Submitted to: Industrial Crops and Products
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/31/2004
Publication Date: 7/1/2005
Citation: Nakayama, F.S. 2005. Guayule future development. Industrial Crops and Products, 22(1):3-13 Interpretive Summary: At present, over 90 percent of the original guayule plant is considered waste bagasse from which useful products can be derived. The economic of such co-products will greatly enhance its agricultural development. Besides latex, the guayule plant synthesizes useful compounds with biological control properties that have industrial and commercial applications. For example, the bagasse itself can be made into composite wood with termite resistant properties. The resin extract can be impregnated into wood to make it termite and marine borer resistant. Because the resin has a high fuel value, wood pellets made from the bagasse have high energy burning equivalent. Similarly, the bagasse can be pyrolyzed into diesel fuel. Furthermore, the deresinated bagasse is essentially a cellulosic material and can be converted into ethanol. Thus, almost 100 percent of the plant can be utilized based on co-products development.
Technical Abstract: Successful commercial development of guayule (Parthenium argentatum Gray) will depend on utilizing as much of the plant as possible with useful applications. At present, latex is the primary product. The remaining plant components that include resin and biomass can play an important role for further its economics. The purpose of this review is to cover alternatives such as coproducts that show promise in the existing marketplace for improving the commercialization of guayule. Coproduct development can augment the commercialization of many natural, renewable resources. In the case of guayule, several hundred thousand hectares are expected to be under cultivation for latex production. Actually, only about 10% of the plant will be used for latex and ways must be found to either to dispose or to develop useful coproducts for the remaining 90% residual. Fortunately, guayule synthesizes many potentially useful compounds for industrial and commercial applications. This resin-containing bagasse can be used without additional chemical processing. For example, it has been combined with a plastic binder to make high-density composite boards that are resistant to attack by termite and wood-rot fungi. In the future, the bagasse could be blended with other wood sources of intermediate density and still have the insect control properties. The crude resinous extract either from the whole plant or latex-processed bagasse can be used without purification. Such resin when impregnated into wood can protect it against wood destroying organisms including marine borers. At present, the most promising area for using bagasse is in the control of harmful arthropods and microorganisms, although only a few insects and fungi have been tested to date. Other potential uses for the bagasse or resin are in energy production. The bagasse can be compressed into fire logs, briquettes, and worms or pellets. Such combustible material has higher energy content than other wood sources because of the resin, which can make up about 10% of the dry mass. On going attempts to increase the rubber content and biomass of the plant, have increased the resin to rubber ratios to 2:2 from that of 1:1. Although unintentional, this crop improving development may be fortuitous because the resin fraction appears be just as economically valuable as the latex component. The Parthenium genus consists of other species that is mainly made up of resin instead of rubber. The future appears promising to develop such species if the resin becomes an economically viable product.