Effect of Plant Density on the Yields of Artemisinin and Essential Oil in Artemisia annua Cropped under Low Input Cost Management in North-Central India

Abstract

A field experiment was conducted on Artemisia annua L. during the winter-summer season of 1995-96 at Lucknow, located at 26.5°N, 80.5°E and 120 m above mean sea level, representing a semiarid-subtropical climate with hot summer and fairly cool winters to study the effect of varying plant densities on the yields of essential oil and artemisinin under the conditions of no interculture and fertilizer applications. Results showed that A. annua at the population density of 2.22 × 10⁵ plants ha^-1 yielded 7.4 kg of artemisinin and 91 kg of essential oil. It was also observed that at the same oil yield level, the yield of artemisinin increased by 1.5-, 2-, and 2.5-fold when the plant densities increased by about 2-, 4-, and 8-fold. Correspondingly, the suppression of weeds occurred by about 33, 133, and 333%, respectively. The plant architecture and canopy structure producedin high density A. annua plots presumably favoured the synthesis and accumulation of artemisinin resulting in artemisinin-rich, mature plants. It is recommended that, under subtropical agroclimatic conditions of north Indian plains, the A. annua should be cultivated at very high plant densities such as 2.22 × 10⁵ plants ha^-1 forgetting high artemisinin yields.