The plants synthetize a big quantity of chemically diverse compounds, which discharged into the environment influence in a decisive manner in the species dynamics that form the agroecosystems, phenomenon denominated allelopathy. The study had the aim of the evaluation of allelopathic effects of turnip aqueous extract under beans and corn seeds. The experimental design was completely randomized with five treatments (concentrations of 0%, 25%, 50%, 75% and 100% of raw extract) and four repetitions. The gross extract was prepared through the mixture of 50 g of turnips aerial part fresh mass in 450 mL of cold distilled water and then blended in a blender. The mixture was kept in rest in absence of light for 24 hours at 25Ўж for posterior filtration and dilution of concentrations. They were evaluated the percentage of germination and the germination velocity index in Germitest paper rolls dampened with the extract or distilled water, according to the treatments and each roll was distributed 50 seeds, kept in germination chamber at 25Ўж ЎА 3Ўж and 12 hours of photoperiod. At the end of seven (corn) and nine (beans) days, the root length (RL) and the aerial part (APL) were evaluated, and after drying in a hothouse (50Ўж), the dry mass of root system (DMR) and aerial part (DMAP) was determined, by the measure of 20 plantlets of each treatment. The results were submitted to an analysis of variance by F test and, when there was statistical significance, it was made the regression analysis test. For the realization of the statistical analysis, the ASSISTAT software was used. The turnip aqueous extract affected negatively the germination and initial development of bean and corn plantlets.