In the study the author presents the problem of winter rape silique cracking and seed shedding. In a three-year experiment (1992 - 1994), using two winter rape varieties - Ceres and Bolko, an assessment was made of the effect of four chemical preparations (Spodnam DC, Reglone, urea, starch) on the resistance of siliques to cracking. This unfavourable feature of rape can be either enhanced or weakened through the application of suitable preparations. An improvement in the resistance of siliques to cracking was observed after the application of Spodnam DC and urea (as additional nitrogen fertilization in the form of sprinkling with 10 % water solution). Desiccation of plants with Reglone had a negative effect on the strength properties of siliques, lowering their resistance to cracking. In comparison to the control, the effect of starch on the strength properties of siliques was statistically insignificant.