Principles of Plant Breeding (2+1)

Heterosis

Heterosis
The term heterosis was first used by Shull in 1914. Heterosis may be defined as the superiority of an F1 hybrid over both of its parents in terms of yield or some other character. Generally, heterosis is manifested as an increase in vigour, size, growth rate, yield or some other characteristic.

History
Koelreuteris first reported hybrid vigour in tobacco produced artificial hybrids. In 1876, Darwin concluded that hybrids form unrelated plant type were highly vigorous. Most of our present knowledge on heterosis comes from the work on maize. Crossing inbred lines rather than open pollinated varieties produces the commercial maize hybrids. Hybridization between inbreds developed from the same variety or from closely related varieties produced only a small degree of heterosis.