What is selection and recruitment

Here, I am providing very useful About Selection and recruitment for all competitive exams.  These are important for all competitive exams.

What is Selection and How many types of selection?

Selecting a verity/strain with a superior character from a population or variable, and growing in the next generation, is called selection.

Read About meiosis

Important Note- In the absence of variation, the selection is impossible and without selection it is impossible to make any improvement in the characteristics of a crop only by variation.

How many types of selection?

Selection is two types.
 1. Natural selection
 2. Artificial selection

 What is Natural selection?

 Due to natural factors such as climate, soil, disease, kitt, etc. some plants of the population accept more climate than other plants resulting in the ability to produce more seeds than other plants, this is called natural selection.

 What is an Artificial selection?

  This type of selection is done by human or human who selects the character of the superior plant in the selection and showing it to the next generation.

How many Methods of selection?

 1. Self-pollination crop
 (a).  Mass selection
 (b).  Pure line selection
 2. Cross-pollination crop
 (a).  Mass selection
 (b).  Ear to row method

 1. Self-pollination crop

 (a).  Mass selection-

 In this method, the seeds of the dead plant are collected together and it is called mass selection.  It is noted that genetic variation is present, without variation,
 Selection is not possible.
 1st, year- In this, select 500-1000 plants, keep the seeds of each plant in separate envelopes.

 2nd year Showing the selected seed of the plant in every line from 1st year and the homozygous progeny is called as individual line and in this year also the selection process is adopted keeping in mind that above 50% in each line is in homozygous condition.  But the selections are made and the pure selected line seeds are mixed together.

 3rd-4rth year - Sowing divided by replication, after sowing, they initially test the yield and evaluate in each block.  After evaluation, we mix the selected seed obtained together and release this variety as a new variety.

 5th year - Seeds obtained from replication are sown without selection, this seed is called foundation seed and the next year after sowing again, the seed obtained from it is called the certified seed. The seeds are distributed to farmers through the agency.

  Merit of mass selection

 1. This method costs less.
 2. This method does not require a qualified person.

 3. The environment in which plants occur has a great effect on the growth of the plant and sushupta.

 4. Mass selection depends on phenotype as homozygous and heterozygous plants are not identified and heterozygous plants are selected only. This method can be improved in 1 year.

 Demerit of mass selection

 1. The selection of this method is limited to the parental plant. Plant breeding has no control over the male and sometimes pollination of the selected plant is achieved by involuntary male plants resulting in involuntary symptoms in the next generation.  

 2. This method is not valid for crop improvement, even after that farmers still use this method for paddy in maize and Assam in Uttar Pradesh.

 (b).  Pure line selection-

 In this, the plants selected from the population variety are collected separately and grow these seeds in individual plant progeny, the best of these are selected as individual plant progeny and this method is called pure line selection.  

 1st year- 500 to 1000 plants are selected from a field or field and all these plants are collected together.

 2nd year- Seeds obtained from the 1st year are grown in individual plant progeny and it is evaluated from these progeny that good plants and other plants collect separately.

 3rd year- Seeds received from the above year are grown in blocks and are evaluated and yield tested.

4th and 5th year - Seeds obtained from 3rd year, sowing in replication, produce test and test immunity, quality, etc. This action is used for at least 2 years.  This seed is called foundation seed and the seed obtained after re-sowing is called a certified seed and it is distributed to the farmers.

 Merit of pure line selection-

 1. Diversity in this method is the greatest improvement possible in the entire population.

 2. The seed obtained by this method is called certified seed which is easy to identify.

 3. Qualified farmer is required to get seeds by this method.

 4. There is a pure line developed by this method, so there is a complete lack of genetic variation in them.

 Demerit of pure line selection-

 1. This method requires more time, labor, and money.

 2. The varieties developed by this method get fewer seeds than the original varieties.

 3. For the success of this method, the presence of genetic variation in the original varieties is mandatory.

 2. Cross-Pollination Crops

 (a).  Mass selection
 (b).  Ear to row method

 (a) Mass selection

This is the oldest method for improving such types of crops that phenotype plants are selected and these plants are allowed to be open pollination and collect the seeds obtained from it.                      
 1st year- The seed obtained from the original population is used for improvement.  In these, plants with 200–500 phenotypes are selected and these plants are collected together.

 2nd year- Sowing of mixed seeds obtained from 1st year.  Variations are found in this type of seed.  This first cycle is completed.

 In most crops, the mass selection is grown for many generations. This method is often very important or effective in improving high hereditary traits such as plant length etc.

 Merit of mass selection-

 1. This method is very simple.

 2. The breeder does not take much time in this method.

 3. The cycle of selection is completed in a year.

 4. If care is taken in this method, yield can also be improved by this.

 5. This method is quite effective in improving the symptoms of high pedigree.

 Demerit of mass selection-

 1. In this method, the selection of plants based on phenotype does not depend on the heredity through which variation in length and yield of plants over the environment is achieved.

 2. Pollination is uncontrolled in this method.

 3. In this method, inbreeding takes place in selection due to which inbreeding is called degradation.

 (b) Ear to row method-

 This method was developed at Hopkins in 1908 AD. This method was used on corn. At the same time, it was named Ear to row method.

 1st year- Plants with 50-100 phenotype are selected in the original population and open pollination is allowed in those plants. Seeds of each plant are collected separately.

 2nd year- original seeds of each plant of the population are sowing in each row. After this, plants are selected in a row with good phenotype and collect seed of each plant of selected row separately.

 3rd year-- This action is repeated like the 2nd year.

 Merit of Ear to row method-

 1. This method is relatively very simple.

 2. Other effective methods have evolved in the conversion of this method.  Eg- recurrent selection.

 3. In this method the selection cycle is completed in a year.

 4. This method is based on the progeny test. This method is more powerful than mass selection.

 5. The selection of more plants is done by this method and many plants should not be selected from the same progeny, which reduces inbreeding significantly.

 Demerit of Ear to row method-

 1. In this method population is present in both excellent and dormant plants, thereby reducing the effects of selection.

 2. This method requires more time and efficiency than mass selection.

 3. In this method there are more errors than mass selection.

Read About mitosis-

The above selection will be useful for students who are preparing for competitive exams.

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