Efeitos alelopáticos e fitotóxicos de extratos da semente de Crotalaria spectabilis na pós-emergência de Digitaria insularis

Abstract

Digitaria insularis is a spontaneous plant that is difficult to control, causing damage to pastures and annual crops, has biotypes resistant to different herbicides used in its management, which is mostly chemical. ln this work, Crotalaria spectabilis seed extracts were obtained, analyzed by gas chromatography and applied to plants of Digitaria insularis in order to evaluate a possible phytotoxic effect. Chemical analysis showed the presence of only three compounds, fatty acids, 15 methyl hexadecanoic acid, linoleic acid and stearic acid. In the different treatments there was no difference in relation to the control for plant height and dry matter. For fresh matter, only the treatment with hexane extract at a concentration of 0.5% showed a statistically different result. Regarding the damage caused to the plants, the treatment with aqueous extract, in the concentration of 0.5% did not differ from the control, however the other treatments showed difference, mainly the treatment with hexane extract which presented higher percentages of symptomatic plants and the treatment with ethanolic extract, which independent of concentration, presented high percentages of dead plants, greater than 90%. In general, the results show that the use of Crotalaria spectabilis seed extracts is promising in the emerging post control of Digitaria insularis.