US: Study informs breeding priorities for Florida strawberry production

In West-central Florida, strawberry breeding is big business. Second only to coastal California in acres of strawberry crops harvested annually, the region is home to large-scale production operations that rely on relevant research to inform practice and sustain success. A new study from a research team from the Gulf Coast Research and Education Center at The University of Florida and the US Department of Agriculture–Agricultural Research Service, Citrus and Subtropical Products Lab, provides strawberries breeders with valuable information that the authors say can help create strategies for genetic improvement.

Since 1968, The University of Florida has been engaged in a continuous breeding program to develop cultivars that are highly adapted to winter production in west-central Florida. Ten new cultivars have been released since that time. A study published in HortScience evaluated the 10 cultivars released since 1968, along with two selections being considered for release at the time of the study. According to lead author Vance Whitaker the research was designed to look at breeding progress over time. Two sites—trial grounds of the Florida Strawberry Growers Association at Dover, Florida, and the Gulf Coast Research and Education Center at Balm, Florida—were used during the 2009–2010 study.

The UF breeding program has focused on breeding new strawberry varieties that feature increased fruit size and uniformity and decreased cull rate. "Larger fruit sizes are not only attractive to consumers, but also result in increased harvesting efficiency," Whitaker said. "For some traits such as fruit size and cull rate, significant gains from recurrent selection are apparent in the breeding program. These remain very important traits for industry acceptance and selection pressure for these traits must be maintained."

The program has also worked to find ways to enhance strawberry color. "We assume that increased internal flesh color is desirable to consumers, and studies have shown that color in foods can affect consumers' perceptions of flavor," Whitaker noted. Results from the current study showed that internal redness was a trait for which progress was observed early in the breeding program, but the gains were not sustained. The authors said this may have resulted from a lack of intentional selection for the flesh color trait. They recommended that genetic relationships between internal color and other traits be the focus of future studies.

The study also found that although there were significant differences among genotypes for all chemical traits affecting flavor, there were no discernible patterns over time. Chemical components of flavor are received increased attention in the breeding program.

The scientists noted that a strawberry variety’s success can depend on a range of genetic traits. For example, 'Strawberry Festival', the dominant strawberry grown in west-central Florida, rarely showed the most extreme values for any of the traits studied. "This illustrates the importance of acceptable performance for many traits, not just a few, in the commercial success of a strawberry cultivar," they said.

Whitaker concluded that the comprehensive study should help guide future genetic studies and inform decisions about future breeding priorities and selection procedures.

he complete study and abstract are available on the ASHS HortScience electronic journal web site: http://hortsci.ashspublications.org/cgi/content/abstract/46/4/553