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GAINESVILLE, Fla. — University of Florida scientists have discovered how much water castor needs in order to grow in North Florida, a key finding in their efforts to determine the feasibility of producing castor in Florida for the first time since 1972.
Castor, grown in Florida during World War II and currently being considered as a component for military jet fuel, contains the toxin ricin. So scientists next must develop a ricin-free cultivar, said Diane Rowland, a professor in agronomy and advisor for the lead author, graduate student David Campbell.
Scientists measure what’s known as “evapotranspiration” – or how much water leaves the plant and its surrounding soil – to get what’s called a “crop coefficient.” A crop coefficient tells scientists and growers the relative water use of the crop in comparison to what’s called a “standard crop evapotranspiration.” That standard comes often comes in the form of grass grown under optimal conditions. Florida growers can obtain site-specific standard evapotranspiration from the Florida Automated Weather Network, or FAWN (http://fawn.ifas.ufl.edu/).
“FAWN provides standard evapotranspiration data for more than 40 locations in the state of Florida already. Thus, one thing we need to provide to prospective castor growers is a crop coefficient for castor,” said Chaein Na, a postdoctoral scientist on the study. A grower can determine crop water use by multiplying the appropriate crop coefficient with the standard evapotranspiration to estimate daily, weekly, monthly or seasonal water requirements for the crop.