Farmers who understand how corn hybrid ear type and corn plant structure can work together are on the road to being able to make better hybrid selections for their fields, says Ken Ferrie, Farm Journal Field Agronomist.
“Corn ear type dictates planting population, and structure affects plants’ ability to capture sunlight,” says Ferrie, one of the keynote speakers for the 2018 Farm Journal AgTech Expo in Indianapolis.
Ferrie describes four hybrid ear types: flex, semi-flex, semi-determinate or determinate. Plant structure also has four types--hybrids with upright, semi-upright, semi-pendulum or pendulum leaves.
“An upright leaf structure harvests more sunlight and will respond in yield if sunlight is the limiting factor,” he notes. “Corn hybrids with more of a ‘floppy’ leaf type will maximize leaf area index at much lower populations than upright hybrids. Semi-upright hybrids split the middle,” he adds.
Ferrie provides a few additional examples of intercepts between ear type and structure:
“When water consumption is a concern, lower the population to lower water usage. Flex-ear hybrids can compensate for lower ear count. Floppy leaf structure will maximize leaf area index at lower populations. Narrow row spacing reaches maximum leaf area index more quickly to harvest more water.
“When lack of sunlight interception is a concern, use upright leaf structure to let sunlight deep into the canopy. Use a determinant ear hybrid to allow you to push populations to achieve maximum leaf area index and a higher ear count. Narrow rows will capture more sunlight.
“When fields have high amounts of variability going from surplus water to droughty soils, use semi-flex ear types and variable-rate planting to mitigate the risks. Use semi-upright leaf structure to maximize sunlight and drought protection. Also, narrow the rows to help with both.”
Ferrie says all hybrids flex but they flex in only one direction—downward.
“In other words, if you plant a hybrid at a very low population, it will maximize ear size to its genetic potential; with enough sun and nutrients you might get multiple ears. As we crowd plants in the row, ears flex downward in size.”
“Some hybrids flex all three—girth, length and depth; I call them full-flex hybrids,” Ferrie says. “Others, which we call determinate, flex only in depth of kernel. In between are some semi-flex and semi-determinate hybrids.
Ferrie encourages farmers to ask their seed rep, in the process of evaluating hybrids for the 2019 season, to explain how and when their respective hybrids flex. He shares an example of why that information is important:
“A semi-flex hybrid that flexes in length and depth will respond differently to certain growing conditions when compared with a semi-flex hybrid that flexes in girth and depth,” he says. “Even if a hybrid flexes only in kernel depth, it could still flex (lose yield) by more than 60 bu.”
You can hear more of Ken Ferrie’s recommendations for 2018 corn production here: