Non-target effects of aqueous leaf extracts of mugwort (<em>Artemisia vulgaris</em>) and herbicides: Impact on nursery tea plants (<em>Camellia sinensis</em>)

Abstract

The weed control potential of Artemisia vulgaris in tea lands has been reported. This study evaluated the non-target effects of the aqueous leaf extracts of A. vulgaris at 25, 50, 75 and 100 g/L (soilapplied, 40 ml/pot) on the growth of 7-months-old nursery tea plants (TRI 4006 and 4046) grown in black polythene bags with 1 kg topsoil. For comparison, commercial herbicides with different modes of action, i.e. Glyphosate, Diuron, MCPA, Pelargonic acid, Pine oil and Glufosinate ammonium, were soil-applied at recommended dosages, with distilled water as the control. Experiments were done in CRD with five replicates, with one plant/replicate. Leaf greenness (SPAD meter) at 20 days after treatment (DAT), visual observations of root growth, and shoot and root dry weights/plant were measured with destructive sampling at 30 DAT. Artemisia leaf extracts did not show significant negative impacts on the aboveground parameters of the tea plant compared to the control. The highest phytotoxicity on nursery tea plants was observed with MCPA (root cell damage; 100% plant mortality). The SPAD readings showed significant leaf chlorosis in TRI 4006 and TRI 4046 with Diuron and Glufosinate ammonium, compared to the control, Artemisia extracts, Pelargonic acid and Pine oil. Poor root growth with lesions was observed with 100 g/L Artemisia leaf extract but at a comparatively low degree to that of herbicides. As the non-target effects of A. vulgaris on tea plants were relatively lower, further studies are warranted to determine an effective dosage for weed control with minimum impact on tea plants and the environment.