The yield of strawberries in the United States has increased by 2755% since the 1960s.
Strawberries are grown worldwide, and although their production volume does not match that of grains, they are produced in large quantities. Their yield has continued to grow since the 1960s, with current production being 27 times higher than in the 1960s. Strawberry breeding has a long history of 300 years, but it was during the era known as the “Green Revolution” that yields began to increase dramatically. Although the Green Revolution mainly focused on grains, strawberries serve as a significant source of vitamins and have had a substantial impact on people’s lives. What has caused such a significant increase in strawberry yield?
Genetic gains underpinning a little-known strawberry Green Revolution
The increase in yield was the result of diligent breeding.
Since the 1960s, breeding has significantly contributed to the increased yield of strawberries. A major breakthrough was the development of the “Perpetual Flowering Hybrid (PF type)”, which is not affected by photoperiod, allowing for consistent flowering. Since flowers lead to fruit, this has resulted in increased yields. Additionally, breeding has reduced the susceptibility to rot and acidity in strawberries. While sweetness has also decreased, it is likely that the relative sweetness increased due to the reduced acidity.
Interestingly, the cultivated area for strawberries in the United States has decreased. According to estimates by the Food and Agriculture Organization (FAO), since 1961, the annual increase in production has been 22,215 tons/year in the United States and 26,782 tons/year in Europe. The processes to achieve these yields in the United States and Europe were quite different. Europe’s production increase was achieved through a 398% increase in harvested area and a 1% decrease in yield, whereas the United States achieved its increase through a 2,755% increase in yield and a 17% decrease in harvested area. This data clearly shows how breeding has significantly increased the yield of American strawberry varieties.
Despite the increased yield, American strawberries have become more susceptible to disease.
While the yield of American strawberries has increased, their resistance to soil-borne pathogens has decreased. Verticillium wilt and Phytophthora root rot are among the most common soil-borne diseases affecting strawberries. These diseases are complex in terms of genetic resistance mechanisms and have been causing plant death and yield loss in strawberries for over a century since their first report in the early 20th century. Initially, the Green Revolution led to the emergence of disease-resistant varieties, but these have since declined.
The increase in yield despite increased disease susceptibility is attributed to improvements in cultivation methods. Various agricultural technologies developed during the Green Revolution have made these diseases less impactful on yield. The introduction of soil fumigation with methyl bromide since 1960 has played a significant role, leading to a decrease in the priority of disease resistance in breeding, resulting in a reduction of resistant varieties.
Is an era of breeding for both quantity and quality upon us?
Research shows that the “Green Revolution” since the 1960s has increased not only grain yields but also strawberry yields in both the United States and Europe, albeit through different methods. Both can be considered successful breeding achievements, but future responses may vary depending on demand changes.
The future of Japanese strawberry breeding is also fascinating. Japanese strawberry varieties are of world-class quality and are extensively exported. While there are challenges to overcome, such as plant variety rights abroad, the rich genetic resources for breeding are not easily replicable. With demographic changes such as aging, there seems to be a trend toward preferring quality over quantity. However, a new variety registered in Saitama Prefecture in 2023 represents an excellent breed that guarantees both quantity and quality, possibly marking the beginning of an advanced phase in breeding.
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