Effects of Artemisia afra leaf extracts on seed germination of selected crop and weed species
Herbicide resistance in weeds is a phenomenon threatening sustainable cereal production in the winter rainfall region of South Africa. Every possible weed control measure that may be used to complement chemical weed control measures should be investigated. The effect of aqueous leaf extracts of the aromatic shrub African wormwood (Artemisia afra) on germination of selected crop and weed species were investigated. The selected plant species included wheat (Triticum aestivum L.), herbicide resistant and non-resistant ryegrass (Lolium spp.), canola (Brassica napus) and lucerne (Medicago sativa). Various dilutions were investigated and the original extract was the most effective in inhibiting seed germination as compared to the inconclusive results from further dilutions. The original extract that completely inhibited seed germination in canola, had no significant negative effect on seed germination of wheat and lucerne. The reduction in seed germination of both the resistant and non-resistant ryegrass was highly significant, although there was no significant reduction in rate of germination. The different seed germination responses of the test species to an aqueous leaf extract of African wormwood raises the possibility of developing a bioherbicide from the extract.