Progress 09/15/00 to 09/30/05
Outputs
Differences in growing environment accounted for over 50% of the variability observed in all traits measured in guayule. These results point to the tremendous impact that environment has on guayule plant growth, biomass, and latex content. Although exposure to herbicides reduced plant growth initially in comparison to the non-treated control, herbicide treatment at harvest had no significant effect on growth and either the concentration or yield of resin, rubber, and latex. Four guayule lines (11591, AZ-1, AZ-3, and AZ-5) were grown at two planting densities to determine the effect of plant density on rubber and latex production. Plants were planted at standard spacing (14 inches) and half the standard spacing (7 inches). Plants from each spacing were harvested every 6 months until the plants were almost four years old starting when the plants were approximately one year old. Higher planting density did not change rubber and latex concentration, but did increase
biomass production per area an average of 27% more than the normal spacing. Higher planting density also increased rubber and latex and average of 36% more than the normal spacing over all harvests. We previously reported that water stress increased rubber concentration while reducing rubber yields. Lines AZ 101 and AZ-2 were grown under water stressed conditions from June through August and from December through February. The water-stressed plants were irrigated when the soil water potential reached -3 bars. Change in stem diameter throughout the growing season was measured in addition to height, width, and carbon exchange. At harvest rubber was extracted not only from whole plants, but also separately from the leaves and stems of a subset of defoliated plants. Rubber concentration was generally higher in the water-stressed plants than in the well-watered plants as a result of decreased leaf biomass in both the summer (33 vs. 45 g kg-1) and winter (36 vs. 52 g kg-1) and decreased
stem diameter in the summer (8.1 vs. 11.0 mm). Rubber is deposited mainly in the bark; therefore, reduced leaf biomass and stem diameter contribute to higher rubber concentration in the water-stressed plants by increasing the relative amount of bark.
Impacts
Guayule is being grown commercially in the southwestern United States. Information about the effect of the management practices discussed here such as herbicide use, water stress, and plant spacing, can be used to grown guayule more economically with a greater yield potential.
Publications
- Veatch-Blohm, M.E., D.T. Ray, and W.B. McCloskey. 2006. Water-stress-induced changes in resin and rubber concentration and distribution in greenhouse-grown guayule. Agron. J. In Press.
- Coffelt, T.A., D.T. Ray, F.S. Nakayama, and D.A. Dierig. 2005. Genotypic and environmental effects on guayule (Parthenium argentatum) latex and growth. Ind. Crops Prod. 22:95-99.
- Veatch-Blohm, M. E. and D. T. Ray. 2005. Water stress effects on rubber concentration and rubber distribution in guayule. In M. J. Pascual-Villalobos, F. S. Nakayama, C. A. Bailey, E. Correal and W. W. Schloman, Jr. (Eds.) Industrial Crops and Rural Development, p. 607-617.
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Progress 01/01/04 to 12/31/04
Outputs
Genotype, environment and genotype x environment effects on latex content and plant growth were evaluated in four lines, planted in two different seasons, over two years. Environment accounted for 50% of the observed variability, plant age accounted for 16% and line for 10% of the variability for all measured traits. Two environmental stresses that were evaluated are competition from weeds or herbicide damage, and water stress. Sixty-day-old seedlings of three lines (N565, 11591 and AZ-2) were evaluated for tolerance to four postemergence herbicides. The herbicides were applied at 1/2x, 1x and 2x rates, and the rates were determined from recommendations for weed control in other agronomic crops. Evaluations were made weekly by recording the number of plants in each treatment that exhibited chlorosis or were dead. One week following spraying, the range in chlorosis was between 9 and 100%, with no shrub mortality. There was less chlorosis in N565 than the other lines,
and the greatest damage occurred in all lines at the 2x level. At four weeks plants were actively growing, and only plants sprayed at the 2x level showed chlorosis and mortality. At six weeks there was no visible chlorosis or mortality. Plant height was significantly lower in all treatments than the control, but rubber and resin yields will not be evaluated until the final harvest in 2005. Lines AZ 101 and AZ-2 were subjected to water stress from June to August, the active growing period of guayule. Water stressed plants were irrigated only when the average soil water potential reached -6 bars. Measurements included plant height, plant width, photosynthesis (carbon exchange), fresh weight, leaf weight, leaf area, and rubber and resin content. Although photosynthetic rates increased after irrigation in the water-stressed plants, the stressed plants had consistently lower photosynthetic rates than the well-watered plants. Water-stressed plants also had a low growth rate, low biomass
production, and decreased leaf area. Rubber concentration was increased in water-stressed plants, but both rubber and resin yields were reduced.
