Herbage seeds of legume and grass were irradiated in penetration by 80 MeV/u ,20,Ne,10+, ions. The results of field tests and observations of the root−tip cells showed that growth of the seedlings was obviously weakened with increasing doses. Frequencies of chromosomal aberration and micronucleus increased significantly with increasing doses. According to the field growth tests, radiation sensitivity of grass herbage to the heavy ion beams was much higher than leguminous herbage, and suitable dose of the heavy ion irradiation for the grass and leguminous herbages is 20—30Gy and 150Gy, respectively.