Air-dry grains of two Polish spring barley cultivars, Rasbet and Barke, were used for treatment with static and alternating magnetic field, irradiation with three different doses of gamma rays, and a combination of magnetic field + gamma rays. After the treatments, the grains were sown in plots in a field experiment in which the date of plant emergence was observed during the vegetation period, and the yield parameters were determined after the harvest. The application of magnetic field alone induced, in both cultivars, a considerable level of variability of the traits under study, expressed by a small reduction in their values and, primarily, by the stimulation effect. In single treatments with gamma rays, the lowest dose (60 Gy) induced a slight stimulation effect, but the higher doses - 100 and particularly 140 Gy � caused a reduction effect as compared to the control and to the magnetic field treatment. The combined effect of magnetic field and gamma rays on the induction of biological damage in the M1 generation indicates that the values obtained were generally lower in comparison with the control and the exclusive use of magnetic field, but for most of the combinations and traits, especially those directly related with plant fertility, they were distinctly higher. In spite of the ability of both kinds of magnetic field (static and alternating) to stimulate the traits studied, the values of the number of fertile spikes per plant and the number and weight of grains per spike and plant indicate higher effectiveness of static magnetic field in reducing biological damage than alternating magnetic field, especially in the case of the Barke variety.