Table 1.
Characteristics of light regimens.
| Parameters | Light regimens |
|||||
|---|---|---|---|---|---|---|
| Fluorescent white | LED Pink | LED Blue | LED RedFR | LED RedLL | LED RedHL | |
| PPFD (400–700 nm) (μmol m-2 s-1) | 249 | 248 | 250 | 253 | 253 | 499 |
| PPF (400–750 nm) (μW/cm2) | 5855 | 5700 | 5917 | 5322 | 5252 | 10007 |
| Blue (400–500 nm) | 1451 | 2215 | 4402 | 657 | 653 | 1274 |
| Green (500–600 nm) | 2280 | 690 | 23 | 1020 | 1022 | 2036 |
| Red (600–700 nm) | 1841 | 2443 | 1490 | 3346 | 3437 | 6424 |
| Far-red (>700 nm) | 283 | 352 | 2.4 | 299 | 140 | 273 |
| Fraction (%) | ||||||
| Blue | 24.8 | 38.8 | 74.1 | 12.3 | 12.4 | 12.7 |
| Green | 38.9 | 12.1 | 0.4 | 19.2 | 19.5 | 20.3 |
| Red | 31.4 | 42.8 | 25.1 | 62.9 | 65.4 | 64.2 |
| Far-red | 4.8 | 6.2 | 0.4 | 5.6 | 2.7 | 2.7 |
| Ratios | ||||||
| Blue: Red | 0.8 | 0.9 | 3.0 | 0.2 | 0.2 | 0.2 |
| Red: far-red | 6.5 | 6.9 | 59.6 | 11 | 25 | 24 |
| Blue: far-red | 5.1 | 6.3 | 176 | 2.2 | 4.7 | 4.7 |
| Energy consumption (kW) | 4.69 | 1.24 | 1.42 | 1.09 | 1.02 | 2.09 |
The Fluorescent white refers to a white light regimen provided by fluorescent lamps. The Pink regimen utilized LEDs with an equal blue and red ratio. In the Blue LED regimen, the blue light was dominant and in the RedLL and RedHL regimens red light was dominant at 250 μmol m-2 s-1 and 500 μmol m-2 s-1 light intensities, respectively. In the RedFR regimen red light was complemented with far-red light. The total Photosynthetic Photon Flux Density (PPFD) was determined with a Li-Cor quantum meter (Li-189, LI-COR, Inc., Lincoln, NE, United States). The spectral energy distribution was determined by a spectroradiometer (UBS4000, Ocean Optics Inc., United States) and the wavelength ratio was calculated with the assumption that blue light ranged between 400 and 500 nm, green light between 500–600 nm, red light between 600–700 nm and far-red between 700–750 nm bandwidth integration. The energy consumption was calculated for the whole chamber with the same illuminated area using a C.A 8230 power and quality analyzer (Chauvin Arnoux Ltd, Dewsbury, United Kingdom).