Corn kernel weight and grain yield stability during post-maturity drydown

Some research reports suggest that corn (Zea mays L.) grain dry matter decreases 1% for every 1% loss in grain moisture after physiological maturity (R6) as corn dries in the field. This dry matter loss reportedly is hybrid specific. We conducted a 3-yr study at Clay Center, NE, to determine whether corn loses dry matter after R6 as it air dries. In 1995, hand-harvested ears were bagged and stored in two environments and hand-shelled on nine dates to determine kernel moisture and dry weight. In 1996, five hybrids were planted and harvested at eight dates. Six hybrids were used in 1997. in both 1996 and 1997 three storage and sampling methods were used to determine kernel moisture and weight over eight dates: (i) laboratory storage; (ii) field drydown/hand harvest; and (iii) field drydown/machine harvest. Neither processing date nor storage environment affected kernel weight as grain moisture decreased from 30 to 9%. In 1996 and 1997, corn grain yields did not differ among the eight harvest dates nor was there any interaction between hybrid and harvest date. Although corn grain yields and moisture contents differed among hybrids in both years, these differences were similar across all harvest dates. Kernel weights differed among hybrids but were consistent across harvest dates within each hybrid. Our results show stable dry matter following maturity and do not support the need for early harvest and the associated energy expense for grain drying.