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Highlights

Concentrating deficit irrigation during the post-anthesis period optimized grain yield and water productivity, while minimizing the seasonal irrigation amount.

Abstract. A three-year study (2018 to 2020) was conducted in west central and northwestern Kansas on silt loam soils to determine corn grain yield and yield component response, water use, and crop water productivity as affected by irrigation capacity and timing, corn hybrid, and seeding rate. A range of four irrigation treatments concentrated greater application amounts in either the pre-anthesis or post-anthesis period. The Pre-38 treatment applied 38 mm weekly pre-anthesis as needed (limited by weather-based scheduling) and only applied 38 mm every two weeks during the post-anthesis period. The Pre-25 treatment applied 25 mm weekly as needed pre-anthesis, followed by 25 mm applications every two weeks post anthesis. Post-38 and Post-25 treatments had application amounts similar to Pre-38 and Pre-25, respectively, but had the weekly applications concentrated during the post anthesis period and less frequent (every two weeks) applications pre-anthesis. Two corn hybrids (Pioneer 1197 and Pioneer 0801) were planted at seeding rates of 62 and 74 thousand seeds ha^-1. Averaged across location and year, the Pre-25 irrigation treatment had approximately 5% less yield than the other three treatments but received approximately 28% less irrigation. Overall, when averaged across all irrigation, hybrid and seeding rate treatments, the yield components of kernels ear^-1 and kernel mass varied approximately 2% and 3%, respectively and were responsible for nearly all of the grain yield variation. The Pre-25 and Post-25 treatment had the greatest water productivity and generally had similar yields to the other deficit irrigation treatments and thus should be considered as effective strategies to reduce irrigation in this region. Seeding corn at 74 thousand seeds ha^-1 increased yield only 2% compared with 62 thousand seeds ha^-1 indicating that a considerable range of seeding rates produce similar yields when using deficit irrigation strategies in this region. Hybrid effects were not consistent across years and locations.