Cutting height effects on guayule latex, rubber, and resin yields

Guayule (Parthenium argentatum Gray) is a perennial shrub native to the Chihuahuan Desert. While guayule traditionally has been cultivated for rubber, more recently it is being cultivated for its hypoallergenic latex. Other uses including termite resistant wood products and as an energy source have also been identified. Major advances have been made since 1970 in the development of improved guayule germplasm. However, the effects of harvesting practices such as cutting height and frequency on latex concentration and yield of newly developed germplasm have not been reported. These results are needed in order to develop production schemes for successful commercialization of guayule. The objectives of this study were to determine the yield and concentration of latex, rubber, and resin of five guayule lines harvested at two cutting heights over 3 years and five harvesting schedules. Harvesting at 100% of plant height gave higher yields than harvesting at 50% of plant height independent of the harvest schedule. Harvesting at 100% after 4 years of growth gave the highest yields, but more research is needed to determine if harvesting on a 2-year schedule may be better for harvesting equipment and extraction equipment. AZ-2 and AZ101 were the largest plants, while N9-3 and 11591 were smaller with AZ-1 intermediate. As indicated in previous studies, the environment plays a large role in determining biomass, latex, rubber, and resin yields in guayule. In the future, optimum harvesting schemes at 100% of plant height may need to be developed for each line and environment.