Affiliation:
1. Centre de Recherche et d’Innovation sur les Végétaux (CRIV), Département de Phytologie, Université Laval, Québec, QC G1V 0A6, Canada
2. Centre de Recherche et d’Innovation sur les Végétaux (CRIV), Département des Sols et de Génie Agroalimentaire, Université Laval, Québec, QC G1V 0A6, Canada
Abstract
Vertical farming is experiencing significant growth, and the optimization of artificial lighting is essential for enhancing the sustainability of this growing system. Therefore, the aim of this study was to examine how light segmentation, the incorporation of a low-intensity lighting phase known as the light compensation point (LCP) instead of the traditional dark phase, and variations in the light spectrum impact the agricultural outcomes of organically cultivated leafy greens. In controlled growth chamber environments, a variety of leafy plant species (Spinacia oleracea L., Ocimum basilicum, Beta vulgaris L., Lactuca sativa L. cv. ‘Garrison’ and ‘Blade’, Brassica rapa cv. ‘Japonica’ and ‘Chinensis’, Brassica juncea cv. ‘Scarlet Frills’ and ‘Wasabina’, Eruca sativa and Perilla frutescens L.) were subjected to four light treatments with varying intensities and durations of lighting, while in a second experiment, five different spectral growing conditions were compared. Irrespective of the plant species, shortening the length of the diel cycle by extending the cumulative daily lighting to 20–24 h per day (5L/1N [5 h at 261 µmol m−2 s−1 + 1 h darkness for a total of 20 h of light per day] and 5L/1LCP [5 h at 256 µmol m−2 s−1 + 1 h LCP at 20 µmol m−2 s−1 for a total of 24 h of light per day]) led to an average increase of +12% in height, fresh weight (+16%), dry weight (+23%), and specific leaf weight (+11%), compared to the control plants (18L/6N; 18 h at 289 µmol m−2 s−1 + 6 h darkness) and 6L/6LCP plants (6 h at 418 µmol m−2 s−1 + 6 h LCP at 20 µmol m−2 s−1 for a total of 24 h of light per day) during the first harvest. This also resulted in better light utilization, expressed as increased fresh (+16%) and dry (+24%) biomass per mol of light received. Conversely, the studied light spectral treatments had no effect on the growth parameters of the four selected species. In conclusion, our study showed that reducing light intensity while extending the photoperiod could potentially represent a cost-effective LED strategy for the indoor cultivation of organically or conventionally grown leafy greens.
Funder
Organic Science Cluster 3 on organic farming from Agriculture and Agri-Food Canada in partnership
L’Abri végétal, PremierTech
Inno-3B
Subject
Agronomy and Crop Science
Reference49 articles.
1. Plant production in a closed plant factory with artificial lighting;Goto;Acta Hortic.,2012
2. Photosynthetic characteristics and growth performance of lettuce (Lactuca sativa L.) under different light/dark cycles in mini plant factories;Zhou;Photosynthetica,2020
3. Light intensity and photoperiod influence the growth and development of hydroponically grown leaf lettuce in a closed-type plant factory system. Horticulture Environment;Kang;Biotechnology,2013
4. Kozai, T., Niu, G., and Takagaki, M. (2020). Chapter 9—Plant Responses to Light, Dans: Plant Factory an Indoor—Vertical Farming System for Efficient Quality Food Production, Academic Press. [2nd ed.].
5. Optimal light intensity for sustainable water and energy use in indoor cultivation of lettuce and basil under red and blue LEDs;Pennisi;Sci. Hortic.,2020