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Submitted to: Maize Handbook
Publication Type: Book / Chapter Publication Acceptance Date: 10/11/2007 Publication Date: 1/5/2009 Citation: Holland, J.B. 2009. Increasing Yield. Maize Handbook. 469-482. Interpretive Summary: Maize yield improvement in the 20th century represents one of the great success stories of plant breeding and agronomy. Maize grain yield in the United States has increased on average by 0.122 metric tons per hectare per year since 1945 (Figure 1). This paper reviews the genetic basis of yield in maize, physiological changes that have accompanied yield gains, and prospects for continuing gains. Technical Abstract: Maize yield improvement in the 20th century represents one of the great success stories of plant breeding and agronomy. Maize grain yield in the United States has increased on average by 0.122 metric tons per hectare per year since 1945 (Figure 1). This is in sharp contrast to essentially zero gain in national yields from 1900 to 1944. What caused this dramatic in-crease after the Second World War? One cause of yield increases has been plant breeding. The period from 1937 to 1960 represents the period in which farmers shifted from planting open-pollinated cultivars to double-cross hybrids, and this coincided with the change from flat yield trends to annually increasing yields. Starting from 1960, single-crosses began to predominate, and this also coincides with an increase in the rate of annual gain for yield. As of 2006, the trend toward higher yield had not abated, testifying to the ability of plant breeders to continually improve maize hy-brids. |
