Rice
"Most crosses between rice strains give only 1% or 2% improvements, [but] IR8 was different. It married a tall high-yielding strain from Indonesia (PETA) with a sturdy dwarf variety from China (DGWG). The results were astounding. There was never any instance in the history of the world where rice yields doubled in one step... In fact, according to some studies, IR8 yields in best conditions could be as much as 10 times that of traditional varieties".