Over the past 60 years plant breeders have been able to point to some great performance charts for corn, soybeans and wheat showing ever-higher yields every year. But there may be a problem brewing for winter wheat based on new research released this week.

Researchers Robert Graybosch, USDA-Agricultural Research Service,a nd C. James Peterson, Oregon State University, did an extensive review of field trial and wheat performance data and reached an interesting conclusion. Their work was reported in the September-October edition of Crop Science and released this week.

The researchers estimated that the average rate of genetic improvement in winter wheat yield potential since 1959 was 1.1% per year. Great news, but it turns out most of that gain came from 1959 to 1989.

The work looked at data collected from long-term USDA-ARS regional nursery trials in the Great Plains. In those trials, plant breeders entered varieties from public and private entities representing the highest current genetic potential for grain yield production. Since the late 1980s, the rate of grain yield improvement has slowed. And it appears that those yields may be reaching a plateau.

One factor that is playing a significant role in wheat breeding is the increasing attention to disease resistance in the face of different strains of stem rust and new strains including Ug99. As researchers focus on beating back this problem, yield potential may have suffered. However, the stall-out in winter wheat yield gains could also be happening because of the exhaustion of available genetic resources for yield improvement.

Graybosch, in a Crop Science Society press statement, notes the industry needs a "second 'Green Revolution' in wheat." Noting the rising world population - and that wheat is one of the three critical grains along with corn and rice - shortages could be a problem in the future.

Yield gains in wheat over the past 60 years have come from adapting plants to their growth zones, adding disease resistance and the introduction of dwarfing genes that shorten stems and force plant energy into producing seed. Yet today, advances in wheat yield technology may have stalled. In their study, the researchers point to work to bring rye genes into wheat germplasm to boost yield, only to find wheat quality problems made the plants undesirable. They also noted the short-term foray into hybrid wheat, which proved uneconomical at the time. In essence, the wheat breeding industry may be looking for a new "great leap forward" technology, and it appears it may need it pretty soon.

The researchers note that given current genetics and varieties, the only way to meet growing world demand for wheat would be to grow it on better land. Today, most wheat is grown only on rain-fed acres. They suggest moving wheat to irrigated ground where corn and soybeans are grown today could be one yield-booster.

Industry observers know that in Europe where intensive farming methods for wheat are common, yields have grown significantly over the past few decades. Wheat yields topping 100 bushels are common in these growth environments. Is that what it would take to push up wheat yields in the U.S.? The wheat industry can meet world demand today, the challenge could be in the next five to 10 years as demand continues to rise - along with quality demands - in the face of rising disease pressure. Wheat breeders may be challenged to hit those higher targets.