Yield Stability Differs in Commercial Maize Hybrids in Response to Changes in Plant Density, Nitrogen Fertility, and Environment

Continued yield increases in modern commercial maize (Zea mays L.) hybrids will require increased plant density, improved nitrogenuse efficiency, and breeding for a hybrid's potential yield response to this management. The objective of this study was to determine the genetic variation of commercial hybrids in response to plant density and nitrogen (N) fertilizer levels to assist breeding programs to select hybrids with high yield stability or adaptability to crop management. From 2011 to 2014, 101 hybrids were grown in eight different environments at two planting densities (79,000 and 110,000 plants ha(-1)) and three N rates (0, 67, and 252 kg N ha(-1)). Broad-sense heritability increased with increased N rate and plant density. Increased plant density altered yield from -0.60 Mg ha(-1) to +0.58 Mg ha(-1) under high N conditions, whereas the yield response to increased N ranged from +4.47 to +5.64 Mg ha(-1). Hybrids that combined above-average yield under unfertilized and low-N conditions exhibited greater-than-average yield stability across environments under high-N conditions. Hybrid yield stability variance was larger under high-N than under low-N conditions because of greater genotype x environment interaction. Hybrids that were adaptable to high plant density and N conditions exhibited greater-than-average yield potential and yield variation across environments. Selecting hybrids with both high yield and yield stability may be difficult, as yield under lower N levels and yield increases with high N fertilization were negatively correlated.