Influence of harvesting stage on herb, essential oil and artemisinin yields in the antimalarial herb, Artemisia annua L.

Abstract

The investigation was carried out to standardize the harvesting stage for maximum oil and essential oil yield in Artemisia annua L. in the semi arid region of Gujarat. The experiment was laid out in randomized block design with seedlings planted at the age of six weeks and harvested at five different phonological stages.viz., early vegetative (March), late vegetative (May), pre bloom (September), bloom (October) and post bloom (November) stages. The results revealed that the maximum herb could be obtained in the late vegetative stage (31.74 t/ha) followed by bloom stage (30.19 t/ha). The leaf yield was maximum in the bloom stage (6.39t/ha). The essential oil content and yield was maximum in the bloom stage (0.61% and 61.30 kg/ha, respectively) followed by post bloom stage (0.55% and 38.87 kg/ha) and minimum in early vegetative stage (0.18% and 8.29 kg/ha). However, the artemisinin content was maximum in the late vegetative stage (0.48%) followed by prebloom stage (0.44%). Similarly, the artemisinin yield per hectare was maximum in the crop harvested during late vegetative stage followed by the prebloom stage. The essential oil obtained during different harvest stages were subjected to GC-MS analysis in which, the main compounds were camphor (28.6–31.7%), 1, 8cineole (2.1–20.8%), germacrene D (3.8–12.0%), β-caryophyllene (2.8–6.9%), trans-β-farnesene (0.7–4.5%), α-pinene (0.5–2.4%), p-cymene (2.1–2.3%) and terpinen-4-ol (0.9–2.1%). Camphor was found to be a major compound in the oil at all growth stages.