Table 1.
Total (PFD) and photosynthetic (PPFD) photon flux densities (μmol m– 2 s– 1) and UV-A irradiance (W m– 2), at the crop level produced by LEDs with different peak emission wavelengths.
| Experiments | Supplemental UV-A radiation PFD, μmol m–2 s–1/W m–2 |
Standard irradiance* PFD, μmol m–2 s–1 |
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|---|---|---|---|---|---|---|---|---|---|---|
| PPFD | ||||||||||
| Photoperiod of UV-A (from–to, h) | UV-A 366 nm |
UV-A 390 nm |
UV-A 402 nm |
B 447 nm |
R 638 nm |
DR 665 nm | FR 731 nm | Total PPFD | Total PFD | |
| EXP 1 | 10 h (8 a.m.–6 p.m.) |
12.4/4.0 | 12.4/3.8 | 12.4/3.7 | 21 | 122 | 155 | 2.2 | 298 | 300 |
| EXP 2 | 16 h (6 a.m.–22 p.m.) |
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*Photoperiod of standard irradiance—16 h. EXP, experiment; UV-A, ultraviolet A; B, blue; R, red; DR, deep-red; FR, far-red; PPFD, photosynthetic photon flux density (400–700 nm); PFD, photon flux density of plant photomorphogenetic response wavelength range (300–800 nm).