Lima beans: Sweet, bitter and fighting worms

Folks at UC Davis are busy breeding lima beans – also known as butter beans -- to be better for both producers and consumers.

Scientists are working on both large-seeded and baby limas, and both bush and vine types. They want higher yields, higher-quality seeds, plants that flower in North American summers, and traits that allow the plants to adapt to regional differences in water, soil and temperature. In addition, they’re interested in seed color and pattern for niche markets including boutique chefs.

The breeding program is led by Christine Diepenbrock, an associate professor in the UC Davis Department of Plant Sciences. Diepenbrock and team members brought growers and others up-to-date on their research at the recent UC Dry Bean Field Day, held on campus fields.

Trials of large- and baby-seeded bush limas have yielded some interesting candidates. Next steps are regional trials, with the goal of releasing top varieties, Diepenbrock said. The breeding team is also field-evaluating their viny materials based on grower interest. Research in this area is supported by the California Dry Bean Advisory Board.

California is a major producer in the United States of dry limas, which are harvested when the seed pod is dry. In contrast, succulent limas are harvested while still moist in the pod, and are more often grown in other parts of the country for both fresh market and processed products.

Ahead of breeding: Taste, texture, genes and education

Federal funding, including $3.3 million from the USDA’s National Institute of Food and Agriculture, is supporting broader areas of research to inform how scientists breed better limas. UC Davis is leading this collaborative, nationwide effort to identify and develop lima beans that taste delicious, cook beautifully and pack nutrition, and also are pleasing to growers and processors.

This USDA pre-breeding project is led by Paul Gepts, a distinguished professor emeritus with the department. The UC Davis team for this project also includes Jaclyn Adaskaveg, Antonia Palkovic, Varma Penmetsa, Travis Parker, and Diepenbrock.

Team members described advances in the third year of the pre-breeding research:

• More information has been gleaned about what growers and consumers want. Research includes taste tests that are continuing this fall.
• Scientists are studying genes that control desired traits and using that information to pull in greater diversity to use in breeding. Traits include resistance to microscopic worms called nematodes. Trials in greenhouses and in the field were conducted.
• Scientists are reviewing the collection of lima beans at the USDA seed bank in Washington state to identify useful material for further analysis. “We’ve worked with hundreds of different kinds of lima beans,” Diepenbrock explained. “We take the seeds and grow them so we can measure all sorts of things about them.”
• People are developing educational materials to teach students at the high school, undergraduate and graduate levels about the beans’ nutritional value.

Adaskaveg, a postdoctoral researcher in the department, also described consumer-oriented testing on 43 kinds of limas.

The work included taste tests led by Jean-Xavier Guinard and Yukina Murata in the UC Davis Department of Food Science and Technology.

• The taste testers coined terms to characterize flavors including sweet, bitter, starchy, earthy and corn-like. More flavors that have industry folks excited include maple syrup and curry.
• Textures include graininess, chewiness, moistness and firmness.
• Appearance includes qualities such as wrinkled, speckled and size of the beans.

“Jaclyn and team are also looking at nutritional quality and cooking time in our lab and in collaboration with the USDA’s Agricultural Research Service,” Diepenbrock wrote.

So far, researchers have found larger limas cook faster, on average, than baby limas. They also found white limas have more absorbable iron compared to colored limas. Colored limas also tend to taste harsher and more bitter than white and green limas, which tend to taste sweeter.

Collaborative effort plus more beans

The larger lima bean project includes collaborations with researchers from the University of Delaware, Clemson University, UC Riverside, Iowa State University, USDA’s National Plant Germplasm System and the National Center for Genome Resources. The team includes researchers from the University of Delaware, Clemson University, UC Riverside, Iowa State University, USDA’s National Plant Germplasm System and the National Center for Genome Resources.

Research on other dry beans – garbanzos, black-eyed peas, common beans and tepary beans – also was presented at the event. Read about it here.

Related links

• Hand-outs giving details on this and more research presented during the UC Dry Bean Field Day can be found here.
• For more information on the national project, read the story here.
• Get the UC ANR manual, “Lima Bean Production in California,” here.