OBJECTIVETo study the effects of different doses of fertilizer N,P and K and different plant densities on the growth of Artemisia annua and the yield of artemisinin which provides a scientific basis for the A. annua cultivation and artemisinin production.

METHODField experiment with an orthogonal experimental design L16(45) was applied.

RESULTN, P and K in moderate supplies increased significantly total biomass, leaf yield, artemisinin content in leaf and artemisinin yield under both per plant and per plot, with N and K having more effective on the artemisinin content in leaves than P. Ample N benefited the formation of leaf yield, but excess N had a significant negative effect on artemisinin content. Extra supply of P or K had hardly obvious father positive efficiency, nor negative on artemisinin content. The plant density had strong negative effects on total biomass, leaf output and artemisinin yield of single plant (per plant), but obvious positive effects on the same indices of population (per plot) with the moderate densities due to the enlarging numbers of the population; over crowded density significantly decreased artemisinin content and artemisinin yield per plot. By multiple comparison, the treatment 12 (N3P4K2 density 3) which produced the highest yields of artemisinin and artemisinin-rich leaf per plot was selected as the best in the experiment.

CONCLUSIONFertilization quantities of N, P and K fertilizer and moderate density were essential for A. annua growth and artemisinin production. The optimal application of N, P and K were respectively 300 (N), 150-300(P2O5), 210(K2O) kg x hm(-2) and the optimum density was 25 000 plant x hm(-2) nearby the test area in Chongqing.