An Inside Look at How Hybrids Flex

November 7, 2015 02:09 AM
An Inside Look at How Hybrids Flex

Farm Journal Test Plots crew harvests ears for a deeper look into hybrid characteristics

At the core of the Farm Journal Test Plots program is the farmer. Each plot is designed to provide instructional, actionable data for replication on farms across the country. However, there are times the lessons learned extend beyond the farmer and influence the industry, which was the case with the hybrid characteristics plots. 

To deepen their understanding of hybrids, Farm Journal Field Agronomist Ken Ferrie and crew hand harvested ears in fall 2014. (For initial results, read “Big Picture Hybrid Selection,” November 2015, Farm Journal.)

What Ken Ferrie Thinks You Need to Know
  • When selecting hybrids, consider kernel size, kernel length and rows around.
  • The data doesn’t suggest a certain population; it just shows 22,000 plants per acre was closer than 36,000 to maximizing genetic potential.   
  • Understand how and where hybrids flex for optimum yield results. 

Following plot protocol, four AgriGold hybrids—two semi-determinate ears, one semi-flex ear and one flex ear—were planted at 22,000 and 36,000 plants per acre. At harvest, the test plots crew performed stand and ear counts and gathered 10 respective ears from each hybrid at both the high and low populations. The ears were hung to dry for one month and then hand harvested by Ferrie and crew in mid-November. 

The purpose of hand harvesting the ears is to analyze where hybrids flex, how kernel set is affected and the role population plays in the process. The test plots crew evaluated ear girth, ear length, grams of grain per ear, grams per cob and overall yield effect. 

Important note: Before diving into the findings from hand harvesting, it’s essential to understand the data does not suggest planting 22,000 plants per acre over 36,000 or vice versa. Ferrie and crew pushed the populations extremely low and high to evaluate changes in ear size, the hybrids’ true characteristics and how the hybrids respond to population. 

The test plots crew shells, counts, measures and weighs each ear to analyze how and where hybrids flex.

“The results show the potential swing between hybrids from the same company,” Ferrie says. “This information is important when striving to vary plant populations because you need background data on how the particular hybrid can flex.”

Let’s start at the beginning and evaluate early season impact on hybrids. When determining where the flex occurs first, it’s essential to assess kernel set. Ferrie wanted to see what happens to kernel set when pushing populations. If the hybrid sets fewer kernels, does the effect show up in rows around or length? Or vice versa if the kernel count increases? 

Across all four hybrids, there was a significant decrease in grams of grain per ear in the 36,000 population. Many factors play a role in this decrease, specifically kernel size, including depth, length and thickness. 
A similar trend is seen in grams per cob. Across all four hybrids, there was a decrease in grams per cob in the 36,000 population. Take note: There’s only a slight decrease in the semi-determinate hybrids. 

Maximum rows around (commonly known as girth) is set early in the season, depending on planting date, usually in April or May. After the rows around is set, the environment has little effect on it the rest of the season. However, the environment plays more of a role in kernel length. 

While maximum kernel length is set before planting, the environment has the ability to adjust kernel length during the growing season. Kernel length can be adjusted through pollination and beyond. Due to water or nutrient constraints, the ear can abort or shrivel kernels. Rows around and kernel length are important to evaluate when increasing populations. 

Hand harvesting ears gives you the opportunity to see how kernel set changes from one hybrid to the next as populations increase. Results show three of the four hybrids made adjustments to ear girth due to population early on, even before closing the row. 

The data shows a minor negative effect on the number of rows around the ear when increasing the population in three of the four hybrids. All four hybrids decreased in overall ear lengths from 22,000 plants per acre to 36,000 plants per acre. 

When evaluating the data, the most important factor to consider is kernel size. Kernel size can change, and it plays a large role in the grams of grain per ear data (see two charts on right). The grams per ear were different among the hybrids and populations because the depth, length, thickness and overall size of the kernel varied. As the grams per ear drop when the population goes up, it indicates resources such as water, sunlight and nutrients are fully allocated.   


