Farm Journal Test Plots: Psst ... Your Corn Has Something to Share

Ears flex — but to what degree and when is different among hybrids. For example, hybrid A on the far left shows no flex in girth and very little in length, so the majority of the difference between the ears of 22,000 and 36,000 plant populations came in depth of kernel. ( Farm Journal Test Plots; Lindsey Pound )
FJ Test Plots - Hybrids
The semi-pendulum hybrid at left is quite different than the upright hybrid when side by side. Photo: Crop-Tech Consulting

Have you ever paid much attention to the leaves on your corn plants? What about the corn ears – beyond estimating yield?

Information on hybrid leaf structure and ear type is readily available from only a few companies. The Farm Journal Test Plots have been studying hybrid characteristics for six years — and with a little effort and practice, you can figure out the types of hybrids you’re planting too.

Farm Journal Field Agronomist Ken Ferrie has identified four types of leaf architecture:

  • Upright-leaf hybrids have upright leaves the entire plant.
  • Semi-upright hybrids have pendulum-type leaves to the ear and upright leaves on the rest of the plant.
  • Pendulum-leaf hybrids have leaves that flop out and run parallel to the ground.
  • In semi-pendulum hybrids the top three or four leaves are upright and the rest pendulum.

Farm Journal Test Plot research has also found all ears flex — but by how much varies. Ferrie has established the following ear types:

  • Flex-ear hybrids will adjust in girth, length and depth.
  • Semi-flex hybrids flex theirsize somewhat less than true flex-ear hybrids.
  • Determinate hybrids are relatively fixed in ear size as population changes.
  • Semi-determinate hybrids are somewhat fixed in ear size, but they will adjust more than determinate hybrids as population changes.

Based on hand-harvested hybrid studies, Ferrie not only determined how much hybrids flex but also where in terms of number of rows of kernels, ear length and depth of kernel as well as what stage:

  • Girth (G): Flex in girth (number of kernels around) occurs from V4 to V6.
  • Early Length (L1): Flex in length happens from V6 to V15.
  • Late Length (L2): Flex in length takes place between R1 and R3 (“tipback”).
  • Depth (D): Flex in kernel depth occurs from R3 to R6.    

“Knowing when a hybrid responds to stress can provide the details to make management adjustments to maximize yield,” says Matt Duesterhaus, who works alongside Ferrie.  “It can also help explain why neighbors planting similar hybrids might see different results. It all comes down to how they managed that hybrid, in particular plant population, nitrogen and disease management.”

Duesterhaus shares two examples of how hybrid selection and management go hand in hand:

  • Choose hybrids that align with your management style. For example, if you apply all nitrogen ahead of planting, then a D hybrid might be risky because you‘re more susceptible to nitrogen loss and poor plant health at the end of the season. Consider a G or L hybrid.
  • Adjust your management to fit your hybrids. If you plant early but don’t use starter, planting G hybrids might be risky because the plants are typically stressed in cooler, wetter conditions. Place that G hybrid in a field that will get planted later, or put it in the back of the shed so it’s not the first hybrid you use.

Being set up to manage the crop from start to finish with starter, split nitrogen applications and fungicide allows you to cover a lot of bases, regardless of the details you have on the hybrids. If you know the hybrid is a G, you might apply more nitrogen earlier in the season. If using a D, you might hold more nitrogen for the sidedress or Y-Drop application.

The Best Hybrid For The Job

Combining what you’ve learned about leaf architecture and ear flex can help you nail down hybrid placement like never before. Anywhere water is limited by sand or slope, for example, requires a lower plant population. A lower plant population requires a more pendulum-leaf hybrid to capture adequate sunlight and a flex hybrid. Because water is limited, there is a greater chance for stress late in the season, so avoid an L or D. Look for a G hybrid that performs well at low populations and has a pendulum leaf.

A high-yield environment with deep soils and good water-holding capacity is better suited for a D hybrid at higher population with upright leaves.

The next step for fields with both environments is finding two hybrids of similar maturity and using multi-hybrid technology.

“Don’t be discouraged if you don’t know this info about your hybrids,” Duesterhaus says. “After pollination, when all leaves are present and plants have finished growing, cut some stalks at ground level. Carry the plants out of the field, stand them up and compare the ringer and other genetics for height, leaf structure and tassel type. Take pictures for future reference. You can also pull ears to count and observe how different hybrids adjust to stress. After you study hybrids this way, the differences will be clear.” 

Thank You to Our Plot Partners

We appreciate the equipment, seed and time provided by the following: AgriGold, Can-Am, Case IH, Central Illinois Ag, Fast, Great Plains Manufacturing, Kinze Manufacturing, New Holland, Unverferth Manufacturing, Trimble, AirScout, Crop-Tech Consulting employees and clients.