Early-stage Dark Treatment Promotes Hypocotyl Elongation Associated with Varying Effects on Yield and Quality in Sunflower and Arugula Microgreens

Microgreens growing under electric (artificial) lighting in controlled environments often have short hypocotyls, which can be difficult for machine harvest. To investigate whether early-stage dark treatment promote hypocotyl elongation without compromising microgreen yield and quality, two different seed-size species, sunflower (Helianthus annuus ‘Black oil’) arugula (Eruca sativa ‘Rocket’), were tested. Seeds of sown pots, the pots placed inside support trays. During first 5 days after seeding, half per species within each tray covered with an upside-down black as treatment, another kept light. The light was provided by continuous (24-h) a combination red (85%) blue (15%) light-emitting diodes at photosynthetic photo flux density around 100 ?mol·m ?2 ·s ?1 . After covers removed plants grown above till harvesting. microgreens harvested 7 d 12 seeding arugula, respectively. Early-stage promoted 26% 28% Microgreen increased 13% reduced 24% treatment. Dark cotyledon succulence 14% sunflower, but size about 25% despite increases color hypocotyls. For both soluble solids content not affected