[en] The Mangelsdorf subvariety, which is the result of cross-breeding Euchlena mexicana Schrad. and Zea Mays L., was chronically irradiated during gametogenesis (500 R at a rate of 11.11 R per hour) and throughout the vegetation (100 R to 5,000 R at a rate of 0.04 R to 1.95 R per hour). The progeny of the irradiated plants showed genetic variability in the plant height, in the number of spadices on the main stem, in the number of leaves and in the period of vegetation. The selected varieties evidenced good and very good combining ability in parameters which influenced the yield rate. Hybrids gained from these irradiated varieties showed positive heterosis in the plant height, the number of branches per plant, shorter vegetation and the number of spadices per main stem. (author)