A generation ago, Iowa farmers would not have imagined harvesting 200 bushels of corn per acre. Now it is commonplace, and crop experts see 300 bushel-per-acre yields on the horizon. [...] Robb Fraley, Monsanto's chief technology officer, told European investors last month that conventional plant breeding on average results in 1.5 percent genetic improvement per year, while molecular breeding - enabled by biotechnology - doubles that rate of improvement. Together, the two approaches promise "to lift the ceiling on yield," Fraley said in his presentation. [...] Traditionally, it has taken 10 to 12 years to develop and commercialize a new seed corn hybrid. Now, that time has been cut in half through the use of biotechnology and off-season production in such places as Hawaii and South America.