Abstract
Methods to improve the bioactive component content of cultivated licorice have become the bottleneck of industrial licorice extraction for pharmaceutical use. To evaluate the effects of genotype, environment and their interaction on major bioactive components, we analyzed the five bioactive components: liquiritin (LQ), liquiritigenin (LQG), glycyrrhizin (GL), isoliquiritin (ILQ) and isoliquiritigenin (ILQG) of four diverse licorice varieties grown in four distinct environments in northern China during 2010–11. Analysis of variance showed that environmental and genotypic effects were significant (p<0.01) for all five bioactive components. Additionally, their interaction was significant (p<0.05) for GL in the 2-year study period. LQ and ILQ were mainly affected by genetic factors and have great potential for genetic improvement, whereas LQG and ILQG were mainly affected by environmental factors. GL was similarly affected by environmental and genetic factors. Biplot of the principal component analysis showed that for quality breeding, G2 (WNT-1) and G3 (JX-1) are two relatively preferable genotypes, and E2 (Chifeng) location is suitable for accumulation of the bioactive components of these two genotypes. Stepwise regression analysis showed that sunshine and rainfall are the dominant environmental factors for licorice bioactive component accumulation; increased duration of sunshine is advantageous to GL accumulation whereas declining rainfall is conducive to LQG and ILQG accumulation. These results provide a theoretical basis for initiating licorice breeding programs with increased bioactive components and improved quality.
