The following are the main breeding methods for self pollinating plants:
- Mass selection
- Pure – line selection
- Hybridization
- Marker assisted selection
- synthetic populations
Mass selection
Mass selection is the process of selection of the crops breeding based on their overall phenotype rather than based on specific traits. Mass selection will improve the frequency of the superior genotypes.
Basic Steps of the Mass selection
- step 1 – Grow a genetically variable population (landrace population)
- step 2 – plants are selected based on their overall phenotypic characters
- step 3 – selfed seed is produced
- step 4 – seed harvested and bulked
- step 5 – bulked seed is grown out
- step 6 – new round of selection is started
- step 7 – test performance of the selected plants until it releases as a new variety.
Advantages of the mass selection
- Mass selection is relatively simple and straightforward compare to other methods.
- Improve multiple traits at the same time because selection is done base on the overall phenotype
- Cost effective – does not require specific equipments
- More suitable for large scale implementations.
Disadvantages of mass selection
- Cause to genetic drift – because mass selection based on overall phenotype, rather than the specific genes.
- Loss of genetic diversity
- Cause to inbreeding depression
- Time consuming – it takes several generation to see improved plants with uniform characters.
- Not suitable for improving the quantitative traits
Mass selected plants are not entirely uniform uniformity will change on plant breeders goal In some cases having certain degree of variation with in the population might be useful because it can improve the resistance for abiotic stress, pests and diseases. However the goal is the commercial large scale production uniformity is must.
Pure – line selection
Pure-line selection is the process that individual plants are selected for specific trait and their seed are used to produce the next generations in order to produce uniform and stable populations.
Steps of the pure line selection
step 1 – single plant progeny are grown out
step 2 – selected plant progenies are harvested individually (not bulked)
step 3 – after the 4-6 round highest performing plants are selected
step 4 – Test the selected plant with existing superior cultivar to evaluate the performance and develop the new variety.
Advantages of the pure line selection
- Very high degree of uniformity
- very high degree of stability
- pure line variety are easy to handle and maintain
- environment conditions and management practices become more predictable when the cultivar becomes more uniform and stable.
Disadvantages of the pureline selection
- loss of the genetic diversity caused to inbreeding depression
- loss of valuable traits
- time consuming, more resources for progeny rows than the mass selection.
Hybridization
Hybridization is the process that improve the genetic variations in the plant population by introducing new genetic diversity form another population.
