Distinctive morphological characteristics contribute to the identification of Artemisia annua L. germplasms with high yield and high artemisinin content

Abstract Artemisia annua L., a famous traditional Chinese medicine, has been used as an antimalarial herbal medicine for thousands of years. Artemisinin, main bioactive constituent of A. annua L., is the principal contributor to its pharmacological effects. Previous studies have shown that A. annua L. of different germplasm has different morphological characteristics, herb yield, and artemisinin content. We propose a hypothesis that the morphological characteristic of A. annua L. may contribute to breeding new cultivars with high yield and high artemisinin content. To test this hypothesis, 8 morphological characteristics (plant height, stem bottom diameter, crown diameter, distance of internode, the number of primary branches, primary branch angle, leaf length, and leaf width) of A. annua L. from 64 germplasm resources were studied. The correlations between morphological characteristics and herb yield, artemisinin content were studied by using partial least squares regression (PLSR) analysis, correlation analysis, and path analysis. The results indicated that: (1) the same characteristic of different germplasm resources varied greatly under the same cultivation and management condition; (2) both the artemisinin content and herb yield were positively correlated to plant height, stem bottom diameter, crown diameter, distance of internode, leaf width, and negatively correlated to the number of primary branches. Nevertheless, the coefficients of correlation are very low and vary between r  = 0.25 to r  = 0.46; (3) the strongest relations were found for plant height and stem bottom diameters. In conclusion, both plant height and stem bottom diameter had the most important positive influence on artemisinin content of the leaves and herb yield. The results of the present study can help to increase breeding efficiency for getting new A. annua L. cultivars with high herbal yield and high artemisinin content.