**2.3 Frequency and spectrum of viable mutations**

All the treatments used have induced the widest spectrum of viable mutations. The range of viable mutations in gamma radiation and GR + EMS (Table-1) was 0.61 to 2.16% and 0.21 to 1.81% respectively. The highest percentage of frequency of mutations noted for plant habit, leaf and pod morphology and maturity, due to various treatments of gamma radiation was 0.77%, 0.66%, 0.58% and 0.30% respectively. These results also indicated that the percentage of plant habit mutations was maximum as compared to others. In combination treatments the percentage of frequency for plant habit, leaf, pod and maturity type mutations, was 0.76%, 0.63%, 0.49% and 0.28% respectively. The highest percentage of mutations was obtained in gamma radiation (2.16%) as compared to combination treatment (1.81%).

The widest spectrum and frequency of viable mutations may be due to differential mode of action of the mutagens on different base sequences in various genes. The results indicated that the variety used for study was sensitive to mutagenic treatments.
