Dynamics of corn dry matter content and grain quality after physiological maturity

• Published in: Agronomy journal 2020-03, Vol.112 (2), p.998-1011
• Main Authors: Parvej, Md Rasel, Hurburgh, Charles R., Hanna, H. Mark, Licht, Mark A.
• Format: Article
• Language: English
• ISSN: 0002-1962; 1435-0645
• DOI: 10.1002/agj2.20042

Delayed corn (Zea mays L.) harvest after physiological maturity (PM) is a universal practice in the U.S. Corn Belt to reduce grain drying cost. However, corn yield is speculated to be lost due to kernel dry matter loss from seed respiration. We evaluated the impact of in‐field dry down on corn dry matter content and grain quality after PM at two locations in Iowa during 2016 and 2017. Each site‐year consisted of two planting dates and three hybrids where ears were collected six to eight times from PM to harvest. Regardless of site‐year and hybrid, grain moisture decreased and test weight increased linearly with harvest dates and plateaued, on average, at 118 g kg–1 moisture and 752 kg m–3 test weight. Test weight was strongly associated with grain moisture. The standard test weight of 722 kg m–3 coincided with calendar dates around the first to second week of October. Kernel weight was unchanged and ear loss from lodging was minimal across harvest dates but differed among hybrids for each harvest date. These differences were not influenced by hybrid relative maturity (RM). Grain protein, oil, and starch concentrations were almost unchanged between PM and harvest though they were affected by the main and/or interaction effects between harvest dates and hybrids for most site‐years. Results suggest that corn can be harvested at any time after PM without any dry matter and quality penalties and harvest should be done based on grain moisture and standard test weight to minimize in‐field grain loss.