Effects of different artificial light spectra on growth of Lettuce in a continuous light plant factory system

Nowadays plant factory systems have been proposed as a viable alternative to increase productivity per unit area of cultivated land by extending crop production in vertical dimension along with efficient resource consumption, without environmental pollution.
To investigate productivity of lettuce plants in plant factory systems, plants were cultivated in closed three layers vertical cultivation systems where they exposed to continuous lighting of LEDs (light-emitting diode). The LED light wavelengths were in the range of 660 to 680, 420 to 440 nm and 730 to 750 nm for red, blue and far-red lights, respectively.
Plants were grown under three lightning spectra: full red (R), 
75% red and 25% blue (RB), and 50% red, 25% blue and 25% far-red (RBF), provided continuous light with 250 µmol m^‑2 s^‑1 PPFD and 21±1°C. Growing of the plants under continuous light resulted in some necrotic spot on the plant leaves exposed to R and RB treatments.
Highest fresh and dry weights and also leaf area were obtained in full R treatment.
However, Plant under this treatment showed deformed leaves (strong epinasty). RBF treatment resulted in very tall plants with limited number of necrotic spots than the R treatment.

XXX International Horticultural Congress IHC2018: III International Symposium on Innovation and New Technologies in Protected Cultivation

M. Khoramtabrizi, S. Aliniaeifard, Gh. Chegini

continuous light, LED lighting, lettuce, light quality, plant factory

https://doi.org/10.17660/ActaHortic.2020.1271.14