Horticultural Science and Technology 원예과학기술지 ISSN:1226-8763(Print) 2465-8588(Online)

Quinoa (Chenopodium quinoa Willd.) is a plant native to the Andean region that has become increasing popular as a food source due to its high nutritional content. This study determined the optimal photoperiod, light intensity, and electrical conductivity (EC) of the nutrient solution for growth and yield of quinoa in a closed-type plant factory system. The photoperiod effects were first analyzed in a growth chamber using three different light cycles, 8/16, 14/10, and 16/8 hours (day/night). Further studies, performed in a closed-type plant factory system, evaluated nutrient solutions with EC (salinity) levels of 1.0, 2.0 or 3.0 dS·m^-1. These experiments were assayed with two light intensities (120 and 143 μmol·m^-2·s^-1) under a 12/12 and 14/10 hours (day/night) photoperiod. The plants grown under the 16/8 hours photoperiod did not flower, suggesting that a long-day photoperiod delays flowering and that quinoa is a short-day plant. Under a 12/12 h photoperiod, the best shoot yield (both fresh and dry weights) was observed at an EC of 2.0 dS·m^-1 and a photosynthetic photon flux density (PPFD) of 120 μmol·m^-2·s^-1. With a 14/10 h photoperiod, the shoot yield (both fresh and dry weights), plant height, leaf area, and light use efficiency were higher when grown with an EC of 2.0 dS·m^-1 and a PPFD of 143 μmol·m^-2·s^-1. Overall, the optimal conditions for producing quinoa as a leafy vegetable, in a closed–type plant factory system, were a 16/8 h (day/night) photoperiod with an EC of 2.0 dS·m^-1 and a PPFD of 143 μmol·m^-2·s^-1.