UV-A (315–400 nm) is a component of solar radiation, which impacts plant physiology. Consequently, the impact was investigated of UV-A supplementation on various aspects of kale cultivation in a plant factory with artificial lighting. Three UV-A intensity treatments (5, 10, or 15 W/m²) were applied to kale plants for 5 days before harvesting. The results revealed that 5 or 10 W/m² UV-A supplementation provided significant advantages for kale growth. The fresh weight of the kale shoots increased by over 35–50% after UV-A exposure. In particular, the 10 W/m² UV-A exposure significantly improved the photosynthetic rate, water-use efficiency, and quantum efficiency of photosystem II (Y(II)). In addition, the treatment with UV-A positively impacted changes in leaf spectral indices, resulting in decreases in the simple ratio index (SR), the normalized phaeophytinization index (NPQI), and the normalized difference red edge index (NDRE). Furthermore, the phytonutrients in kale (Vitamin C, soluble protein, and total phenolics) were enhanced using the 10 W/m² UV-A treatment. One notable outcome was the consistent reduction in nitrate contents across all UV-A treatment intensities. Therefore, supplementing kale cultivation with UV-A radiation was a valuable strategy for enhancing kale yield and quality in plant factory production.

UV-A (315–400 nm) is a component of solar radiation impacting plant physiology. Consequently, the impact was investigated of UV-A supplementation on various aspects of kale cultivation in a plant factory with artificial lighting. Three UV-A intensity treatments (5, 10, or 15 W/m2) were applied to kale plants for 5 days before harvesting. The results revealed that 5 or 10 W/m2 UV-A supplementation provided significant advantages for kale growth. The fresh weight of the kale shoots increased by over 35–50% after UV-A exposure. In particular, the 10 W/m2 UV-A exposure significantly improved the photosynthetic rate, water use efficiency and quantum efficiency of photosystem II (Y(II)). In addition, the treatment with UV-A positively impacted changes in leaf spectral indices, resulting in decreases in the simple ratio index (SR), the nor-malized phaeophytinization index (NPQI), and the normalized difference red edge index (NDRE). Furthermore, the phytonutrients in kale (vitamin C, soluble protein, and total phenolics) were enhanced using the 10 W/m2 UV-A treatment. One notable outcome was the consistent reduction in nitrate contents across all UV-A treatment intensities. Therefore, supplementing kale cultiva-tion with UV-A radiation was a valuable strategy for enhancing kale yield and quality in plant factory production.

Saline water is a significant concern for agricultural productivity. Although the effects of salt stress on food crops have been extensively studied, research on non-food crops, such as orchids, has been limited. This study investigated the impact of salinity on the multiplication of protocorm-like bodies (PLBs) in two Dendrobium cultivars, 'Earsakul' and 'Jindasweet', in which 'Jindasweet' PLBs had already initiated some small shoots, whereas 'Earsakul' PLBs had not. PLBs were cultured under control and salinity conditions (150 mM NaCl). Salinity significantly reduced PLBs multiplication, while increasing electrolyte leakage and photosynthetic pigment content. Salt-treated PLBs also exhibited rougher surfaces, smaller cell sizes and denser tissue, suggesting impaired growth and development. Gene expression after 24 hr of treatment revealed no significant changes in genes related to cell division and development ( CDKA1, TUBB3, EXP and CKX1 ). However, rbcL expression was upregulated in 'Jindasweet'. The expression of LEA was suppressed in 'Earsakul' but not in 'Jindasweet'. 'Jindasweet' PLBs appeared to maintain better multiplication and physiological parameters, supporting the gene expression finding. However, as the two cultivars differed in the stages of PLBs used, the difference in salt tolerance may also be attributed to the developmental stage. These findings highlight the potential of PLBs as an in vitro model for screening salt stress responses. This may provide insight into the mechanisms underlying salt stress in Dendrobium , which could contribute to the development of enhancing salt stress tolerance in orchids, particularly through tissue culture approaches.

Kale is widely recognized as a nutritional superfood. This study investigated the impact of carbon dioxide (CO₂) concentrations (400, 800, and 1200 µmol mol⁻¹) on the growth, yield, physiological responses, and nutritional contents of two kale cultivars (‘Curly Kale’ and ‘Red Ursa’) grown in a plant factory. A completely randomized design was used to evaluate these parameters. Based on the results, increasing the CO₂ concentration to 1200 µmol mol⁻¹ significantly enhanced stem height, shoot, and root fresh weight and dry weight in ‘Curly Kale’ and ‘Red Ursa’, compared to the other CO₂ concentrations. Increasing CO₂ concentration to 1200 µmol mol⁻¹ significantly enhanced net photosynthesis rate, stomatal conductance, transpiration rate, and water use efficiency in ‘Curly Kale’. In addition, compared to ambient CO₂, the increase in the CO₂ concentration to 800 µmol mol⁻¹ significantly increased the vitamin C, soluble protein, and total phenolic contents, while reducing the nitrate accumulation in both cultivars. However, further elevation to 1200 µmol mol⁻¹ CO₂ markedly decreased the vitamin C content and total amino acids, including both the essential and non-essential amino acids. Among the tested concentration gradients, 800 µmol mol⁻¹ CO₂ was identified as the most cost-effective level for maintaining nutrient density, whereas 1200 µmol mol⁻¹ CO₂ increased unit production costs for ‘Red Ursa’ due to a lack of significant yield returns. In conclusion, enriching the CO₂ concentration to 800 µmol mol⁻¹ provided a balance between improved growth, photosynthetic performance, and optimal nutritional quality, while ensuring economic feasibility and preserving the superfood identity of kale.