Evaluation of Growth, Photosynthetic Pigment, and Nursery Period of Korean Angelica (Angelica gigas Nakai) Plug Seedlings under Elevated CO2 Conditions

This study aimed to evaluate the shoot and root growth, changes in photosynthetic pigments, and nursery period of Korean angelica plug seedlings under different CO 2 concentrations in plant factories with artificial lighting systems (PFALs).Korean angelica seeds were sown in 72-cell plug trays, and the seedlings were grown for 40, 50, and 60 days to evaluate their morphological characteristics and chlorophyll contents.The internal CO 2 concentrations in PFALs were set at three levels: ambient (475 ± 40 µmol•mol -1 ), 'high concentration' ('HC', 758 ± 29 µmol•mol -1 ), and 'very high concentration' ('VHC', 1,197 ± 37 µmol•mol -1 ).CO 2 supply started 20 days after sowing when cotyledons were fully extended, and the first true leaf was observed.As a result, from 50 days after sowing, the crown diameter, leaf area, root development, and dry weight were higher in HC and VHC than in ambient, indicating a faster growth speed.However, there was statistically no significant difference in the dry matter accumulation between HC and VHC.From a morphological point, VHC had the longest petioles and the widest leaf area at 60 days after sowing, and the canopy expanded horizontally.The chlorophyll a, b, and total chlorophyll content were also the lowest.Additionally, the leaf area index was higher compared to the ambient, and the specific leaf weight, which indicates leaf thickness, was reduced.This is thought to be because the growth speed is fast, resulting in competition between individuals within the narrow plug tray environment.Therefore, the appropriate CO 2 concentration for shortening the nursery period of Korean angelica is considered to be approximately 800 µmol•mol -1 and the appropriate nursery period in 800 µmol•mol -1 condition is 50 days.