Abtract: Comparing with water extract of tobacco on the germination of wild tobacco, nan-lei-ban sun cured tobacco and Yun-yan 85"s seeds. The results showed that tobacco water extract have certain allelopathic effects on tobacco seed. Different varieties of tobacco have different allelopathic degree. Different tobacco extract concentrations have different allelopathic degree too. At low concentrations the germination rate and the fresh weight of tobacco increased slightly. But at high concentration the germination rate and the fresh weight o...