Pure Line Theory and Pure line Selection
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- Johannsen developed the pure line theory while working with princess beans in 1901. He established 19 pure lines through individual plant selection and followed with selection among the pure lines. - Johannsen concluded that continuous inbreeding leads to homozygosity, variation within a pure line is due to environment only, and selection within a pure line is not effective because all plants have the same genotype. - A pure line is the progeny of a single homozygous, self-pollinated plant. Pure line selection involves evaluating individual plant progeny from a self-pollinated crop to release the best as a pure line variety.
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This document discusses mass selection, a method of plant breeding where individual plants are selected based on desirable phenotypes from a mixed population. Seeds from selected plants are then combined to grow the next generation. Mass selection can be used to improve self-pollinating or cross-pollinating crops. It has resulted in improved varieties of crops like bajra, yellow sarson, brown sarson, maize, desi cotton, and castor. While mass selection is simple and applicable to many crops, the improvements may be less than other methods and varieties developed have more genetic variation than pure lines.
15. mass selection in cross pollinated crops
This document discusses breeding methods for cross-pollinated crops. It describes 10 different breeding methods including mass selection, backcrossing, heterosis breeding, and transgenic breeding. It focuses on two main categories of breeding for cross-pollinated crops: population improvement and hybrid/synthetic varieties. Population improvement methods include mass selection and progeny testing methods like ear-to-row selection and recurrent selection. Mass selection involves selecting plants based on phenotype without progeny testing, while ear-to-row selection and recurrent selection do involve progeny testing over multiple generations.
Principles and methods of breeding in cross pollinated crops
This document discusses principles and methods of breeding in cross-pollinated crops. It begins by defining cross-pollination and listing several mechanisms that promote it, such as dicliny, dichogamy, heterostyly, herkogamy, and self-incompatibility. Characteristics of cross-pollinated plants are provided, as well as an overview of various breeding methods used for these crops, including plant introduction, mass and progeny selection, recurrent selection, heterosis breeding, backcross method, synthetic and composite breeding, mutation breeding, and polyploidy breeding. Each method is described in one to two paragraphs.
SELECTION METHODS IN SELF-POLLINATED CROPS viz., mass selection, pureline sel...
SELECTION METHODS IN SELF-POLLINATED CROPS viz., mass selection, pureline sel...AMIT RANA Ph. D Scholar
MASS SELECTION
Mass selection is a method of breeding in which individual plants are selected on the basis of phenotype from a mixed population , their seeds are bulked and used to grow the next generation.
Selection cycle may be repeated one or more times to increase the frequency of favorable alleles - phenotypic recurrent selection.
PURELINE SELECTION
A pureline is the progeny of a single homozygous plant of a self-pollinated species. All the plants in a pureline have the same genotype and the phenotypic variation within a pureline is due to the environment alone and has no genetic basis. However, variation within a pureline is not heritable. Hence selection in a pureline is not effective. Johannsen (1903,1926), a Danish biologist, developed the concept of pureline theory working with Princess variety of French bean (Phaseolus vulgaris), which showed variation for seed size. From a commercial seed lot he selected seeds of different sizes and grew them separately. The progenies differed in seed size. Progenies from larger seeds produced larger seeds than those obtained from smaller seeds. This clearly showed that the variation in seed size in the commercial seed lot of princess variety had a genetic base. As a result selection for seed size was effective.
Introduction
PEDIGREE SELECTION
Pedigree selection is a widely used method of breeding self-pollinated species.
A key difference between pedigree selection and mass selection or pure-line selection is that hybridization is used to generate variability (for the base population), unlike the other methods in which production of genetic variation is not a feature.
The method was first described by H. H. Lowe in 1927.
Pedigree selection is a breeding method in which the breeder keeps records of the ancestry of the cultivar.
The base population is established by crossing selected parents, followed by handling an actively segregating population.
Documentation of the pedigree enables breeders to trace parent–progeny back to an individual F2 plant from any subsequent generation.
The breeder should develop an effective, easy to maintain system of record keeping.
Pedigree selection is applicable to breeding species that allow individual plants to be observed, described, and harvested separately.
Breeding Methods in Cross Pollinated crops, Mass Selection, Ear to row method...
General Introduction to Breeding Methods in Cross Pollinated crops, Mass Selection, Ear to row method and Progeny Selection Schemes
Plant breeding techniques
The most important step in plant breeding techniques are the screening and selection methods and their types are mentioned with easily understandable pictures
Pure and Hybrid Seed Production
The document discusses pure line seed production. Pure line selection involves selecting individual plants from a population, growing out their progeny separately, and evaluating the progeny for traits like yield and disease resistance. The best progeny is selected and released as a new variety. Pure line selection is useful for developing uniform varieties in self-pollinated crops, but it is labor intensive and does not provide wide adaptability.
selection in clonally propagated crops assumtions and realities
- Clonally propagated crops reproduce asexually, preserving genotypes indefinitely but lacking genetic variation.
- A clone is a group of plants produced from a single plant through asexual reproduction. Clones are identical in genotype but can vary phenotypically due to environment.
