ABSTRACT
Red light in addition to white light improve commercial characteristics and yield of purple cabbage microgreens

Arthur Bernardes Cecílio Filho1*, Maria José Yañez Medelo1, Wellington Missiano Pindobera1, Thatiane Nepomuceno Alves1, Laura Matos Ribera1, Rogério Falleiros Carvalho2, Lucas Natan Camacho da Silva1, Manuela Oliveira de Souza3, and Luis Felipe Villani Purquerio4
 
White light has been used in plant factories due to its broad light spectrum, which has positive effects on photosynthesis and photomorphogenesis, lower LED costs, and greater comfort for workers’ eyes. However, it is also known that higher proportions of red light can have a positive effect on growth and, consequently, productivity. So, an experiment was carried out in plant factory conditions with the hypothesis that the addition of low-intensity red to white light can increase yield of the purple cabbage (Brassica oleracea L. var. capitata L.) microgreens. The experimental design was completely randomized, in a 2 × 3 + 1 factorial scheme, where the photosynthetic photon flux density (PPFD, 20 and 40 μmol m-2 s-1) and photoperiod (12, 16, 20 h d-1) of red light were evaluated in addition to white light at 250 μmol m-2 s-1 and 20 h (control treatment). Red light did not affect hypocotyl length, but photoperiod and PPFD affected cotyledon area and yield of microgreens separately. Photoperiod 16 h d-1 provided greater cotyledon area (+10.0%) and yield (+17.9%) than 12 h d-1 and did not differ from 20 h d-1. Compared to microgreens that received only white light (control treatment), red light promoted 22.7% higher cotyledon area and microgreens irradiated with 40 μmol m-2 s-1 had greater cotyledon area (+7.0%) than those under 20 μmol m-2 s-1, but without increasing yield. Therefore, it is recommended to grow purple cabbage microgreens with the addition of 20 μmol m-2 s-1 and 16 h d-1 red LED to white light (250 μmol m-2 s-1 and 20 h d-1).
Keywords: Brassica oleracea var. capitata, functional food, light spectrum, plant factory, urban farm.
1Universidade Estadual Paulista (Unesp), Departamento Producao Vegetal, Jaboticabal, Brazil.
2Universidade Estadual Paulista (Unesp), Departamento de Biologia, Jaboticabal, Brazil.
3Universidade Federal do Reconcavo da Bahia (UFRB), Centro de Ciencias Exatas e Tecnologicas, Cruz das Almas, Brazil.
4Instituto Agronomico de Campinas, Campinas, Brazil.
*Corresponding author (arthur.cecilio@unesp.br)