Blue light and ultraviolet (UV) light have been shown to influence plant growth, morphology, and quality. This study investigates the effects of pre-harvest supplemental lighting using UV-A and blue (UV-A/Blue) light and red and blue (RB) light on the growth and nutritional quality of lettuce grown hydroponically in two greenhouse experiments.
The RB spectrum was applied pre-harvest for two days or nights, while the UV-A/Blue spectrum was applied pre-harvest for two or four days or nights. All pre-harvest supplemental lighting treatments had the same duration of 12 h with a photon flux density (PFD) of 171 μmol m−2 s−1.
Results of both experiments showed that pre-harvest supplemental lighting using UV A/Blue or RB light can increase the growth and nutritional quality of lettuce grown hydroponically. The enhancement of lettuce growth and nutritional quality by the pre-harvest supplemental lighting was more effective under low daily light integral (DLI) compared to a high DLI and tended to be more effective when applied during the night, regardless of the spectrum.
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Hooks, Triston & Masabni, Joseph & Sun, Ling & Niu, Genhua. (2021). Effect of Pre-Harvest Supplemental UV-A/Blue and Red/Blue LED Lighting on Lettuce Growth and Nutritional Quality. Horticulturae. 7. 80. 10.3390/horticulturae7040080.