“When it comes to hybrid selection, it’s important to know how much it flexes to set the ideal agronomic and economic population,” Ferrie says. “It’s also useful when making replant decisions in fields with tough stands.”

Kernel size is important because you can have two hybrids, both 16 rows around, but one you can reach around with your hand and the other you can’t because kernel size is so large. Farmers often underestimate the value of kernel size. 

“For example, compare a ear with 16 rows around and 45 kernels long planted in a low population to another ear with 16 rows around, 43 kernels long planted in high population, and the higher population should win each time in yield,” Ferrie says. “However, you can’t use the same kernel factor when evaluating both scenarios; you have to find how many kernels based on kernel size it takes to get 1 bu.”  

Across the board, it’s apparent all four hybrids received significant yield increases in the 36,000 population. However, the biggest takeaway from the data is how Hybrid C and Hybrid D, the semi-flex and flex ears, were able to flex the difference in yield compared with Hybrid A and Hybrid B. 

In the charts attached, all four hybrids received more grams of grain per ear and grams per cob in the 22,000 population compared with 36,000. The data shows in the lower populations you’re closer to achieving maximum genetic potential with kernel sets compared with higher populations. 

However, when seeing the overall yield results in the chart at right, it clearly shows a yield advantage at the 36,000 population in all four hybrids. At first glance, planting at 36,000 seems like the logical option due to the strong yield response. However, Ferrie is not trying to suggest the optimum planting population through the results. By pushing these hybrids to extreme populations, the goal is to evaluate how the ears flex and where the flex takes place. 

The data clearly shows Hybrid C and Hybrid D, the semi-flex and flex ears, were able to flex and make up  more of the difference in yield compared with the semi-determinate ears.  Hybrid D, the flex ear, had a 33.7 bu. gap between populations compared with Hybrid A, which had a 96 bu. difference. The difference shows by altering and pushing the populations, we see how the exact same hybrid responds much differently in yield. The relationship between population and ear type is critical to yield. 

Ferrie reminds farmers to use this information when making key hybrid decisions. The best way to learn is to plant your own hybrid characteristic plots to evaluate how your hybrids respond to varying populations. This type of high-end management is critical as the industry moves forward with multi-hybrid and variable-rate populations, Ferrie says. 

The Farm Journal Test Plots will continue to study hybrid characteristics because there’s more to learn as hybrid technology evolves. 

“This baseline information provides us with a good foundation to continue to study and identify similar trends next year,” Ferrie says. “The hand harvesting process isn’t easy. But it’s worth it—knowledge is key.” 

Thank You to Our Test Plot Partners

We appreciate the equipment, seed and time provided by the following: AgriGold Hybrids, Mike Kavanaugh and Justin Warren; AirScout and Brian Sutton; Case IH, Dan Klein, Kyle Russell, Ryan Schaefer, Bill Hoeg, Luke Gazaway and CJ Parker; Central Illinois Ag and Kip Hoke; GeoVantage; Great Plains Manufacturing, Tom Evans and Doug Jennings; Kinze Manufacturing and Susanne Veatch; OmniStar and John Pointon; Trimble, Sid Siefkin and Brian Stark; Unverferth Manufacturing and Jerry Ecklund; Wells Equipment; Versatile and Adam Reid; Bob Kuntz and Mike Craig; Mike McLaughlin; Crop-Tech Consulting, Isaac Ferrie, Jeanenne Ferrie, Katie Ferrie, Nicholas Sherman, Kevin Mohrman, Thomas Zerebny and Fred Cunningham

Farm Journal Test Plots Pledge

You can count on our test plots to be conducted on real farms with real equipment using a high-touch set of protocols. The information will be com-pletely independent and actionable. Our hands will always be in the dirt researching the production practices and technology that are best for you. 

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