Explain mass selection and pure line selection. How is pure line selection a better method for crop improvement?
Pure Line
Selection:
A. Procedure:
The plants are
selected for their desirability of characters that may not be similar
phenotype.
The selected
plants are subjected to progeny test.
The procedure is
more effective as careful progeny test and yield trials are conducted.
Generally 9-10
years are required to develop a new variety.
This method is
used in self pollinated crops only.
B. Product:
The new variety is
a pure line.
The new variety is
highly uniform, genetic variation is very less.
Pure line variety
is expected to have a narrower adaptation and lower stability in performance as
there is less genetic variation.
The variety is
easily identified in seed certification programmes.
C. Quality of
improvement:
The improvement of
quality of the variety is generally the best which is present within the
existing variety of the original population, i.e., this method brings about the
best improvement over the original variety.
Mass Selection:
A. Procedure:
The selected
plants should be of similar phenotype as the seeds are mixed together.
In normal mass
selection progeny test is not performed.
As a large number
of plants are selected, extensive yield trials are not necessary; less
demanding process.
Generally 5-7
years are required to develop a new variety.
This method is
used in both self and cross pollinated crops.
B. Product:
The new variety is
a mixture of pure lines.
The variety has
genetic variation, so in general appearance it is less uniform.
The variety has
wider adaptation and greater stability than pure line varieties.
The variety is
relatively more difficult to identify in seed certification programme.
C. Quality of
improvement:
The variety is
inferior to the best pure line because most of the lines included within it
will be inferior the best pure line.
Pure Line Selection:
A. Procedure:
The plants are selected for their desirability of characters that may not be similar phenotype.
The selected plants are subjected to progeny test.
The procedure is more effective as careful progeny test and yield trials are conducted.
Generally 9-10 years are required to develop a new variety.
This method is used in self pollinated crops only.
B. Product:
The new variety is a pure line.
The new variety is highly uniform, genetic variation is very less.
Pure line variety is expected to have a narrower adaptation and lower stability in performance as there is less genetic variation.
The variety is easily identified in seed certification programmes.
C. Quality of improvement:
The improvement of quality of the variety is generally the best which is present within the existing variety of the original population, i.e., this method brings about the best improvement over the original variety.
Mass Selection:
A. Procedure:
The selected plants should be of similar phenotype as the seeds are mixed together.
In normal mass selection progeny test is not performed.
As a large number of plants are selected, extensive yield trials are not necessary; less demanding process.
Generally 5-7 years are required to develop a new variety.
This method is used in both self and cross pollinated crops.
B. Product:
The new variety is a mixture of pure lines.
The variety has genetic variation, so in general appearance it is less uniform.
The variety has wider adaptation and greater stability than pure line varieties.
The variety is relatively more difficult to identify in seed certification programme.
C. Quality of improvement:
The variety is inferior to the best pure line because most of the lines included within it will be inferior the best pure line.
