EFFECT OF IRRIGATION INTERVAL ON GROWTH AND ARTEMISININ CONTENT OF WORMWOOD (Artemisia annua L.) CHEN YOUNG VARIETY IN SOKOTO

Artemisinin is the main antimalarial compound in Artemisia annua, used in the formulation of artemisinin-based combined therapies (ACT) to treat malaria. Artemisinin is largely obtained from A. annua plant but the content is very low and its production commercially is not cost effective worldwide. In view of the importance of this phytomolecule and plants being the only source of its production, this study evaluated the effect of irrigation interval on the growth and artemisinin content of A. annua. A greenhouse experiment was conducted at Botanical Garden of Usmanu Danfodiyo University Sokoto. The experiment was laid out in completely randomized design with 4 replications. The two factors examined were: (1) irrigation interval at different growth stage and (2) artemisinin content of A. annua. Irrigation interval (W) was taken at four levels (W1, W2, W4, and W6 days interval) while growth stage at three levels: early vegetative stage (EVS), mid vegetative stage (MVS) and late vegetative stage (LVD) and artemisinin were determined and quantified using High Performance Liquid Chromatography (HPLC). The calibration curve was constructed by plotting the peak area against the concentration by the external standard method on five concentration levels of artemisinin standard (5, 10, 15, 20, and 25 µg/ml), with three injections per level. Linear regression was used to establish the calibration curve. Results were calculated using the peak areas with determination coefficient (R2) of 0.951. Results revealed that W2 days irrigation interval had significantly (p<0.05) affected fresh weight, dry weight, stem diameter and root length during the EVS. At MVS, irrigation interval had no significant (P>0.05) effect on plant height and number of branches but significantly reduces stem diameter. During the late vegetative stage (LVD), irrigation intervals have no significant effect on all parameters evaluated. Artemisinin content was not significantly (P>0.05) affected by irrigation intervals during the EVS but significantly affected at mid and late vegetative stage and our result demonstrated that prolong mild irrigation interval (W2) could significantly enhanced artemisinin content in A. annua.