Principles of Plant Breeding (2+1)

Single seed descent method

• Single seed descent method This method is amodification of bulk method
• Single seed from each F2 plants is bulked to raise the F3 generation. Similarly F3, F4, F5 generation when the plants are homozygous plant progenies are advanced to next generation. Selection is done mainly among the progenies and number of progenies is sufficiently reduced to permit replicated trail. Individual plants may be selected from outstanding families showing segregation. So preliminary yield trial and quality tests beginin F7 to F8.

Objectives
1. Rapidly advance of generation of crosses.
2. F2 and subsequent generation are grown with a very high plant density.
3. F2 plant is represented equally in the end population.
4. Off season nursery/green house facilities are utilized.
5. Maximum possible speed.
6. Require very little space/effort/ labor.
7. Do not permit any form of selection during the segregating generation.
8. In each successive generation the population size become small due to poor generation and death of plants due to disease/pest.

Merits:
1. Simple, convenient and inexpensive.
2. Due to elimination of undesirable types, isolation of desirable types is easier.
3. Natural selection increase the frequency of superior types in the population.
4. No pedigree record is to be kept which save time and labor.
5. Isolation of transgressivesegregants is more.

Demerits:
1. Needs more time.
2. Little opportunity for a breeder to use selection.
3. Information on the inheritance of character cannot be obtained.
4. Naturalselection act against agronomicallydesirable types.