Allelopathic Potential of Hesperozygis ringens Extracts on Seed Germination of Soybeans and Beggarticks

Hesperozygis ringens L., popularly known as espanta-pulga, is a native shrub found in rocky fields in Rio Grande do Sul. Its leaves produce a lot of essential oil, which contains pulegone as a main component that may be allelopathic. The objectives of this study were to analyze the allelopathic effects of H. ringens leaf extracts on the germination and initial development of soybean seeds and to evaluate the herbicidal potential of these extracts on beggarticks (Bidens pilosa L.). The seeds were placed on paper embedded in an aqueous extract of H. ringens leaves at concentrations of 0, 25, 50, 75 and 100% and maintained in a germination chamber at 25 °C and a photoperiod of 12 h. The tests included the following: germination, first germination count, germination speed index, and length and dry mass of seedlings. The experimental design was completely randomized. Based on the results, the aqueous extracts of Hesperozygis ringens leaves had a detrimental effect on the germination and seedling growth of the soybeans and beggarticks, evidencing their allelopathic action.