Castor (Ricinus communis L.): Valuable Crop or Toxic Weed in North America?.

Castor (Ricinus communis L.) is an important industrial crop which produces the unique fatty acid, ricinoleic acid. Ricinoleic acid is used in the production of nylon, cosmetics, lubricants, and medicines. Currently, most castor oil used in North America is imported from India, China, and Brazil. From 2011 to 2013, five castor cultivars were evaluated in 12 diverse environments across North America. These five cultivars were planted in a Latin square plot design with five replications and were evaluated on seed yield, oil content, seed weight, seed harvest index, oil harvest index, and total oil production.

            Analysis of variance and F-tests of mean squares of genotypes, environments, and the genotype x environment showed that there were highly significant differences (p = 0.001) between all three factors except for seed yield and oil yield. Seed yields of the five genotypes averaged over the 12 environments ranged from 1073 kg ha^-1 for Brigham to 1291 kg ha^-1 for Memphis. Average total oil yields of the five genotypes over the 12 environments ranged from 568 kg ha^-1 for Energia to 480 kg ha^-1 for Brigham. Seed harvest index and oil harvest index were highest for Ultra Dwarf (22.2 % and 13.5 %, respectively).

            These trials indicated that castor was well suited to several diverse environments of North America and appears to be surprisingly well adapted to the shorter growing season of northern temperate regions. In the future, it is hoped that with the development of regionally adapted cultivars with reduced levels of toxins that castor can be grown competitively across most of North America.