Effects of Photoperiod and Light Intensity on the Growth and Glucosinolates Content of Three Brassicaceae Species in a Plant Factory

Abstract

This study was conducted to investigate the effect of each light intensity and photoperiod combination on the growth and glucosinolates (GSLs) content of three species of Brassicaceae plants under the same daily light integral (DLI) conditions. Seeds of leaf mustard (Brassica juncea (L.) Czern.), red mustard(Brassica juncea L.) and kale (Brassica oleracea L. var. acephala (DC.) Alef.) were sown in a rockwool cubes and grown for three weeks. DLI was set to 10 mol•m -2 •d -1 and treated with 10h-280, 14h-200, 18h-155, 22h-127 µmol•m -2 •s -1 for three weeks. As a result at 14h-200 µmol•m -2 •s -1 treatment, shoot fresh/dry weight, the number of leaves, and leaf area were increased in leaf mustard and kale but there was no significant difference in other treatments. In the total GSLs content, the treatment of 14h-200 µmol•m -2 •s -1 increased significantly 139.95, 135.87, 154.03% compared to 10h-280, 18h-155, 22h-127 µmol•m -2 •s -1 treatment in red mustard, and 14h-200 µmol•m -2 •s -1 treatment increased significantly 132.96, 132.96, 134.03% compared to other treatments in kale. In red mustard, the treatment of 18h-155 µmol•m -2 •s -1 showed an increase in shoot fresh/dry weight and the total GSLs contents than other photoperiods and 14h-200 µmol•m -2 •s -1 treatment, the number of leaves significantly 15.62, 12.12, and 32.14% higher than other photoperiods. Since the DLI response is different depending on species even for similar Brassicaceae crops, it is necessary to get more detailed results by conducting optical light quality studies and deriving optimal DLI conditions to achieve minimum power consumption and maximum efficiency.