Impact of maize hybrid selection on water productivity under deficit irrigation in semiarid western Nebraska

The future economic and agricultural sustainability of semiarid western Nebraska will largely depend on more efficient utilization of the declining groundwater resources. The scope of this research was to evaluate the maize hybrid yield, water productivity (WP; i.e. grain yield produced per unit of water consumed), and irrigation water productivity (IWP; i.e. increase in grain yield per unit of irrigation water applied) across a range of semiarid climatic conditions (i.e. drought, normal, and wet) and irrigation treatments. Total of 13 maize hybrids were evaluated under full irrigation (FI), deficit irrigation (DI, receiving similar to 50% less irrigation water than FI), and dryland (DRY; rainfall only) at the University of Nebraska-Lincoln Brule Water Laboratory near Brule, Nebraska, in 2011 and 2012 and Bayer's Gothenburg Water Utilization Learning Center near Gothenburg, Nebraska, in 2010 and 2011 (i.e. four site-years). Compared to FI, DI caused yield reduction of as much as 33% in a dry, 11% in a normal, and 2% in a wet year, resulting in consequently 22-47% improvement in IWP. Depending on site year and irrigation level, a difference of up to 7.2 t ha(-1), 3.6 kg m(-3), and 5.9 kg m(-3) was observed in yield, WP, and IWP, respectively, as a consequence of hybrid selection, with few top-performing hybrids yielding similarly under DI and FI in a normal and/or wet year. This study highlights the impact hybrid selection and DI have on crop water productivity (WP) and IWP as well as provides insight into strategies that can maintain productivity and profitability in water limited environments.