Growth response of Artemisia afra Jacq. to different pH levels in a closed hydroponics system

Abstract

In this study the effect of varying levels of pH on the fresh and dried yield and chlorophyll content of Artemisia afra Jacq. was investigated. Five groups of plants received deionised water adjusted to a certain pH. The pH for the treatments were 4.5, 5.5, 6.5 (the control), 7.5, and 8.5. The fresh weight of the plants was highest for the pH treatment of 6.5, while the fresh weight of the 4.5, 5.5 and 7.5 treatments did not differ significantly. The plants grown with a pH of 8.5 were significantly reduced in fresh weight. The total dry weight, shoot dry weight and root dry weight of the plants did not show significant variation between the 5.5, 6.5 and 7.5 treatments, but was significantly lower for the 4.5 and 8.5 treatments. The chlorophyll content of the leaves of the plants showed a marked variation between treatments. The chlorophyll content of the plants grown at pH 6.5 was highest, followed by those grown at the pH of 5.5 and the pH 4.5. The chlorophyll content of the pH 7.5 treatment was the second lowest, while the content of the 8.5 treatment was the lowest. These results indicated that the optimum pH of water supplied to A. afra can have a significant effect on the fresh and dried yield of this plant. The study shows that, although A. afra can survive at a range of acidic pH’s, it does not fare well with regards to chlorophyll content, fresh weight, root dry weight and shoot dry weight in an alkaline or acidic situation.