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Chapter List
Principles of Plant Breeding – Chapter List
- Introduction to Plant Breeding
- Evolution and Diversity of Crop Plants
- Plant Genetic Resources and Pre-breeding
- Genetic Basis of Plant Breeding
- Gene Action and Combining Ability
- Breeding Methods in Self-pollinated Crops
- Population Breeding in Self-pollinated Crops and Transgressive Breeding
- Breeding Methods in Cross-pollinated Crops
- Recurrent Selection and Population Improvement
- Hybrid Breeding
- Special Reproductive Systems in Plant Breeding
- Breeding of Asexually Propagated Crops
- Special Breeding Techniques
- Modern Breeding Approaches
- Cultivar Development and Plant Variety Protection
Course Coverage
This Principles of Plant Breeding study material covers classical and modern plant breeding concepts, including genetic variability, selection, hybridization, breeding methods, population improvement, heterosis, hybrid breeding, special reproductive systems, mutation breeding, molecular breeding, marker-assisted selection, genomic approaches, cultivar development, and plant variety protection.
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Syllabus
Content: Historical aspect of heterosis, nomenclature and definitions of heterosis; Heterosis in natural population and inbred population; Evolutionary aspects – Genetic consequences of selfing, sibbing and crossing in self-and cross-pollinated and asexually propagated crops; Pre-Mendelian and Post-Mendelian ideas – Evolutionary concepts of heterosis; Genetic theories of heterosis – Physiological, Biochemical and molecular factors underlining heterosis; theories and their estimation; Biometrical basis of heterosis. Prediction of heterosis from various crosses, inbreeding depression, coefficient of inbreeding and its estimation, residual heterosis in F2 and segregating populations, importance of inbreeding in exploitation of heterosis – case studies.; Relationship between genetic distance and expression of heterosis, case studies; Divergence and genetic distance analyses, morphological and molecular genetic distance in predicting heterosis; Development of heterotic pools in germplasm/ genetic stocks and inbreeds, their improvement for increasing heterosis. Male sterility and use in heterosis breeding; Male sterile line creation and diversification in self-pollinated, cross pollinated and asexually propagated crops; Creation of male sterility through genetic engineering and its exploitation in heterosis; Maintenance, transfer and restoration of different types of male sterility; Use of self-incompatibility in development of hybrids. Hybrid seed production system: 3-line, 2-line and 1-line system; Development of inbreeds and parental lines- A, B and R lines – functional male sterility; Commercial exploitation of heterosis, maintenance breeding of parental lines in hybrids; Fixation of heterosis in self, cross and often cross pollinated crops, asexually/ clonally propagated crops, problems and prospects; Apomixis in fixing heterosis-concept of single line hybrid; Organellar heterosis and complementation. Hybrid breeding in wheat, rice, cotton, maize, pearl millet, sorghum and rapeseedmustard, sunflower, safflower and castor oilseed crops and pigeonpea.
Frequently Asked Questions.
Frequently Asked Questions (FAQs) – Principles of Plant Breeding
1. What is Plant Breeding?
Plant breeding is the science and art of genetically improving crop plants to develop varieties with desirable characteristics such as higher yield, better quality, disease and pest resistance, stress tolerance, and improved adaptation.
2. What are the main objectives of Plant Breeding?
The major objectives of plant breeding are to increase yield, improve crop quality, develop resistance to diseases and insect pests, enhance tolerance to abiotic stresses, improve adaptability, modify maturity duration, and develop varieties suitable for specific production environments.
3. What is the difference between self-pollinated and cross-pollinated crops?
Self-pollinated crops are predominantly fertilized by pollen from the same plant or flower, resulting in greater homozygosity. Cross-pollinated crops mainly undergo pollination between genetically different plants and generally maintain higher levels of heterozygosity.
4. What is genetic variability in Plant Breeding?
Genetic variability refers to differences in genetic constitution among individuals within a population. It provides the basic material required for selection and genetic improvement of crop plants.
5. What is heritability?
Heritability is the proportion of phenotypic variation that is attributable to genetic variation. Broad-sense heritability considers total genetic variance, whereas narrow-sense heritability considers additive genetic variance.
6. What is genetic advance?
Genetic advance is the expected improvement in the mean performance of a population resulting from selection. It depends on selection intensity, heritability, and phenotypic variability.
7. What is pure line selection?
Pure line selection is a breeding method in which superior individual plants are selected from a genetically variable self-pollinated population and their progenies are evaluated to develop a uniform, homozygous variety.
8. What is mass selection?
Mass selection involves selecting a large number of desirable plants based mainly on their phenotype and bulking their seeds to form the next generation. It is one of the oldest and simplest methods of plant breeding.
9. What is the pedigree method?
The pedigree method is a breeding method used mainly in self-pollinated crops in which superior plants are selected from segregating generations and detailed records of ancestry are maintained throughout the selection process.
10. What is backcross breeding?
Backcross breeding is used to transfer one or a few specific desirable traits from a donor parent into an otherwise desirable recurrent parent. The selected progeny are repeatedly crossed with the recurrent parent.
11. What is recurrent selection?
Recurrent selection is a population improvement method involving repeated cycles of selection and intermating of superior individuals or progenies. It is designed to increase the frequency of favorable alleles while maintaining genetic variability.
12. What is heterosis?
Heterosis, or hybrid vigour, is the superior performance of a hybrid compared with its parents or a suitable reference variety for one or more traits. It is widely exploited in commercial hybrid breeding.
13. What are GCA and SCA?
General combining ability (GCA) refers mainly to the average performance of a parent in hybrid combinations and is primarily associated with additive genetic effects. Specific combining ability (SCA) refers to the performance of a particular cross beyond what would be expected from the parents' GCA and is mainly associated with non-additive genetic effects.
14. What is male sterility?
Male sterility is the condition in which a plant is unable to produce functional or viable pollen while its female reproductive function remains sufficiently functional. It is an important tool for hybrid seed production because it can reduce or eliminate the need for manual emasculation.
15. What is cytoplasmic male sterility (CMS)?
Cytoplasmic male sterility is male sterility controlled primarily by cytoplasmic factors, usually mitochondrial genes. In the three-line hybrid breeding system, CMS is maintained using a maintainer line and fertility is restored in hybrids using a restorer line.
16. What is mutation breeding?
Mutation breeding involves the use of physical or chemical mutagens to create heritable genetic variation. Useful mutants are identified through screening and selection and may be developed into improved varieties.
17. What is marker-assisted selection (MAS)?
Marker-assisted selection is a molecular breeding approach in which DNA markers linked to genes or quantitative trait loci are used to identify plants carrying desirable genetic regions. It can accelerate selection for traits that are difficult or expensive to measure phenotypically.
18. What is genomic selection?
Genomic selection is a breeding approach in which genome-wide molecular marker information is used to predict the genetic or breeding value of individuals. It is particularly useful for traits controlled by many genes with small effects.
19. What is an ideotype in Plant Breeding?
An ideotype is a conceptual model of a plant possessing a specific combination of morphological, physiological, and other traits expected to provide desirable performance in a defined production environment.
20. What is Plant Variety Protection?
Plant variety protection is a legal framework that provides specified rights and recognition for qualifying plant varieties. In India, plant variety protection is primarily governed by the Protection of Plant Varieties and Farmers’ Rights Act, 2001, which also recognizes important rights of farmers and researchers.
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Last Updated: August 2026
