PLENARY SESSION (BIOENERGY/BIOPRODUCTS)
The New Uses Council (NUC) and the Association for the Advancement of Industrial Crops (AAIC) should be positioned to play a cooperative and major role in the advancement of the biobased economy/carbohydrate economy. This partnership will be strengthened by including the Biobased Manufactures Association (BMA), the marketing arm for products produced through the joint efforts of AAIC and NUC.
We should see this extended partnership as three distinct industries working synergistically to bring a new and wide range of renewable products into the American and world marketplace: several biofuels, including ethanol, biomethanol, biodiesel, bio-oil, biogas, and biohydrogen; biopower and cogenerated thermal energy; and, a plethora of biobased products. The AAIC will focus on industrial crops for the more profitable production of these bioproducts; the NUC will assist by encouraging support for development of these crops that will not only increase productivity and offer value-added options, but also enhance the environment while improving the soil.
The NUC will also work for supportive public policy, heightened interest by governments at all levels, and the advancement of industries to refine crops, residues and waste streams into products. The BMA will market these products which, in the end, is the principal determinant of success in this overall process.
Contact: William (Bill) C. Holmberg, Chair, NUC, 2816 Claudia Ct., Vienna, VA 22180, USA. Tel.: 703-204-2344. E-mail: biorefiner@aol.com
The likely outlines of integrated biorefining systems are now beginning to emerge. Integrated biorefining systems will produce a wide variety of chemicals, materials, food, animal feed, and fuels from many different plant sources. We will discuss features of biorefining systems on which there are both substantial agreements, and also much less agreement, or at least certainty. Life cycle analysis will also be described in terms of its value to help optimize our choices and pathways to a more biomass-dependent future.
Some features of biomass refining systems on which there are substantial agreements include: 1) their inherent advantages conferred by low cost, widely available and diverse biomass raw materials, 2) their increasing future competitiveness due to relative technological immaturity, particularly the relatively immature state of bioprocessing technology, 3) the probable continuing diversification of biobased products, 4) the impact that advances in the life sciences will have on biomass production and biorefining, and 5) the effect that increasing efficiency of biomass raw material utilization over time will have on the system (National Research Council, 2000). The consequences of these and other high consensus features will be briefly discussed.
Other features about which there are fewer consensuses, and which, therefore will be treated in more depth, include, among others: 1) possible competition of biomass derived chemicals (including fuels) and materials with food production (in the context of possible land use constraints), 2) whether large scale fuel production from biomass is possible, or even desirable (in a life cycle context), 3) the likely trajectories of the biorefining industry (will it diversify like the petroleum refining industry, from high volume toward high value products, or will it take the other direction?), and 4) how biorefineries will or might integrate with the agricultural production sector.
It is crucial to develop this new biobased products industry in an environmentally sustainable manner. The tools of life cycle analysis are available to help guide the development of biorefining systems. In many ways we have a unique opportunity to choose whether or not we would like to inhabit a world based more on renewable plant sources - and then to construct sustainable pathways that will take us to such a future.
Contact: Bruce E. Dale, Dept. of Chemical Engineering and Materials Science, 3247 Engineering Building, Michigan State University, East Lansing, MI 48824-1226, USA. Tel.: 517-353-6777. Email bdale@egr.msu.edu
The "Vision for Bioenergy and Biobased Products in the United States" sets forth the goal that by 2030, 5% of the nation's power, 20% of transportation fuels, and 25% of the chemicals will be derived from biomass. This production of fuel, power, and chemicals is about 15 quadrillion Btus (quads) annually and will require approximately 1 billion tons of biomass feedstock per year.
Achieving the 1 billion tons/year goal by 2030 is a significant undertaking and will require a focused research and technology development program. This program will have four critical objectives as follows:
Biomass Availability - Current U.S. availability of biomass is estimated to be approximately 400 million tons/year. Therefore biomass production must be more than doubled, which will require significant changes in the U.S. agricultural system.
Sustainability - Currently, the U.S. food, fiber, and feed production system produces about 1 billion tons of product annually. A viable lignocellulosic biorefining industry will double this production demand, whose doubling can only be sustainably achieved through enhanced utilization of natural resources and reduced environmental impacts at both the enterprise, national and global levels.
Infrastructure - The current biomass harvest, collection, transport and storage infrastructure system is designed primarily to meet the low volume dispersed demands of the diary and livestock industries. This system is inadequate to meet the high volume, centralized demand of the biorefinery concept, and hence, new technology and infrastructure are needed.
System Profitability - The economics of fuels, power and chemicals productions from biomass dictate that the delivered lignocellulosic biomass feedstocks costs (including preprocessing) must approach $35 per ton. Within this price target growers, brokers/transporters, equipment suppliers, and every other involved industry sector must realize a self-sustaining profitable business venture to ensure an economically viable feedstock supply chain.
A series of colloquies has been held involving growers, equipment suppliers, harvesters, transporters, processors, and other involved stakeholders to define the high priority research and technology development needs. From this input, a feedstock supply roadmap has been developed to guide the biorefinery feedstock research and technology development program.
Contact: T.D. Foust, Idaho National Engineering and Environmental Laboratory, PO Box 1625, Idaho Falls, ID 83415-2210, USA. Tel.: 208-526-0147. E-mail: foustd@inel.gov
Conventional wisdom among academics and bioscience laboratories is that further research is the most important contributing factor to the successful development of the biobased market. University and National Laboratories have certainly provided the needed technologies upon which a multitude of excellent biobased products are based. However, with biobased manufacturers struggling financially in virtually all 20 major product categories, their overwhelming concern is for increased sales. Biobased manufacturers now needs support not only in science and technology, but in marketing and finance as well. As a representative of biobased manufacturers, I would like to recommend ways in which Universities, Federal and State governments can help to promote the growth of the biobased economy.
Contact: Kim C. Kristoff, Biobased Manufacturers Association, 3808 N 28th Ave., Phoenix, AZ 85017, USA. Tel.: 602-265-8586. E-mail: kristoff@gemtek.com
The energy demand of the United States is huge and current use of fossil fuel to meet that demand creates security and environmental concerns. Bioenergy crops have the potential to address these concerns, while also benefitting the rural economy. However, there are several challenges to be overcome before the potential of growing crops for use as energy feedstocks can be realized.
Issues such as economics, production, logistics, conversion, and sustainability must be addressed in order to achieve significant development of energy crops and their commercial conversion into liquid fuels and other forms of energy. Research and development are needed for improving the genetics and production of bioenergy crops; for gathering, handling, storage, and delivery of large quantities of energy-crop biomass with appropriate characteristics; and for converting such biomass into more useful energy forms. The Agricultural Research Service and other agencies of the U.S. Department of Agriculture have research underway to solve these technical problems.
Though technical challenges are great, other challenges exist that may be even greater. Currently, the cost of fossil feedstocks is, and will for some time likely remain lower than the cost of bioenergy feedstocks and as a result fossil-based energy is cheaper than biobased energy. Therefore, because comparative cost is of such importance in making purchasing decisions, bioenergy has a significant marketing disadvantage. For bioenergy to be competitive, there is a need for implementation of policies that cause the true overall cost (including energy security, the environment, and the rural economy) of each energy option to be reflected at the point of sale.
Contact: D.C. Erbach, National Program Leader, Engineering and Energy, USDA-ARS-NPS, 5601 Sunnyside Ave., Beltsville, MD 20705-5139, USA. Tel.: 301-504-4610. E-mail: dce@ars.usda.gov
Natural rubber is an irreplaceable raw material vital to industry, transportation, medicine, and defense. At present, most of this rubber is produced from clonal plantations of Hevea brasiliensis in southeastern Asia. Temperate-zone rubber-producing crops are greatly desirable to increase the biodiversity, protect supplies, and provide a safe natural-rubber alternative for the large number of people suffering from Type I latex allergy to proteins in existing Hevea latex products.
We have used a combination of basic and applied research approaches, from biochemistry and metabolic engineering to process chemistry and performance testing, to make the production of latex from Parthenium argentatum (guayule) a commercial reality. However, new guayule lines are still needed that have high latex yields, improved agronomic characteristics, and broader environmental cultivation ranges. Understanding the biochemical regulation of rubber yield (principally rate) and quality (principally molecular weight) in guayule is an essential preliminary step to the identification and manipulation of the key regulatory steps in rubber synthesis.
In this presentation, the biochemical regulation of guayule rubber biosynthesis will be discussed, and features unique to guayule highlighted.
Contact: K. Cornish, Western Regional Research Center, USDA, ARS, 800 Buchanan St., Albany, CA 94710, USA. Tel.: 510-559-5950. E-mail: kcornish@pw.usda.gov
Breeding a new industrial crop, such as guayule, is not appreciably different from enhancement and breeding of conventional crops. In both instances, plant breeders take the extant germplasm and search for genetic variability in the desired traits. The major differences are that in new crops plant breeders are often working with an unfamiliar species that is not yet fully domesticated and the available germplasm is often limited.
The main objective of the guayule breeding program is to facilitate successful commercialization by developing higher yielding cultivars. Improvement has been accomplished, with newer lines yielding up to 250% more rubber than lines developed in the 1940s and 1950s. This is surprising because the genetic base from which improvement has been made appears to be very narrow, and because guayule reproduces predominately by apomixis (asexual reproduction by seed).
