Guayule rubber and latex content - seasonal variations over time in Argentina

Rubber from guayule (Parthenium argentatum Gray, Asteraceae) is essentially equivalent to that from the rubber tree (Hevea brasiliensis). Increased in cidents of 'latex allergies', especially among health care workers, have re sulted in a renewed interest in guayule, because it has been shown that ind ividuals sensitive to latex allergies do not react to guayule latex. Little work documenting changes in guayule latex content with plant age, from sea son to season, or among lines has been reported. To provide some of this in formation and hence to assist with the commercialization of guayule, a proj ect was initiated to determine rubber and latex changes over time in guayul e plants growing in Catamarca, Argentina. Lines G7-14, N-565 and 11591 were sampled every 2 months, whereas lines A-Z-5, A-Z-3, P2-17, P1-12, P3-11, G 10-130 and G1-16 were sampled every 6 months over a 3 year period. Statisti cally significant differences in plant weight, and in rubber and latex cont ents, were found among some lines. Plant weights were positively correlated with age. Latex and rubber contents showed little correlation with age. Th e latex and rubber contents were well correlated (0.73 for all lines). Late x and rubber production among some lines was statistically different. Seaso nal effects on latex and rubber percentages were significant only for lines G7-14 and 11591, whereas seasonal effects on latex and rubber production w ere significant only for lines G7-14 and N-565. The results for the various lines indicates that time of harvest may not be critical to maximize yield . Harvesting the crop throughout the year would require a smaller capacity processing facility than seasonal harvesting and reduce the cost of a proce ssing facility and production. (C) 2001 Elsevier Science B.V. All rights re served.