Wheat Yield Barrier


"Yield Barrier" In Wheat Experts From 8 Countries Warn Of "Yield Barrier" In Wheat; Report Calls For New Strategies For World's Crucial Crop

As Population Grows, Wheat Yields Fail to Keep Pace

WASHINGTON, D.C., October 23, 1996 - As the world population booms, the staff of life for millions _ wheat _ may not be keeping pace, according to a new report released today by the Mexico-based International Maize and Wheat Improvement Center (CIMMYT). The report lays out a plan for breaking the "yield barrier" in wheat. It was developed by the world's most respected wheat scientists from 8 different countries and constitutes a synthesis of the most innovative thinking for increasing wheat yields into the next millennium.

Among other strategies, the scientists call for a global quest for genetic diversity in wheat, tapping into wild wheat relatives and wheat collections of countries around the world _ from Australia to Russia _ to find new, high-yielding genes.

"In the 1960s and early 1970s, when financial backing for agricultural research was in its heyday, wheat yields grew at a level of about 100 percent," said Timothy Reeves, Director General of CIMMYT. This was based on the combined effect of genetic improvement and enhanced crop husbandry (collectively know as the "Green Revolution"). "While the population is growing at a rate of 2.5 percent per year, these yields are now increasing only 1 percent a year," said Reeves. With wheat projected to feed more people than any other crop in the 21st century, stagnating wheat yields could put many at risk of hunger and poverty. Science must go further and find new answers for boosting wheat yields, especially since a population equivalent to Australia's is added to the earth every 12 weeks."

According to Matt Reynolds, Wheat Physiologist at CIMMYT and lead author of the report, there are three possible options for increasing wheat yields _ increasing the land area that is sown to wheat; increasing the use of fertilizer, irrigation, and other inputs; or increasing the yields of wheat so that more wheat can be harvested on the same land, using the same amount of inputs. "We have selected the last option because the first and second options come with high environmental price tags," said Reynolds.

The report lays out six main scientific strategies to break the yield barrier in wheat:

1.) Exploiting the genetic diversity of wheat _ Though scientists have made great strides in wheat research, there may be unknown genes that could push wheat yields up further while still producing good-tasting grain and adaptable plants. Wheat scientists are launching a worldwide search for genetic diversity in order to find such new genes.

"Hundreds of thousands of years ago, wheat was a wild grass," said Reynolds. "By a chance cross of two wild grasses, something similar to wheat was created. Early humans then found this plant and began to grow it, selecting for the best grain or for adaptability. Thousands of years later, breeders have applied the best in science to create today's elite varieties of wheat _ thoroughbreds _ in the fight against hunger.

"We are going back to wild grasses _ wheat's distant relatives _ and even to alien, nonwheat plants to find even better genes than we have now," continued Reynolds. "We can use biotechnology _ genetic maps and markers _ to identify good characteristics for yield, adaptability, resistance to pests and diseases, and, of course, good grain size and taste."

Scientists will produce new "synthetic" wheats, which are formed by crossing a distant relative of wheat _ such as goat grass _ with elite durum wheats. Synthetic wheats will serve as a bridge for moving additional yield-enhancing traits from distant relatives to modern bread wheats.

The new wheat strategy also calls for scientists to scan the world wide pool of elite wheat varieties. CIMMYT will serve as an information clearinghouse, and will make several different kinds of innovative crosses in the lab and in experimental fields. Scientists have been crossing wheats grown in cool climates (winter wheats) with wheats grown in warmer climates (spring wheats) for years. However, there are still vast untapped gene pools, particularly in the states that formerly made up the Soviet Union. Crossing them enhances genetic diversity and may create even more high-yielding plants.

2.) Developing a new wheat plant prototype _ In the 1960s, scientists dramatically changed the architecture of wheat plants in an advance called "semi-dwarfing." Semi-dwarfing shortened plants, allowing them to make use of fertilizers and irrigation without falling over. This advance also directed more of the plant's energy and biomass to grain as opposed to leaves and roots.

Wheat scientists are hoping to build on those advances by creating prototypes possessing traits that will enable them to yield even more than current wheats.

3.) Testing the hypothesis that increasing the length of time for the development of the immature wheat spike will produce a larger grain _ Just as humans spend a longer time than any other animal in an immature state in order to more intelligently adapt to their environment, scientists believe that prolonging the spike development stage of wheat may result in more useful wheat plants.

4.) Making better use of scientific selection criteria to identify useful traits _ When scientists cross two wheat plants, they may end up with thousands of offspring. However, the scientists can't currently identify all the characteristics of the new plants. CIMMYT will be utilizing technologies that will help identify the best plants early in the process; thus speeding the breeding process.

5.) Better adapting wheat varieties to particular farming systems and styles within regions of the world _ Scientists may be able to increase yields simply by creating wheat plants that are better suited for the realities of particular farming conditions in various regions.

6.) Exploitation of "hybrid" wheats _ Scientists will cross elite, pure bred lines with each other, seeking a phenomenon called "heterosis," where the hybrid offspring have tremendous advantages over either parent. However, unlike pure breeds (normal varieties), hybrids do not breed. But if the offspring of hybrids cross, heterosis does not occur because the two parent wheat varieties involved must remain pure. Farmers must therefore purchase new seed each year. Though expensive, the yield gains from hybrids may offset the cost of purchasing new seed each year. China, for example, chooses to encourage hybrid rice varieties.

"These strategies should help us to break the yield barrier in wheat, but they will need support," said Reeves. "One of the main causes of stagnating wheat yields may be the declining public and private investment in agricultural research. Today, CIMMYT's budget is 30 percent less than it was ten years ago, and, after factoring for inflation, we have 50 percent fewer funds to conduct research. Without these funding cuts, we may have already made more headway against the yield barrier."

CIMMYT employs more than 100 scientific staff from 39 countries together with more than 800 support staff. Its experimental research station is located outside of Texcoco, an hour from Mexico City. CIMMYT scientists work with national research systems in developing countries worldwide. Financial backing for CIMMYT's work comes from public and private foundations as well as some 40 countries, with the majority of funds administered through the Consultative Group on International Agricultural Research (CGIAR).

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