Improvement through plant breeding is dependent upon having genetic diversity within the available germplasm, and being able to identify different genotypes. Our measurements have shown that the available guayule germplasm exhibits extreme variability both within and between lines for morphological traits such as height, width, and biomass, chemical constituents such as rubber, resin, and latex contents, and genetic (isozymes), chromosomal, and molecular (RAPD) markers.
The measured variation is due partly to the facultative nature of apomixis in guayule (asexual reproduction and sexuality coexisting), which periodically releases genetic variation among progeny. It has also been shown that a great amount of this measured variation is due to environment, and selections, to take advantage of only the genetic differences, must be made within the first two-years of growth.
There have been relatively few individuals involved in guayule breeding. Thus, with limited resources and time, most of the improvement has been made by single-plant selections from within populations. Although this method has the potential for only modest long-term gains, it requires a relatively short time period to realize improvements. To facilitate the selection process, indirect measures have been developed so that many more plants can be evaluated by relatively few individuals. For instance, most selections are made for plant height, width and biomass because they have been found to be highly correlated with rubber yield. As pointed out by Dr. Francis Nakayama, by making selections in this manner, we may be inadvertently changing the plant in ways that are not necessarily desirable, such as the increased resin to rubber ratio found in some newer lines. To facilitate guayule improvement, a breeding scheme is being suggested that combines recurrent crosses between sexual and apomictic genotypes, which will allow the release of more genetic diversity from which selections can be made.
Contact: Dennis T. Ray, Department of Plant Sciences, Forbes Building, Rm. 303, The University of Arizona, Tucson, AZ 85721, USA. Tel.: 520-621-7612. E-mail: dtray@u.arizona.edu
Irrigation is a critical factor influencing guayule establishment and production. Standards were developed during the Emergency Rubber Project that included annual water requirements for guayule production, and irrigation water quality. Early investigations confirmed that stress played an important role in rubber production. Approaches to controlling water stress focused on the theory that plant stress, caused by soil water deficits, could increase rubber production. A simple, reliable method was needed for following water stress so that the stress/rubber production interrelationship could be clearly defined. The Crop Water Stress Index (CWSI), developed for other economic crops, was adapted to transplanted guayule in the early 1980s by Dr. Francis Nakayama and co-workers at the USDA-ARS, U.S. Water Conservation Laboratory (USWCL). The CWSI was computed from the plant and air temperature difference, versus the water vapor pressure deficit of the atmosphere. The CWSI/rubber yield correlation revealed that under low stress rubber yields averaged 930 kg/ha, and only 540 kg/ha under high stress. The index has become a valuable tool for monitoring and managing water stress and irrigation scheduling.
Understanding plant stress and the water requirements of guayule led to successful stand establishment by direct-seeding. Dr. Nakayama and others at the USWCL found that conditioned seed could be planted 10 mm deep and its germination was superior to untreated, raw seed. They reported that under drip irrigation, intermediate water levels were best for stand establishment (two irrigations per week during the first five weeks following planting, and a single irrigation per week between weeks six and ten). These studies led to successful establisment trials by Texas A&M University and New Mexico State University.
Extensive weed control research has been conducted since the 1970s, but no treatments are currently labeled by the U.S. Environmental Protection Agency for guayule production. Investigations by New Mexico State University revealed that DCPA (9.0 kg ai/ha) and Prowl (1.1 kg ai/ha) demonstrated adequate selectivity for preemergence weed control in direct-seeded guayule. Studies by Texas A&M University confirmed these results. Herbicide injury is decreased in transplanted stands because the older, larger plants are more tolerant to herbicides, and are also more competitive against weeds. Field experiments in New Mexico indicated that Treflan, Prowl, and Surflan applied as preeemergence treatments were safe for transplant establishment. Texas A&M University scientists reported that Barricade (2.2 kg ai/ha), Gallery (0.6 kg ai/ha), Prowl (1.1 kg ai/ha), and Treflan (1.1 kg ai/ha) were all adequate for controlling annual broadleaf weeds and grasses. Presently, no herbicides are safe for use as postemergence, over-the-top sprays in either direct-seeded or transplanted situations.
Contact: M.A. Foster, Texas A&M University Agricultural Research Station, Box 1549, Pecos, TX 79772, USA. Tel.: 432-445-5050. E-mail: ma-foster@tamu.edu.
Guayule rubber (GR) has not been an article of commerce for more than 60 years. Nevertheless, the production of bulk rubber or latex from guayule has been pursued at various times throughout this period. We describe here the most recent efforts in this area, with particular consideration given to the properties of guayule cis-1,4-polyisoprene that influence process development.
As recently as 1990, multi-ton lots of bulk GR have been produced for evaluation in tires and other rubber goods. At a prototype processing plant operated by Bridgestone/Firestone, Inc., 8.8 t of GR were produced by simultaneous extraction of rubber and resin with a mixed organic solvent. The rubber component of the resulting miscella was fractionated to yield material meeting standard specifications established for bulk rubber from Hevea (NR). The nameplate capacity of the Sacaton, Arizona, facility was 152 t (150 long tons) of GR/y. Running at capacity, the pilot plant would have consumed an estimated 860 kg/h of baled shrubs.
More than 3.3 t (37%) of the rubber product met the specification for TSR20 NR. This material was tested as a direct replacement for NR in aircraft tires. Another 2.1 t (24%) met the FEMA specification for bulk GR and was used to fabricate light truck tires.
The need for a fractionation step arose from the fact that GR has lower bulk viscosity than NR, the result of a lower Mn and a broader molecular weight distribution. GR bulk viscosity varies with the cultivar, the date of harvest, and the level of entrained resin (non-rubber extractables). Because GR lacks the protein components of NR, GR must be stabilized from both thermal and oxidative degradation.
On the threshold of pilot-scale production, guayule latex has been prepared to date in 25- to 50-kg batches. The latex is washed from ground shrubs, and then concentrated by a combination of multistage centrifugation and creaming. Development of a commercially-viable latex process will have to take into account several factors that distinguish GR latex from Hevea (NR) latex, among them a greater sensitivity to changes in temperature and solids concentration, a lower protein content, and a higher resin content.
In terms of its cure characteristics, the resulting product behaves more like synthetic polyisoprene (IR) latex than NR latex. Most importantly, dipped goods prepared from GR latex are free of the protein allergens that elicit a Type I allergic response in individuals sensitized to NR latex.
Contact: W.W. Schloman, Jr., Department of Chemistry, The University of Akron, Akron, OH 44325-3601, USA. Tel.: 330-972-7359. E-mail: wwschlo@uakron.edu
Successful commercial development of guayule (Parthenium argentatum Gray) will depend on using as much of the plant as possible. At present, latex is the plant's primary product. Utilization of the remaining components that include resin and biomass can greatly improve the economics of guayule. The purpose of this presentation is to review new and possible alternate products that can be made from guayule "waste" material that can enhance the commercialization of guayule.
Coproduct development can augment the commercialization of natural, renewable resources. For guayule, about 90% of the plant material to be grown in several hundred thousand hectares would be available for coproduct development. Fortunately, guayule synthesizes many potentially useful compounds for industrial and commercial applications. These include fatty acid triglycerides, flavonoids, polyphenols, terpenes, sesquiterpenes, and waxes that make up about 10% of the whole plant. Also, we cannot neglect the other 80% of the cellulosic material. The resinous material is of special interest because of its antitermitic and wood-rot resistance properties.
Because of the water-based process used to extract latex, the residual plant material or bagasse will still contain the resin. This resin-containing bagasse without additional chemical processing has been fabricated into high-density, construction-grade, composite boards that are resistant to attack by termite and wood-rot fungi. In the future, bagasse could be blended with many other wood sources with different densities and physical proerties that have insect control properties. The bagasse or the resinous extract could be incorporated into wood putty or caulking, for example, to make such repair material insect resistant.
The resin extracted from the latex-processed bagasse with a polar organic solvent can be used without purification. Such resins when impregnated into wood can provide protection against other wood destroying organisms such as marine borers. Possibly, this resin extract can be used to protect wood and trees against wood attacking insects such as carpenter ant and bark beetle. In addition, the resin can be used in paint primers and varnishes with similar insect control properties. The resin has been incorporated with epoxy polymers to produce coatings that are readily strippable, a useful property for storage-protection of aircrafts, ships, and other industrial equipment undergoing environmental exposure.
Other potential uses for the bagasse or resin is in the area of energy production. The bagasse can be formed into fire logs, briquettes, and pellets. Such combustible material has higher energy value than other wood sources because of the resin, which can make up about 10% of the dry mass. The bagasse has been converted into gaseous and liquid fuel, and with improved pyrolysis technology, could become a source of diesel-type fuel. De-resinated bagasse could be converted into a source of alcohol and other type of chemical entities for liquid fuel or solvents.
Ongoing attempts to increase the rubber content and biomass of the plant, have increase the resin to rubber ratio to 2:1 from that of 1:1. Although unintentional, this crop improving development may be fortuitous because the resin fraction appears to be just as valuable as the latex component. The Parthenium genus, consists of numerous species that can grow faster than guayule with larger biomass, but consists mostly of resinous material instead of rubber. The future commercial development of these other Parthenium genus also appears promising.
