Abstract The influence of physical factors, such as microwave radiations, is today an alternative in agriculture for stimulation of plant vitality. In this study we aimed to evaluate the influence of microwaves in the early seedlings stages for 4 Romanian barley genotypes: Cardinal, Sistem, Dana and Maresal. This study was conducted to determine whether there are differentiated responses to microwave irradiation, at different powers and different exposure times, on the dynamics of root growth in some barley cultivars. Root growth measurements were performed after 3, 7 and 14 days of treatment with microwaves. It was observed that genotype, power or exposure time had significant influence both on root growth and on the number of roots of the studied barley genotypes. Microwave treatment caused significant differences in seedlings root growth. The greatest influence on root growth had the time of exposure. The best results in terms of root growth were obtained for the Cardinal and Sistem variety. At these varieties we observed the best stimulation effect, and the lowest influence of the microwave action. The most affected genotype was Dana, with the lowest stimulation effect.