The biological effects of wheat seeds irradiated by 48MeV/u and 20 MeV/u ¹⁴N⁷⁺ beams are studied, respectively. The results show: both penetration and implantation of heavy ions can significantly inhibit growing power (height of plant stem) of wheat seeds. The greater dose is, the weaker growing power is, and the implantation influence on growing power is stronger than the penetration; a great variety of chromosomal aberrations were observed in root tip cells of irradiated seeds and the aberration frequencies were several hundred times higher than that of the corresponding control; it has been proved by 3H-TdR incorporation test that unscheduled DNA synthesis exists in irradiated wheat seed embryos. It is found by ESR spectroscopy that the variation of free radical concentration with total dose has different features for the penetrated and implanted seeds.