Irradiation of dry seeds of Arabidopsis with heavy ions (HZE-particles) produced by UNILAC-accelerator (GSI, Darmstadt) yielded aberrations in varied developmental endpoints such as survival rate and embryo vitality. The damage increased with particle density and charge. Cross sections in the range of 0.2-1.0 micrometer2 for Ne and Ar and 2.0-10.0 micrometers2 for Xe were estimated. Soaked seeds were more sensitive than dry seeds (cross-section 2.0-10.0 micrometers2 for Ar). The induced total damage in the irradiated seeds was estimated adding the different damages weighted by certain factors. These results will be used as base data for the interpretation and evaluation of spaceflight experiments on the biological effects of cosmic radiation.