Impacts
Guayule is beconming a commercial crop in the semiarid and arid siouthwestern United States. This work is helping the commercial interests now developing a guayule rubber industry.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
Rapidly growing, six-month old AZ-2 and N565 guayule plants were evaluated for susceptibility to over-the-top applications of glyphosate herbicide [N-(phosphonomethyl) glycine, 41 % AI with surfactant} at rates of 0.5 to 2.0% product in an aqueous spray. Observed injury was proportional to the rate, ranging from yellowing of leaves at the low rate to apparent death of tops of plants at 2.0%. Directed spray of 15 month old plants showed little or no apparent injury. An over-the-top application of glyphosate at a 2% rate on a six-year-old stand of AZ-2 and CAL-6 showed little or no apparent injury to the guayule plants. Research has progressed in purification and measurement of quality parameters in guayule shrub samples from the Arizona field experiments. Latex was extracted and purified from 448 samples generated from three different trials. Differences were observed in latex content among lines and between planting dates, planting densities and harvest times, with
the largest differences occurring among the youngest plants. Latex protein concentrations were higher in the youngest plants. In older plants rubber particle size was slightly larger in plants grown at 22,000 plants/acre, than when grown at 11,000 plants/acre. The data indicate that older plants (based on date of planting) at lower planting density make less rubber in fewer but larger particles than older plants at higher density or younger plants in general. Extraction and purification of latex from guayule requires that harvested shrub first be homogenized in an alkaline aqueous buffer. We have shown that guayule homogenate provides a stable environment for latex yield and quality, even at room temperature, for at least 13 - 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. In another study, we quantified, purified, characterized and tested latex produced from four subfractions of five year-old guayule plants of three lines from New Mexico, including small, medium and large branches as well as a root and stem base fraction, and included a comparison of harvest time for one line. Data indicate that guayule latex is quite uniform among lines and throughout the plant in healthy guayule plants and that high quality latex, which produces films with good tensile properties, should be obtainable whether the shrub is harvested by pollarding or digging.
Impacts
Guayule is beconming a commercial crop in the semiarid and arid siouthwestern United States. This work is helping the commercial interests now developing a guayule rubber industry.
Publications
- Cornish, K., McCoy III, R.G., Brichta, J.L., Coffelt, T.A., Nakayama, F.S., Ray, D.T. Quality of latex extracted and purified from guayule agronomic trials with different spacings and dates of planting. Association for the Advancement of Industrial Crops Annual Meeting, Portland, OR, October 12-15, 2003.
- Cornish, K., McCoy III, R.G., Van Fleet, J.E., Martin, J.A., Fowler, J.L. Quality and performance of latex purified from different plant parts of mature guayule shrubs. Association for the Advancement of Industrial Crops Annual Meeting, Portland, OR, October 12-15, 2003.
- Cornish, K., Van Fleet, J.E., Brichta, J.L., Knuckles B.E. Latex yield and quality during storage of guayule (Parthenium argentatum gray) homogenates. Association for the Advancement of Industrial Crops Annual Meeting, Portland, OR, October 12-15, 2003.
- Cornish, K., McCoy III, R.G., Brichta, J.L., Coffelt, T.A., Nakayama, F.S., Ray, D.T. 2003. Quality of latex extracted and purified from guayule agronomic trials with different spacings and dates of planting. Association for the Advancement of Industrial Crops Annual Meeting, Portland, OR, October 12-15, 2003.
