Potential of Adapted x Exotic Crosses for Breeding Maize for Organic Farming in the USA.

Organic farmers need productive hybrids that have good grain quality, are able to compete with weeds, utilize more slowly-released sources of nitrogen, and have native disease and insect resistance. Germplasm populations selected through LAMP (Latin American Maize Project) are adapted to low-input environments similar to those of organic farming, and may have characteristics that in combination with adapted Corn Belt germplasm would be valuable in a maize breeding program for organic farmers. We chose 35 high yielding breeding crosses of exotic LAMP populations crossed to one or two Corn Belt inbred lines developed by private cooperators of GEM (Germplasm Enhancement of Maize Project). The 35 GEM breeding crosses were each crossed to three GEM breeding crosses of the Stiff Stalk (SS) heterotic pattern previously identified as having breeding potential in conventional farming. The 35 GEM breeding crosses were of the non-SS heterotic pattern except for 8 which were SS. We included SS x SS crosses because many LAMP populations do not fit into Corn Belt heterotic patterns. The 105 variety crosses were evaluated in yield tests on seven conventional, low-input, and organic farms during two years. Checks included commercial hybrids sold to organic farmers, variety crosses of breeding populations developed in conventional systems, and a population developed in an organic system. Seventeen variety crosses were selected based on their yield and grain protein content and further evaluated in yield tests on seven farms during two years. Results of agronomic and grain composition will be discussed in reference to farming system and potential of the breeding crosses in an organic breeding program.