[Allelopathic interactions between Borreria latifolia and two common Asteraceae species]. / 阔叶丰花草与2种菊科植物之间的化感作用.

Borrelia latifolia is an annual herb suitable to be used as cover crop for weed control in orchards in southern China. To understand the competition between B. latifolia and common weeds in orchards, we investigated the allelopathic interactions between B. latifolia and two Asteraceae species, Ageratum conyzoides and Bidens alba. The results showed that the aqueous extracts of B. latifolia at 10-50 mg·mL-1 significantly inhibited seed germination and seedling growth of A. conyzoides and B. alba, with the radicle length of A. conyzoides and B. alba being reduced by 57.4%-90.2% and 57.3%-62.3%, respectively. The aqueous extracts of A. conyzoides and B. alba also had strong allelopathic effects on seed germination of B. latifolia. Under the treatment of 50 mg·mL-1 aqueous extracts, the two Asteraceae species almost entirely inhibited the germination of B. latifolia. After treated with 10 mg·mL-1 aqueous extract of B. latifolia for 30 d, net photosynthesis, plant height and biomass of A. conyzoide were reduced by 15.2%, 20.6% and 41.5%, respectively, compared with the control, while the biomass of B. alba also showed a decreasing trend. Instead, the growth of B. latifolia was not affected. Under mixed culture, biomass of B. latifolia was comparable to that under monoculture, whereas those of A. conyzoides and B. alba were reduced by 86.0% and 27.1%, respectively. Compared with A. conyzoides and B. alba, the allelopathic advantage of B. latifolia is that it can inhibit growth of the two Asteraceae species as well as inhibit seed germination.