Why wheat yield gains continue to lag behind corn, soybeans

Wheat ranks third among U.S. field crops in planted acreage, production, and gross farm receipts, behind corn and soybeans. Production has, however, dropped off over the past decade. USDA estimates U.S. farmers planted 46 million acres to wheat for the 2017-2018 growing season, down from 50 million in 2016-2017 and over 63 million in 2008. In contrast, U.S. farmers this spring planted over 90 million acres each of corn and soybeans.

Market fundamentals certainly influence planting decisions, but steady gains in corn and soybean yields also have helped motivate farmers to plant those crops while gains in wheat yields have fallen behind. According to a University of Minnesota study, global wheat yields are increasing at a rate of 0.9% annually, compared with 1.6% for corn and 1.3% for soybeans. USDA figures show similar trends (See Graph).

A shortage of research finding for wheat breeding plays a key role in the yield trends, says Steve Joehl, Director Research & Technology at the National Association of Wheat Growers (NAWG). He estimates that total annual spending on wheat-breeding research averages around $150 million, compared with near $2 billion for soybeans and $3 billion for corn.

Private-sector seed companies account for the lion's share of funding for corn and soybean research, while most funding for wheat projects comes from USDA or state wheat-producer checkoff programs, Joehl says.

Two key barriers have limited progress in wheat-breeding research.

Hybridization

First, as a self-pollinating plant, hybridization in wheat has lagged far behind corn. Farmers potentially can plant harvested wheat for several years with minimal decline in yields, unlike corn, where farmers need to purchase certified F1 hybrid seed every season to capitalize on hybrid vigor and produce cost-effective yields. This makes it difficult for seed companies to generate adequate returns on their investments in developing new wheat varieties, Joehl says.

That could change over the next few years though, as researchers develop systems for producing hybrid wheat seed, a task more difficult than producing hybrid corn, but possible. According to Texas A&M University wheat breeder Amir Ibrahim, PhD, breeders can cross inbred wheat lines using advanced techniques to create pollen-producing or seed-producing plants. Crossbreeding those lines can produce more resilient, higher-yielding hybrids.

The process is, however, significantly more expensive and time-consuming than creating new corn hybrids. The Texas A&M researchers currently are working under a three-year USDA grant, funding just under $1 million, titled "Developing the Tools and Germplasm for Hybrid Wheat."

Commercial wheat hybrids have seen some limited use in Europe, and at least three major seed companies have indicated they will launch commercial wheat hybrids by the early 2020s. Researchers believe lower seeding rates and higher yields will help account for higher costs for hybrid wheat seed.

GMO perceptions

Joehl also notes that wheat, almost exclusively a food crop in the United States, experiences more market scrutiny over genetic engineering than crops such as corn and soybeans, which are used mostly for livestock feed. Joehl says downstream resistance to genetically modified organisms (GMO) in food crops has significantly slowed progress in addressing production challenges including grain quality, weed management, insect and disease resistance, cold and drought tolerance and yields.

Those pressures were evident in the early 2000s, when Monsanto developed a glyphosate-resistant GMO wheat variety. The company received FDA approval use of the GMO wheat in food, but withdrew its EPA application to market the seed in 2004 due to resistance from export and domestic customers. The issue of GMO wheat received more negative publicity in 2013, when testing confirmed the presence of the unapproved GMO variety in a commercial field in Oregon.