Neem (Azadirachta indica) oil affects morning glory (Ipomoea purpurea) seedling development.
The weed Ipomoea purpurea L. (Convolvulaceae), known generically as morning glory, is an important invasive plant introduced in Brazil, which not only causes significant losses in annual crops, but also makes harvesting difficult and already presents herbicide-tolerant biotypes in the country. In this context, alternative and sustainable ways of managing this plant are sought. The objective of this work was to evaluate the effect of neem oil on morning glory seeds and seedlings. The experiment was carried out in a completely randomized design, with six treatments composed of different oil dilutions, applied before and after germination, in addition to the control. Based on the experiment, it was observed that neem oil delayed seed germination by up to 1.4 days, although without significance. On the other hand, seedling fresh weight was severely affected by application after sowing, leading to a symptom of leaf blight. Morning glory seedling survival followed the same pattern, where there was a significant reduction by the application of neem oil only after sowing. It was concluded that neem oil has a phytotoxic effect on I. purpurea seedlings, reducing their survival and fresh weight when applied after germination, as well as influencing (delaying) seed emergence when applied to the soil. The study of the effect of lower concentrations, close to economically viable and practiced in the field, should be carried out in the future.