Planting Too Few Seeds Can Limit Yield

Mississippi cotton expert says that research shows that a stand of 40,000 to 55,000 cotton plants per acre has consistently produced the highest yields for the last 40 years. Compiled by staff

Published on: May 4, 2004

As with most crops, cotton varieties have been modified to develop or enhance desirable traits. Depending on the technology, fees to cover the research and development can account for two-thirds of the total cost of seed, or as much as a few hundred dollars per bag of seed.

"You're no longer simply buying a seed. Now you're buying a planting unit," says Will McCarty, state program leader for agriculture and natural resources with Mississippi State University's Extension Service. "The embryonic cotton plant now may have superior yield potential and include the ability to resist certain herbicides and cotton insect pests."

McCarty said cotton seed prices have gone from about $1,000 to $2,000 a ton at the start of his more than 20-year career to as much as $10,000 per ton today, depending on variety and associated traits.

Coinciding with the improved varieties is the availability of very accurate and precise planting equipment. As the price of "planting units" increased and technology gave producers full control over seeding rates, producers started planting fewer seeds per acre to cut cost.

But research indicates that lowering planting rates to cut costs is not the way to go.

"If you look at population studies of the most common varieties in the 1960s, 1970s, 1980s, 1990s and 2003, you will find that the optimum plant populations are the same from the 1960s to today," McCarty says.

This research shows that a stand of 40,000 to 55,000 cotton plants per acre has consistently produced the highest yields for the last 40 years. On standard 38- to 40-inch rows, McCarty said growers should have three or four living plants per foot. Producers must drop four or five seeds per foot to ensure that survival rate.

With precise planters, many growers are tempted to drop one or two fewer seeds per foot to significantly reduce their overall seed costs.

"It may be false economy," McCarty says. "For growers to plant the very minimum number of seed, if anything adverse happens in the field, they could face replanting. Planting one extra seed per row is cheap insurance."

McCarty encouraged growers to request of the seed companies the standard germination and vigor data for the seed lots they purchase. Plant the highest germination, highest vigor seeds first in the cooler soils. This data also should be used to adjust seeding rates to ensure producers drop enough seed to get the desired final plant population.

"Long-term experience has shown that under most conditions, expected field survival will be very close to the vigor test value for that lot of seed," McCarty says.

The Bureau of Plant Industry is authorized under the Mississippi Pure Seed Law to routinely sample seeds and to respond to inquiries about the quality and vigor of seed. Mike Tagert, director of the Bureau, said this work includes laboratory sampling of seeds and inspection of seed labels to see that the correct information is provided on them.

"The focus and only motivation is to ensure the Mississippi grower is getting good quality seed when they purchase it," Tagert says.