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Give population a ‘pop’

During the last 80 years, corn planting populations have increased steadily and so have yields. While there are many factors that have led to the rise in corn yields, it’s clear a correlation exists between increased plant populations and increase in yield.

Give population a ‘pop’

During the last 80 years, corn planting populations have increased steadily and so have yields. While there are many factors that have led to the rise in corn yields, it’s clear a correlation exists between increased plant populations and increase in yield.

At the same time, growers have also been decreasing row widths to allow placing more seeds per acre. Researchers at Stine Seed Co. are experimenting with 20-inch rows at up to 50,000 seeds per acre. “We are testing our hybrids at populations well above the current industry average.

It’s our belief that the future of the seed industry and farming will be focused around finding and developing corn genetics that handle high populations,” says Warren Stine, corn products adviser for Stine Seed.

Key Points

Plant populations have a significant impact on corn yields and profitability.

Choosing the right seed and population helps result in a bigger corn yield.

New hybrids with the best genetics lend themselves to a higher planting rate.

Recommendations on proper planting populations are commonly based on past experience with existing genetics and, as a result, are consistently too low for the newest and best genetics, he says. While planting corn at a higher population can mean a bigger investment in seed, it’s important to remember that choosing the right seed, and the right population, will result in higher yields and profits.

Stine’s corn research is geared toward discovering new hybrids that lend themselves to a higher planting rate, to increase yields and potential profit for growers.

When it comes to higher populations, not all hybrids are created equal. The decision to move toward higher populations requires selection of the right genetics. In general, the newer genetics, the better the ability to handle higher plant populations.

Because of this, the hybrids of tomorrow cannot be planted at the same populations as hybrids of the past. That was the conclusion of the late Don Duvick, renowned corn breeder who was a professor at Iowa State University after retiring as research director at Pioneer Hi-Bred.

Seed companies are developing corn hybrids that favor higher planting populations. “Today at our company we’re evaluating experimental hybrids in 20-inch rows at up to 50,000 seeds per acre,” says Stine.

“The good news is these hybrids are yielding higher than ever before. The compact plant structure with heavier stalks creates sturdy plants that are up to the task of high populations, and represent the future of corn genetics. These genetics are key for higher plant populations and higher yields.”

The best yields of the future will likely come from new corn genetics with plant populations exceeding 40,000 plants per acre, and in row widths less than 30 inches.

A recent study indicates almost half of farmers had not changed their seeding rate in the past five years, even though seed technology has changed dramatically. How do you choose the best population for your farm? The answer isn’t black and white.

Plant population impacts yield. For many hybrids the suggested population ranges from 20,000 to 40,000 plants per acre, with the variance based on row width, soil type, available moisture and yield goal.

Typically, lower planting rates are recommended for fields with low yield potential or poor soil, and higher rates are encouraged with fertile soil. Today’s technology lets seed companies develop hybrids that excel in each scenario, so they can forecast the optimum planting rate by hybrid in each situation.

Best population for you?

Besides fertility, the key to higher yield is sunlight. Ideally, you should look down the row at pretassel and not see any filtration of sunlight. If this is done, you are maximizing sun exposure and photosynthesis. “Our researchers are developing plants with a greater leaf area index, allowing for maximum light interception,” says Stine.

At planting, agronomists remind you to plant 5% to 15% more seed than your expected final stand to allow for germination failure and seedling mortality. For good, strong stalks make sure soil tests are in the very high category for phosphorus and potassium. Avoid certain hybrids on soils that lack fertility. Hybrids that have upright, narrow leaves work well in a high-population environment.

“Stine hybrid genetics tend to be shorter in height than some of our competitors’ products, which translates into better standability in high populations,” he says. “As an added bonus, the shorter hybrids leave behind less crop residue to deal with. Another factor for success at high populations is to protect the plant to avoid extra stress. We recommend using seed products that have in-plant protection, such as VT Triple Pro, and a seed-applied insecticide like Poncho 250.”


YIELD BOOST: Plant populations and yields have risen in recent years. The U.S. average corn yield in 2009 was 165.2 bushels per acre, the highest ever.

This article published in the March, 2011 edition of WALLACES FARMER.

All rights reserved. Copyright Farm Progress Cos. 2011.

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