Course Content
Qualitative and quantitative characters (qualitative and quantitative characters in crops and their inheritance)
0/2
Biometrical techniques in plant breeding (assessment of variability, aids to selection, choice of parents, crossing techniques, genotype-by- environment interactions)
0/3
Selection in self-pollinated crops (progeny test, pureline theory, origin of variation, genetic advance, genetic gain)
0/5
Hybridization techniques and its consequences (objectives, types, program, procedures, consequences)
0/4
Genetic composition of cross-pollinated populations (Hardy-Weinberg law, equilibrium, mating systems)
0/4
Breeding methods in self-pollinated crops (Mass, Pure line, Pedigree, Bulk, Backcross, etc)
0/5
Learn Introductory Plant Breeding with Rahul
About Lesson

Origin of variation in pure lines

Pure lines show genetic variation after some time because of the following reasons.

  1. Mechanical Mixture: During cultivation, harvesting threshing and storage, other genotypes may get mixed up.
  2. Natural hybridization: Through pure lines are produced in self-pollinated crops, some amount of natural cross pollination occurs in them also can be avoided by isolation and rouging.
  3. Mutation: occur spontaneously in nature at random

 

Genetic Advance

  • Genetic advance is the difference between the mean of the selected plants in the original population and the mean of the progeny raised from the selected plants in the next generation. It can be predicted by the following formula.

Genetic advance (GA) = s P * H * K

K = selection intensity 2.06 when 5% of the population is selected

P = phenotypic standard deviation of the character in the population

H = heritability in broadsense

 

Genetic gain

  • Genetic gain from selection, or simply “genetic gain,” is defined as the improvement in average genetic value in a population or the improvement in average phenotypic value due to selection within a population over cycles of breeding (Hazel and Lush, 1942).
  • It is calculated by following formula:

Genetic gain=selection differential *heritability/generation interval.

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