Mutation Studies in Onion (Allium Cepa). III. Types and Frequency of Macro-Mutations

Frequency and spectrum of macromutations was recorded in M₂ generation of three onion varieties raised after seed treatment with different doses of gammarays and three chemical mutagens EMS, NMU and EI. The order of mutation frequency observed in three varieties was Pusa Red > Pusa Ratnar > White Warangal. Of the total number of macromutations detected in M2, chlorophyll mutations accounted for more than 60 per cent in the three varieties. Sectorial mutations or chimerism in true sense was absent in the types of chlorophyll mutations. These events in onion were described by adopting a suitable nomenclature, like solid albina, inner and outer albina, indicating the position of mutated leaves. A total of 29 different types of morphological mutations affecting foliage, bulb formation, flowering, seed and growth habit were recorded in three varieties. Some of the mutations recovered in the present experiment with ‘tall plant’, ‘waxless leaves’, ‘pink flowers’ and bulb colour are being evaluated further for their genetical behaviour and to find the possibilities of their use in onion breeding programmes.