Principles of Plant Breeding

Concept of heritability

• The concept of the reliability of the phenotypic value of a plant as a guide to the breeding value (additivegenotype variance) is called the heritability of the metric trait. As previously indicated, plant breeders are able to measurephenotypic values directly, but it is the breeding value of individuals that determines their influence on the progeny. Heritability is the proportion of the observed variation in a progeny that is inherited.
• Heritability measures this degree of correspondence. It does not measure genetic control, or trait. Heritability is, therefore, defined as a fraction: it is the ratio of genetically caused variationto total variation (including both environmental and genetic variation).