µmol m⁻² s⁻¹) and three spectral combinations: red and white (1:1); red, white, and blue (1:1:1); and white. Growth parameters, including plant height, petiole length, leaf number, and yield metrics such as fresh weight and leaf area, were measured alongside photosynthetic activity and chemical analysis of glucosinolate levels. The results indicate that higher light intensities (particularly 140 µmol m⁻² s⁻¹) greatly enhance overall plant biomass, with red-dominant spectra promoting more significant growth and glucosinolate accumulation, a key secondary metabolite in wasabi. Lower intensities increased chlorophyll content and produced darker green foliage but decreased growth performance. Additionally, the interaction of red and blue light spectra with increased light intensity suggests that specific red light conditions are optimal for maximizing wasabi biomass and biochemical yield. These findings contribute valuable insights for optimizing light regimes for wasabi and similar shade-adapted crops in controlled indoor farming systems, potentially improving yield and quality in plant factories and supporting the future of indoor farming.

Nitrogen (N) is an essential determinant of strawberry growth and productivity. However, plants exhibit varying preferences for sources of nitrogen, which ultimately affects its use efficiency. Thus, it is imperative to determine the preferred N source for the optimization of indoor strawberry production. This study employed the ¹⁵N-tracer technique to investigate the effects of N sources on N uptake, distribution, and use efficiency, as well as the plants’ growth, for ‘Praratchatan 80’ strawberries in a greenhouse. Five treatments were applied: T1 (5.0 mM ¹⁵NO₃⁻), T2 (2.5 mM ¹⁵NO₃⁻ + 2.5 mM NH₄⁺), T3 (5.0 mM ¹⁵NH₄⁺), T4 (2.5 mM ¹⁵NH₄⁺ + 2.5 mM NO₃⁻), and T5 (N-free, control) in a completely randomized design. Significant (p < 0.05) differences were observed in N uptake and distribution and total N concentration among the treatments. Sole NH₄⁺ promoted early N uptake and accelerated flowering, while NO₃⁻ enhanced vegetative growth and later-stage nitrogen use efficiency (NUE). The application of combined NO₃⁻ and NH₄⁺ was most efficacious, balancing the benefits of both N forms. NO₃⁻ treatment enhanced ¹⁵NUE by 46% compared to NH₄⁺, and mixed N sources demonstrated superior and consistent ¹⁵NUE over time. NH₄⁺, alone or with NO₃⁻, expedited flowering by 20 days compared to sole NO₃⁻ and N-free treatments. This study elucidates the importance of the sources of N in optimizing strawberry growth and flowering, providing a foundation for developing tailored N-management strategies. Future research should focus on refining mixed N application ratios and timings, exploring molecular mechanisms of N metabolism, and evaluating long-term impacts on strawberry production sustainability.

Growing Hippeastrum in an open field or a greenhouse requires precision irrigation and fertilizer to promote plant growth and development. Therefore, this research aimed to study the effect of irrigation level combined with fertilization rate on the growth and development of Hippeastrum. Two experiments were carried out to determine the influence of irrigation and fertilizer on the growth, flowering, and bulb quality of Hippeastrum. In the first experiment, bulbs of Hippeastrum ‘Red Lion’ with circumferences of 25 cm were grown in plastic plots using mixed soil as growing media under a 50% shading net. Plants were irrigated daily until drainage and water contained in macropores by gravity action (Field capacity: FC) for 90 days after planting (DAP) and supplied with three different 15N-15P₂O₅-15K₂O fertilization rates, i.e., 0, 2.5, and 5 g per pot. Plant growth and water use efficiency were measured at 45, 60, and 90 DAP. The results showed that plants supplied with 0 g of fertilizer had the lowest plant height and number of leaves per plant at 90 DAP, whereas there was no significant effect of fertilizer rate treatments on flower quality. The water use efficiency, evapotranspiration rate (ET), crop evapotranspiration under standard condition (ETc), crop coefficient (Kc), photosynthetic rate, and stomatal conductance were decreased when plants were supplied with fertilizer at a rate of 0 g per pot at 90 DAP. In the second experiment, plants were irrigated with four levels, i.e., 100, 75, 50, and 25% ETc combined with three fertilization rates, i.e., 0, 2.5, and 5 g per pot. At 180 DAP, the results showed that water deficit treatment (50 and 25% ETc) decreased plant growth and bulb quality. Irrigation with 100% ETc combined with 2.5 or 5 g per pot and irrigation with 75% ETc combined with 5 g per pot were the optimum levels to promote plant growth and bulb quality in Hippeastrum.