|Nakayama, Francis - USDA-ARS-USWCL RETIRED|
Submitted to: Proceedings Assoc for Advancement of Industrial Crops (AAIC) Annual Meeting
Publication Type: Proceedings
Publication Acceptance Date: August 15, 2005
Publication Date: September 21, 2005
Citation: Coffelt, T.A., Nakayama, F.S. 2005. Determining optimum harvest time for guayule latex and biomass. pp. 563-564. In M.J. Pascual-Villalobos, F.S. Nakayama, C.A. Bailey, E. Correal and W.W. Schloman, Jr. (ed.) Industrial Crops and Rural Development. Proceedings Assoc for Advancement of Industrial Crops (AAIC) Annual Meeting, Murcia, Spain, 17-21 September 2005. Technical Abstract: Guayule (Parthenium argentatum Gray) is a perennial shrub native to the Chihuahuan Desert of Northern Mexico and Southern Texas. New germplasm has shortened harvest time period from 3 to 5 years to 2 to 3 years. One of the most valuable products from guayule is its hypoallergenic latex. However, little research has been done on the optimum harvest time for latex concentration and yield. The objective of this study was to determine the optimum harvest time during the growth cycle for latex content, plant biomass, and latex yield of guayule. Treatments consisted of three guayule lines (Cal 6, AZR2, and AZ101) harvested monthly for two years. Plants were transplanted on October 13-14, 1999, at the U.S. Water Conservation Laboratory in Phoenix, Arizona. Harvesting began in February 2002 and continued each month through January 2004. Samples were analyzed for latex concentration and latex yields were calculated based on the latex concentration and the dry plant biomass. The experimental design was randomized complete block with four replications. Results varied among lines. During the first year, peaks in latex concentration generally occurred in March/April, September, and again in December/January. During the second year peaks occurred in February/April, June/July, October, and again in January. Plant biomass was less variable and generally was highest in late summer and fall. Latex yield which is a function of both latex concentration and plant biomass was highest the first year in September and December, and the second year in June and October. These results indicate that for maximum latex a later spring (May/June) or fall (October/November) harvest may be best. More research must be done to determine whether specific environmental factors can be associated with the optimum harvest time. There appears to be enough difference among lines, that planting lines selected for different optimum harvest dates would allow growers to spread the optimum harvest time throughout most of the year.