Table 3.
LED effects on the polyphenol content of different plants. Blue light (BL), red light (RL), green light (GL), yellow light (YL), white light (WL), blue-violet light (BVL), fluorescent light (FL), white fluorescent light (WFL), high-pressure sodium light (HPS), ultraviolet B radiation (UV-B), ultraviolet A radiation (UV-A), white, blue, and green light combination (WBG), total phenolic compounds (TPC), total flavonoid compounds (TFC).
| Plant Species | LED (Wavelength, Intensity), Photoperiod, and Experimental Parameters | Type of Application | Effect | Reference |
|---|---|---|---|---|
| Broccoli (Brassica oleracea L. Var. Italica) | BL (467 nm, 21 µmol m−2·s−1), GL (522 nm,24 µmol m−2·s−1), YL (587 nm, 27 µmol m−2·s−1) RL (625 nm, 66 µmol m−2·s−1) WL (3000 K color temperature, 40 µmol m−2·s−1); continuous irradiation at 4 °C | Postharvest | RL > YL > BL increased the TPC throughout the storage period | [56] |
| Brussels sprouts (Brassica oleracea var. gemmifera) | UV-B (300 nm, 0.02 µmol m−2·s−1), UV-A (365 nm, 14 µmol m−2·s−1), BL (470 nm, 11 µmol m−2·s−1), RL (660 nm, 2 µmol m−2·s−1); 16-h photoperiod | Sprouting | Compound specific effects | [91] |
| Buckwheat sprouts (Fagopyrum esculentum Moench) | BL (460nm), RL (625nm), FL (35 µmol m−2·s−1); 16 h of light; supplement and 8 h of dark per day | Sprouting | BL > RL > FL increasedTPC, TFC, and antioxidant capacity using ABTS radical cation assay. BL increased orientin, isoorientin, vitexin, isovitexin, rutin, and quercetin-3-O-robinobioside | [92] |
| Basil (Ocimum basilicum), arugula (Eruca sativa), and bloody dock (Rumex sanguineus) | BL (450 nm, 300 µmol m−2·s−1), BVL (440–420 nm, 300 µmol m−2·s−1), HPS (600nm, 400 W); | Growth | BL and BVL increased the phenolic acid content in basil, BV the flavonoids in arugula. No increase was registered in bloody dock with either BL or BV | [93] |
| Cherry tomato seedlings (Solanum lycopersicum L. ‘Cuty’) | RL (655 nm, 200 µmol m−2·s−1), BL (456 nm, 200 µmol m−2·s−1), GL (518 nm, 200 µmol m−2·s−1), WL (456 nm, 200 µmol m−2·s−1) | Growth | BL > WL > RL > GL increased the TPC and TFC | [94] |
| Tea (Camellia sinensis cv. Fujian Shuixian) | BL (450nm) at low (50 µmol m−2·s−1) medium (100 µmol m−2·s−1) and high (200 µmol m−2·s−1) intensity, WL (100 µmol m−2·s−1); 12-h photoperiod, 14 days | Growth | High-intensity BL down-regulated several genes involved in flavonoid biosynthesis; no effects elicited by low- and medium-intensity BL. BL increased the levels of 3′,5,6-trihydroxy-3,4′,7,8-tetramethoxyflavone 3-glucoside, galangin 3-[galactosyl-(1-4)-rhamnoside], and neocarthamin, and reduced the levels of 3-(2-caffeoylsophoroside) 7-glucoside, quercetin 3-(4‘-acetylrhamnoside) 7-rhamnoside, and spinacetin 3-(2‘- feruloylgentiobioside | [95] |
| Navel oranges (Citrus sinensis Osbeck) | UVC (10–280 nm, 100 µmol m−2·s−1), UVB (270–315 nm, 100 µmol m−2·s−1), UVA (315–400 nm, 100 µmol m−2·s−1), BL (470 nm, 200 µmol m−2·s−1), RL (660 nm, 150 µmol m−2·s−1), WL (100 µmol m−2·s−1); Continuous irradiation for 6 days; sampling after 0, 6, and 15 days | Postharvest | BL and RL retained more PC during the irradiation period, while WL, UVB, and UVC stimulated their accumulation after the irradiation period. RL and BL maintained the levels of diosmin, diosmetin 6,8-di-C-glucoside, hesperidin, didymin, neoeriocitrin, and narirutin; all Uvs increased narirutin, neoeriocitrin, and didymin | [98] |
| Sweet pepper (Capsicum annuum L cv. California Wonder, King of the North, Citrine F1 Hybrid) | RL (660 nm, 150 µmol m−2·s−1) BL (450 nm, 100 µmol m−2·s−1); 8-h photoperiod | Postharvest | RLwas more effective than BL in increasing the TFC, and PAL activity | [101] |
