Corn Plant Population Research

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Pioneer Plant Population Research

  • Pioneer has been conducting plant population studies with corn hybrids for over three decades.
  • Research studies have been conducted at over 320 locations throughout the U.S. and Canada in the last 6 years (Figure 1 below).
  • For more information see: Corn Plant Population Research - Water-Limited Sites.
Map showing Pioneer plant population water-limited test locations in North America, 2013-2018.

Figure 1. Pioneer plant population test locations in North America.

  • Pioneer researchers target representative environments based on maturity zone, expected yield (high or low), specific stresses, and other unique location characteristics. Research trials are all conducted in 30-inch rows.
  • Additionally, hundreds of on-farm Pioneer® GrowingPoint® agronomy seeding rate trials are conducted each year comparing multiple corn products at up to four seeding rates at each location. These trials have considerable value for local observation, evaluation and refinement of plant population agronomic response (Figure 2 below).
  • Growers can use the multi-year and multi-location results to identify the best potential planting rates specific to their hybrid, location, and management practices.
Photo showing Pioneer GrowingPoint agronomy on-farm seeding rate trial prior to harvest (Iowa, 2017).

Figure 2. Pioneer GrowingPoint agronomy on-farm seeding rate trial prior to harvest (Iowa, 2017).

Optimum Seeding Rate by Yield Level

  • Like previous Pioneer studies, recent multi-year trials across the U.S. and Canada show that corn hybrid response to plant population varies by yield level (Figure 3 below).
  • The seeding rate required to maximize yield increases as yield level increases.
  • The economic optimum seeding rate varies from about 30,000 seeds/acre for locations yielding 150 bu/acre to over 37,000 seeds/acre for yields of 240 bu/acre.
Corn yield response to population and optimum economic seeding rate.

Figure 3. Corn yield response to population and optimum economic seeding rate by location yield level (7-yr average of all hybrids tested).

(Averaged across all hybrids tested. Economic optimums based on a corn rain price of $3.50/bu and a seed cost of $3.00 per 1,000 seeds; assumes 5% overplant to achieve target population.)

Optimum Seeding Rate by Hybrid Maturity

  • Previous research has shown that early maturity hybrids (<100 CRM) may require higher populations to maximize yield. Although this trend can still be detected when examining the response curves closely, it is a smaller difference than in the past (Figure 4 below).
Chart showing yield response to plant population for corn hybrids from five maturity ranges.

Figure 4. Yield response to plant population for corn hybrids from five maturity (CRM) ranges (7-yr average of all hybrids tested).

Planting Rate Estimator

  • The Pioneer Planting Rate Estimator, available on, allows users to generate estimated optimum seeding rates for Pioneer® brand corn products based on data from Pioneer research and Pioneer® GrowingPoint® agronomy trials.

Planting Rate Estimator Features

  • The Planting Rate Estimator provides flexibility in customizing the graph display based on grain prices and seed costs.
  • The Planting Rate Estimator has the ability to display population response curves for a wide range of yield levels, which can provide guidelines for creating variable rate seeding prescriptions.
  • It is possible to display plant population response curves at 10 bu/acre increments for all yield levels where there was a statistically significant response based on the available research data.
  • The yield levels available for display will vary among hybrids based on the available research data.
  • Users also have the option of selecting a "Water-Limited Sites” version of the planting rate estimator, which includes data from studies conducted in drought environments in the Western U.S.
  • Growers should use the Planting Rate Estimator as an initial guide and work with your Pioneer sales professional for refinements based on local observations and on-farm trials.
  • View plant population responses from either standard or water-limited research sites.
  • Select and compare plant population responses based on hybrid, yield level, corn grain price, and seed cost.
  • Graph shows plant population response curves with economic optimum seeding rates based on the criteria selected above. Results are displayed as net income/acre.
  • To provide a wider range in yield levels for variable rate seeding (VRS) the seeding rate optimum response trend line is now extrapolated to lower yield levels -- that is, extended beyond the regression trend response based on data to yield levels as much as 40 bu/acre lower, but not lower than 150 bu/acre. This extrapolation is indicated with the change from gray to green in the trend line.
  • Net income/acre data can also be displayed in tabular form.

Go to the Planting Rate Estimator.

For more information review Corn Plant Population Research - Water-Limited Sites.

Author: Mark Jeschke
January 2019

The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation. Product performance is variable and depends on many factors such as moisture and heat stress, soil type, management practices and environmental stress as well as disease and pest pressures. Individual results may vary.