Current estimates suggest that the world population may increase to 9,6 billion in 2050. Demand for agricultural products may also increase by 50% by 2030, as situation that requires intensification of food production systems. Therefore development of crops tolerant to environmental extremes is necessary. Maize is one of the most important crops in terms of output and nutritional value. Analyses of exposure to gamma rays at 5, 15 and 20 Gy suggest that there are significant differences in root elongation across homozygous lines from Mexico and Costa Rica.