Phytomedicine Research Centre, Department of Botany, University of Fort Hare, Alice 5700, South Africa.
Biol Res. 2012;45(4):363-8. doi: 10.4067/S0716-97602012000400006.
Turnip (Brassica rapa var. rapa L.), beetroot (Beta vulgaris L.) and carrot (Daucus carota L.) are common vegetables in South Africa. The allelopathic potential of aqueous leaf and root extracts of Aloe ferox Mill.- a highly valued medicinal plant- was evaluated against seed germination and seedling growth of the three vegetables in Petri dish experiments. The extracts were tested at concentrations of 2, 4, 6, 8, and 10 mg/mL. Leaf extract concentrations above 4 mg/mL inhibited the germination of all the crops, while the root extract had no significant effect on germination irrespective of concentration. Interestingly, the lowest concentration of leaf extract stimulated root length elongation of beetroot by 31.71%. Other concentrations significantly inhibited both root and shoot growth of the vegetable crops except the turnip shoot. The most sensitive crop was carrot, with percentage inhibition ranging from 29.15 to 100% for root and shoot lengths. Lower percentage inhibition was observed for the root extract than the leaf extract against shoot growth of beetroot and carrot. The results from this study suggested the presence of allelochemicals mostly in the leaves of A. ferox that could inhibit the growth of the turnip, beetroot and carrot.
芜菁（ Brassica rapa var. rapa L.）、甜菜根（Beta vulgaris L.）和胡萝卜（Daucus carota L.）是南非常见的蔬菜。在 Petri 盘实验中，评估了高度有价值的药用植物龙舌兰（Aloe ferox Mill.）的叶和根水提物对三种蔬菜种子萌发和幼苗生长的化感潜力。提取物以 2、4、6、8 和 10 mg/mL 的浓度进行测试。叶提取物浓度高于 4 mg/mL 抑制了所有作物的萌发，而根提取物无论浓度如何，对萌发均无显著影响。有趣的是，最低浓度的叶提取物刺激甜菜根的根长伸长了 31.71%。其他浓度显著抑制了蔬菜作物的根和茎的生长，除了芜菁的茎。最敏感的作物是胡萝卜，根和茎的长度的抑制率范围为 29.15%至 100%。与叶提取物相比，根提取物对甜菜根和胡萝卜的茎生长的抑制率较低。本研究的结果表明，龙舌兰的叶子中存在化感物质，可能会抑制芜菁、甜菜根和胡萝卜的生长。
