X-ray induced mutations in French Bean

Dry seeds of an early and high yielding bush variety, Wax Podded, having yellow coloured pods were irradiated with 7 kr, 14 kr and 21 kr of X-rays with a view to isolating mutants with green pod colour. The maximum frequency of mutations was observed in 7 kr. Among the qualitative characters, the colours of pod and seed were greatly affected, particularly the latter. Eleven green-podded mutants including nine in 7 kr and two in 14 kr treatments were obtained in M₂ generation. Several polygenic and economic characters like number and size of pods, number of seeds per pod, seed yield and 100-seed weight were also affected. The variance was enlarged in the treated progenies in M₂, although the mean was shifted in the negative direction. Selection was, however, effective and through recurrent selection, several families with a higher pod and seed number per plant and a higher 100-seed weight were isolated in the M₄ generation. Mutation breeding thus offers considerable scope for altering both qualitative and quantitative characters in a desirable direction.