Neem oil influences morning glory seed germination

In Brazil, morning glory (Ipomoea purpurea L.) is a prominent weed found with sugarcane, maize, and soybean crops, which harms their mechanized harvesting. Its seeds germinate asynchronously, making their management difficult, and glyphosate-tolerant biotypes are also observed in the country. Neem (Azadirachta indica L.) is a medicinal plant, and farmers have widely used its oil for alternative pest and disease management. In this context, this work aimed to evaluate the effect of neem oil, at different concentrations (85, 65, 45, 25 and 5%), on the germination of morning glory seeds. The experiment was carried out in gerbox, in a completely randomized design, and consisted of the five treatments mentioned and a control (without oil), with four replications, containing 50 seeds each. The data obtained were used to calculate the germination time and index. Based on the analysis of the data obtained, it was observed that neem oil at concentrations of 85, 65 and 45% delayed the germination of I. purpurea seeds by 1.83, 1.28 and 1.42 days, respectively. Regarding the germination index, it was observed that oil concentrations of 85 and 45% significantly reduced germination by less than 5 and 6%, respectively. The present study evidences the antagonistic potential of neem oil in relation to morning glory seeds, so that it can be used in alternative management programs for this invasive plant, delaying and reducing germination. Further studies will be carried out to evaluate the effect on seedlings.