Correlation analysis on main agronomic characters, yield per plant, artemisinin percentage contents and total artemisinin content per plant of Artemisia annua Effect of soil nitrogen levels on the growth, photosynthetic properties and artemisinin content of Artemisia annua seedling Effects of Overexpression of the Endogenous Farnesyl Diphosphate Synthase on the Artemisinin Content in Artemisia annua L. Effect of Different Soil Conditions on The Growth and Artemisinin Content of Artemisia annua L. Seedlings