Drought-Tolerant and Short Season Corn (Zea mays L.) Hybrids to Optimize Yield, Water Use Efficiency, and Net Returns.

Mid-South corn producers are often faced with sub-optimal climate conditions throughout the growing season. Drought and water-stress are often the most limiting factor in a production system. To alleviate water-stress, growers irrigate. Over the last 10 years, there has been a sharp increase in well permits, therefore, putting stress on our depleting ground water source, the Mississippi River Alluvial Aquifer. The objectives of this research were to determine the effects of using delayed irrigation trigger, planting earlier, and drought-tolerant and short season hybrids on corn grain yield, water use efficiency (WUE), and net returns above seed, and irrigation costs. Trials took place in Mississippi State, MS, and Verona, MS in 2016 and 2017. Treatments were randomly assigned in a split-split plot arrangement. Irrigation events applied to each field were monitored with flowmeters, and timings were initiated based on two soil moisture sensor triggers, -50kPa and -125kPa. Two planting dates, 30 days apart, within the corn-planting window in each location were utilized. Selected germplasm includes drought-tolerant, short season and full season hybrids. In result, delaying the irrigation event to -125kPa resulted in similar yield, increased WUE by 34%, and produced similar net returns. Planting in March, as opposed to April, increased yield by 2.2 Mg ha^-1, increased WUE by 29%, and increased net returns by $351 ha^-1. The full season hybrid produced the greatest yield, WUE, and net returns compared to either the drought-tolerant or short season hybrid. In conclusion, by utilizing a delayed irrigation trigger of -125kPa and planting a full season hybrid in March, Mid-South corn producers can reduce the stress on groundwater depletion while and concurrently maintaining profitability.