Growth and Photosynthetic Responses to Increased LED Light Intensity in Korean Ginseng (<i>Panax ginseng</i> C.A. Meyer) Sprouts

Abstract

Compared to the traditional production of ginseng roots, Panax ginseng sprouts (PGSs) are currently regarded as a substitute due to the relatively short-term culture but still high nutrition. However, the optimal light intensity for the growth ability of PGSs and the characterizations of the responses of PGSs to the light intensity have been largely neglected. This study aimed to determine the influences of the light intensity on the growth, morphogenesis, and photosynthetic responses in PGSs. To this end, two-year-old ginseng rootlets were subjected to one of six light intensities (from 30 to 280 PPFD with 50 PPFD intervals) in a plant factory with artificial lighting (PFAL) via LED light for 10 weeks. On the whole, the recorded parameters of the PGSs showed gradually decreasing trends in response to the increasing light intensities. However, the 80 PPFD-treated PGSs possessed similar or greater root dry weights, leaf areas, carotenoids levels, and photosynthesis (the maximal PSII quantum yield) compared to those in the 30 PPFD regime. Additionally, photoinhibition symptoms as evidenced by chlorosis, necrosis, and stunted growth were observed as the light intensity attained 180 PPFD. Thus, 130 PPFD could be considered a safe point for the appearance of photoinhibition in PGSs. Taken together, we show that the light intensity range of 30–80 PPFD is suitable for maximizing the production of PGSs in PFALs.

Keywords

• photosynthetic photon flux density (PPFD)
• morphogenesis
• photosynthesis pigments
• plant factory
• quantum yield
• leaf area