A search for the ideal plant population led DuPont Pioneer researchers to focus on ears grown per acre to help corn growers achieve maximum yield.
“The key components of yield are ears per acre, kernels per ear and kernel weight,” says Scott Nelson, DuPont Pioneer agronomy research manager. “Of these factors, ears per acre have the most impact on total yields.”
Genetic improvement of corn hybrids for superior stress tolerance has contributed to increased yields by allowing hybrids to be planted at higher plant populations. During high-stress growing seasons, corn plants still produce ears, although they may be somewhat smaller. In favorable weather, higher plant populations produce more ears and higher yields.
Even during less-than-ideal weather, today’s hybrids maintain a more stable shedding-to-silking interval, which leads to better pollination of all the ears in the field.
“While kernels per ear and kernel weight are important, the name of the game for increasing yields is more ears per acre,” Nelson says. “We’re working to help growers get consistent yields in stressful environments while maintaining the ability to achieve outstanding yields in ideal environments.”
“Growers should try to achieve the maximum number of ears per acre that their soil and growing environment allow,” Nelson says. “The best way to do that is to make sure you have high enough plant populations to take advantage of favorable growing conditions.”
Studies conducted by Pioneer across 165 environments in 17 states and three Canadian provinces resulted in a 4 to 8 percent difference in planting rate recommendations. The optimum planting rates ranged from 32,000 to 33,300 seeds/acre for hybrids with over 100-day Comparative Relative Maturity (CRM). Earlier-maturing hybrids were most profitable at 34,700 seeds/acre.
“If you drop down to 30,000 seeds, you’ve limited your potential, in essence putting a ceiling on yields,” Nelson says. “If the soil is fertile and the growing environment is favorable, higher plant populations offer the potential of the best yields — and the highest profits.”
Growers also should take care not to plant more seed than they need to avoid risks such as lodging.
When weighing plant population options, growers may want to consider varying planting rates based on field and hybrid. While it seems logical to plant more seeds on the best soil, Nelson says there are exceptions.
“Some lower-yielding soils may need more seeds per acre to get enough leaf area to lift yields,” he explains. “We know hybrids differ in their response to plant populations. Some may not respond to higher populations even on the best soils.”
Pioneer continues research to find the optimal plant density levels for all hybrids under all environments. The goal is to avoid overplanting or underplanting each field. Please contact your Pioneer sales professional for planting rate suggestions specific to your operation.