Improving Spinach, Radish, and Lettuce Growth under Red Light-emitting Diodes (LEDs) with Blue Light Supplementation

Abstract

<jats:p>Radish (<jats:italic>Raphanus sativus</jats:italic> L. cv. Cherriette), lettuce (<jats:italic>Lactuca sativa</jats:italic> L. cv. Waldmann's Green), and spinach (<jats:italic>Spinacea oleracea</jats:italic> L. cv. Nordic IV) plants were grown under 660-nm red light-emitting diodes (LEDs) and were compared at equal photosynthetic photon flux (<jats:italic>PPF</jats:italic>) with either plants grown under cool-white fluorescent lamps (CWF) or red LEDs supplemented with 10% (30 μmol·m<jats:sup>-2</jats:sup>·s<jats:sup>-1</jats:sup>) blue light (400-500 nm) from blue fluorescent (BF) lamps. At 21 days after planting (DAP), leaf photosynthetic rates and stomatal conductance were greater for plants grown under CWF light than for those grown under red LEDs, with or without supplemental blue light. At harvest (21 DAP), total dry-weight accumulation was significantly lower for all species tested when grown under red LEDs alone than when grown under CWF light or red LEDs + 10% BF light. Moreover, total dry weight for radish and spinach was significantly lower under red LEDs + 10% BF than under CWF light, suggesting that addition of blue light to the red LEDs was still insufficient for achieving maximal growth for these crops.</jats:p>

Light signaling and plant responses to blue and UV radiations—Perspectives for applications in horticulture

“…Under blue light alone compared to white light, total chlorophyll (chl) content decreases in some species but is not affected in others (Abidi et al, 2013). Nevertheless, when blue light is present with other wavelengths, chl content tends to increase with the proportion of blue light in plant lighting (Hernández and Kubota, 2014;Hogewoning et al, 2010;Matsuda et al, 2007;Yorio et al, 2001). Independently of species, both monochromatic blue light and higher proportion of blue light in plant lighting tend to increase the chl a/b ratio (Abidi et al, 2013;Hogewoning et al, 2010;Johkan et al, 2010;Kopsell and Sams, 2013;Matsuda et al, 2007;Ohashi-Kaneko et al, 2007;Wang et al, 2014).…”

“…Photosynthetic activity increases proportionally with the level of blue light in plant lighting (Hernández and Kubota, 2014;Hogewoning et al, 2010;Matsuda et al, 2007;Yorio et al, 2001), but only when blue light is present together with other wavelengths. Photosynthetic activity is reduced under blue light alone compared to white light (Abidi et al, 2013;Hogewoning et al, 2010;O'Carrigan et al, 2014), or when blue wavelengths are missing in the light spectrum (Goins et al, 1997;Hogewoning et al, 2010;Matsuda et al, 2007;Yorio et al, 2001).…”

In Vitro Shoot Multiplication and Root Induction in Silk Banana Variety Nanjanagud Rasabale as Influenced by Monochromatic Light Spectra

“…Considering the response obtained during present study, use of blue light for incubation could be explored for potential use in slow growth cultures. However, as the blue light requirement has been observed to be genotype specific in case of potato [23] and species specific in case of lettuce, radish and spinach [24], detailed studies in each species are required to obtain the desired results.…”

“…The light requirement, however, is different for each genus and species, and hence needs to be studied in detail for obtaining the desired response from in vitro cultures [23,24]. Thus, in order to understand the effect of different light spectra on shoot multiplication and induction of rooting in banana, the present investigation was undertaken.…”

Co₂ assimilation and chlorophyll fluorescence in green versus red Berberis thunbergii leaves measured with different quality irradiation

“…The emission wavelength peak of CIRAS-2 LED light was 640 nm with a small peak in the blue radiation at 446 nm, whereas the emission wavelength peak of Handy-PEA RR was at 660 nm. Yorio et al (2001) reported that photosynthesis was not enhanced by supplement of blue radiation in leaves of lettuce under red-LED radiation. Furthermore, due to carotenoid and flavonoid absorption, blue radiation has a lower quantum efficiency of carbon fixation in the visible region (Clark and Lister 1975, Evans 1987, Sun et al 1998.…”