Hétérosis
This article treats biology . In physics, as regards bosonic theory of the cords, one also speaks about heterosic cord: to see Theory of the cords.
The hétérosis indicates the increase in the capacities and or the strength of a Hybride compared to the races, lines… in which it is originating.
The effect of hétérosis, also named hybrid strength , results in a performance profit which results from the mixture of different Gène S from various races. The term is invented in 1914 and corresponds to discovered of the scientist George Harrison Shull, by widening the theory of its rival Edward East, of a “physiological stimulation” due to the state Hétérozygote.
The effect of heterosis indicates in Génétique the increase particularly marked in the performance of the individuals Hybride S or Métis. This effect is exploited in animal Sélection and vegetable Sélection. One will speak about effect of hétérosis when the generation Hybride F1 presents performances higher than the average performance of the generation relationship P , Homozygote or of pure Lignée.
Thus at the Cereal S, like the Corn or the Rye, the effect of hétérosis led to a strong increase in the potential output, provided the real conditions of production make it possible this potential to be fully expressed. The use of F1 hybrid in the production of the Maïs made it possible to multiply the average output by 5,7 in France between 1950 and 2000 (from 15 to 86 q/ha)
The share of the hybrid varieties used in agriculture increased considerably in the last decades, in particular at the Vegetables. In 1995, more than 80% of the varieties of Broccoli, Tomato and cabbage were Hybride S. In addition to their increased performances, the Hybride S present a great homogeneity: all the plants resulting from the crossing of two pure lines are genetically identical.
The experiment showed that, for characters such as the productivity or the fertility, the favorable Allèle S are rather dominant. The hybrid individual, who inherits a specimen of all the alleles of his two parents, will express the whole of favorable genes and thus will show an increased performance.
Parents: ABC ABC ABC X ABC Phenotype: ABC X ABC
F1: ABC ABC phenotype: ABC
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