The most important step in plant breeding techniques are the screening and selection methods and their types are mentioned with easily understandable pictures

2. • Plant breeding is the purposeful manipulation of qualities in
plants to create new varieties with a set of desired
characteristics.
• Plants with higher qualities are selected by and crossed to
obtain plants with desired quality.
• This results in a plant population with improved and desired
traits.

3. • Field screening
• Greenhouse screening
• Laboratory screening
• Bioassay techniques

4. • One major technique of plant breeding is selection, the process
of selectively propagating plants with desirable characteristics
and eliminating or "culling" those with less desirable
characteristics.
• Types:
– Pure line selection
– Mass selection
– Clonal selecion

5. Pure line Selection
• Pure line selection is a method in which new variety is
developed by selection of single best plant progeny among
traditional varieties or land races.
• In pure-line selection, a large number of plants are selected
from a self-pollinated crop and are harvested individually;
individual plant progenies from them are evaluated, and the
best progeny is released as a pure-line variety.
• pure-line selection is also known as individual plant selection.

7. Merits
• This is a good method of isolating the best genotype
• The variety developed by this method is uniform and more
attractive than mass selected variety. .
• Due to extreme uniformity variety is easily identified in seed
certification programmes.
• This is an easy and cheap method of crop Improvement.

8. Demerits
• Pure-line selection requires more time and space
• Isolate only superior genotypes from mixed population.
• In pure-line selection, new variety can not be developed by
breeders.
• The selection method is applicable only in Self -pollinated
crops.

9. Mass selection
• Mass selection refers to a methods of crop improvement
in which individual plants are selected on the basis of
phenotype from a mixed population, their seeds are
bulked and used to grow next generation.
• The oldest methods of crop improvement
• Applicable to both self and cross pollinated species.

11. Merits
• Mass selected varieties have provide good protection against
diseases.
• This method is applicable to both self and cross pollinated
species.
• Easy and simple method of crop improvement
• Varieties developed through mass selection are likely to be
wide adapted than any other selection.

12. Demerits
• Progeny test is not carried out in mass selection
• The varieties developed through mass selection show variation
is not as uniform
• Varieties developed by mass selection are more difficult to
identify than pure-lines in seed certification programmes.

13. Clonal selection
• Clonal selection is the method of selection of desirable clones
from the mixed population of vegetatively propagated crops.
• It is one of the methods for improving the vegetatively
propagated crops such as sugarcane, banana, potato, citrus,
ginger etc.

15. Merits
• Clonal selection is an easy and less time consuming method.
• Easy maintenance because there is no problem of out crossing
and loss of seed viability.
• Clonal selection is the only method of breeding in vegetatively
propagated fruit plants.

16. Demerits
• There is limited chance of getting new and useful type of
variability
• The multiplication rate is low.
• It is only useful for vegetatively propagated plants.