Lemon-scented gum extracts influence the germination of morning glory seeds

Weeds have developed skills to compete with cultivated plants, making the former a major problem in agricultural areas. Morning glory (Ipomoea purpurea) is an important invasive plant that, in addition to competing for nutrients, makes harvesting difficult and presents seed dormancy mechanisms in soil banks. Some plants in this group have already been reported to be tolerant or resistant to herbicides. Therefore, it is necessary to seek alternative methods of management for these plants. The present study aimed to evaluate the influence of four extracts of lemon-scented gum (Corymbia citriodora) on the germination of morning glory seeds. Extracts were obtained from infusion, crushing, boiling and the alcoholic extract of the leaves. The experiment was carried out in gerboxes, containing three sheets of paper, with four repetitions of fifty seeds in each and in a completely randomized design. The germinated seeds were examined daily, until they all emitted the radicle. At the end of the experiment, it was understood that the alcoholic extract was the one that stood out the most, as it led to the delay and reduction in the germination rate of morning glory seeds by up to 2.22 days and 38.5% fewer seeds germinated, respectively. Extracts obtained by infusion and aqueous extracts also delayed germination with a significant difference. None of the extracts advanced germination. The results are promising in the sense that the allelopathy exerted by lemon-scented gum extracts can help to manage banks of morning glory seeds in the soil, delaying and reducing their germination.