SUMMARY The meiotic behaviour of one wheat cultivar (RS1) and two triticales (TSA1 X S-8017 and TSA1 X Jacuí) irradiated with cobalt 60, was studied in order to detect variability about fertility for plant improvement purposes. Radiation doses received by the wheat cultivar were 35.0 and 37.5kr and by the triticales was 30kr. Chromosome pairing and segregation as well as meiotic index was observed in Ml and M3 pollens mother cells prepared by the smear method. Ali the genotypes observed had meiotic pairing above 90%. The chromossomic segregation was variable between genotypes. The meiotic index indicated that the wheat irradiated with the lower dosage mantained the highest percentage of normal tethrads. The M3 generation of the TSA1 X Jacuí cross had meiotic indexes above 90%- Thoses genotypes will be evaluate for agronomic traits, since citogeneticaly will not bring problems to the plant breeder.
cytogenetic; wheat; triticale; irradiation; cobalt 60