- Veatch, M.E., Ray, D.T. 2003. Effect of photosynthesis on growth and photosynthetic rate in guayule. Association for the Advancement of Industrial Crops Annual Meeting, Portland, OR, October 12-15, 2003.
- Majeau, G.H., Ray, D.T., Coffelt, T.A., Foster, M.A. 2003. New guayule (Parthenium argentatum Gray) variety trials. Association for the Advancement of Industrial Crops Annual Meeting, Portland, OR, October 12-15, 2003.
- Coffelt, T.A., Nakayama, F.S., Ray, D.T., Cornish, K. 2003. Post-harvest guayule storage tests. Association for the Advancement of Industrial Crops Annual Meeting, Portland, OR, October 12-15, 2003.
- Teetor, V.H., Ray, D.T., Veatch, M.E. 2003. Concentration of resin, rubber, and guayulins in various parts of guayule plants. Association for the Advancement of Industrial Crops Annual Meeting, Portland, OR, October 12-15, 2003.
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Progress 01/01/02 to 12/31/02
Outputs
The tolerance of a direct-seeded guayule population to the following preplant incorporated herbicides was studied at the University of Arizona Maricopa Agricultural Center (MAC): Prefar (bensulide) (2, 3, 4 lb ai/A), Dacthal (DCPA) (4, 8, 10 lb ai/A), and Prowl (pendimethalin) (1/2, 1, 2 lb ai/A). Guayule seed (AZ-2) was planted 1/2 in deep, and sprinkler irrigated for 14 days before being maintained by furrow irrigation. Maximum seedling emergence occurred 10 days-after-planting. Seedling density was not significantly lower in the herbicide treatments as compared to the control 17 days after planting. Some mortality was noted, and was due to salt damage by the sprinkler. Prowl controlled purslane at all rates, and the medium rate did not cause any crop injury. Latex has been extracted and purified from field samples, and measurement of quality parameters indicates that guayule latex is consistently low in protein content, and except for shrub that is less than
one-year-old, it produces high molecular weight rubber. Rheological characterization of the latex has shown that guayule latex is more viscous than Hevea latex, which has implications in extruded product manufacture. Variety trials were planted in 7 locations: Maricopa, Marana, and Yuma, AZ, Pecos, TX, Los Cruces, NM and Saltillo, Mexico; with 24 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, G7-11-1, G7-11-2, G7-11-3, G7-11-4, G7-11-5, G7-11-6, G7-11-7, G7-11-8, G7-11-9 and G7-11-combo). Data collected to date include: stand count after planting, plant height and width (twice a year), and in the future data will include seed yield (spring and fall), latex, rubber and resin content, plant biomass, and survival, height and width of regrowth after harvest. Four lines (AZ-1, AZ-2, AZ-3 and AZ-101), common to all locations, have a highest growth rate. Spacing/Date of Planting study: monthly plant measurements for plant height and
plant width were begun on 4 lines (AZ3, AZ5, AZ1, and 11591) with two within row spacings (18 cm and 36 cm), and harvested at 18 and 24 months. Storage Time/Storage Conditions test: two lines (AZ2 and 11591) were harvested and placed into one of 10 different postharvest treatments. Cutting Height/Regrowth test: five lines (AZ2, AZ 101, N9-3, 11591, and AZ1) will be harvested annually starting in 2003. Irrigation/Fertility test: soil moisture measurements are being made to develop water use curves for guayule using 2 lines (11591 and AZ2). Postemergence (over-the-top) herbicides: little or no visible damage was evident on either guayule line (AZ-R2, Cal-6); most of the weed species in the field were killed by the herbicide (2% solution of Roundup) application. Seed of several guayule lines grown and harvested over a four year period at locations in Arizona, California, New Mexico, and Texas have been cleaned and germination tests completed. These data are being evaluated to determine
if differences in time of harvest and location affect seed quality of guayule. Other quality determination tests that are ongoing include the effect of seed size and color on germination and seedling vigor.
