Division of Genetics, Indian Agricultural Research Institute, Delhi-12
*Present address: Botany Dept., Faculty of Science, M. S. University of Baroda, Baroda-2.
Dry dormant seeds of three varieties of Triticum durum (N.P. 410, N.P. 411 and N.P. 412) were treated with fast neutrons, gamma rays and ethyl methane sulphonate. Chimeral changes were observed in ear characters in the M2 generation. Chlorophyll mutations were observed in the M2 generation. The spectrum was rather wide indicating thereby the occurrence of a large number of non-reduplicated loci in the genomic constitution with reference to chlorophyll development. The frequency of viable mutations was generally low. The highest value recorded was 1.82 per cen.t (on the basis of number of mutations per 100 M2 plants). The mutation spectrum was found to be very restricted and this suggests that there are only a few loci at which phenotypic buffering does not exist. This finding supports the conclusion arrived at from studies in nulli-tetra plants, that in T. durum the chromosomes of the A and B genomes have considerable homeologous relationships. For obtaining more number of mutations in a species like T. durum with a partly disomic and partly polysomic genetic architecture, it will be essential to continue the screening for mutations to later generations.