- Genetic variation within clones can arise from somatic mutation, mechanical mixtures, or sexual reproduction. Selection of superior clones is used to breed new clonal crop varieties.
History of Plant Breeding
This document provides information on breeding methods for self-pollinated crops. It discusses pureline selection, mass selection, and multiline breeding. Pureline selection involves isolating homogenous lines from a mixed population and selecting the best ones. Mass selection selects desirable plants directly from a mixed population based on phenotype. Multiline breeding develops mixtures of isolines or related lines that differ in specific genes to provide disease resistance while maintaining uniform agronomic traits.
Mutation breeding presentaion
This document provides an overview of mutation breeding. It discusses the history of mutation breeding from its origins in the 1930s to recent developments. It describes the two types of mutations as micro- and macro-mutations. It outlines the structure and procedure of developing a mutation, including the types of mutagens used, stages of the segregating population from M1 to selecting superior lines, and screening and selection techniques. Finally, it discusses the advantages of mutation breeding in introducing novel variation and targeting specific genes/traits, and the disadvantages of it being a random process and requiring large populations to find rare mutants.
Plant breeding methods of vegetatively propagated crops
Vegetatively propagated crops are bred by intentionally crossing of closely or distantly related individual to produce new crop varieties or lines with desirable traits. Breeding of vegetative crops have successfully improved quality, yield, tolerance of crops to environmental pressure. Breeding helps in producing crops that are resistant to viruses, fungi and bacteria and helps in longer storage period for the harvested crop.
Similar to Pure Line Theory and Pure line Selection (20)
Pureline and Mass selection methods of plant breeding
Pureline and Mass selection methods of plant breeding
Methods of plant breeding in self pollinating plants
Methods of plant breeding in self pollinating plants
Principles and methods of breeding in cross pollinated crops
Principles and methods of breeding in cross pollinated crops
SELECTION METHODS IN SELF-POLLINATED CROPS viz., mass selection, pureline sel...
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selection in clonally propagated crops assumtions and realities
selection in clonally propagated crops assumtions and realities
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plant breeding methods in asexually or clonally propagated crops
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Pure Line Theory and Pure line Selection
- 1. SAM HIGGIN BOTTOM UNIVERSITY OF AGRICULTURE, TECHNOLOGY & SCIENCES, NAINI, ALLAHABAD DEPARTMENT OF PLANT BREEDING AND GENETICS TOPIC: PURE LINE THEORY AND PURE LINE SELECTION PRESENTED BY P. NIKHIL 19MSCGPB177 SUBMITTED TO: Dr.B.G.SURESH DEPT OF GENETICS AND PLANT BREEDING
- 2. • Started experiments in 1901.Established 19 pure lines by selection of individual beans from the mixed seed lot of 8kg.(named those as A,B,...,T) • Followed selection among these purelines too and selected the smallest and largest beans (seeds).planted those selected seeds. Pure LineTheory Johannsen developed concept of pure line while working with princess bean ( Phaseolus vulgaris nana).Princess bean exhibits self -pollination Procedure:
- 3. Johannsen’s theory and conclusions: • Continuous inbreeding (selfing) leads to homozygosity. • Variation with in a pure line results from environment only. • Selection with in pure line is not effective because all the plants in a pure line have some genotype. • Selection in the original population is effective because the plants have genetic variation.
- 4. PURE LINE SELECTION INTRODUCTION: • A pure line is the progeny of a single homozygous, self pollinated plants. • In pre line selection a large number of plants are selected from a self pollinated crop and harvested individually; individual plants progeny from them are evaluated and the best progeny is released as a pure line variety. • All the individuals within a pure line have identical genotype and any variation present within a pure line solely due to environment.
- 5. Characteristics of Purelines: • All the plants within a Pureline have the same genotype as the plant from which the pureline was derived since the parent plant was homozygous and self-fertilized. • Variation present within a pureline is due to the environment and non heritable. • Purelines become genetically variable with time due to mechanical mixture, natural hybridization and mutations.
- 6. Uses of Purelines • As a variety • As Parents in hybridization programme. • In studies on mutation • Pure lines are used for studying mutations and other biological investigations such as medicine, immunology, physiology, and biochemistry.
- 7. Application of Pureline selection • Improvement of local varieties. • Selection in introduced varieties. • Improvement of old Pureline varieties. • Selection for a new characteristic in a pureline.
- 8. Pure line selection Procedure:
- 9. Advantages of Pureline Selection • It achieves the maximum possible improvement over the original variety. • Pureline varieties are extremely uniform; they are therefore preferred by farmers and consumers to a less uniform variety developed through mass selection. • Due to extreme uniformity, the variety is easily identified in seed certification programmes.
- 10. Disadvantages of Pureline Selection • The varieties developed through Pureline selection generally do not have the wide adaptation and stability in the production possessed by the local varieties from which they are developed. • Pureline selection requires more time, space and expensive yield trials than mass selection. • The improvement is dependent on the genetic variation present in the original population. • The breeder has to devote more time to pureline selection than to mass selection.
- 11. THANKYOU