Contact: F.S. Nakayama, U.S. Water Conservation Laboratory, 4331 E. Broadway Rd, Phoenix, AZ, 85040, USA. Tel.: +1 602-437-1702 (X255). E-mail: fnakayama@uswcl.ars.ag.gov
NATURAL RUBBER AND RESINS - SESSION 1
Type I latex allergy has continued to be a critical problem for the health care community since the late 1980s when the increased use of tropical latex medical devices, especially medical gloves, precipitated an epidemic of latex allergy in the United States. Studies of serum antibodies from the general population conducted by the USDA in 1994 identified approximately 20 million Americans who have developed some level of sensitivity to tropical proteins. Although synthetic lattices are now utilized for manufacturing latex medical devices, performance attributes are inferior to natural latex while material costs are significantly higher.
Yulex Corporation ("The Company"), through an exclusive licensing agreement with the USDA-ARS, has embarked on an ambitious commercialization project to meet the critical demands for nonallergenic natural rubber latex. The pilot project is privately financed and focused on three key areas: 1) agricultural expansion of the guayule plant (Parthenium argentatum, Gray), 2) scale-up of the latex bioprocessing methods developed by Dr. Katrina Cornish and her team at the USDA-ARS laboratories, and 3) product development relating both guayule latex products and various co-products derived from the guayule plant.
The Company announced in July 2003 the completion of the first guayule natural rubber latex pilot plant facility. The pilot facility is located in Maricopa, Arizona with the desinged capacity to process approximately 750 metric tons per annum of biomass (green weight). This pilot facility is located in close proximity to the company's mature guayule crops, which will be harvested and utilized as feedstock for the pilot facility.
With the completion of the pilot facility, Yulex has entered into agreements with medical device manufacturers who are assisting Yulex with process scale-up and product development. The Company believes guayule natural rubber latex will be competitive in the short-term against high-priced synthetic latex for the premium medical device sectors while projecting competitiveness against tropical latex with the successful commercialization of co-products currently under development.
Contact: J.A. Martin, Yulex Corporation (www.yulex.com), 1947 Camino Vida Roble, Ste. 104, Carlsbad, CA 92008, USA. Tel.: 760-476-0320. E-mail: jmartin@yulex.com
Current guayule commercialization efforts are based upon the production of hypoallergenic latex. However, little is known about the optimal agronomic condition for maximum latex production. In this study, we tested the effect of planting density and date of planting on the yield and quality of latex in four guayule lines harvested at three times.
We found differences in latex content among lines, planting dates, planting densities, and harvest times. Line AZ-5 had the highest latex concentrations followed by AZ-1, 11591 and AZ-3. Latex concentrations were lower in all lines harvested in October 2002, compared with harvests in April of 2002 and 2003, reflecting plant growth and low latex production between April and October. Three of the four lines (AZ-3 being the exception) had higher latex concentrations at a density of 54,000 plants/ha, than at 27,200 plants/ha. Also, the date of planting did affect the latex content, but in a line-specific manner. Most strikingly, AZ-5 shrubs planted in June 2001 had a much higher latex content in April and October 2002 than the older AZ-3 shrubs planted in November 2000. This difference was no longer apparent in April 2003. Variation between shrubs from the two dates of planting was large in April 2002, but had substantially decrease by April 2003.
Rubber particle size also varied slightly. At 27,200 plants/ha, the older plants had a larger particle size than the younger plants, but this was only seen in AZ-5 at 54,400 plants/ha. In the older plants, particle size was consistently greater in shrubs grown at the lower plant density. Little difference was found in particle size among younger plants regardless of planting density. Protein concentrations in April 2002 followed a similar trend as the latex concentrations - protein concentrations were higher in the latex of younger plants and also in the latex of plants for the higher field densities, with 11591 and AZ-3 showing the largest differences. Data from the later harvests are not yet available.
The data indicate that the older plants (based on date of planting) at lower planting density make less rubber in fewer, but larger particles than the older plants at higher density or the younger plants in general. No information is yet available on plant size at the different harvests so that extrapolations to the actual latex yield/ha are not yet possible.
Contact: K. Cornish, Western Regional Research Center, USDA, ARS, 800 Buchanan St., Albany, CA 94710, USA. Tel.: 510-559-5950. E-mail: kcornish@pw.usda.gov
Guayule (Parthenium argentatum Gray) produces rubber primarily during the winter months. There is evidence from growth chamber studies that cold night temperatures are responsible for this increase. The objective of this preliminary study was to determine what physiological changes occur in guayule when exposed to cold night temperatures that might account for the rubber accumulation during the winter months.
Plants from the lines N6-5, AZ6, and 11591 were placed in open containers inside an unheated greenhouse so that all plants were exposed to the same daytime temperatures. At night, covers were placed on all of the containers and heat provided to one-half of the containers to maintain the average nighttime temperatures above 20°C. The unheated containers were exposed to ambient night temperatures, which averaged less than 10°C.
Plant heights were recorded every 15 days. Photosynthetic rate estimated by CO2 exchange was measured three times in January and February 2003 within one hour of solar noon. Photosynthesis measurements were also taken once 4 h before solar noon and 3 h after solar noon. On 19 March 2003, all plants were harvested by cutting the plants at the soil surface and roots were removed from the soil and washed.
Those plants exposed to cold night temperatures were significantly smaller in both height and fresh weight than those plants subjected to heated conditions during the night. Photosynthetic rates were not significantly different between cold- and warm-night-treated plants in the early morning and late afternoon, but were significantly higher for the cold-night treated plants when measured around solar noon.
The higher photosynthetic rate at solar noon in plants exposed to cold night temperatures could account for some of the increased rubber production during the winter months. These plants have low growth rates. Therefore, rubber production could be a sink for the photosynthates being produced.
Contact: M.E. Veatch, Department of Plant Sciences, The University of Arizona, Forbes 303, Tucson, AZ 85721. Tel.: 520-621-2817. E-mail: veatchm@email.arizona.edu
Complementary data on guayule varieties along with guidelines on suitable locations for its growth and management practices are needed. Nine locations were chosen for a breeding yield trial, Maricopa (AZ), Marana (AZ), Yuma (AZ) (2 sites), Pecos (TX), Tucson (AZ), Safford (AZ), Los Cruces (NM), and Saltillo (Mexico). The different locations were chosen for their differences in elevation, annual rainfall, frost-free season, and soil type. The following summary only concerns the first 5 locations, i.e., the Maricopa Agricultural Center, Marana Agricultural Center, and two at the Yuma Agricultural Center, which are all part of the University of Arizona and the Texas A&M Research Station, Pecos, TX.
A total of 14 different lines (11591; AZ-1; AZ-2; AZ-3; AZ-4; AZ-5; AZ-6; AZ-101; AZ-R2; N565; N6-5; N9-3; N13-1; G1-16) were planted in a completely randomized complete block design with 4 replicates in Maricopa on 27 and 28 November 2001, in Marana on 16 May 2002, at both sites in Yuma (the first 13 lines only) on 29 and 30 May 2002, and in Pecos (the first 13 lines only) on 2 May 2002. Measurements taken at each site included: stand count after planting; plant height and width (twice a year, late October-early November and late April-early May); latex, rubber and resin content; and plant biomass (yearly for 3 years starting 2 years after planting).
After only 2 sets of plant measurements (height and width), four lines (AZ-1, AZ-2, AZ-3, and AZ-101), common to all locations, have a higher growth rate. Although these lines do better overall, differences in plant height among the various locations for these 4 lines are quite different. For instance, even with 6 months difference in the planting date, the plant heights from Marana are comparable with the ones from Maricopa for the fall 2002 measurement (Pr - 0.0001).
Early in the trials, and with only one year's data, no conclusions can be made at this time. However, environmental factors such as elevation, annual rainfall, frost-free season, soil type, and also the field management (irrigation, fertilization and weed control) may be responsible for the differences among locations. These trials will help establish the lines that have the best commercial potential for growers in different locations where guayule will be grown. It can also provide useful guideline information for future guayule growers.
Contact: D.T. Ray, The University of Arizona, Department of Plant Sciences, 303 Forbes Building, P.O. Box 210036, Tucson, Arizona 85721-0036, USA. Tel.: 520-621-7612. E-mail: dtray @u.arizona.edu
Guayule (Parthenium argentatum Gray) remains a potential commercial source of hypoallergenic natural rubber latex that may be used for the production of different products. Currently, there are no guayule plantations in México. Guayule grows wild in the arid and semiarid regions as natural stands. These stands are exclusive to the country. Evaluation of the plant natural spreading is important allowing the identification and selection of high yielding varieties in different environmental zones.
The present objective was to determine the morphological characteristics as well as rubber and resin contents of wild guayule plants at four sites over a period of three years.
The study sites were defined within the localities of Rocamontes (Coahuila), Norias de Guadalupe (Zacatecas), and two at Gomez Farías (Coahuila). We had evaluated the sites previously during 1997. The present study was carried out from January 1999 to February 2002 with samples collected generally every month. Ten plants per site that were representative of the population were measured in the field for height and spread, and then uprooted and transported to the laboratory for biomass, main stem diameter, rubber and resin content measurements.
