Agriculture has been suffering adaptations throughout time, from hard hand labor to the most advanced sowing and harvesting techniques. Invasive plants are a constant, diminishing productivity by competing for space, nutrients, and water. Therefore, farmers have adopted, on a large scale, the use of efficient synthetic chemicals, which are highly toxic to the environment, in order to control plant production. However, there are other alternative means to control those competitors: using allelochemicals present in some plants, such as medicinal ones. The objective of this paper is to analyze allelophatic properties of the medicinal plants Cymbopogon citratus (DC) Stapf. and Sambucus australis Cham. and Schltdl., and inhibit Bidens pilosa L. without interfering on Glycine max L. Merrill germination. The extracts were obtained by crushing 200 g of leaves and mixing them with 1 liter of distilled water. The seeds were kept in B.O.D. at a temperature of 25ºC, with a photoperiod of 12 hours of light. Considering the conditions in which the experiment was performed, it was concluded that the warm liquid extract of Cymbopogon citratus restrained the germination of Bidens pilosa L. without interfering on the germination of soybean, whereas the warm liquid extract of Sambucus australis Cham. constrained soybean and Bidens pilosa L. germination. Thus, the use of Cymbopogon citratus (DC) Stapf. as a natural herbicide for Bidens pilosa L. is recommended.
allelopathy; invasive specie; agriculture