| Okra (Abelmoschus esculentus L.) | RL (630 nm, 17.28 W/m2), BL (470 nm, 17.28 W/m2), GL (560 nm, 17.28 W/m2); 8-h photoperiod | Postharvest | WL and BL increased the TFC content and the activity of key enzymes involved in the biosynthesis of phenolics | [102] |
| Bananas (Musa acuminata cv. Berangan) | BL (464–474 nm, 3920 µmol m−2·s−1), GL (515–525 nm, 4340 µmol m−2·s−1) equivalent to photosynthetic intensity of 100 W m−2, RL (617–627 nm, 5200 µmol m−2·s−1); continuous irradiation for 8 days | Postharvest | BL was more effective than RL and GL in increasing in TPC | [107] |
| Broccoli (Brassica oleracea L. Var. Italica cv. Chaoda No. 1) | WFL (300–700nm, (12–13 µmol m−2·s−1), GL (520 nm, 12–13 µmol m−2·s−1); 12-h photoperiod | Postharvest | GL increased the TPC | [108] |
| Red leaf lettuce (Lactuca sativa L., cv. Sunmang) and green leaf lettuce (Lactuca sativa L., cv. Grand Rapid TBR) | Various combinations of BL (456 nm) and RL (655 nm) BL: RL = 0:100%, 13%:87%, 26%:74%, 35%:65%, 47%:53%, 59%:41%, (171 µmol m−2·s−1), 12-h photoperiod | Postharvest | Intermediate BL/RL ratios (35%:65% > 47%:53% > 59%:41% in cv. Sunmang) stimulated the accumulation of TPC | [110] |
| Pea sprouts (Pisum sativum L.) | RL (635 nm), BL (460 nm), YL (585 nm), WL (30 µmol m−2·s−1); 12-h photoperiod | Sprouting | BL was more effective than WL, RL, and YL in increasingd the TPC and TFC with respect to the dark. BL increased the content of chlorogenic acid, p-hydroxybenzoic acid, caffeic acid, gallic acid, p-coumaric acid, ferulic acid, rutin, and resveratrol; WL increased the content of chlorogenic acid, p-hydroxybenzoic acid, caffeic acid, gallic acid, ferulic acid, rutin, and resveratrol; RL increased the content of p-hydroxybenzoic acid, caffeic acid, p-coumaric acid, ferulic acid, and rutin; YL increased p-hydroxybenzoic acid, caffeic acid, gallic acid, p-coumaric acid, ferulic acid, rutin, and resveratrol. | [112] |
| Canola sprouts (Brassica napus L.) | WL (380 nm, 50 µmol m−2·s−1), BL (470 nm, 50 µmol m−2·s−1), RL (660 nm, 50 µmol m−2·s−1), BL + RL; 16-h photoperiod | Sprouting | BL was more effective than WL, BL + RL, and RL in increasing the content of phenolic acids, flavonoids, and catechin. BL increased the content of benzoic acid, (+)-catechin, caffeic acid, and (−)-epicatechin; WL increased the contents of rutin. | [113] |
| Lettuce (Lactuca sativa L. Cv. ‘Grizzly’ | WL (380–760 nm, 300 µmol m−2·s−1), RL (650–665 nm, 300 µmol m−2·s−1), BL (460–475 nm, 300 µmol m−2·s−1) or RL + BL (70%:30%), 14-h photoperiod | Growth | WL > BL increased the TPC | [96] |
| Longan (Dimocarpus longan Lour.) | BL (457 nm, 32 µmol m−2·s−1), GL (515 nm, 32 µmol m−2·s−1), WL 32 µmol m−2·s−1), and RL (660 nm, 32 µmol m−2·s−1) 12-h photoperiod; different BL intensities (16, 32,64, 128, and 256 µmol m−2·s−1), 12-h photoperiod; BL at 32 µmol m-2·s-1 with different photoperiods: 8, 12, 16, 20, and 24 h | Growth | BL was more effective than GL and WL in increasing the TFC; 32 µmol m−2·s−1 was the most effective intensity to increase the TFC; 12-h photoperiod was the most effective in increasing TFC; BL promoted the accumulation of epicatechin, but inhibitedthe synthesis of rutin. | [99] |
| Sarcandra Herb (Sarcandra glabra) | WL (380–760 nm, 80 µmol m−2·s−1), RL, 656 nm, 80 µmol m−2·s−1), BL, 450 nm80 µmol m−2·s−1); 16-h photoperiod | Growth | BL increased the levels of cinnamic acid, 4-coumaric acid, chalcone, naringenin quercitin,kaempferol, and rutin, while it reduced the caffeic acid content. BL increased the expression of of key enzymes involved in the biosynthesis of phenolics (PAL, FLS) | [97] |
| Van’sweet cherry (Prunus avium L.) | UV-B (310nm, 0.046 W m−2), BL (444 nm, 1 W m−2), WBG composed by BL (470nm), GL (520 nm) and WL with a total 3.6 radiant flux W m2 | Postharvest | BL increased the content of cyanidin 3-O-glucoside, cyanidin 3-O-rutinoside; BL was more effective than WBG in increasing PAL activity | [100] |