The results showed plant spreading and development during the three years study causing an apparent reduction in the average biomass production, but an increase in rubber and resin content. The present global average biomass value (242 g) is greater than that (52 g) found in our previous evaluation of the sites. Rubber content increased from 8.9% to 10.9% in the three years, whereas resin content changed from 12% to 11.2%. The average rubber content in the sites is approaching the highest average value (11.7%) found in the native stands at Mapimi, Durango. Accordingly, plant natural reestablishment is noticeable and will create a good source of raw material and seeds that may be able to support and develop commercial plantations.
Contact: D. Jasso de Rodríguez, Universidad Autónoma Agraria Antonio Narro, Saltillo, Coahuila. M‚xico 25315. Tel.: (844) 4110220. E-mail: dianajassocantu@yahoo.com.mx
NATURAL RUBBER AND RESINS - SESSION 2
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 from 3 to 5 years to 2 to 3 years. Biomass yields of newer lines approach 22 t ha-1 within 2 years. One of the most valuable products from guayule is its hypoallergenic latex. However, little research has been done on methods to handle the shrub from the time it is harvested in the field until it is processed for latex extraction. Past results have shown that extractable latex yields from shrubs stored under ambient conditions are almost zero within 24 h following harvest. The development of storage and handling systems to maintain latex yields during the critical period from shrub harvest until latex extraction would be very beneficial for growers and processors.
The objective of this study was to determine the effects of various storage treatments on the latex content of harvested guayule. The treatments consisted of storing the shrub dry in the shade, and with various moisture treatments in the shade.
Results indicate that storage under dry conditions results in almost zero latex being extracted. These results confirmed our previous observations. However, storage under several different moist conditions maintained latex yields equal to freshly harvested guayule latex yields for periods of up to four weeks. Results from these tests indicate that harvested guayule shrub can be stored and processed following field harvest without losing latex yield.
Contact: T. A. Coffelt, U.S. Water Conservation Laboratory, USDA, ARS, 4331 East Broadway Road, Phoenix, AZ 85040-8832, USA. Tel.: 602-437-1702 ext. 238. E-mail: tcoffelt @uswcl.ars.ag.gov
Extraction and purification of latex from guayule (Parthenium argentatum Gray) require that harvested shrub first be homogenized in an alkaline aqueous buffer. We have extended an earlier investigation into the stability of the latex in homogenates made in different ways and stored under different conditions.
Neither the length of post-harvest storage (up to five weeks) nor the diameter of the branch affected the concentration of the latex in homogenates. Latex concentration was not affected by the length of grinding used to make the homogenate. However, latex concentration declined at acidic pH, and after one month at 24°C in one experiment, and after six months in another when the initial latex concentration in homogenate prepared from defoliated shrub was below 5 mg/ml. This decline was less apparent in homogenates made from leafy shrub, which suggests a protective effect derived from the leaves. Storage at 4°C prevented latex loss under all treatments.
The quality of the rubber polymers in the latex fraction was investigated using size exclusion chromatography/multiangle laser light scattering detection. Polymer molecular weight and molecular radius declined in parallel, but declined faster in the dilute homogenate generated from the second grind of the guayule bagasse than in the more concentrated homogenate from once-ground shrub. Degradation was greatly slowed in all treatments when the homogenates were stored refrigerated. Polydispersity values were low in all treatments, and only slightly increasing over time, with the exception of homogenate generated by the second grinding of shrub in the presence of leaves and stored at 24°C. The relatively rapid polymer degradation of the latex fraction in this homogenate led to an increase in polydispersity followed by a decrease as the latex fraction was degraded to below detection levels.
We conclude that guayule homogenate provides a stable environment for latex yield and quality, even at room temperature, for at least 13 to 16 weeks provided that the pH is basic and the concentration of rubber particles is at least 5 mg/ml. This is in contrast to the extractable latex content of harvested branches, which is prone to rapid coagulation and degradation in situ unless the branches are stored hydrated and refrigerated.
Contact: K. Cornish, Western Regional Research Center, USDA, ARS, 800 Buchanan St., Albany, CA 94710, USA. Tel.: 510-559-5950. E-mail: kcornish@pw.usda.gov
In guayule production, seed quality is important for stand establishment. The X-ray technique is a nondestructive procedure that can provide information about internal structures and seed quality. The objective of this work was to evaluate the physical and physiological quality of guayule seeds by correlating X-ray radiographs, seed coat color, weight, and percentage germination.
Three lines were studied: 11591, N13-1, and AZ1. Seeds were classified by width using a 1/14 (1.8 mm) rounded sieve, and separated by color using a magnifying scope equipped with fluorescent lights. The seeds were separated into four grades, yellow, gray, opaque black, and bright black. These same seeds were further separated by weight using a precision balance. For X-ray analysis, the seeds were placed on a plastic film and X-rays taken with adjustments in the radiation level and time for better quality of the images that could characterize the seeds as filled, partially filled, and empty.
Before the germination tests, seeds were pre-soaked in water for 6 h, treated with 1.5% sodium hypochlorite (3 min) and rinsed with water. Standard germination tests were performed with four 25-seed replicates for each seed lot. Seeds were placed in Petri dishes with two filter papers on the bottom moistened with water equivalent to 2.5 times the substratum weight (the two filter papers) and germinated at 25oC and constant fluorescent lighting for 10 days.
There was a high correlation between X-ray pattern, seed weight, seed coat color, and percentage germination. Filled-gray and filled-opaque black seeds had statistically higher percentage germination than the empty, filled, partially filled, and bright black and yellow seeds.
According to the results, the X-ray technique can be used for seed analysis of guayule to identify the quality of seed lots and for information about the presence or absence of internal structures.
Contact: D.T. Ray, Department of Plant Science, The University of Arizona, Forbes Building, Tucson, AZ 85721, USA. Tel.: 520-621-7612. E-mail: dtray@u.arizona.edu
Guayulins A and B are esters of the sesquiterpene alcohol partheniol present in the resin, or acetone-extractable fraction of guayule (Parthenium argentatum). Guayulin A has been identified as a potent elicitor of contact dermatitis. It is quantified by reverse-phase HPLC in samples that have been analyzed for resin and rubber. A potential problem was discovered with this analysis, however. Some duplicate samples with small deviations in percent resin were found to have large deviations in percent guayulin. Our hypothesis was that guayulin content varied significantly among plant parts and that the sub-samples contained different ratios of these plant parts. The objective of this study was to determine whether there are differences in resin, rubber, and guayulin concentrations among the various plant parts.
One- and two-year-old guayule plants of three lines (11591, AZ-1, and AZ-3) were harvested from the U.S. Water Conservation Laboratory in Phoenix, AZ in October 2002. A total of 12 plants (two of each age and line) were separated into eight parts: brown leaves, green leaves, stem tips (including several immature leaves), stems less than 5 mm in diameter, stems between 5 and 10 mm, stems greater than 10 mm, green stems (where multiple green leaves were attached), and flower (inflorescence) parts. The samples were dried and sequentially extracted by the homogenizer method with acetone and cyclohexane to remove resin and rubber, respectively. The resin fraction was analyzed by reverse-phase HPLC to quantify guayulins.
In all ages and lines, resin content was highest in green stems. Rubber and guayulin A were most prevalent in stems larger than 10 mm in diameter, and a rank test showed a high correlation. This can be explained by the fact that both compounds have a common precursor. Flowers contained the least amount of both resin and rubber. When yields are calculated, resin content is highest in stems less than 5 mm, whereas rubber content is highest in stems greater than10 mm for all ages and lines. Resin and rubber yields are lower overall in 11591 than the two AZ lines, which are newer and have been selected for higher yields. The ratio of resin to rubber is lowest in the largest stems, meaning that those stems have the most amount of rubber with the least amount of resin. They can also be assumed to be the oldest tissue. This experiment will be repeated with another 12 plants harvested in April 2003 to determine whether the time of harvest is a factor.
In reviewing other literature in which rubber was determined in each plant part, it was discovered that most authors assumed that there was no rubber in the leaves of guayule, and state that plants should be defoliated as a first step in any procedure to determine rubber content. The results of our study show that there is indeed rubber in the leaves, with an average of 1.7 % in the brown leaves and 2.0% in the green leaves. This amounts to a total yield of 52.9 g in all leaves in all the 12 plants, which is 25.8% of the total rubber recovered.
Contact: V. H. Teetor, The University of Arizona, Plant Sciences Department, P.O. Box 210036, Tucson, AZ 85721, USA. Tel.: 520-621-2817. E-mail: teetor@ag.arizona.edu
Guayule (Parthenium argentatum Gray) is a natural source of high-quality latex and rubber. Improvement through conventional selection techniques has been made and further improvement is being attempted by transforming guayule with one of three genes in the rubber biosynthesis pathway. The objective of this study was to evaluate the effect of these transgenes on growth and rubber and resin production in field grown guayule.
Tissue culture generated transgenic plants, provided by Katrina Cornish, for lines AZ 101, G7-11, and N6-5 were placed into field plots for two consecutive years. Terry Coffelt planted the initial field and we planted the second field. In both plots, plant height and widths were measured monthly. Resin, rubber, and guayulin production were sampled every four months starting at one year of growth. Resin and rubber were sequentially extracted by the homogenizer method using acetone and cyclohexane, respectively. Guayulin production was quantified using HPLC. The first plot was harvested at the end of two years of growth, whereas the second plot has just completed the first year of growth and will remain in the field for an additional year before harvest.
