Submitted to: Industrial Crops and Products
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/23/2008
Publication Date: 11/29/2008
Citation: Coffelt, T.A., Nakayama, F.S., Ray, D.T., Cornish, K., Mcmahan, C.M., Williams, C.F. 2009. Plant Population, Planting Date, and Germplasm Effects on Guayule Latex, Rubber and Resin Yields. Industrial Crops and Products. 29(1):255-260. Interpretive Summary: Guayule is being commercialized in the southwestern USA utilizing new germplasm lines that have not been fully evaluated for the effects of various agronomic practices on their biomass, latex, rubber, and resin yields. This study evaluated three of the lines being used in commercialization for biomass, latex, rubber, and resin concentrations and yields at two plant populations (recommended and 2X recommended), two transplant dates (fall and spring), and six harvest dates (1 year old – 3.5 years old). Results showed little effect of transplanting date or plant population, but that spring harvests were better than fall harvests and the lines AZ-1 and AZ-3 were larger while AZ-5 was higher in latex, rubber, and resin content. These results should be of benefit to the new guayule industry to determine optimum transplanting and harvesting dates, plant populations, and lines to use in guayule production.
Technical Abstract: Guayule (Parthenium argentatum Gray) is a perennial shrub native to the Chihuahuan Desert. While guayule traditionally has been grown for rubber, more recently it is being grown for its hypoallergenic latex. Other uses such as termite resistant wood products and as an energy source have also been identified. However, the effects of various agronomic practices such as planting and harvesting dates, plant spacing, cutting height and frequency, irrigation frequency, and herbicide application, on newly developed germplasm and the effects on latex concentration and yield have not been reported. The objectives of this study were to determine the yield and concentration of latex, rubber, and resin of four guayule lines planted at two populations and two planting dates. Four guayule lines (AZ-1, AZ-3, AZ-5, and 11591) were transplanted at two dates (28 November 2000 and 7 June 2001) and two plant populations (27,000 and 54,000 plants/ha). Treatments were replicated four times. Each treatment plot was subdivided into six subplots for harvesting at six month intervals beginning one year after transplanting. Results showed that transplanting date did not consistently affect plant size or latex concentration or yield. Instead, it appeared that time of harvest (fall vs. spring) was more important. The last harvest (sixth) in the fall planting date and the fifth harvest date in the spring planting date were the optimum for plant biomass and latex, rubber, and resin concentrations and yields. AZ-1 and AZ-3 were larger, while AZ-5 had higher latex and rubber concentrations than the 11591 control. The higher plant population (54,000 plants/ha) was higher in biomass, rubber, and resin yields than the lower population (27,000 plants/ha) at the early harvest dates, but not at the later harvest dates (5-6). More studies need to be conducted to determine the optimum plant population and transplanting date for other newly developed guayule germplasm lines.