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Spatial and Temporal Bioactive Compound Contents and Chlorophyll Fluorescence of Kale ( Brassica oleracea L.) Under UV‐B Exposure Near Harvest Time in Controlled Environments
Author(s) -
Yoon Hyo In,
Kim Damin,
Son Jung Eek
Publication year - 2020
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/php.13237
Subject(s) - brassica oleracea , photosynthesis , chlorophyll fluorescence , chemistry , brassica , horticulture , flavonoid , chlorophyll , dry weight , fluorescence , botany , biology , antioxidant , biochemistry , physics , quantum mechanics
UV‐B irradiation has been used to enhance the secondary metabolite content in plants, but its spatial effect on plants has not been considered. The objective of this study was to compare spatial photosynthetic traits and bioactive compound accumulation in kale ( Brassica oleracea L. var Acephala ) according to the distribution and length of UV‐B exposure near harvest. Plants were exposed to UV‐B of 0–3, 3–6 and 6–9 W m −2 for 4 h per day at 5 days (Exp. 1) and 4.2 W m −2 at 5, 4, 3, 2 or 1 days (Exp. 2) before harvest. In spatial distribution, the higher the UV‐B intensity, the lower the mean F v / F m (maximal photochemical efficiency of PSII) and the higher the concentration of total flavonoid compound (TFC). With UV‐B stress, F v / F m and fluorescence transient parameters decreased except for DI 0 /CS (dissipated energy flux per cross section) and PI abs (performance index of PSII). When exposed to UV‐B radiation for 2 days before harvest, the total phenolic compounds and TFC per plant were highest, not always proportional to the local F v / F m but affected by dry weight. Short‐term UV‐B stress near harvest would be more efficient for the accumulation of bioactive compounds by minimizing the loss of plant weight.