Transformation had no significant effect on growth in G7-11 and N6-5 in both plots. In the first plot, transformation appeared to have a drastic effect on the height and width of transformed AZ 101 compared with its empty vector control. However, the first plot was not randomized and lacked the non-transformed controls. In the second plot, which was randomized and contained both positive and negative controls, the AZ 101 transformants were significantly larger than the empty vector AZ 101 control, but were not significantly different from the non-transformed controls.
Resin content increased throughout the year up to January 2003, but decreased by the time of harvest in March. Rubber content, on the other hand, was high in May 2002, but decreased throughout the summer, before steadily increasing during the winter months. Guayulin production was low overall, especially Guayulin A production, compared with the conventional lines. Guayulin A production was particularly low in the AZ 101 transformants compared with their empty vector controls.
Insertion of genes for precursors in the rubber biosynthetic pathway did not appear to have any affect on overall growth. However, due to the significantly lower growth in the empty vector control of AZ 101, the gene may have been inserted into the genome in an area important for growth. Although transformation did not affect growth, it did appear to have an effect on Guayulin A production. The low levels of Guayulin A, a contact allergen, may be a beneficial effect of transformation and is worthy of further investigation.
Contact: M.E. Veatch, Department of Plant Sciences, The University of Arizona, Forbes 303, Tucson, AZ 85721, USA. Tel.: 520-621-2817. E-mail: veatchm@email.arizona.edu
In the last 15 years, the pine rosin industry in Argentina has moved toward the production of goods of higher value such as printing inks. While the value of extracted gum rosin is around 0.45 $US/kg and that of a manufactured resin can be as high as 1.80 $US/kg. The main product is resin-based. Inks are mostly exported to the U.S. and Europe. The industry in Brazil exports larger volumes than Argentina although of an unmodified resin. Chile is the third country producing resin in South America with sensibly lower export values.
Economic changes in the region in the last two years, especially the currency devaluation in Argentina (and of lesser degree in Brazil) has greatly improved the conditions to produce and manufacture exportable goods. Added to this general condition, resins from Argentina have been included in the U.S. Generalized System of Preferences (GSP) with no import taxes. On the other hand, higher wood prices threaten to reduce the availability of pine rosin creating a situation of high demand by the industry and low availability of raw materials. These and other changes have broadened the niche for alternative resins to enter the naval stores industry. Grindelia resin is one of these alternatives. After the discovery of the resins by Joseph Hoffmann and Steve McLaughlin, at the University of Arizona, it was originally conceived as a substitute for pine rosin. The source of Grindelia resin was G. camporum although, particularly due to low resin content (high cost of biomass production, manipulation and extraction) it was concluded that it could not compete with pine-rosin. The idea was "resurrected" a few years ago, with the finding that one South-American Grindelia species, G. chiloensis had resin contents up to 40% D.W. Since 1995, we have developed a cropping system, based on eco-physiological responses both at the plant and at the crop levels as well as selected populations and clonal material with resin yields greater than 0.1 kg/plant, resulting in yields that could reach 6,600 kg of resin/ha. At these production levels, there is enough margin to grow, harvest and extract the resin for a value close to 0.30 $US/kg.
A central theme of our current research is resin extraction and processing. We are testing three alternative methods intended for different scale processing facilities. Because all three methods are based on solvent extraction, the different polarities of the solvents result in different residues (non-diterpene) extracts that have to be removed in the purification process as they reduce resin quality. Alternative uses, such as disinfectant solutions and concentrates, are also under investigation.
Our presentation will expand on the economics prospects of new resins in South America, on the development of Grindelia as a crop, and on the current status of extraction, purification, and characterization of the resin, keys to the successful cultivation of this species.
Contact: D. Ravetta, Cátedra de Cultivos Industriales, Facultad de Agronomía UBA. Av. San Martín 4453, (1417) Capital Federal, Argentina. E-mail: ravetta@ifeva.edu.ar
Worldwide demand for resins continues to increase due to their use in manufacturing high quality copier and laserjet paper, as well as specialty chemicals, ester gums, and rubber. The traditional raw material for these resins is pine rosin, although the supply of such materialsfluctuates dramatically with wood and pulp prices. Grindelia camporum, a native of California, and Grindelia chiloensis, a native of Argentina, both produce significant quantities of grindelic acid and related resins on the surfaces of their leaves, flowers, and stems, although the proportions vary dramatically depending on species. Previous studies in Oregon have shown that G. camporum grows well and can produce large amounts of biomass and crude resin. Studies in Argentina have shown similar results for G. chiloensis.
This study was done to compare biomass yield, resin production, survival, and related physiological observations for several accessions of G. chiloensis and G. camporum in southwestern Oregon and Patagonia, Argentina, in order to better understand the growth and resin production characteristics of these selected accessions as well as to determine likely production sites.
Replicated field plots were established near Medford, Oregon, USA, and near Trelew, Chubut, Argentina. One G. camporum accession collected in California and six G. chiloensis accessions collected in Argentina were grown in the glasshouse and transplanted to the field in the spring at both locations. Observations on growth and flowering were made during the season, and whole plants were harvested for biomass yield in the fall (approximately a 7-month cycle). Plant components were separated, and then resin was extracted with dicloromethane and refined following standard protocol.
At both locations, total biomass of G. camporum was more than double that of any G. chiloensis accession, with most of the difference due to much greater stem and flower biomass in the G. camporum. G. camporum biomass in Oregon was almost twice that in Argentina. Among the G. chiloensis accessions, 533 and 576 had much greater total biomass in Oregon, 555 and 575 had greater biomass in Argentina, and 561 and 569 were similar at both locations. On a whole-plant basis, resin content was greater for all six G. chiloensis accessions than the G. camporum at both locations, ranging from 9.2% to 14.4% in Oregon (compared with 6.7% for G. camporum), and from 10.6% to 19.0% in Argentina (compared with 7.0% for G. camporum). However, due to the much greater biomass of G. camporum in Oregon, its resin yield of 71.2 g/plant was greater than all G. chiloensis accessions, which ranged form 7.9 g/plant for 561 to 51.1 g/plant for 533. This contrasted with the result in Argentina, where the resin yield of G. camporum (39.7 g/plant) was less than accession 555 (54.2 g/plant), but greater than the others, which ranged from 5.5 to 35.1 g/plant. Flowering and maturity patterns were similar between the two locations, although the G. chiloensis accession 533 did not flower by the time of killing frost in Oregon. Winter survival was best for G. camporum at both locations (nearly 100%), whereas no plant of accession 576 survived the winter at either location. Other accessions of G. chiloensis had intermediate survival rates at both locations. Accession 575 survived better than the others in Oregon (69%), but its survival was very poor in Argentina, a difference that is not yet understood.
Similar field trials continued for several years, although only first year results are included here. Based on these results it appears that both G. camporum and G. chiloensis are good semiarid, temperate zone crop candidates to fill industry's need for commercial resin production. Differences in response to climate and management will dictate which accession is best suited for a particular location.
Contact: R.J. Roseberg, Oregon State Univ.-SOREC, 569 Hanley Road, Central Point, OR 97502, USA. Tel.: 541-772-5165 (ext. 223). Email: richard.roseberg@orst.edu
Certain rare plant species called Ni-hyperaccumulators contain more than 1% Ni in the dry shoots when grown on Ni-mineralized or contaminated soils. Because Ni metal sells for about $8.75/kg and plants could phytomine about 400 kg Ni/ha-y, it seemed possible to develop a new commercial crop for northwestern U.S. serpentine soils naturally rich in Ni. Co in the soils could be phytomined after Ni has been largely removed. This presentaiton will summarize the development of the crop and management practices, obtaining patents, and commercialization of the technology in Oregon and Canada.
After examining all species reported to be Ni hyperaccumulators, the team selected several species for development. Seeds were collected for some germplasm and initial work completed, which justified a Utility Patent for Ni phytomining. Then diverse germplasm was collected to breed improved cultivars for production on serpentine soils in OR and CA, and separately in Ontario, Canada. All nutrient requirements were established by experiments. The species Alyssum murale was developed the most. This species occurs naturally across southern Europe wherever serpentine soils occur. By collecting seed from different eco-niches and testing their growth and Ni accumulation potentials in replicated field plots in Josephine Co., Oregon, we were able to demonstrate the probability that a commercial crop could be introduced. The plant is highly adapted (endemic) to serpentine soils that are very low in Ca and P fertility, and contain high Mg and Ni levels. The plants accumulate Ni to defend themselves against diseases and chewing insects. Because the plants were adapted to serpentine soils, they were able to obtain adequate phosphate for sufficient yields with only small P fertilizer applications. One of the most surprising outcomes in our research was that acidification of the soil, which increased soil Ni solubility, decreased Ni uptake to the shoots; and for some soils lower in Fe, liming increased Ni uptake even though solution Ni decreased. Existing hay-making equipment could be used to harvest the crop. Baled biomass can be burned to produce a Ni-rich ash that can be sold as a high grade Ni ore and as an energy source. A test for Ni recovery from the biomass ash was conducted at the Inco Ltd. smelter in Sudbury, Ontario, Canada, with easy recovery of the Ni for sale.
