For the production of multiline variety genes for rust resistance R1 to R5 are transferred to recurrent parent from donor parent.
Isolines are created with such transfer. Isolines constituting variety are maintained so as to resynthesize multiline variety as and when needed.
Production steps for Multiline Variety
- Selection of recurrent parent
- Selection of donor parent
- Transfer of resistance
- Mixing of isolines
Advantages of Multiline Variety
Merits of the multiline breeding are discussed below.
- At the time of disease outbreak, only one or few lines of the mixture get attacked, others remain resistant. So the loss to the farmer is comparatively less.
- Multiline varieties are more adaptive to environmental changes than individual pure line.
Disadvantages of Multiline Variety
Demerits of the multiline breeding are given below.
- Races of pathogen change as time goes on, so farmer has to change seeds every few years which contains seeds of lines resistant to new pathogen races.
- No improvement in yield or other characters
- Takes more time to develop new variety, in the due course of time new pathogen races may evolve.
- Costly
- All the lines constituting multiline variety may get attacked by the new race of pathogen.
- Not suitable for cross pollinated crops