Abstract:

In the farmland ecosystem, one reason for the crops postponed seed germination and weak seedling was attributed to the influence of allelochemicals released from the weeds. The root exudates of Commelina benghalensis were collected with a continuous trapping system. The allelopathic effects of the root exudates from Commelina benghalensis L on four crops-Sorghum vulgare, Zea mays, Vigna radiate and Brassica napus were investigated in seed germination and seedling growth with petri-dish and sand cultivation. The results showed that the root exudates from C. benghalensis had different allelopathic effects on the four crops, and varied with crop species in the descending order of Brassica napus > Zea mays > Vigna radiate > Sorghum vulgare. Allelopathic index of seed germination and seedling growth depended on the concentration of root exudates, that is, when the concentration was lower than 0.025 g·mL-1, the germination and seedling growth of acceptors were promoted. While the concentration was over 0.050 g·mL-1, they were inhibited, and the level of inhibition was improved with the increase of the root exudates concentration. In conclusion, Brassica napus was inhibited more strongly than the other species at the same concentration. The results also indicated that the allelopathic effects of C. benghalensis to the four acceptors were not so strong in low concentration．

Key words: Commelina benghalensis, allelopathy, root exudates