Source Year: 1996

Guayule (Parthenium argentatum) has substantial quantities of resin which is often discarded after rubber extraction. Resin from 13 cultivars of guayule from India was analysed for its qualitative and quatitative variations. The stem had 6.15;resin followed by the roots (5.91;), branches (5;), leaves (3;), and flowers (3.06;). The resin percentage varied significantly among the cultivars. it varied from 10.7;in cv. USDA 10 to 5.5;in UCR 1; however, resin synthesis and biomass of the shrub had poor correlation. Guayulins (sesquiterpene cinnamic acid esters) were analysed by HPLC. The composition of guayulins varied among cultivars. Guayulin A was in the range 0.27-3.7g/plant, the lowest being in USS 2X and the highest in USDA 17. Regression analysis between resin yield and guaylin A as well as guaylin B per plant showed poor correlation. Guaylin A dominated over guaylin B in all plant parts analysed. Variation in resin percentage and guyalin composition in different cultivars may be due to differences in the origin of the cultivars and not necessarily due to temperature or other environmental factors. Resin synthesis appears to be independent of rubber synthesis and is not influenced by temperature minima, which is obligatory for cis-polyisoprene biosynthesis