Abstract

This study determined the optimal ultraviolet (UV)-B dose of major vegetable seedlings in a plant factory with artificial light for labor saving. Four vegetable seedlings, cucumber, watermelon, tomato, and pepper, were used as test crops. UV-B irradiation was conducted at four different UV-B doses of 1.08, 2.16, 3.24, and 4.32 kJ·m⁻² d⁻¹ for 3 h a day for 3 days after graft-take and temporary planting of fruit vegetable seedlings. After UV-B irradiation, seedlings were moved to a greenhouse and exposed to ultraviolet rays of sunlight; growth was observed; and chlorophyll fluorescence was measured. When subjected to UV-B irradiation, minimal changes in external traits of fruit vegetable seedlings were observed at doses below 2.16 kJ·m⁻²·d⁻¹, while at higher intensities, issues such as chlorosis emerged. When UV-B was irradiated at 4.32 kJ·m⁻²·d⁻¹, cucumber exhibited a decrease in hypocotyl length by 6.4 cm, and watermelon by 1.7 cm compared with the control. Additionally, cucumber and watermelon both showed a decrease in leaf area by 75.6 cm² and 49.8 cm², respectively, indicating a tendency of growth inhibition. For tomatoes and peppers, when UV-B was irradiated at 1.08 kJ·m⁻²·d⁻¹, they exhibited an improvement in compactness by 5 and 2.5 mg·cm⁻¹, respectively, compared with the control. Chlorophyll fluorescence parameters indicated a positive correlation between ABS/RC and DI_O/RC with increasing UV-B doses, while F_V/F_M and PI_ABS showed a negative correlation. Using UV-B during the seedling acclimation period, seedlings can adapt to external UV radiation, thereby suppressing excessive growth and promoting the production of robust seedlings. Moreover, the utilization of UV-B within a plant factory allows for conducting the acclimation process within the facility, reducing the need for seedlings to be transported to conventional nurseries and offering potential benefits in terms of operational efficiency.

中文翻译：

---

人造光植物工厂果蔬幼苗的紫外线B照射驯化和硬度增强

摘要

本研究确定了采用人造光的植物工厂中主要蔬菜幼苗的最佳紫外线 (UV)-B 剂量，以节省劳动力。黄瓜、西瓜、番茄和辣椒四种蔬菜幼苗被用作试验作物。在果菜幼苗嫁接和临时种植后，以1.08、2.16、3.24和4.32 kJ·m ^-2 d ^{-1四种不同的UV-B剂量进行UV-B照射，持续3 ha day，持续3天。}UV-B照射后，将幼苗移至温室，暴露于太阳光的紫外线下；观察到生长；并测量叶绿素荧光。^{当接受UV-B照射时，在低于2.16 kJ·m -2} ·d ^-1的剂量下观察到果菜幼苗外部性状的微小变化，而在较高强度下，出现了诸如缺绿等问题。当UV-B以4.32kJ·m ^-2 ·d ^-1照射时，与对照相比，黄瓜的下胚轴长度减少了6.4cm，西瓜的下胚轴长度减少了1.7cm。此外，黄瓜和西瓜的叶面积分别减少了75.6 cm ²和49.8 cm ²，表明有生长抑制的趋势。对于西红柿和辣椒，当UV-B以1.08kJ·m ^-2 ·d ^-1照射时，与对照相比，它们的致密性分别提高了5和2.5mg·cm ^{-1 。}_{叶绿素荧光参数表明ABS/RC和DI O} /RC随着UV-B剂量的增加呈正相关，而F _V /F _M和PI _ABS则呈负相关。在幼苗驯化期使用UV-B，可以使幼苗适应外界紫外线辐射，从而抑制过度生长，促进健壮苗的产生。此外，在植物工厂内使用 UV-B 可以在设施内进行驯化过程，减少将幼苗运输到传统苗圃的需要，并在运营效率方面提供潜在的好处。