Effects of aqueous extracts from Artemisia afra parts and soil on seed germination and early seedling development in selected plant species

Abstract

Aqueous extracts from leaves, stems, roots of the aromatic shrub Artemisia afra and soil on which Artemisia was grown, were used to investigate their inhibitory effects on germination and seedling development of maize (Zea mays), bean (Phaseolus vulgaris) and ryegrass (Lolium perenne). Dilutions of 1:1,1:2.5 and 1:5 v/v of the original extracts were prepared by adding deionised water to the original (undiluted) extracts. Deionised water and extracts from soil on which A. afra had never grown were used as controls. Extracts from A. afra soil and plant parts significantly (p < 0.05) reduced seed germination, height and dry matter of all the seedlings compared with the controls. However, as the dilution of the original extracts increased, there was a significant increase in seed germination and dry matter yields. This observation was consistent in all the plant species indicating that there was reduction in the concentration of the compounds inhibiting germination and seedling growth. The inhibitory effects on both seed germination and seedling development by the extracts was in the order leaves > stems = roots > soil. It was observed that germination was the process relatively more adversely affected by the inhibitory compounds in the extracts than growth of the seedlings. The results confirm that there are water-soluble compounds in the tissue of the A. afra shrub which can inhibit seed germination and growth of plant seedlings. © 1998 Taylor & Francis Group, LLC.