Genetic architecture for yield potential, density tolerance, and yield stability in maize (Zea mays L)
Plant breeders through selection accumulate favorable traits such as density tolerance, grain yield and grain yield stability. Only traits controlled by additive genetic effects can be predictably selected and improved upon. We investigated the genetic architecture of two traits: density tolerance, which has improved via selection, and yield potential, which has not. Using a North Carolina Design II genetic model, estimates of the magnitude of additive genetic effects for grain yield under low density (37 000 plants ha-1), commercial density (74 000 plants ha-1) and high density (148 000 plants ha-1) were calculated for a set of elite inbred lines. Type II stability statistics (b-values) were also calculated. No link was seen between b-values and density tolerance. Significant additive genetic variation was observed at each of the three densities tested, suggesting genetic variation for yield potential and for density tolerance. No association was observed between yield potential and density.