title: Photosynthesis rates, growth, and ginsenoside contents of 2-yr-old Panax ginseng grown at different light transmission rates in a greenhouse.
abstract: BACKGROUND
  Ginseng is a semishade perennial plant cultivated in sloping, sun-shaded areas in Korea. Recently, owing to air-environmental stress and various fungal diseases, greenhouse cultivation has been suggested as an alternative. However, the optimal light transmission rate (LTR) in the greenhouse has not been established.
  
  
  METHODS
  The effect of LTR on photosynthesis rate, growth, and ginsenoside content of ginseng was examined by growing ginseng at the greenhouse under 6%, 9%, 13%, and 17% of LTR.
  
  
  RESULTS
  The light-saturated net photosynthesis rate (A sat) and stomatal conductance (g s) of ginseng increased until the LTR reached 17% in the early stage of growth, whereas they dropped sharply owing to excessive leaf chlorosis at 17% LTR during the hottest summer period in August. Overall, 6-17% of LTR had no effect on the aerial part of plant length or diameter, whereas 17% and 13% of LRT induced the largest leaf area and the highest root weight, respectively. The total ginsenoside content of the ginseng leaves increased as the LTR increased, and the overall content of protopanaxatriol line ginsenosides was higher than that of protopanaxadiol line ginsenosides. The ginsenoside content of the ginseng roots also increased as the LTR increased, and the total ginsenoside content of ginseng grown at 17% LTR increased by 49.7% and 68.3% more than the ginseng grown at 6% LTR in August and final harvest, respectively.
  
  
  CONCLUSIONS
  These results indicate that 13-17% of LTR should be recommended for greenhouse cultivation of ginseng.
authors: Department of Herbal Crop Research, NIHHS, RDA, Eumseong, Korea; Department of Horticultural Biotechnology, Kyung Hee University, Yongin, Korea.
authors: In-Bae
authors: IB
authors: Jang
authors: Department of Herbal Crop Research, NIHHS, RDA, Eumseong, Korea.
authors: Dae-Young
authors: DY
authors: Lee
authors: Department of Herbal Crop Research, NIHHS, RDA, Eumseong, Korea.
authors: Jin
authors: J
authors: Yu
authors: Department of Herbal Crop Research, NIHHS, RDA, Eumseong, Korea.
authors: Hong-Woo
authors: HW
authors: Park
authors: Department of Herbal Crop Research, NIHHS, RDA, Eumseong, Korea.
authors: Hwang-Sung
authors: HS
authors: Mo
authors: Department of Herbal Crop Research, NIHHS, RDA, Eumseong, Korea.
authors: Kee-Choon
authors: KC
authors: Park
authors: Planning and Coordination Division, NIHHS, RDA, Suwon, Korea.
authors: Dong-Yun
authors: DY
authors: Hyun
authors: Department of Herbal Crop Research, NIHHS, RDA, Eumseong, Korea.
authors: Eung-Ho
authors: EH
authors: Lee
authors: Department of Herbal Crop Research, NIHHS, RDA, Eumseong, Korea.
authors: Kee-Hong
authors: KH
authors: Kim
authors: Department of Horticultural Biotechnology, Kyung Hee University, Yongin, Korea.
authors: Chang-Sik
authors: CS
authors: Oh
keywords: Panax ginseng; ginsenoside; greenhouse cultivation; light stress; photosynthesis