Effect Of Different Light Spectral Energy Distribution On Growth Of Schizonepeta Tenuifolia

Light is one of the most important environmental factors. Light play an important role in plant development, morphogenesis, metabolism and geneexpression. Light regulat plant growth by light receptors which were affected by light quality, light intensity and photoperiod. LED can emit the exact spectrum based on the need of plant, so that it can be widely used in modern agricultural production.This study used Schizonepeta tenuifolia (Benth.) Briq. as experimental material to study effect of different light spectral energy distributions on growth of S. tenuifolia, and select the suitable light sources for facility cultivation of S tenuifolia.Main research results were as follows:1. The effect of different light spectral distribution on growth of S. tenuifolia was investigated. The results showed that, S tenuifolia vigorous growth, chlorophyll content, photosynthetic rate, soluble protein content, starch content and biomass were greatest in plants under R:B=1:1 light. Green and yellow were not suitable for growth of S. tenuifolia, because of low biomass. Thus, R:B=1:1 was the best light spectrum for the growth of S. tenuifolia.2. The effect of different percentage of red and blue spectrum on growth of S. tenuifolia was investigated. The results showed that, S. tenuifolia vigorous growth, chlorophyll content, biomass, pulegone and menthone yield were greatest in plants under R:B=3:1 light The pulegone content was highest under R:B=1:3 light. There were no significant differences among different percentage of red and blue spectrum of soluble protein and ascorbic acid. The content of nitrate was lowest under the red and blue spectrum. Thus, R:B=3:1 was the best percentage of red and blue spectrum for the growth of S. tenuifolia.3. The effect of different light intensities on growth of S. tenuifolia was investigated. The results showed that, S. tenuifolia vigorous growth, chlorophyll content, biomass, pulegone and menthone yield were greatest in plants under the 200 μmol m-2 s-1, and the content of nitrate were lowest. The content of soluble protein and nitrate was greatest in plants under the 300 μmol m-2 s-1. The content of pulegone was highest under the 100 μmol m-2 s-1. Thus, the light intensity of 200 μmol m-2 s-1 was suitable for the growth of S. tenuifolia.4. In conclude, different light spectral energy distributions have different effects on growth of S. tenuifolia. Red plus blue spectrums benefit the growth of S. tenuifolia. The R:B=3:1 was the best percentage of red and blue spectrum for the growth of S. tenuifolia. It was bad effect on growth of S. tenuifolia under too low or too high PPFD. The plants grow stronger and all kinds of indexes are lager under PPFD of the 200 μmol m-2 s-1. This study supported the feasibility of application of LED be widely used in S. tenuifolia cultivation.