Based on the experience to date, Viridian LLC initiated commercial contracts for production of Alyssum murale on serpentine soils in several locations in Oregon, California, and smelter-contaminated soils near Port Colborne, Ontario. Especially cold tolerant germplasm was used in the Canadian production location with tillage adapted to the poorly drained soils by ridge-tilling the field to provide adequate drainage. A recurrent-selection breeding program has been conducted for about five years with clear improvement in the plant for this use.
Contact: Rufus L. Chaney, USDA-ARS, Bldg. 007, BARC-West, Beltsville, MD 20705. Tel.: 301-504-8324. E-mail: Rufus.Chaney@usda.gov
Nickel is used in large quantities for production of stainless steel, rechargeable batteries, etc. The U.S. currently imports all the Ni it uses. Traditional strip mining is very costly and can be environmentally damaging. However, certain rare plants, called hyperaccumulators, accumulate more than 1% Ni dry weight in their aboveground biomass, and thus have the potential to phytoextract Ni from enriched soil, avoiding the cost and problems of traditional mining methods. Alyssum murale and A. corsicum were selected by the USDA and University of Maryland researchers as potential temperate zone Ni phytoextraction crops due to their significant biomass production and Ni uptake as observed in the wild. Because little is known about the crop production requirements of these wild species, a series of agronomic and genetic improvement studies were done in southwestern Oregon in the largest area of Ni-rich serpentine soils in the U.S.
Seed from wild collections made in southern Europe was used in these studies, conducted near Cave Junction, OR on a classic serpentine soil containing more than 4000 mg Ni/kg. The area was prepared using standard farming and plot research equipment appropriate to each experiment. Herbicides used for canola controlled weeds in Alyssum. Crop biomass was harvested by hand and weighed, and plant Ni content was measured using ICP-atomic emission spectroscopy..
In fertilizer tests, only small amounts of added P were required to obtain full yields. Plant density and biomass yield were improved with added gypsum, but not with lime. Plant density was significantly reduced when the soil was acidified. In the planting date tests, the yield from a spring planting date harvested one year later was just as good or better than yields from fall plantings made 1.5 years before harvest, regardless of whether the fall plantings were also harvested on one intermediate harvest date or not. Planting in April, May, or June did not have a significant effect on yield when harvested the following June. Seedbed preparation tests showed that emergence and density tended to be better when seeds were planted on the surface after minimal disturbance compared with those planted at 6 mm depth following more extensive preparation with a rotary tiller. Tests in rocky soil showed that Alyssum germinates readily given minimal soil disturbance. Although early growth is favored by some irrigation, plants that germinate in the spring can persist through the summer and the following winter without irrigation, although the resulting yield will be less than those that have at least some irrigation through the first summer. Fall seeding will result in a greater number of plants that persist through the following summer if no irrigation is available.
Alyssum tends to concentrate the stored Ni more in the leaves than stems. Leaves senesce and rapidly fall off the plant as it moves into its flowering phase, so harvest is done at early flowering. Plants that germinate in the late fall are less likely to be vernalized than those planted earlier, and thus will persist in the vegetative state longer the following summer, resulting in improved biomass and Ni yield the first year, although flowering behavior and biomass yield will be the same in subsequent summers. Ni uptake was not affected by any of the planting date treatments as long as harvest was made before flowering occurred. A plant breeding program was begun starting with more than 160 wild accessions using traditional cross pollination and recurrent selection methods. This has resulted in genotypes with a wide variety of growth habits and Ni uptake rates. Subsequent rounds of selection are ongoing.
Based on limited agronomic tests, the first commercial fields of Alyssum have been planted in Josephine Co., Oregon. Although early results have been encouraging, many factors are not well understood, making it difficult to consistently and confidently produce predictable quantities of seed and biomass for a given situation.
Contact: R.J. Roseberg, Oregon State Univ.-SOREC, 569 Hanley Road, Central Point, OR 97502, USA. Tel.: 541-772-5165 ext. 223. Email: richard.roseberg@orst.edu
Many people have recognized that agriculture has an important role to play in solving some of the nation's projected energy problems. A concept, named the Sun Grant Initiative, has been developed to broaden the role that land grant universities play in their unique approach to higher education by implementation of a new program that will focus the efforts of the land grant universities on renewable energy and biobased industries. A network of five land-grant universities serving as regional Sun Grant centers has been proposed. The universities include South Dakota State University, Oklahoma State University, the University of Tennessee - Knoxville, Cornell University, and Oregon State University. The regional centers will emphasize integrated research, extension, and educational programs on renewable energy and biobased industries based in rural communities. Each center will receive base federal funding to solidly establish them as leading research, extension, and higher education institutions for the biobased economy. In addition to the five centers, significant resources and expertise exists at other land grant institutions throughout the nation. The Sun Grant centers will engage with them as a synergistic mechanism for technology transfer and higher education for the benefit of a rural biobased economy. These programs will embrace the multistate, multifunction, multidisciplinary integrated approach that is at the heart of the land-grant method of addressing problems. Moreover, the centers will interface their activities with DOE research laboratories. The mission of the Sun Grant Initiative will be to (1) enhance national energy security through development, distribution and implementation of biobased energy technologies, (2) promote diversification and environmental sustainability of America's agriculture through land grant-based research, Extension, and education programs in renewable energy and biobased products, and (3) promote opportunities for biobased economic diversification in rural communities.
The Western region held two planning meetings in July and November of 2002. A list of "principles to follow" was established for the Western Center that includes an inventory of regional biobased activity, and a list of planned goals, objectives criteria, and priorities. Through these meetings, we learned that the Western region has many similarities than differences when compared with the other regions of the U.S. This Western region already has established research efforts in the utilization/engineering of biobased products, plant genetics, and biotechnology programs for the production and development of new biobased feedstock materials, and small-scale energy systems consistent with the needs of isolated and remotely located communities. Planning activities for 2003 to 2004 will continue to refine this model. The activities will include developing a road map and establishing administrative, technical, and stakeholder committees. Oregon State University will begin routine communications within the region about the status of the Sun Grant Initiative and relevant activities that occur throughout the region.
Contact: C.Y. Hu, 138 Strand Ag. Hall, Oregon State University, Corvallis, OR 97331, USA. Tel: 541-737-1915. E-mail: chingyuan.hu@oregonstate.edu
The cost of hydrocarbon-based energy in rural areas to heat homes, shops, and other work areas as well as to dry grain continues to escalate. People living in rural areas have sufficient space (acres) to raise enough fuel to supply their energy needs for heating and grain drying. This capability has been in place for a number of years. What has been missing is the right technology to burn the biomass as well as applying the correct manufacturing process to produce an acceptable fuel source in the right form.
The objective of this project is to bring together the correct burn technologies and a manufacturing process that will allow people in rural areas to grow their own fuel for creating heat energy as well as electrical power. This project will be designed to create a model that may be used in any rural area of our country
Our fuel source will be Switchgrass (Panicum vergatum), a native warm season grass that grows well in North America from Canada to Texas and from Nebraska to the Atlantic Ocean. We will pelletize the Switchgrass using low-cost technology to size the material and a standard, but small, pellet mill setup. This facility will serve a 4 to 6 county area and will have a low capital cost. Eventually, a Coop will be formed to own the facility. Three burn technologies will be demonstrated. A forced air unit that can be attached to a standard forced air home heating system, a hot water boiler system that can be used for a hot water system, and a gasifier that can produce hot gases which in turn can be burned for heat generation or combusted in an internal combustion engine attached to a generator to produce electricity.
The various parts of this project have been demonstrated over the past few months. We have manufactured the pellets using known technology in a different way and reducing the capital cost significantly. We have burned our pellets in the three burn technologies described with great success. What remains, is to bring all the parts together in a structure that will be acceptable to people living in a rural area. It is estimated that one acre of Switchgrass will produce enough BTUs to heat a normal-size rural home in the Midwest. This can be accomplished with considerable cost savings while utilizing a completely renewable fuel source. In the process, we will create a new rural enterprise.
The successful completion of this project will be a step forward in reducing fuel cost in rural America and demonstrating how rural communities can be active participants in the goal of becoming less dependant on foreign energy and the use of an environmentally friendly and renewable fuel source.
Contact: Alan W. Teel, Iowa State University Extension, 805 W 10th, Atlantic, IA 50022, USA. Tel.: 712-243-1132. E-mail: teel@iastate.edu
The dispersed, diverse, and low density nature of biomass feedstock is a major constraint on the wider commercial utilization of biomass. For low specific costs, improved or alternative methods are needed to collect, handle, and store biomass such as corn stover. So far, biomass collection has depended on baling, initially with small rectangular balers, then with large round balers. But round-baling of corn stover is a two- or three-pass operation. Also, balers pick up dirt and most of the cobs are left in the field. There is a strict limit in stover moisture if bales - whether round or square - are to be stored.
The objectives of this program at Iowa State University were to design, develop, and evaluate single-pass harvesting systems capable of simultaneously collecting the grain along with clean stover and facilitate densification of the stover to reduce transportation costs.
Several prototype machine systems were developed and evaluated that addressed what was perceived as the most likely clientele for such harvesting approaches. They were successfully operated at several sites for Iowa corn crops and preliminary economic assessments were made.
Stover cost with the single-pass harvesting of the whole plant in two streams was well below $10 per ton, whereas the method used to date to collect stover costs from $12 up to $30 per ton. The stover was free of any dirt picked up from the ground. Harvesting of corn for grain need not be significantly delayed, provided that suitable stover haul-out equipment is available. The equipment can be adjusted to leave behind sufficient residue in accord with local soil conservation requirements.
