Breeding of Fruit and Plantation Crops

Handling of the Mutagen – Treated Population

The following handling procedure is based on the selection for a recessive mutant allele.

1. M1 generation: Several hundred (500 or more) seeds are treated with a mutagen and are space-planted. M1 plants will be chimeras for the mutation present in heterozygous state. About 20 seeds from each M1 plant are harvested to raise the M2 progeny rows.
2. M2 generation: About 2,000 progeny rows are grown. Careful and regular observations are made on the M2 rows. But only distinct mutations are detected in M2 because the observations are based on single plants. All the plants in M2 rows suspected of containing new mutations are harvested separately to raise individual plant progenies in M3. If the mutant is distinct, it is selected for multiplication and testing. However, most of the mutations will be useless for crop improvement. Only 1-3 per cent of M2 rows may be expected to have beneficial mutations.
3. M3 generation: Progeny rows from individual selected plants are grown in M3. Poor and inferior mutant rows are eliminated. If the mutant progenies are homogeneous, two or more M3 progenies containing the same mutation may be bulked. Mutant M3 rows are harvested in bulk for a preliminary yield trial in M4.
4. M4 generation: A preliminary yield trial is conducted with a suitable check, and promising mutant lines are selected for replicated multi location trials.
5. M5-M8 generation: Replicated multilocation yield trials are conducted. The outstanding line may be released as a new variety.


• It may be noted that above procedure is recommended for all horticultural crops, which are exclusively propagated by sexual means.e.g.Vegetables, Crossandra, Periwinkle etc.A detailed method to isolate stable solid mutants in vegetatively propagated horticultural plant is presented.