The deep gene pool that has allowed wheat to achieve ever increasing gains in yield may be draining. Crop scientists estimate that 50% of the gain in wheat production over the past century has been due to breeding. According to a new study, however, that improvement has been slowing since the late 1980s, with little chance that future increases in yield can be met by breeding efforts alone.
The researchers, Robert A. Graybosch of USDA-ARS and C. James Peterson of Oregon State University, estimated that the average rate of genetic improvement in winter wheat yield potential since 1959 was 1.1% per year. However, most of this gain was realized from 1959-1989.
The study, reported in the September-October 2010 edition of Crop Science, published by the Crop Science Society of America, evaluated data collected from long-term USDA-ARS regional nursery trials in the Great Plains. The varieties entered into these trials from public and private entities represent the highest current genetic potential for grain yield production.
Since the late 1980s, the rate of grain yield improvement has slowed, and now appears to have reached a plateau. There are several reasons for this, including the perpetual evolutionary arms race against new pathogens, the resurgence of old pathogens, or perhaps merely the exhaustion of available genetic resources for yield improvement.
“We truly are in need of a second ‘Green Revolution’ in wheat,” says Graybosch, a wheat geneticist.
Fifty years ago, it was estimated that world population growth would out-strip world food supplies. These dire forecasts never reached fruition, as advances in genetic improvement via plant breeding and improved plant production practices have been able to keep pace with food demands.
Since inception of modern breeding efforts, improvements in wheat grain yield were driven by major breakthroughs, from adapting the plants to their climate, introducing disease resistance, and the introduction of dwarfing genes that caused plants to put more energy into growing seeds rather than stems. However, since these developments, no other major breeding advances have produced the “great leap forward” necessary to continue improving yields.
Unless some significant advance shortly impacts wheat genetic potential for grain yield, any increased demand for wheat can only be met by changes in current production practices or expansion of cultural environments.
The full article is available for no charge for 30 days following the date of this summary. View the abstract at https://www.crops.org/publications/cs/abstracts/50/5/1882.
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