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Glossary
Sections:
Introduction
Principles of inheritance
Genotypic variation
Other forms of heritable variation
Quantitative variation and heritability
Quantitative variation
Quantitative variation, contd.
Additive genes
Dominant gene action
Epistasis
Heritability
Genotype x environment (GxE) interaction
Heterosis
Inbreeding depression
Novel sources of genetic variation
The practice of plant breeding
Breeding methods
Plant Breeders' rights
New technologies for plant breeding
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Heritability

Defined as the proportion of the total variation in a population which is due to genotypic (as opposed to environmental) factors. Often denoted as h2. Because it is a proportion, it varies between 0 and 1.

Broad sense heritability includes includes additive, dominant and epistatic effects. Narrow-sense heritability includes only additive variation.

If h2 = 0, none of the variation is genotypic, it is all due to variation in the environment

If h2 is small, the trait is strongly influenced by the environment – e.g., yield

If h2 is large, the trait is only slightly influenced by the environment (e.g. flower colour).