Ray Stewart and Harry Minor are optimistic that a new temperature-controlled seed coating for soybeans will boost the popularity of relay cropping.

"Relay cropping of soybeans and winter wheat can be a huge winner for growers economically. But it's like landing an airplane on a carrier - it's very tricky," says Stewart, senior vice president of Intellicoat, at Menlo Park, CA.

"Relay cropping is challenging," says Minor, a University of Missouri-Columbia extension agronomist. "If growers plant their soybeans too late, they'll damage the wheat. If they plant too early, the soybeans can be smothered by the wheat or damaged when the wheat's harvested."

Intellicoat's patented seed coating, made of acrylic acid and fatty alcohols derived from corn and soybean oils, could widen the planting window and boost yields, says Stewart. Soybeans coated with the micro-thin polymer can be planted in early spring before wheat heads.

"Growers can bring drills or other planting equipment into the field and get the soybeans in the ground before the wheat is at the stage where any sort of field activity can destroy it," he explains.

Adds Minor: "The product could be especially beneficial in areas where the growing season isn't long enough to doublecrop."

The coating provides a protective barrier, keeping the seed dry and dormant for about 30 days.

As soil slowly warms, the coating becomes permeable, allowing the seed to absorb water and germinate. By the time the wheat is harvested, the soybeans will likely be in the early to mid-vegetative growth stages.

In addition to tests Minor conducted in Missouri last year, the coating was tested by university researchers in Ohio and Indiana, and in Kansas and Oklahoma on-farm research trials.

"With seed-coating products, you have to look at them in several environments," says Stewart.

More large-scale, on-farm tests are scheduled for this summer. Soybean seeds coated with the new coating could be available in 2001. Prices haven't been established yet.

In related research, Intellicoat is collaborating with several seed companies to develop temperature-controlled coatings for inbred seed corn. Typically, when farmers are contracted by seed companies to grow inbred seed corn, they make multiple plantings. Usually, female inbreds are planted first, followed by one or more plantings of male inbreds.

But it's possible that Intellicoat's new seed coatings could eliminate multiple plantings. Male and female inbreds could be planted at the same time, with males coated to delay their emergence.

Another possibility: Mixing coated and uncoated male seeds could produce a longer pollination period, improving yield and minimizing pollination risks.

"Ultimately, the cost of hybrid seeds could decrease and new hybrids with improved agronomic characteristics could be available sooner," says Stewart.

The company also is developing seed coatings for several other crops.