Wittayathanarattana T.Wanichananan P.Supaibulwatana K.Goto E.Mahidol University2023-06-182023-06-182022-07-01Plant Physiology and Biochemistry Vol.182 (2022) , 202-21509819428https://repository.li.mahidol.ac.th/handle/20.500.14594/83203Baby-leaf vegetables are a trade name for leafy vegetables sold as leaves with petioles at the seedling stage. Amaranth (Amaranthus tricolor L.) is a nutritious baby-leaf vegetable containing many bioactive compounds. The effects of short-term ultraviolet B (UV–B) treatments on the growth and quality of baby leaf amaranth were studied, including the conditions of a 24-h recovery period after irradiation, and different irradiation intensities (3.0–9.0 W m−2), irradiation periods (4–16 h), and cumulative energies (130–170 kJ m−2). A recovery period experiment was conducted to observe the changes in the growth and quality of leaves at 0 and 24 h after UV-B irradiation. The results showed that the concentrations of phenolic compounds, flavonoids, anthocyanin, and ascorbic acid in the leaves, as well as the leaf antioxidant capacity increased 24 h after UV-B irradiation. Increases in target compound concentrations and antioxidant capacity without negative growth and appearance effects were observed in leaves irradiated with UV-B at 3, 6, and 9 W m−2 for irradiation periods of 12 and 16, 8 and 12, and 4 h, respectively. The highest bioactive compound concentration was found in leaves irradiated with UV-B at 6 W m−2 for 7 h (cumulative energy: 150 kJ m−2). It was concluded that UV-B irradiation at 6 W m−2 with a cumulative energy of 150 kJ m−2 and a 24 h post-irradiation recovery period could be an appropriate treatment to increase bioactive compounds in baby leaf amaranth without causing appearance abnormalities.Agricultural and Biological SciencesArticleSCOPUS10.1016/j.plaphy.2022.04.0032-s2.0-85129236341