Risks of yield loss due to variation in optimum density for different maize genotypes under variable environmental conditions

Understanding the nature of complex genotype‐by‐environment‐by‐management interactions is crucial to identify risks and opportunities for increasing maize yield and profitability in rainfed production systems. The objectives of this study were to (i) define the conditions where hybrids of different maturity and plant densities are viable options in terms of improving productivity, and (ii) quantify the risk levels associated with different genotype‐by‐management combinations in relation to target environments. Responses to plant density were analysed on field experimentation with different genotypes representing early, medium and late maturity types and 2, 4 and 6 plant/m² plant densities at three major or potential dryland maize production environments in Queensland, Australia. Agricultural Production Systems sIMulator (APSIM)‐Maize module was employed to simulate yield responses and compute the cumulative probability distribution. APSIM simulations suggested that the risk of expecting a yield level less than 2 t/ha increased up to about 17 and 27% for quick and late maturing types, respectively, when density increased to 10 plants/m² in marginal environments such as Emerald. In relatively better environments, however the risk increased only up to 10% for late hybrids, and 7% for a quick hybrid at 10 plants/m². In both high and low potential environments, choice of hybrids and plant densities should be based on seasonal weather forecasts to minimize risks and maximize opportunities for higher yields.