Plant breeding: past achievements and expectations for the future
Duvick, D.N.
Plant breeding improvements have been responsible for 50 percent or more of the gains in yield per unit area of major crop plants in the United States over the past 50 yr. Rates of gain attributable to genetic improvements have averaged 1% per year, have generally been linear, and show no sign of slackening. Extrapolations indicate that varieties and hybrids of the year 2000 will yield, on average, 15% more than those of 1985 Improvements in tolerance to environmental stress, in grain-to-straw ratios, and in standability, as well as maintenance of required levels of resistance to disease, insect and nematode pests, have been the major genetic causes of higher achieved yields and will continue to be the foundation for further gains in productivity and stability. Broadened genetic diversity is also an increasingly important goal to promote stability and increase productivity potentials. Proportionately large research inputs are now needed to maintain desired rates of improvement, compared to earlier years. It seems likely that contributions from biotechnology will become increasingly important in years to come if improvement rates are to be maintained.
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