Glossary

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Heterosis Effect

Observed when two in-bred lines are crossed, resulting in progeny with "hybrid vigour"

The crossing of two in-bred lines results in progeny that are more vigorous than either parental line: they are often larger and more resistant to disease. The offspring of hybrid plants, however, do not necessarily show the heterosis effect. Characteristics of the original parents are often restored. This is why hybrids are used in agriculture, and new seed is purchased from specialised seed farms each year.

The heterosis effect is observed in maize, rye, sunflower, sugar beet, onion, cucumber, cauliflower, fir, pine, larch, and poplar, among others. It is widely used in plant breeding.