Low Light Stress On The Effects Of Licorice Quality

The growth and. secondary metabolites of medicinal plants have been affected greatly by the low light intensity. The test was designed by solution cultivated one year-old rhizome seedlings of one medicinal species-liquorice (Glycyrrhiza uralensis Fisch) were grown under three low irradiances,200,100, and 50 mmol m-2 s-1 (showed as LL1, LL2 and LL3) for 135 days. Control plants were cultured under natural light condition. Effects of low light intensity on growth, yield, photosynthesis and secondary metabolites (glycyrrhizic acid and liquiritin) were investigated. Based on the growth and quality of G. uralensis were affected by the low light intensity, the regulation technical foundation of cultured G. uralensis maybe used in the agroforestry systems. The major results are followed:1. The growth and medicinal materials yield were affected greatly by the low light intensity:The plant height and compound leaf were increased at the binging and were not affected at the late in plant growth by the low light intensity. Low light intensity stress decreased root size, fibre quantity and leaf thickness, but increased leaf area and stomatal density, The dry weight were not affected significantly at early days and decreased at the late by the low light intensity.2. Effect of low light intensity on photosynthesis physiology characteristic:Net photosynthetic rate (Pn), photochemical efficiency (Fv/Fm), photochemical quenching (qP) and electron transport rate (ETR) decreased with low light intensity decrease. The.most of decrease degree was observed at LLI3 treatment compared to the Control. However, low light intensity significantly increased total chlorophyll concentrations, while did not affect chlorophyll a/b.3. Effect of low light intensity on active components contentAccumulation of glycyrrhizic acid, liquiritin, total flavone and total saponin in root significantly increased with low light intensity down and treatment time prolong. Polysaccharid content decreased and then increased with low light intensity stress time, while decreased continually in natural light condition. Ash content of LLI1 increased and then decreased, decreased in LLI2, and increased in LLI3, compared with ash content of LLI1 decreased. There was not significantly in acid no dissolve ash content between low light intensity stress and the Control at the beginning, and increased at the late. 4. Effect of low light intensity on net add values of glycyrrhizic acid and liquiritin in rootConcentrations of glycyrrhizic acid and liquiritin were negatively correlated with root biomass in low light intensity and natural light condition. Net content of glycyrrhizic acid and liquiritin in the whole plants have not been affected by light intensity and treatment time.