Optimization of Photosynthetic Photon Flux Density and Root-Zone Temperature for Enhancing Secondary Metabolite Accumulation and Production of Coriander in Plant Factory

Coriander is an important aromatic plant, and contains abundant secondary metabolites that are considered to be beneficial for health. The demand for high-quality and fresh coriander in large cities has been growing rapidly. Plant factories are advanced indoor cultivation systems that can produce high-quality plants inside cities with a high productivity. This study aimed to maximize plant growth and the secondary metabolites production of coriander, by regulating photosynthetic photon flux density (PPFD) and root-zone temperature (RZT). Three PPFDs (100, 200, and 300 mu mol m(-2) s(-1)) and three RZTs (20, 25, and 30 degrees C) were applied on coriander plants grown hydroponically in a plant factory. The plant biomass and water content of leaf and stem were highest under RZT of 25 degrees C with a PPFD of 300 mu mol m(-2) s(-1). However, chlorogenic acid, rutin, trans-2-decenal, total phenolic concentrations and the antioxidant capacity of the coriander plant were greatest under the combination of PPFD (300 mu mol m(-2) s(-1)) and RZT (30 degrees C). Chlorogenic acid in leaves responded more sensitively to PPFD and RZT than rutin. Controlling PPFD and RZT is effective in optimizing the yield and quality of coriander plants. The findings are expected to be applied to commercial plant production in plant factories.