Effect of plant spacing on herb, essential oil and artemisinin yields in the antimalarial herb (Artemisia annua)

An experiment was conducted to work out the optimum spacing for obtaining maximum biomass, essential oil and artemisinin yields in antimalarial herb (Artemisia annua L.) in the semi-arid region of Gujarat. It was laid out in a randomized block design with 5 spacing treatments, viz. 30 cm × 45 cm, 30 cm × 60 cm, 45 cm × 45 cm, 45 cm × 60 cm and 60 cm × 60 cm. There were no significant differences in growth parameters like plant height and number of branches among different spacings. However, significant differences were observed in yield characteristics and was found that the mean fresh (30.79 t/ha) and dry (18.35 t/ha) herb yield and fresh (7.7 t/ha) and dry (3.91 t/ha) leaf yields, were maximum under spacing of 45cm × 45 cm. The leaf harvest index and leaf: stem ratio were also significantly higher under optimum spacing of 45 cm × 45 cm. No significant differences were observed in essential oil content, their composition and artemisinin contents among the different spacing but the yields of essential oil (54.95 kg/ha) and artemisinin (8.88 kg/ha) were found maximum in the spacing of 45 cm × 45 cm.