Nearly all modern cultivars results from the Green Revolution (https://en.wikipedia.org/wiki/Green_Revolution) and I think typical organic cultivars are derived from those experiements (otherwise, their yields would be too low to be economic). Organic rules don't require that cultivars using in organics are free of this technique.
What level of citation are you seeking? Like, a science paper showing that at least one organic cultivar was derived from mutation breeding? A historically verified cultivar history?
The article you quote largely defines The Green Revolution as being the use of pesticides, fertilizers and selective breeding. It makes no mention of radiation based mutation. Comment above mine was specifically saying that radiation based mutation is widespread in organic agriculture.
What level of citation are you seeking? Like, a science paper showing that at least one organic cultivar was derived from mutation breeding? A historically verified cultivar history?