Growth and morphological responses of gerbera seedlings to narrow-band lights with different light spectral combinations as sole-source lighting in a controlled environment

Abstract

To optimize light-emitting diode (LED) spectral recipes for gerbera (Gerbera jamesonii) seedling propagation, seed germination and seedling morphology, biomass, flowering, and storage quality were observed in four cultivars, ‘Midi Dark Purple’, ‘Majorette Red Dark Eye’, ‘Maxi Pink’, and ‘Maxi White’, under six spectrum treatments: (1) FL, cool white fluorescent light; (2) RB, a photon flux ratio of 85% red and 15% blue (RB-LED); (3) RB + UVB, RB-LED combined with 0.5 μmol·m−2·s−1 of ultraviolet-B; (4) RB + UVA, RB-LED combined with 9.6 μmol·m−2·s−1 of ultraviolet-A; (5) RB + G, a photon flux ratio of 60% red, 15% blue, and 25% green; (6) RB + FR, RB-LED combined with 17.3 μmol·m−2·s−1 of far-red. For all treatments, the photosynthetic photon flux density was 165 μmol·m−2·s−1 under a 16-h photoperiod. Seedling growth and morphology were similar under FL and RB for all cultivars, except for a wider canopy of ‘Majorette Red Dark Eye’ under RB. Each of the tri-chromatic light treatments (i.e., RB + UVB, RB + UVA, RB + G or RB + FR) showed similar effects as RB, except for thicker ‘Maxi Pink’ stems under RB + FR. Furthermore, the quality index, an integrated evaluation of seedling quality, was similar under all the treatments for each cultivar. Given the similar seedling quality and the advantages of LEDs, RB-LED can potentially replace FL for controlled-environment gerbera seedling production, but the tri-chromatic lights tested in this study appear to be unnecessary.

Diverse Flowering Response to Blue Light Manipulation: Application of Electric Lighting in Controlled-Environment Plant Production

“…Differently, the addition of FR at ≥20 µmol m −2 s −1 to RB-LED accelerated the flowering of at least some long-day plants such as snapdragons, but did not affect the flowering of day-neutral or short-day plants [61]. However, in our recent study on gerbera transplants under sole-source lighting, when adding low-level UVB, UVA, green, or far-red light to RB-LED (15% B) and keeping the same total PPFD for all treatments, the flowering time after transplanting was not different among the different lighting treatments [63]. When the low levels of other light wavelengths were added to RB-LED, and the phytochrome activity was changed little (with the PPS values varying 0.84−0.88).…”

Magic Blue Light: A Versatile Mediator of Plant Elongation

“…Sole-source lighting with RB-LEDs is commonly used for indoor transplant production. A recent study in our lab indicated that RB-LEDs (15%B) can potentially replace fluorescent light, but the trichromatic lights appear to be unnecessary for the indoor production of compact gerbera transplants [ 137 ]. Compared with red or blue LEDs alone, RB-LEDs (50%B) caused more compact seedlings in bedding plants such as impatiens, petunias, and salvia [ 57 ].…”