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Corn germination test helps fine-tune seeding rate

Germination test poster
DECISION-MAKING TOOL: Wyatt Summers conducted rag doll germination tests to zero in on actual germination percentages for hybrids his dad, Jason, would plant this year.
Corn Illustrated: A young 4-H’er turns his corn project into a decision-making tool for his dad.

Who says kids don’t learn in 4-H anymore? 4-H still enables kids to use their imagination and get creative.

Wyatt Summers, Hendricks County, Ind., based his 4-H corn project for 2018 on a topic that could help his dad zero in on exact seeding rates for hybrids this spring. Instead of bringing a stalk of corn to the county fair and labeling the parts of the plant or adding information about insects or diseases — all options in his county project — he decided to make a poster. But not just any poster — he displayed the results of the experiment at the heart of his project on a board.

“I wanted to see how many seeds of a hybrid actually germinated,” Wyatt says. “I figured I could use that information to help Dad determine the correct seeding rate to get the final stand of corn plants he wanted in the field.”

The test itself is not difficult, notes his dad, Jason Summers. Often referred to as a “rag doll test,” you simply count out 100 seeds selected out of a bag at random, roll them up inside a paper towel, keep them moist for several days, and then unroll the paper towel and see how many seeds germinated.  The number that germinated out of 100 becomes the percent germination.

Strong germination
Wyatt found that 97 of the 100 seeds he selected for the test sprouted. He displayed each one on his poster in an easy-to-understand graph. He mounted the three kernels that didn’t germinate together just under the kernel-shaped information box that explained how he calculated the seeding rate they would need to obtain 35,000 plants per acre for that hybrid with that seed.

To determine the percentage of seeds that wouldn’t germinate if 35,000 seeds per acre were planted, Wyatt multiplied by 0.03, representing 3%. The math is: 35,000 times 0.03 equals 1,050 seeds that would not germinate. Then he added that many seeds back to get the final seeding rate where the planter should be set: 35,000 plus 1,050 equals 36,050 final seeding rate.

To check the math, do another simple calculation: 36,050 kernels times 0.03 equals 34,969, which is close to 35,000 plants per acre. If you are a purist and want the exact answer, the equation is: Seeding rate times 0.97 equals 35,000 final plant stand. Based on algebra, you would divide 35,000 by 0.97 to solve for seeding rate: 36,082 seeds per acre.

Wyatt’s method got him very close to that number. The key was determining that the actual germination rate was 97%, not 95% or whatever was listed on the seed tag. His dad didn’t show him the seed tag so it wouldn’t influence him.

2nd lesson
If you look closely, you see that a few of the 97 germinated seeds are red, while the rest are green. Wyatt’s dad confirms that this is GMO corn, with “refuge in a bag.” The red seeds are a different hybrid that do not contain the GMO trait.

He explained to his son that in theory, having some plants susceptible to the target insect mixed in the bag should prolong development of insect resistance.

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