Plant Breeding Methods: Mass vs. Pureline Selection

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Questions and Answers

What is the first step in the clonal selection procedure?

A preliminary yield trial is conducted.

The best clone is released as a new variety.

Clones from selected plants are grown separately.

A few superior plants are selected. (correct)

Which of the following is NOT a merit of clonal selection?

It preserves existing gene combinations in clones.

It generates new genetic variability. (correct)

It avoids inbreeding depression.

It helps maintain the purity of clones.

What occurs during the third year of the clonal selection process?

A few superior plants are initially selected.

Seed multiplication for distribution begins.

Outstanding clones are selected based on desirability. (correct)

Multilocation yield trials are conducted.

What is a demerit of clonal selection?

It relies solely on natural variability in the population. Signup and view all the answers

What is the main purpose of multilocation yield trials conducted in the fourth to sixth years?

To identify the best clone for release as a new variety. Signup and view all the answers

What is the main characteristic of plants selected in mass selection?

Plants are selected based on their phenotypic characters. Signup and view all the answers

Which year does the seed multiplication for distribution occur in mass selection?

Sixth Year Signup and view all the answers

What is one of the demerits of mass selection?

Developed varieties can show variation and are less uniform. Signup and view all the answers

Which is a merit of mass selection?

Method retains considerable genetic variability. Signup and view all the answers

What defines a pureline in plant breeding?

Progeny of a single, homozygous, self pollinated plant. Signup and view all the answers

Why is mass selection not commonly used for self-pollinated crops?

Pure-line varieties are more popular. Signup and view all the answers

What phase occurs in the second year of mass selection?

Phenotype of the selected population is evaluated. Signup and view all the answers

Which of the following statements about mass selection is NOT true?

It generally provides significant improvement compared to pure-line methods. Signup and view all the answers

What advantage does pureline selection have over mass selection?

It achieves maximum possible improvement over the original variety. Signup and view all the answers

Which characteristic is NOT true about purelines?

The variation within a pureline is heritable. Signup and view all the answers

What is one of the main uses of purelines in biological research?

To reduce genetic variation for consistent results. Signup and view all the answers

In which year are undesirable progenies rejected during the pureline selection process?

Second Year Signup and view all the answers

Which of the following is a demerit of pureline selection?

It requires more time and space for yield trials. Signup and view all the answers

How does pureline selection contribute to plant breeding efforts?

By ensuring uniform genotypes among selected plants. Signup and view all the answers

What is a primary characteristic of a clone in plant selection?

All members of a clone are genetically identical to the parent plant. Signup and view all the answers

Which of the following describes an inherent challenge of pureline selection?

There is a limited application spectrum for pureline varieties. Signup and view all the answers

Study Notes

Mass Selection

Several plants with desirable traits are selected from a population based on phenotype.
Used to improve existing varieties and purify pureline varieties.
Involves several years of selection and testing.
Demerits:
- Less uniform varieties compared to purelines.
- Less improvement than purelines.
- Less common than purelines for self-pollinated crops.
- Difficult to identify in seed certification programs.
- Requires genetic variation within the population to be effective.
Merits:
- Wider adaptation than purelines.
- Less time and cost intensive than other methods.
- Retains genetic variability.
- Relatively easy to perform.

Pureline Selection

Progeny of a single, homozygous, self-pollinated plant.
All plants within a pureline have identical genotype, variation is environmental.
Involves selecting individual plants and evaluating their progeny over several years.
Characteristics:
- Uniform genotype.
- Environmental variation.
- Genetic variability develops over time due to mixing, hybridization, and mutations.
Uses:
- Commercial variety.
- Parent in hybridization programs.
- Mutation studies.
- Research in biology, medicine, etc.
Applications:
- Improving local varieties.
- Improving existing pureline varieties.
- Improving introduced varieties.
Merits:
- Maximum possible improvement over the original variety.
- Extremely uniform.
- Easy identification for seed certification.
Demerits:
- Limited adaptation.
- More time, space and expensive than mass selection.
- More demanding for breeders.

Clonal Selection

A group of plants from a single plant through asexual reproduction.
All members have the same genotype.
Selection focuses on selecting superior plants and propagating them asexually.
Procedure:
- Select superior plants.
- Propagate clones.
- Evaluate clones in yield trials.
- Select outstanding clones.
- Release best clone as a new variety.
Merits:
- Only method applicable to clonal crops.
- Avoids inbreeding depression.
- Can be combined with hybridization to generate variability.
- Useful for maintaining purity of clones.
Demerits:
- Utilizes existing variability, does not generate new variability.
- Sexual reproduction is needed for hybridization and variability creation.

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Description

This quiz explores the key concepts of mass selection and pureline selection in plant breeding. It discusses the merits and demerits of each method, as well as their applications in improving crop varieties. Test your knowledge on how these selection methods differ in genetic variability and adaptation.