Post-harvest storage effects on guayule latex quality from agronomic trials

Current guayule commercialization efforts are based upon the production of hypoallergenic latex. The objective of this study was to determine how latex yield and quality are affected by post-harvest plant storage in order to provide flexibility in the harvesting, chipping, and processing steps for guayule latex. The experiments were conducted on two lines (11591 and AZ-2) at the University of Arizona Maricopa Agricultural Center, from March 2001, through December 2004. Weight-average molecular weight of guayule latex increased as the plants aged from 1.7 to 2.7 years. Guayule latex quality was affected by shrub storage conditions, and addition of moisture extended the storage time for guayule shrub without negatively impacting molecular weight for both varieties. However, under extreme conditions, for example, high temperatures and extended dry storage times, polymer molecular weight reduction of up to 30% occurred.