Contact: Graeme R Quick, Leader, Power & Machinery Engineering Section, Agricultural and Biosystems Engineering Department, Iowa State University, Ames, IA 50011-3080, USA. E-mail: grquick@iastate.edu
With the reduced profitability of corn and soybeans, growers are looking for ways to supplement their businesses. An attractive option for these growers involves the introduction of new crops into their farming practices. One crop of particular interest is common milkweed (Asclepias syriaca) for the production of industrial fibers, oils, latex, and a potent nematicide.
The primary objective of this study was to examine numerous production variables affecting pod and biomass development in common milkweed production fields. Experiments from 2001 addressed the effects of intra-row plant spacing on pod formation and the effects of coal dust on plant establishment. The 2002 studies focused on planting times, inter-row spacing, and nitrogen requirements.
Milkweed transplants were planted in replicated 2.5 m by 2.5 m plots in late May in 2001 and 2002. Information on pod and stalk biomass was collected on individual plants after two and three years of growth.
Milkweed growth indicated pod weight and total number of pods per plant increased with row spacing. The dry stalk biomass per plant also increased with row spacing. However, the total dry biomass per hectare decreased with wider row spacing. Nitrogen and coal applications do not appear to have any effect on either pod or stalk biomass. First year transplants produced pods late in the season. However, they were not of sufficient quality or maturity for either floss or seed material.
Milkweed being a perennial crop with several market opportunities offers a tremendous advantage for farmers looking toward expanding their production with minimal costs.
Contact: W. B. Phippen, Agriculture Department, Western Illinois University, 1 University Circle, Macomb, IL 61455, USA. Tel.:309-298-1251. E-mail: WB-Phippen@wiu.edu
In recent years, wood composites have grown in popularity due to limited lumber resources. Fiberboard and particleboard are increasingly used in the manufacture of furniture and cabinets as a more economical alternative to natural wood. Current industrial composite manufacturing methods employ formaldehyde-based resins such as urea-formaldehyde (UF) as the adhesive. Formaldehyde emissions from such materials are a health concern, as formaldehyde is a probable human carcinogen. Moreover, formaldehyde-based resins are derived from petrochemicals, a non-renewable resource. Increasingly stringent environmental regulations and the growing awareness of "green chemistry" have caused researchers to reconsider natural resources for composites. Furthermore, utilization of soybeans and soybean byproducts is a growing area of interest.
The objective of this study was to prepare wood composites using formaldehyde-free soybean protein-based adhesives that demonstrate performance properties comparable with commercial particleboards manufactured with UF resin.
Adhesives were made from soy protein isolate (SPI), defatted soy flour (DSF), and SPI/DSF blends. The composition of DSF is approximately 53% protein, 30% carbohydrates, 18% fiber, and 9% moisture. Further purification of soybean meal results in SPI that consists of more than 90% soybean protein and 6% moisture. The adhesive and wood furnish were blended and then heated in an oven at 50°C to remove excess moisture. The mixture was compressed at 160°C and 1.65 to 1.79 MPa (240-260 psi) for 5 min. After cure, modulus of rupture, modulus of elasticity, internal bond, and face pull of the particleboards were determined. Moisture content and water absorption tests were also conducted. All tests were performed according to ASTM D 1037-96a and the results were compared with ANSI A208.1-1999.
The mechanical properties of SPI boards exceeded ANSI standards by 15% and were equal to or exceeded the properties of control boards manufactured with UF resin. The mechanical properties of DSF and SPI/DSF blend boards exceeded ANSI standards with the exception of modulus of rupture. It is notable that soybean protein boards have much higher modulus of elasticity than the UF control boards. SPI and SPI/DSF boards exhibited decreased water resistance compared with UF control boards. DSF boards, however, had outstanding water resistance.
The Thames Research Group has demonstrated that soybean protein-based adhesives can be used to make wood composites. The adhesives were made almost entirely from natural products and are completely formaldehyde-free. The particleboard properties compared favorably with that of commercially available products made from UF resin. The development of soybean protein-based adhesive and utilization on a commercial scale will not only reduce formaldehyde emissions, but also benefit soybean farmers in the United States.
Contact: J.N. Shera, The University of Southern Mississippi, Box 10076, Hattiesburg, MS 39406. USA. Tel.: 601-266-5683. E-mail: jeanne.norton@usm.edu
Meadowfoam enjoyed another financially successful business year filled with new opportunities. The 9+ % growth in cosmetic oil sales provided revenues to eliminate all loans and retire the largest grower payment pool six months ahead of schedule. This trend is expected to continue in 2004. Current oil research should provide several new meadowfoam seed oil products to the worldwide cosmetic market in the near future. Distributors universally are confirming new products and the reformulation of existing products using meadowfoam seed oil (MFSO).
Meadowfoam research efforts have seen many positive results in a wide range of areas:
Biobased hydraulic fluid has been successfully formulated and test results confirmed.
Biobased lubricant products containing MFSO are currently being formulated.
Pharmaceutical uses of MFSO are currently in the research stage.
Pesticide and herbicide research is ongoing with both MFSO and meal.
Meadowfoam meal sales in nursery market remain slow, but use in organic production areas is showing increasing interest.
Researchers continue to explore the growth enhancement potential of MF meal.
Current estimates indicate demand for new meadowfoam seed production will be required in 2004 as oil inventory declines. Future outlooks for establishing meadowfoam as stable crop are beginning to take shape.
Contact: Jerry Hatteberg, Natural Plant Products, Inc., 276719th Street, SE, Salem, OR 97302, USA. Tel.: 503-363-6402. E-mail: jhatteberg@meadofoam.com
Meadowfoam (Limnanthes alba) is grown in Oregon for its high quality seed oil. Meadowfoam seedmeal (MSM) remaining after oil extraction contains chemicals, such as glucosinolates, that may degrade to release byproducts inhibitory to weeds, insects, and soilborne pathogens. MSM in soil also has been shown to stimulate plant growth.
The objectives of our studies were (1) to determine if MSM, alone or in combination with the oil, would have any effect on pathogenic soilborne fungi in vitro, and (2) to determine if there were any adverse effects on non-target beneficial arbuscular mycorrhizal (AM) fungi in soil.
Combinations of meadowfoam oil and MSM, or MSM alone, were incorporated into agar media in Petri plates, and the pathogens inoculated to the agar surface. Colony diameter after 72 h was compared with the non-amended control plates. In tests for volatile effects, MSM alone or incorporated into soil (4% by volume) was placed on one side of the divided Petri plates and the pathogen inoculated on the opposite side. Colony diameter and sporulation of test pathogens were measured after several days of incubation. For tests on the effects on mycorrhiza formation, MSM was amended at three rates into an organic soil mix, into which marigold or onion plants, inoculated or not with the AM fungus Glomus intraradices, were planted and grown in the greenhouse for 10 weeks before assessing plant biomass and level of AM colonization.
Mycelial growth of most fungal pathogens was inhibited by combinations of oil and MSM, as was sporulation by some Pythium and Phytophthora species. Amendment of soil with MSM enhanced growth of marigolds at 0.594 or 1.188 kg m-3, but inhibited growth at 1.782 kg m-3. AM formation on marigold or onion was inhibited at all rates tested, but additional tests indicated that the AM fungal inoculum was inhibited, not killed. Ground MSM alone incorporated into agar did not inhibit pathogen mycelial growth, but did inhibit production of oospores by Pythium irregulare and sporangia, but not chlamydospores of Phytophthora ramorum. In vitro tests for volatile effects with MSM alone or mixed into soil showed that the volatiles released from the MSM inhibited sporulation of P. ramorum.
These results indicate that the volatile or non-volatile compounds released from MSM could inhibit soilborne fungal pathogens, at least in vitro, but tests on plants in MSM-amended soils are needed to determine whether MSM can suppress the diseases they cause. The adverse effects of MSM on non-target mycorrhizae and the mode of action against AM fungi in soil remain problematic. Nonetheless, the potential for MSM amendment to soil or potting media for disease control deserves further research.
Contact: R. G. Linderman, USDA-ARS, Horticultural Crops Research Laboratory, 3420 NW Orchard Avenue, Corvallis, OR 97330, USA. Tel.: 541-738-4062. E-mail: lindermr@ science.oregonstate.edu
This presentation will review the evaluation of vegetable-oil-based hydraulic fluid containing Meadowfoam oil. The improvements in performance properties over conventional hydraulic fluids due to the presence of the Meadowfoam oil will be highlighted. These improvements occur in the high- and low-temperature properties of the hydraulic fluid. The properties of a demonstration formula will be compared with the specifications of the U.S. Navy for bio-based hydraulic fluid.
Contact: B.N. Rhodes, 15908 S.E. Newport Way, Bellevue, WA 98006, USA. Tel.: 425-644-6179. E-mail: BNRhodes00@aol.com
Although L. fendleri has been chosen as the prime candidate for domestication in fall-sown crops in the southwestern U.S., the best alternative for cool, Mediterranean climates is still not clear. In the process of selecting our best cropping system, we have taken an approach that includes the understanding of eco-physiological responses associated with growth and development of the different candidate species and planting dates. Our objective was to evaluate seed-yield for five species of Lesquerella in fall and spring sowings and to characterize the relationships between seed-yield and phenology, biomass accumulation and partition.
