Course Content
Qualitative and quantitative characters (qualitative and quantitative characters in crops and their inheritance)
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Biometrical techniques in plant breeding (assessment of variability, aids to selection, choice of parents, crossing techniques, genotype-by- environment interactions)
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Selection in self-pollinated crops (progeny test, pureline theory, origin of variation, genetic advance, genetic gain)
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Hybridization techniques and its consequences (objectives, types, program, procedures, consequences)
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Genetic composition of cross-pollinated populations (Hardy-Weinberg law, equilibrium, mating systems)
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Breeding methods in self-pollinated crops (Mass, Pure line, Pedigree, Bulk, Backcross, etc)
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Learn Introductory Plant Breeding with Rahul

Types of hybridization

a) Intervarietal Hybridization:

  • The parents involved in hybridization belong to the same species; they may be two strains, varieties or races of the same species.
  • It is also known as intraspecific hybridization.
  • The intervarietal crosses may be simple or complex depending upon the number of parents involved.

 

i) Simple Cross: In a simple cross, two parents are crossed to produce the F1. The F1 is selfed to produce F2 or is used in a backcross programme, e.g., A X B à F1 (A X B).

ii) Complex Cross: more than two parents are crossed to produce the hybrid, which is then used to produce F2 or is used in a backcross. Such a cross is also known as convergent cross because this crossing programme aims at converging, i.e., bringing together, genes from several parents into a single hybrid.

 

b) Distant Hybridization:

  • Distant hybridization includes crosses between different species of the same genus or of different genera.
  • When two species of the same genus are crossed, it is known as interspecific hybridization; but when they belong to two different genera, it is termed as intergeneric hybridization.
  • Generally, the objective of such crosses is to transfer one or few simply inherited characters like disease resistance to a crop species.
  • Sometimes, interspecific hybridization may be used for developing a new variety, e.g., Clintonoat variety was developed from a cross between Avena sativa x A. byza ntina (both hexaploid oat species), and CO 31 rice variety was developed from the cross Oryza sativa var. indica x O. perennis.
  • Almost all the present-day sugarcance varieties have been developed from complex crosses between Saccharum officinarum (noble canes), S. barberi (Indian canes) and other Saccharum species, e.g., S. spontaneum (Kans.).
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