Tempering Beans Reaction to Heat
January 15, 2008
USDA Geneticist Timothy Porch is out to help dry beans beat the heat.
Working from the USDA Agricultural Research Services Tropical Agriculture Research Station at Mayagüez, Puerto Rico, Porch is trying to reduce the impact of heat stress in dry beans grown in the continental United States by breeding for heat tolerance.
Average temperatures exceeding 86°F in the day and 68°F at night can impede common beans reproductive development and that this translates into smaller potential yields during hot summers, he says.
Porch is trying to equip U.S. beans with high-temperature adaptation and other traits such as drought tolerance and disease resistance.
An important limitation is the narrow genetic diversity thats available, he says. U.S. breeding programs use less than 5% of available Phaseolus germplasm. New diseases, climate change, limited inputs, and market competition are all reasons to diversify the U.S. bean germplasm base.
Porch says that germplasm from the Tropics is the key to introducing the protective traits U.S. producers need. It harbors the vast majority of beans genetic diversity, he says. Tropical beans are often sensitive to the long photoperiods in the continental United States, so conversion must also involve introduction of photoperiod insensitivity through crossing and selection.
Ultimately, Porch says, converting tropical bean germplasm into U.S.-adapted types will lead to increased yields in stressful environments, lower consumer costs, and new genetic material that scientists can use for varietal development.
USDA ARS Geneticist Tim Porch examines the effects of high-temperature stress on pod development. He is trying to breed new lines of dry beans that can tolerate higher temperatures and drought stress. Photo: USDA