Allelopathic potential of Arctotis arctotoides (L.f.) O. Hoffm aqueous extracts on the germination and seedling growth of some vegetables

Aqueous shoot and root extracts of Arctotis arctotoides were tested for their allelopathic properties on cabbage, carrot, tomato and spinach seed germination and seedling growth. The addition of the two extracts at 8 and 10 mg ml -1 resulted in the highest germination inhibitions. The shoot extract at 10 mg ml -1 inhibited cabbage, carrot, tomato and spinach seed germination by 79.1, 75.6, 82.0 and 46.0%, respectively while the root extracts at the same concentration had inhibitions of 66.0, 64.0, 64.7 and 42.1%, respectively on each of the vegetables. The decreases in the radicle growth of the four targets were highest in 10 mg ml -1 of the shoot extract with cabbage, carrot, tomato and spinach having 95.3, 98.9, 92.9 and 87.6%, respectively. Considerable reductions also occurred in the plumule length of all the seedlings. The present study has demonstrated the inhibitory properties of the shoot and root aqueous extracts of A. arctotoides on the germination and seedling growth of the four vegetables. Key words : Arctotis arctotoides, allelopathy, germination, seedling growth, vegetable seeds.