The value of the seeds was $15.3 billion in 2015, down from $15.7 billion in 2014. That represents 34 percent of the global commercial seed market, the report said.
Most of the genetically modified crops contain genes from bacteria that make the crops resistant to certain insects or tolerant of Roundup or other herbicides. That tolerance of herbicides can allow farmers to spray those chemicals to kill weeds without harming the crop.
The crops were eagerly adopted from the moment they first became widely commercialized in 1996, particularly in the United States. Global acreage grew year over year, in many years by double digits, until a slowdown in the last two or three years.
The United States remained the largest grower of such crops in 2015, with 175.2 million acres planted, down 5.4 million acres from 2014. That decline was largely offset by an increase of nearly five million acres in Brazil, bringing its total to 109.2 million acres. Acreage in Argentina, the third-largest grower, increased to 1 percent, at about 60.5 million acres.
Plantings in India, whose only genetically engineered crop is cotton, were flat at about 28.7 million acres while cultivation in Canada fell by about 5 percent to 27.2 million acres because of lower overall cultivation of canola, the report said.
L. Val Giddings, a proponent of biotech crops, said the small yearly decline was a sign of a maturing market.
“I’m completely unsurprised to see this slight evidence of cycles, which are normal in agriculture,” said Dr. Giddings, senior fellow at the Information Technology and Innovation Foundation, an organization in Washington that advocates for policies that enable innovation.
Efforts to introduce different traits and different crops have been slow to take hold.
In the United States, two notable new genetically engineered crops were approved since late 2014 — apples that do not turn brown when sliced and potatoes that produce less of a potential cancer-causing chemical when fried. But in response to activists, some food companies like McDonald’s, Wendy’s and Gerber have said they have no intention to use one or both of those products at present.
Development of those markets will be gradual, with only about 400 acres of the potatoes and 15 acres of the apples planted in 2015, according to the report.
With Vermont now set to require labeling of foods containing genetically modified crops, some big food companies like Campbell, General Mills and Mars have said they will start labeling all their foods nationwide. Del Monte Foods went even further, saying it would eliminate ingredients from genetically modified crops in many of its products.
In China and India, growers have widely adopted cotton engineered to be resistant to insects. But efforts to expand the use of biotechnology to food crops have faltered. China has devoted a lot of research into developing its own versions of genetically engineered corn and rice but has not approved them yet for commercial use.
In India, the government in 2010 imposed a moratorium on commercial cultivation of insect-resistant brinjal, a type of eggplant. Recently, the government has said it would reduce the fees that Monsanto and its local partner can charge cotton seed companies for their genes, prompting Monsanto to threaten to re-evaluate its business in that country.
Europe remains the center of opposition to the crops. Cultivation in the European Union fell 18 percent to only about 300,000 acres, almost all of that insect-resistant corn grown in Spain.
The report said the global acreage could expand if genetically modified corn were to be adopted in China and in other parts of Asia and Africa. Vietnam began growing such corn commercially in 2015. The report also said there were 85 potential new products being field tested, including drought-resistant corn and pest-resistant cowpeas for Africa