Table 2.
Phenolic compound concentration of ‘Levistro’ lettuce plants grown hydroponically under ambient light enriched with different LED light spectra.
| Treatments | DLI 1 | PAR 2 | Caftaric Acid | Chlorogenic Acid | Caffeoylmalic Acid | Chicoric Acid | Quercetin-3-O-glucoside | Quercetin-3-O-glucuronide | Total Quercetin | Luteolin-7-O-glucoside | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Light | Spectrum | R:B Ratio 3 | mol m−2 day−1 | µmoles m−2 s−1 | mg g−1 Dried Weight | |||||||
| Blue (B) | 47:22:21:10 | 0.5:1 | 9.4 ± 1.1 | 331 ± 26 | 0.3 ± 0.0 c 4 | 6.1 ± 0.6 a | 0.5 ± 0.1 a | 5.9 ± 0.2 ab | 0.8 ± 0.2 ab | 1.8 ± 0.3 ab | 2.5 ± 0.4 ab | 0.4 ± 0.1 c |
| White (W) | 30:38:23:9 | 0.8:1 | 9.1 ± 1.0 | 330 ± 25 | 0.3 ± 0.0 c | 4.7 ± 0.4 b | 0.5 ± 0.1 a | 5.7 ± 0.3 b | 0.6 ± 0.2 bc | 1.6 ± 0.3 ab | 2.3 ± 0.2 ab | 0.7 ± 0.1 b |
| Blue-Red (BR) | 33:15:44:8 | 1.3:1 | 9.5 ± 1.1 | 336 ± 20 | 0.3 ± 0.0 c | 6.1 ± 0.4 a | 0.5 ± 0.1 a | 6.3 ± 0.6 a | 0.6 ± 0.2 bc | 1.6 ± 0.3 ab | 2.2 ± 0.3 ab | 0.6 ± 0.1 b |
| Red (R) | 16:16:60:8 | 3.8:1 | 9.6 ± 1.1 | 328 ± 24 | 0.4 ± 0.0 a | 5.1 ± 0.4 b | 0.6 ± 0.0 a | 5.3 ± 0.5 b | 0.5 ± 0.1 c | 1.4 ± 0.4 b | 1.9 ± 0.5 b | 0.4 ± 0.1 c |
| Control 5 | 25:30:31:14 | 1.2:1 | 16.9 ± 1.9 | 702 ± 126 | 0.4 ± 0.0 bc | 4.5 ± 0.3 b | 0.5 ± 0.0 a | 5.6 ± 0.4 b | 1.0 ± 0.2 a | 1.9 ± 0.2 a | 3.0 ± 0.2 a | 1.0 ± 0.1 a |
1 Daily light integral; 2 photosynthetically active radiation measured at midday; 3 red:blue ratio; 4 different letters in the same column indicate significant differences using Tukey’s test (p ≤ 0.05). Mean (n = 3) ± SE; 5 ambient light.