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Seeds for global warming

If global climate change occurs, seed companies say they will be ready for it. They are confident that their efforts to breed seeds that better handle environmental stresses will allow Corn Belt farmers to adapt to the changing environment for decades to come.

Representatives from Pioneer, Monsanto, Mycogen and Syngenta emphasize that the pace of climate change projected in mainline global warming scenarios can be addressed through their current breeding programs. In recent years, these programs have used both traditional and transgenic technologies to develop seeds that are more tolerant to drought, heat, insects and diseases. These are the very attributes likely to be needed as the climate changes.

“Most models of climate change predict significant, but not abrupt, changes, which will be consistent with the pace of change that we can make through breeding,” says David Fischhoff, technology strategy and development lead for Monsanto.

“Corn is a semitropical plant. I think that unless environments become very extreme, we can develop varieties for temperate climates” as the climate changes, says Dean Christensen, a corn research director for Pioneer Hi-Bred.

Hot and cold on global warming

Seed company executives' views toward global warming range from ambivalence and skepticism to a belief that human-induced climate change already is under way. However, they are convinced that ongoing efforts to breed more productive seeds will allow them to cope with global warming, should it occur.

Fischhoff says Monsanto has assembled a group of its top scientists to study global warming, assess its potential effects on crop systems and devise strategies for change.

Tom Wiltrout, Mycogen Seeds global business leader for corn, says, “I don't think we are doing anything consciously or extraordinary to address global warming in our breeding program. Is it something we worry about and have anxieties over? No. Whether you have global warming or not, there continues to be a huge pressure to increase productivity. That drives us to ask how we can drive science and technology to maximize yield potential.”

“We aren't predicting global warming will happen,” says Ben Hable, North American corn breeding lead for Syngenta. “But we have structured our breeding and research program to cope with changes in the global environment as they occur.”

Christensen, from Pioneer, says that concern over climate change hasn't led to major changes in the types of research that the company conducts. “What it has done is driven a change in emphasis on programs that were already in place,” he explains. “What the discussion of global warming has done is to raise those traits [drought and heat tolerance] to a higher place on our priority list than in the past. All of that leads to greater resources going to those particular areas.”

Gradual warming

According to Gene Takle, an Iowa State University climatologist with the Regional Climate Modeling Laboratory, over the past 50 years, the number of frost-free days in central Iowa has increased by eight or nine days. In Nebraska, and other parts of the Plains, the heading/flowering date of winter wheat, which is dependent on cumulative heat units during the growing season, has moved up a full two weeks over the past 70 years, adds Steve Hu, a climatologist at the University of Nebraska-Lincoln. (See “Climate change winners and losers,” December 2006, page 6.)

Steadily increasing corn yields, which have climbed at an average rate of 2 bu./year for the past three decades, could be partly due to the impact of climate change, says Dale Hicks, who recently retired as an extension agronomist at the University of Minnesota. “I've wondered about global warming as one possible reason for the yield trends of both corn and soybeans,” he says.

“Yields have been steadily increasing year after year, so you could say that breeders are already dealing with and overcoming the slow, continuous change that already has been occurring,” adds Fischhoff of Monsanto.

Climate change could at least partially explain the trend toward earlier planting in recent decades, notes Hable of Syngenta. “Is earlier planting because of the weather, the seed treatments we have available or improved seed vigor?” he asks. “It is difficult to say that earlier planting is due to the weather, but it also is difficult to say weather isn't involved. Climate change is kind of like watching kids grow. Can you really see it?”

Climate change models suggest that, in general, Corn Belt crop production could benefit from weather changes over the next few decades. Some models suggest that the Midwest growing environment will gradually become hotter and wetter, with longer periods between rains. These trends imply the potential for greater productivity but more stress on crops as rain becomes less frequent.

Breeding targets

Seed companies clearly are targeting drought and heat tolerance as they develop seeds that can withstand more extreme growing conditions and still produce consistent, high yields. Additional protection against diseases and insects and other traits are likely to be of secondary importance.

Drought and heat tolerance have been a major focus of corn-breeding programs across the industry in recent years and precede recent concerns about climate change. This is evidenced in increased research and infrastructure investments. (See “Dealing with drought,” page 90.)

Syngenta, for example, has a research group dedicated to enhancing water optimization. Working in the irrigated West, where moisture can be controlled to assess the impact of the timing of drought stress, the company hopes to commercialize hybrids based on this research early in the next decade.

“Every cornfield every year has some drought stress,” Hable says. “Our goal is to provide hybrids that can handle drought, not ‘drought hybrids.’ What we are developing is drought genes that will enable plants to make better use of water, eliminating or reducing yield reduction caused by variable water conditions.”

As plant breeders focus more on drought tolerance, they are learning that drought and heat, while often related, are separate factors that affect plant growth. “We are finding that heat tolerance is somewhat different than drought tolerance,” says Christensen of Pioneer. “There can be conditions where corn is not drought-stressed, but you have excessive heat. We are especially finding out that warm nights [as predicted in some climate change models] can be a distinguishing factor in hybrid performance. If nights are fairly warm, that recovery period is lessoned.”

In addition to producing corn for the heart of the Corn Belt, Mycogen is focused on providing hybrids that perform well on the western edge of traditional production areas. Producing hybrids suitable for those areas will help the company adapt its products to more extreme conditions, should they occur, Wiltrout says.

“We think moisture will continue to be a limiting resource,” he says. “We sell dryland corn in western Colorado and Nebraska and Texas. We think that addressing this in our hybrids is an opportunity to expand our seed production today. It is an opportunity to us no matter how climate change moves.”

Like other seed companies, Monsanto is developing hybrids adapted to drought and other environmental stresses. It also is focusing on nitrogen use efficiency and other factors that could help address the climate change challenges, Fischhoff says.

“This is significant because the main greenhouse gases coming from agriculture are not carbon dioxide, but nitrous oxide and methane,” he says. “Monsanto's nitrogen-use trait should help maintain high grain yield at lower nitrogen levels and could contribute to a significant reduction of agricultural greenhouse gas emissions.”

Wild cards

While most climate change models predict significant environmental changes, these changes aren't expected to be rapid. If changes are unexpectedly abrupt, changing germplasm fast enough will be challenging.

“What breeders can't prepare well for is an abrupt climate change, or chaotic behavior,” Fischhoff says. “Breeding alone would struggle to keep up with incredibly fast changes in the climate.”

“The major challenge is speed,” adds Mycogen's Wiltrout. “If you get global warming, and I am not saying you do, what is the speed at which it occurs? Can you adapt fast enough if change is rapid?”

If climate change presents unexpected surprises, plant breeders are in a position to respond more rapidly than in the past, notes Hable of Syngenta. “The tools we have today allow us to react faster,” he says.

However, the range of likely challenges from climate change suggests that the key crops grown in the Corn Belt will remain the same as they are today, although the range of where corn is grown could broaden, says Pioneer's Christensen. “Perhaps the [cropping] changes will come in those environments worldwide where small grains and canola have typically been grown,” he says. “Corn may become a viable alternative there. We are looking at central Canada, where corn is a minimal crop today, but could become a greater opportunity as we think about the future.”

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