Assessing the Sap Flow and Rooting Characteristics of the Castor Plant (Ricinus communis L.): Developing a Sustainable Cropping System for Florida.

An increased energy demand combined with rising costs of fossil fuels and the need for profitable agricultural products has created an interest in new crops and optimization of cropping systems for sustainable production of biofuels.  Further, castor (Ricinus communis L.), while a candidate for biodiesel production, has high economic value as an industrial oil and lubricant as well. Because of this economic potential, several U.S. states including Florida are considering castor as a biodiesel and industrial feedstock, due to its unique oil composition and high potential yield.  In an effort to develop a sustainable cropping system for castor in Florida, we conducted research into agronomic characteristics of the crop including water usage and the effect of plant growth regulators on root architecture of the Brigham variety.  Plots were established at the Plant Science Research and Education Unit in Citra, FL in 2011 and 2012.  Daily measurements of sap flow were regularly logged and quantified to determine total daily and seasonal water use.  Sap flow values will be combined with evaporation rates to develop seasonal crop water-use curves and crop coefficients for castor grown in north Florida.  Root architecture among plant growth regulator treatments was assessed through the use of minirhizotrons installed within plot rows and root images were taken throughout the growing season.  Images were analyzed to determine the development of total root depth, root length, and root surface area. This research has quantified water-use and root architectural characteristics in castor that were previously unknown and that can be used to determine the best management practices for castor grown in Florida.