The Breeding and Genetics
The breeding and genetic advances have produced more efficient varieties, both by improving the yield potential by that tolerance to the presence of biotic or tolerance to the depressive effects of the environment (abiotic stress: freezing cold, drought, heat, wind, excess water) most often suffered by farmers to the development of rational breeding schemes.
It is only from the late nineteenth century breeders apply the principles of agricultural science emerging with a more rigorous and less empirical selection for wheat than had prevailed before. At first, they exploit the natural variability within the species (including the existence of spontaneous mutations) and will implement crosses with species or genera relatives. In the middle of the twentieth century, the creation of corn hybrides1 will revolutionize the production of American cereal. Other plants follow: beet, sunflower, for some varieties only, rye, triticale, rice, rapeseed and even so recent, wheat and barley.
Only the protein, in particular the “fabulous soy” (which combines the ability to fix nitrogen from the air and a wealth of seed oil, strategic culture in the world), but also peas and faba beans ” escape “this technology due to a pronounced autogamie3 complicating the creation of hybrids.
From 1950, the creation of new varieties based on the parallel technique of “induced mutagenesis” to create new characters (genetic mutations induced by human intervention, acceleration of the natural process of evolution that is mainly based on the spontaneous mutation). This technology is widely practiced in all plant species, especially cereals including rice, durum wheat and barley.
The late 1990s saw the cultivation of genetically modified (GMO), mainly in the Americas and Asia. The first deployment of this technology has not directly participated in significantly higher yields. The two characters are introduced via transgenesis tolerance to total herbicides (herbicide destroying all weeds affected, but also the non-tolerant crops) and resistance auxinsectes on maize, which facilitate the protection of crops, but have no direct effect on the amount of grain harvested.