Hybrid Corn: Increased Vigor and Yield

Patrick Kirchhofer - Peoria County Farm Bureau

With the beginning of July, the corn is tasseling in the Peoria area and kernels are being set on the cob. Corn is considered a grass, and pollination occurs when the tassel (at the top of the corn stalk) produces pollen grains (male reproductive part of the plant), and that pollen falls on the end of a silk (female reproductive part of the plant). The pollen grain then travels through the inside of the silk and attaches to the cob to form a kernel of corn. Farmers know fertilization has occurred when the silks turn from golden to brown.

In the early days of corn production (about 1900 to 1930), farmers would find the largest and best ears of corn and save those kernels to plant the following year. It was a tedious and time-consuming job taking special care of these select ears and removing the kernels. Expected yields would be 30 to 50 bushels an acre.

A breakthrough occurred in the 1930s when hybridization came along. Hybrid corn basically refers to the crossing of two different corn-plant parents. In other words, the pollen from one corn plant is used to fertilize the silk of another corn plant. The result is increased vigor and yield in the corn plants.

In Peoria County, LG Seeds near Elmwood produces hybrid corn for farmers to buy and plant. Contracting with a few farmers in the area, they use their fields to plant two different corn-plant parents. Corn is planted in rows about 30 inches apart—four rows of the female parent and then one row of the male parent. To produce the hybrid, the tassels are removed from the female corn plants so they do not produce pollen. The row of male parents are left to tassel, pollinating the four rows of corn where the tassel has been removed. Hence, cross-pollination occurs between the two different plants and hybrid seed corn is produced.

How are tassels removed from the corn plants? First, a special cutter machine will go through the field and cut the tassels from the tops of the plants. Because it cuts evenly across the field, the machine will not be able to remove all of the tassels, as some corn plants are shorter than others. A day or two later, a wheel puller machine will go through the fields and remove what the cutter machine missed. Between the two machines, 80 to 90 percent of tassels will be removed. The final step in removing tassels from the male parent involves manual labor. LG Seeds will hire 300 to 400 people to detassel the remaining stalks of corn.

How and when are these fields harvested? Typically, fields planted to produce hybrid corn are harvested a month prior (in August) to the other common cornfields (late September to October). The corn is harvested while still on the ear and the moisture is nearly 40 percent. (By comparison, common corn fields in Illinois are harvested when moisture is between 15 and 25 percent.) The reason for harvesting higher-moisture corn while still on the ear is to protect the embryo in the kernels. These ears of corn are then taken to a processing plant, where the kernels are carefully removed, dried down to 12-percent moisture, and placed in bags or boxes to store for the following spring for farmers to plant.

Fields planted to produce hybrid corn are few and far between in Illinois—around one percent of corn acreage—but you will see them occasionally. One sure sign of a hybrid-producing cornfield is much shorter corn plants with tassels remaining on the plants every fourth or sixth row. Yields will be between 50 and 80 bushels per acre.

So what is the yield advantage of today’s hybrid seed corn? In 2017, the average corn yield in Illinois was 201 bushels per acre; the average yield in Peoria County was 228 bushels per acre. Hybrid corn was a tremendous breakthrough when it was commercially developed in the 1930s and quickly adopted by farmers. And Peoria County’s entrepreneur-farmers played a significant role in this development. iBi

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