Effect of light quality of blue and red fluorescent lamps on growth of St. John's wort (Hypericum perforatum L.)
2006
Nishimura, T.(Chiba Univ., Matsudo (Japan). Faculty of Horticulture) | Zobayed, S.M.A. | Kozai, T. | Goto, E.
St. John's wort (Hypericum perforatum L.) is a medicinal plant widely used for treatments of neurological disorders, depression, etc. Recently, studies have reported the production of St. John's wort plants under controlled environments with artificial light as a promising technique to standardize and enhance the growth and medicinal contents. The present study investigated the effect of the light quality of fluorescent lamps on the growth of St. John's wort plants. The seedlings with 6-8 unfolded leaves were grown for 28 days under blue and red lamps in growth chambers under controlled environments. Dry weight of plants grown under the red lamps was greater compared with that of plants grown under the blue lamps. The CO2 absorption rate of plants grown under the red lamps was similar to that under the blue lamps. Absorption of red light (600 - 700 nm) by leaves was lower than that of blue light (400 - 500 nm). Leaf area, number of unfolded leaves, number of branches from the main stem, and number of nodes of plants grown under the red lamps were greater than those of plants grown under the blue lamps. These findings demonstrated that the difference in dry weight of plants grown under these conditions was not due to the spectral characteristic or photosynthetic ability of leaves but due to the amount of light actually absorbed by the leaves. In conclusion, controlling the light quality can be an important technique for enhancing production of St. John's wort plants.
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