Corn varieties engineered to withstand drought offer planters hope
By Brad Plumer,
In western Kansas, the corn looks unsalvageable. The landscape is rife with curled brown leaves, an unmistakable sign of severe drought.
Yet beneath those wilted leaves, some of the corn shows promise. The kernels have held up surprisingly well in a few places given this summer’s swelter. At hundreds of sites across the Great Plains, seed companies such as Monsanto and Pioneer are testing a slew of corn varieties engineered to withstand drought. As the harvest approaches, they’re anxious to see the results.
This year, the worst U.S. drought in half a century could cause $18 billion in damage to corn, soybean and other key crops. On the heels of a Texas drought last year that cost nearly $8 billion, farmers are more interested than ever in innovations that could make crops more resilient. That includes improved farming practices, better plant-breeding techniques and even — most controversially — genetic engineering.
Given the severity of this year’s drought, many crops will wither no matter what. Still, some planters remain cautiously optimistic.
“I’ve been surprised so far. The plants are responding well,” said Clay Scott, a Kansas farmer who planted two plots of Monsanto’s genetically engineered DroughtGard Hybrids among his 3,000 acres of corn. The experimental strain, which carries a gene that helps it draw water more gradually from the soil, is slated for wider release in 2013. “The ear size, kernel counts, the ear weights look good,” Scott said. But, he cautioned, “pretty corn doesn’t always result in yield.”
For Scott, who lives in a region prone to dry spells, where irrigation water from the nearby Ogallala Aquifer needs to be conserved, these crops could prove indispensable.
It’s a pitched battle between nature and human ingenuity that will only grow more difficult. Earth’s population has soared past 7 billion. Climate models suggest that drought will become more frequent in North America. Water will become increasingly precious. Feeding the world will require wringing as much food as possible from every last drop of water.
It’s far from assured that human ingenuity will win out.
“This is perhaps the biggest challenge that we face,” said Mark Edge, who’s in charge of marketing DroughtGard for Monsanto, the world’s largest seed company. “And there’s so much complexity to it that it’s one of those things you dive into with humility.”
Adapting to drought
Since the 1920s, crop scientists have focused on breeding improved strains of corn and wheat to provide ever bigger yields. In the past decade, however, researchers at private companies and land-grant colleges have put a renewed emphasis on developing crops that can also withstand extreme weather events. Like drought.
“Ultimately, plants need water,” said Thomas Sinclair, a crop scientist at North Carolina State University. “If they don’t have the water, then farmers are going to take a yield loss. But our work is to minimize that yield loss.”
Traditionally, this has been accomplished by breeding hardier crops. Scientists might look for genetic traits that allow corn to adapt to drier areas. These traits could include roots that burrow deeper in the soil or stomata that close earlier in the growing cycle to retain moisture. By interbreeding these varieties with high-yield corn, scientists create crops that use water more efficiently or withstand dry spells.
The process involves plenty of trial and error. Yet recent genomic techniques have enabled breeders to track traits more efficiently.
A slew of drought-tolerant hybrids are hitting the market. In 2011, DuPont’s Pioneer released eight versions of AquaMax corn, which was found to boost yields by up to 7 percent. The company is introducing 17 varieties this year.
Then there’s genetic engineering. Seed companies such as Monsanto have taken crop science to a new level by manipulating a plant’s genes directly or transplanting genes from unrelated organisms. DroughtGard, for instance, contains a bacterial gene that enables it to retain water. It’s the only genetically engineered crop bred for drought tolerance that has been approved by the Agriculture Department.
Scientists caution that there are huge challenges in breeding — or engineering — these crops. For one, there’s no such thing as a single drought.
“A genetic trait that expresses itself well for early drought tolerance may not be a solution for a drought later on in the season,” said Tony Vyn, an agronomist at Purdue University. “And something that expresses itself well as being drought tolerant under normal temperatures may not help when temperatures are extremely high.”
Also, climate change could lead to more extreme variation in weather — say, a drought one year and a flood the next.
“The big challenge with climate change is that I can’t just work on drought,” said Mitch Tuinstra, a corn breeder at Purdue. “It’s the variability of all these different stresses that makes this so difficult.”
Companies such as Monsanto have genetically modified crops that are resistant to pesticides or pests, such as Bt corn. But that often involves manipulating a few genes. Drought can prove more complicated.
“The reality is that drought impacts every process in the plant,” Sinclair said. “There’s not one magic gene out there that’s going to make the plant perform better under drier conditions.”
In June, a report by the Union of Concerned Scientists noted that developing and testing such crops can take 15 years. The seeds are often more expensive, and the benefits appear modest so far — the report estimated that DroughtGard would boost U.S. corn productivity by just 1 percent.
“There’s little to suggest that genetic engineering will make a major contribution to drought tolerance and water-efficiency use in the next five to 10 years,” report author Doug Gurian-Sherman said. “But 20 years down the line? I don’t know.”
The slow pace of biotechnology is one reason experts say it’s crucial not to overlook less-flashy techniques.
“I sometimes worry we put too much emphasis on the genetics,” said Larry Wagner, an agronomist at South Dakota State University. “Certainly the genetics are getting better. But farming practices are getting better every year, as well.”
The practice of no-till farming — in which seeds are planted without churning up the soil — has become more widespread, Wagner said. Modern equipment enables farmers to plant seeds through old crop residue, enabling the soil to hold more moisture. Computer technology allows farmers to analyze their soil and calculate how much fertilizer to use.
These techniques add up. One 2009 study estimated that a combination of improved practices and conventional breeding had boosted the drought tolerance of U.S. corn by 1 percent a year in the past few decades.
Drought anxiety has also revived interest in organic practices, such as covering the soil with compost or cover crops to hold more moisture. Amid the current drought, Iowa State University’s Kathleen Delate has been studying these farms. “Overall, the organic plots seem to be faring better,” she said, “but we need to quantify this.”
Other experts contend that the United States may need to rethink its dependence on corn, a lucrative, much-subsidized crop that is especially susceptible to drought. Planting a wider variety of crops, such as alfalfa or sorghum, could prove more sustainable.
“All of these agro-ecosystem approaches that build soil fertility are extremely valuable,” Gurian-Sherman said. “But they don’t get nearly as much money or attention from the big companies.” He added that the U.S. government spends just 2 percent of its agricultural research budget on sustainable farming.
Climate change has given the task a renewed urgency. Recent modeling work by Aiguo Dai of the National Center for Atmospheric Research suggests that droughts could become far more frequent in the next 20 to 50 years due to rising temperatures and natural variations in ocean cycles. “These two factors lead to a very dire outlook for the U.S., especially the West,” Dai said.
The advances may not come fast enough. “There’s more investment now [in drought-tolerance] than there was 20 years ago,” Purdue’s Vyn said. “But is that enough? I’m hopeful that the science will continue to improve. But I’m also mindful of the ticking clock.”