The Physiological Effects of Allelochemicals From Artemisia annua L. on Lemna minor 5

Abstract

This investigation was designed to evaluate the physiological effects of allelochemicals from Artemisia annua L. on Lemna minor 5. A bioassay was used to examine the effects of artemisinin and arteannuic acid on frond growth, dry weight, total chlorophyll production and total chlorophyll/dry weight of tissue on Lemna minor 5. Tissue culture plates were established using a random block design and fresh E medium without sucrose and tartaric acid for a seven day test period. Photosynthesis and respiration were also determined using L. minor 5 and artemisinin or arteannuic acid. An 80 minute test period with intervals of light and dark was conducted with a differential respirometer. At 2.5 uM of artemisinin, all parameters were inhibited. At 1.0 uM, arteannuic acid inhibited all parameters tested in the bioassay. Slight stimulation was observed for photosynthesis and respiration at the 2.5 uM level of arteannuic acid. In most cases, the bioassays tested with artemisinin and arteannuic acid, there existed a concentration relationship in which toxicity increased with higher concentrations of the test chemical. This differed from the experiments involving photosynthesis and respiration. At 1.0 uM artemisinin, photosynthesis was inhibited and respiration was stimulated. At 1.0 uM arteannuic acid, photosynthesis and respiration were stimulated.