Allelopathic effect of crude plant extract on Ipomoea purpurea L.

Weeds are among the main phytosanitary problems and are responsible for numerous losses in agriculture. Integrated management has become increasingly important in weed control. Therefore, the present study aimed to investigate the allelopathic effect of 24 plants on morning glory (Ipomoea purpurea L.). The tests were performed in a completely randomized design, both in in vitro and in vivo experiments. The in vitro germination data were used to calculate the time and germination index, and in the in vivo experiment, the length and fresh weight of the aerial part and root of the seedlings were evaluated, with subsequent comparison of averages by ANOVA. The plant extracts used exerted allelopathy, delaying (negative) and advancing (positive) the germination of this species. The extracts of banana, black plum, carqueja, Mexican sunflower, rosemary, guaco, lavender, lemongrass and garden mint resulted in high germination delays of up to +5 days. Rosemary, garden mint, Mexican sunflower and guaco extracts also reduced the germination rate by up to -10.5%. None of the tested extracts reduced the length of the aerial part of morning glory. In all treatments, shorter root length was observed. The extracts of lemongrass, rosemary and guaco reduced the dry weight of the aerial part, and in all treatments a lower fresh weight of roots was observed, except for the treatment with guaco. It can be concluded that the germination or growth of some problematic weeds such as I. purpurea may be affected by allelochemical extracts from different plants such as bananas, black plum, boldo, Mexican sunflower, rosemary, guaco, lavender, lemongrass, and garden mint.