Effects of Different Temperature Conditions on the Growth and Photosynthesis of Korean Angelica Plug Seedlings in Plant Factories with Artificial Lighting Systems

Abstract

In this study, we aimed to evaluate the growth characteristics of Korean angelica (Angelica gigas Nakai) seedlings grown under different temperatures in plant factories with artificial lighting systems (PFALs). The temperatures in the PFALs were maintained at 22/19°C (light/dark), 25/22°C, and 28/25°C, with an alternating 12-hour photoperiod used in each case. Light-emitting diodes (red : green : blue = 7 : 1 : 2) were used as the light sources. Before sowing, Korean angelica seeds underwent two weeks of a cold treatment to break their morphophysiological dormancy. Seeds were sown in 72-cell plug trays, and the resultant seedlings were grown for 60 days to evaluate their growth and development. Additionally, principal component analysis (PCA) was employed to examine the relationships between shoot and root development. It was found that the shoot growth parameters of the crown diameter, leaf area, and leaf dry weight increased at 22/19°C and 25/22°C compared to 28/25°C. Seedlings grown at 22/19°C showed a larger root volume and a significantly higher root : shoot ratio, which was more effective for root development. The net photosynthesis rate tended to increase with a decrease in the temperature. The PCA results confirmed a strong correlation among the petiole length, crown and root diameters, leaf area, leaf and root dry weights, and root volume. These results indicate that Korean angelica seedlings exhibit enhanced root development and net photosynthesis at relatively low temperatures in PFALs.