Resumen
The history of maize breeding methods in the USA is reviewed to examine the question of types of maize cultivars in sustainable agriculture. The yield potential of OP cultivars was much higher than national average yields prior to 1930, but hybrid cultivars today often out-yield OP cultivars by 50?100% or more. However, rates of gain for yield using recurrent selection on populations appear equal to that recorded for commercial hybrid breeding. The inbred-hybrid method, while successful, was not ?the only sound basis? for maize improvement, as evidenced by later experiences in the United States and worldwide. It appears that maize breeders have practiced objective science and achieved concrete goals, although personal interests and goals clearly direct the work at times. As society looks for tools for sustainability based on achieving multiple goals, a special dedication to scientific validation and broad objectivity may be required. The potential for OP cultivars today is evaluated and research questions are identified.