Three plots each of the L. fendleri, L. angustifolia, L. gracilis (annuals), and L. pinetorum and L. mendocina (perennials) were established by direct seeding in March (fall) and September (spring) in Patagonia (43° 16" S, 65° 21" W) in a completely randomized design. Plant phenology was recorded, and growth and partition were measured harvesting whole plants when fruits were ripen, which occurred at different times during the summer.
Average yield per plant was strongly influenced by species and planting date (P < 0.05). Yields were (fall and spring sown, respectively): 1.58 g/pl and 0.33 g/pl for L. angustifolia, 1.02 g/pl and 1.74 g/pl for L. pinetorum, 0.99 g/pl and 0.60 g/pl for L. gracilis, 0.63 g/pl and 0.61 g/pl for L. fendleri, and 0.29 g/pl and 1.24g/pl for L. mendocina. L. angustifolia and L. gracilis accumulated significantly more total biomass in fall than in spring sowings (P < 0.05), whereas the harvest index did not change. The same pattern of biomass accumulation was found for L. fendleri although seed-yield did not drop on spring planting dates, due to a significant increase in harvest index (15.5% and 18.4% for fall and spring dates, respectively with P < 0.05). Both perennial species did not flower the first summer when sown in spring, and completed their first growth cycle one whole year after the annual species. This pattern resulted in more total biomass for spring planting dates (P < 0.05). In contrast for L. pinetorum, the partition to roots increased from 2.5% (fall) to 8% (spring) and the harvest index remained unchanged (ca. 20%, for both planting dates), both partition to roots (10% vs. 13%) and harvest index (7% vs. 15%; P < 0.05) increased in L. mendocina when planted in the spring. For all species tested, there was a significant correlation between the length of the growth cycle and total biomass, probably related to more total accumulated radiation.
This experiment confirms previous results and supports the idea of developing L. angustifolia for fall plants as an alternate hydroxy-fatty acid crop for Patagonia and similar cool, Mediterranean climates. On the other hand, L. pinetorum and L. mendocina combine adequate seed yields and perennial growth habit, an important characteristic in erosion-prone environments and for crops such as Lesquerella, which have very low initial growth rates and poor competitive ability against weeds.
Contact: G. Cerdeiras, Catedra de Cultivos Industriales, Facultad de Agronomia UBA. Av. San Mart¡n 4453, (1417) Capital Federal, Argentina. E-mail: cerdeira@agro.uba.ar
Lesquerella fendleri is an annual oilseed crop under the process of domestication for irrigated arid lands. L. mendocina is a perennial species native from Argentina. Some of the anatomical, physiological, and developmental traits present in L. mendocina and related to the perennial habit could be exploited in breeding programs oriented to nonirrigated systems, with frequent water stress. The objective of this work was to analyze the impact of water stress during seed-filling for yields of both L. fendleri and L. mendocina.
A field experiment was conducted in Buenos Aires, Argentina. Plants were sown in late autumn of 2001 in 2.0 m x 1.5 m plots under a rain shelter. Crop density was 30 plants/m2, 0.2 m between plants, spaced 0.3 m apart. Water-stress conditions were set by withholding water from visible floral-bud stage during 75 days (this is ca. 40 days before harvesting). Yields of stressed plants were compared with those of plants subjected to irrigation during the overall cycle.
Similar yields were found for both species under high water availability conditions, reaching 1g plant-1 (average of both species). Water stress drastically reduced yield up to 80% respect to that of irrigated plants in L. mendocina, whereas no reductions attributed to water stress were observed in L. fendleri. Differences between species responses were positively associated with leaf area compensations after the end of water stress period until maturity.
The results clearly indicate that the annual L. fendleri is capable of great yield-compensation after being released from a severe water stress. Although similar yields were found in both L. fendleri and L. mendocina under irrigation, yield stability would be greater in the former. Hence, promising yields would be expected in L. fendleri grown under nonirrigated systems when early crop establishment is assured.
Contact: E.L. Ploschuk. Departamento de Produccion Vegetal, Catedra de Cultivos Industriales, Facultad de Agronomia (UBA), Av. San Martin 4453, 1417 Buenos Aires, Argentina. Tel.: 54-11-4524-8070. E-mail: ploschuk@ifeva.edu.ar
Hydroxy fatty acids (HFA) are the major components of the seed oil profile of Lesquerella species. One of three different HFA predominates in the seed oils of species of plants from this genus. Lesquerolic acid (C20:1OH) is the primary HFA found in species from the western and southwestern U.S. The range of quantity varies depending on the species. Lesquerella fendleri is being developed for commercialization because of its productivity and adaptability to farm management practices. However, the range of natural variability for this trait is limited in this species. Lesquerolic acid accounts for only around 60% of the total fatty acids compared with other species that have up to 85% of this acid, but they lack other important yield-related traits.
Our objective has been to introgress the trait for high HFA content into L. fendleri from other species. We measured various characters to follow the pattern of inheritance between crosses. L. pallida and L. lindheimeri both have high HFA amounts and were used along with L. fendleri, crossed among each other and also self-pollinated. It was necessary to double the chromosome number of plants using colchicine to overcome sterility and obtain seed from hybrids. Ovule culture was used in cases when seed did not develop to produce plants of the next generation. The traits measured were petal length, number of ovules per silique, number of seeds per silique, and weight of 1000 seeds. Fatty acid compositions were also measured, and flower color and fertility were scored. Parent plants were diploids, n = 6, and hybrids were amphidiploids, n = 4x = 24.
L. pallida has a white flower color and the other two species have yellow flowers. Petal length was smaller on L. pallida and L. lindheimeri than L. fendleri. The 1000 seed weights and the number of ovules per silique were different among all three species. L. lindheimeri had the highest seed weight and lowest ovules per silique. L. fendleri had the lowest seed weight and highest number of seeds per silique. Seeds per silique counts indicated that autofertility occurred in L. pallida but not in the other two species. HFA oil content of L. fendleri seeds was 50.5% compared with 84.1% for L. lindheimeri. F1 hybrids indicated maternal influence over flower color and petal length when reciprocal crosses were examined. White flowers were expressed on hybrids when the female parent had yellow flowers (L. fendleri). Petals were smaller in this case than the reciprocal cross but still intermediate of both parents. Pale yellow flowers were expressed and petals were longer than both parents when the female parent had white flowers (L. pallida).
These measurements will help predict the value of the different types of interspecific crosses for breeding. Segregation for various yield-related traits should allow selection for favorable improvements in the HFA trait and seed yield.
Contact: D.A. Dierig, U.S. Water Conservation Laboratory, 4331 East Broadway Road, Phoenix, AZ 85040, USA. Tel. 602-437-1702(X265). E-mail: ddierig@uswcl.ars.ag.gov
Lesquerella and Physaria species (Brassicaceae) are sources for three types of hydroxy fatty acids (HFA), auricolic, densipolic, and lesquerolic, with potential for industrial applications including lubricants, novel plastics, protective coatings, cosmetics, surfactants, drying agents, and pharmaceuticals. Although identified as possible new crops in the 1950s, a breeding and selection program has been developed for them only within the last 15 years. While much progress has been made within this time using traditional selection methods for increased seed size, yield, oil content, oil composition, and improved agronomic characteristics, DNA-based markers should accelerate the selection time frame and should be useful in precisely identifying trait loci.
Many DNA-based markers are used for crop improvement. However, simple-sequence repeat (SSR) loci, or microsatellites are becoming the molecular marker of choice in marker-assisted plant breeding and marker-based genetic analysis because they are easy to use, abundant, dispersed throughout the genome, usually co-dominant, and generally more polymorphic than other genetic markers. However, developing these markers de novo is costly and time-consuming. Several studies have shown the ability of SSRs developed for one species to be amplified in related species or genera, thus saving time and money. Hundreds of SSR primers have been developed for related species in Brassicaceae, particularly from Arabidopsis thaliana L. and Brassica crop species, so that a great potential exists to use these SSR primers in our breeding program with Lesquerella and Physaria.
The goal of this study was to test 24 SSR primer pairs developed for A. thaliana, Brassica napa L., and B. rapa L. for their transferability to loci in Lesquerella and Physaria, with the long term aim of using these SSR loci to construct a genetic linkage map for the several species of Lesquerella and Physaria.
Sixteen primer pairs developed for A. thaliana that cross amplified with Brassica spp. These were shown to contain micro satellite repeat regions. Eight additional primer pairs for Brassica napa and B. rapa (4 from each species) were chosen for this study. Preliminary results indicate that a majority of the primer pairs amplify fragments in both Lesquerella and Physaria. DNA sequencing and probe hybridization assays are underway to determine whether the loci contain SSRs.
These SSR markers are the first DNA markers to be developed in our breeding program and the first step toward developing genetic maps for Lesquerella and Physaria. Once constructed, the genetic map will allow us to investigate genes influencing important traits and their location along the chromosomes. Also, it will help us implement marker-assisted selection for improvement of specific phenotypes.
Contact: A. Salywon, U.S. Water Conservation Laboratory, 4331 E. Broadway Rd., Phoenix, AZ 85040, USA. Tel.: 602-437-1702 (X190). E-mail: asalywon@uswcl.ars.ag.gov