Effect of castor oil (Ricinus comunnis L) on morning glory (Ipomoea purpurea L.) seed germination

Morning glory (Ipomoea purpurea L.) is a significant weed in summer crops in Brazil. Castor bean (Ricinus comunnis L.) is an oleaginous plant of high economic and social importance, and its oil has numerous purposes, including pest and disease control. The objective of this work was to evaluate the effect of castor oil at different concentrations (100, 90, 80, 60, 40, 20, 10 and 5%) on the germination of morning glory seeds. The experiment was carried out in a gerbox containing three sheets of germitest paper, in a completely randomized design, corresponding to the seven treatments mentioned (oil dilutions) and the control (only water), with four replications, containing 50 seeds each. Data were obtained by daily reading, where the germinated seeds of each repetition were noted and used to calculate the index and germination time. Based on the experiment, it can be seen that castor oil at a concentration of 100% led to a greater delay in the germination of morning glory seeds, although it did not differ significantly from the concentrations of 80, 60 and 10. The treatment with oil at 5% and 20% advanced germination, although with no significant difference between the control and the 40% dilution. Regarding germination, the 40% dilution significantly reduced the germination index by 1%. It is concluded that castor oil influences (delays) the germination of morning glory seeds, emphasizing on the 100% treatment, which should be studied regarding its effect on germination and seedling development of this weed.