Editing Intensive farming (section)

==== Seeds ====
In the 1970s, scientists created high-yielding varieties of maize, [[wheat]], and rice. These have an increased nitrogen-absorbing potential compared to other varieties. Since cereals that absorbed extra nitrogen would typically lodge (fall over) before harvest, semi-dwarfing genes were bred into their genomes. [[Norin 10 wheat]], a variety developed by [[Orville Vogel]] from Japanese [[dwarf wheat]] varieties, was instrumental in developing wheat cultivars. [[IR8]], the first widely implemented high-yielding rice to be developed by the [[International Rice Research Institute]], was created through a cross between an Indonesian variety named "Peta" and a Chinese variety named "Dee Geo Woo Gen".<ref name="ir8">{{cite web|title=Rice Varieties|work=IRRI Knowledge Bank|url=http://www.knowledgebank.irri.org/regionalSites/nepal/RiceVarieties.htm |access-date=2006-07-13|url-status=dead|archive-url=https://web.archive.org/web/20060713032524/http://www.knowledgebank.irri.org/regionalSites/nepal/RiceVarieties.htm |archive-date=2006-07-13}}</ref>

With the availability of molecular genetics in ''[[Arabidopsis]]'' and rice the mutant genes responsible (''reduced height (rht)'', ''gibberellin insensitive (gai1)'' and ''slender rice (slr1)'') have been cloned and identified as cellular signalling components of [[gibberellic acid]], a [[phytohormone]] involved in regulating stem growth via its effect on cell division. [[Photosynthate partitioning|Photosynthate investment]] in the stem is reduced dramatically in shorter plants and nutrients become redirected to grain production, amplifying in particular the yield effect of chemical fertilizers.

High-yielding varieties outperformed traditional varieties several fold and responded better to the addition of irrigation, pesticides, and fertilizers. [[Heterosis|Hybrid vigour]] is utilized in many important crops to greatly increase yields for farmers. However, the advantage is lost for the progeny of the [[F1 hybrids]], meaning seeds for annual crops need to be purchased every season, thus increasing costs and profits for farmers.