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 (Asat) and stomatal conductance (gs) 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, 6e17% 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.
Conclusion: These results indicate that 13e17% of LTR should be recommended for greenhouse cultivation
of ginseng.