Opportunities for Managing the within Field Gxe Interaction.

Applying the right rate of fertilizer N, selecting the appropriate hybrid, and sowing the correct number of seeds are all factors under a grower’s control that can have a large impact on yield and profitability in corn production.  Each of these factors exhibits substantial variation within individual fields, and each interacts with the other two to determine the final productivity.  Identifying hybrids that can tolerate higher planting densities and that can respond to additional N provides an opportunity for progressive growers to improve yield and profitability through intensive crop management. Conversely, identifying hybrids that can tolerate N loss is another way to improve overall farm performance, because it is the check plot yield (yield with low or no fertilizer applied N) that varies spatially in individual fields.  Grain yield of hybrids grown under optimal conditions does not indicate those that have the potential to respond to increased plant density, or those that can tolerate N loss, and for these reasons we have developed a screening system that characterizes a hybrid’s potential for variable management.  Briefly, by simultaneously determining a hybrid’s check plot yield, its initial and maximal response to N, and its tolerance to high plant density we can position appropriate hybrids within field management zones to help manage the within field genotype by environment interaction.