|Peterson, C -|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 13, 2010
Publication Date: August 16, 2010
Repository URL: http://hdl.handle.net/10113/44566
Citation: Graybosch, R.A., Peterson, C.J. 2010. Genetic Improvement in Winter Wheat Yields in the Great Plains of North America, 1959-2008. Crop Science Volume 50:1882-1890. Interpretive Summary: 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 plant breeding and plant production have been able to keep pace with food demands. It is estimated that approximately 50% of the gain in wheat production has been derived from breeding (genetic improvement programs). Periodic assessment of genetic improvement in wheat grain yield potential is necessary for scientists and policy makers to determine whether future demands can be met. Using data from long-term USDA-ARS coordinated regional nursery trials in the Great Plains, the average rate of genetic improvement in winter wheat yield potential since 1959 was estimated as 1.1% per year. Most of this gain, however, was obtained in the first 30 years after 1959. Since the late 1980’s, this rate has slowed, and now, appears to have reached a plateau. 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.
Technical Abstract: Data from USDA-coordinated winter wheat regional performance nurseries collected over the time period 1959-2008 were used to estimate genetic gain (loss) in grain yield, grain volume weight, days to heading, and plant height in winter wheats (Triticum aestivum L.) adapted to the Great Plains. In both the Southern Regional (SRPN) and Northern Regional Performance Nurseries (NRPN), linear regression revealed significant positive relationships between relative grain yields of advanced breeding lines and calendar year of the nursery trial. The estimated genetic gain in grain yield potential since 1959 was approximately 1.1% (of the control cultivar Kharkof) yr-1 for all entries in the SRPN, and 1.3% yr-1 if only the most productive entry was considered. For the NRPN, the estimates of genetic gain in grain yield were 0.79% yr-1 for all entries, and also 0.79% yr-1 for the most productive entry. Relative grain volume weights and days to heading have remained fundamentally unchanged since 1959, but relative plant heights have declined at rates of approximately 0.43% yr-1 in the SRPN, and 0.32% y-1 in the NRPN. Linear regressions of relative grain yields versus year over the time period 1984-2008, however, showed no significant trend in the SRPN, and a very weak positive slope in the NRPN. Relative grain yields of Great Plains hard winter wheats may have peaked in the early to mid-1990’s, and further improvement in the genetic potential for grain yield awaits some new technological or biological advance.