Genotypic Differences among Argentinean Maize Hybrids in Yield Response to Stand Density

Maize ( Zea mays L.) stand density selection is an important management practice because yield is maximized at a particular optimum value. Optimum stand density (OSD) varies across environments, and many have argued that current commercial genotypes differ in their optimum stand density for a similar environment. We tested this concept by planting 11 Argentinean commercial genotypes from four seed companies at a range of stand densities (1, 8, and 16 plants m −2 ) in two environments. Genotypes differed in their yield response to changes in stand density, and their OSD varied from 7.3 to 11.9 plants m −2 . Yield of tested genotypes was similar at the lowest stand density but different at the highest density, indicating no differences in potential yield per plant but significant differences in crowding tolerance. When using a crop growth and biomass partitioning framework for understanding kernel set differences among genotypes in their response to stand density, hybrids differed in most measured traits, showing differential strategies for coping with stress tolerance. Under high stand density conditions, genotypic strategies for avoiding barrenness were key for hybrid tolerance to crowding stress. We conclude that stand density management needs to take into account not only the environment but also the specific genotype, especially under high density management systems.