Impacts
Establishment by direct seeding will help reduce establishment costs, and from these studies we recommend sprinkler irrigation for maximum germination and seedling emergence, with the sprinklers being removed 7-10 days after planting, and furrow irrigation (alternate rows) adopted for shrub maintenance. The rate of Prowl found to work best in direct-seeded guayule is comparable to the recommended rate for cotton at MAC. The results from the variety trials will help us develop recommendations for the best lines to grow in each of the potential guayule cultivation areas. It will also provide useful information toward developing guidelines for growers.
Publications
- Keys, R. N., Ray, D. T. and Dierig, D. A. 2002. Characterization of apomictic potential in guayule (Parthenium argentatum) in vivo and in vitro. Journal of the American Society for Horticultural Science 127: 404-408.
- Cornish, K. and Brichta, J.L. 2002. Rheological properties of latex from Parthenium argentatum Gray compared with latex from other rubber-producing species. Journal of Polymers and the Environment 10:13-18. Cornish, K. and Wood, D.F. 2002. Visualization of the malleability of the rubber core of rubber particles from Parthenium argentatum Gray and other rubber-producing species under extremely cold temperatures. Journal of Polymers and the Environment 10: 155-162.
- Cornish, K., Brichta, J.L., Chapman, M.H., Scott, D.J., Van Fleet, J.E., Wood, D.F. and Xie, W. 2002. Biological and physical characteristics of Parthenium argentatum (guayule) latex in comparison with latex from Hevea brasiliensis and Ficus elastica. Proceedings of the 5th International Latex Conference, July 30 -31, 2002, Akron, Ohio, p 1-15. Cornish, K., Brichta, J.L., Chapman, M.H., Scott, D.J., Van Fleet, J.E., Xie, W. and Wood, D.F. 2002. Guayule latex: a clinically-proven, natural solution to Type I latex allergy. Proceedings of Latex 2002, December 4-5, 2002, Berlin, Germany.
- Foster M.A., Coffelt T.A. and G. Majeau. 2002. Effects of herbicides on direct-seeded guayule. Abstract from the Annual Meeting, The Association for the Advancement of Industrial Crops, Saskatoon, Saskatchewan, Canada, 25-28 August 2003.
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Progress 01/01/01 to 12/31/01
Outputs
Storage Time/Storage Conditions: the storage time/storage conditions test was transplanted March 22, 2001. The test has two lines (AZ2 and 11591). Cutting Height/Regrowth: the cutting height/regrowth test was transplanted April 12, 2001. This test has five lines (AZ2, AZ 101, N9-3, 11591, and AZ1). Breeding Tests: the breeding line yield test at MAC was transplanted in November, 2001. The test has 20 breeding lines. Seed harvest: nine machine harvests were made on existing plots of AZ-R2 and Cal-6, to determine the optimum time of harvest. All available clean guayule seed lots (150) in the inventory at Las Cruces, NM were tested for germination and viability (seed stored at ambient temperatures for more than two years had a very low germination). Pre- and postemergence herbicide tests: data has been collected on the use of Dacthal W-75, Prowl 3.3 EC, Barricade 65 WG, and Prefar 4E for weed control in direct-seeding; and Treflan EC and Prowl 3.3 EC for transplanting.
Seed cleaning system: a study was initiated to evaluate existing seed cleaning techniques. Cleaned seed was separated into three quality classes depending on size, weight, and amount of trash. Third quality seed was generally the smallest and lightest fraction. The highest percentage clean seed obtained was 6.5% with line CAL-6 ( 1st quality - 2.3%, 2nd quality - 0.6%, 3rd quality - 3.6%). Some analyses of commercially cleaned seed report clean seed yields of 10% or greater. However, these samples can contain as much as 10% trash. Optimum time of harvest for producing the highest quality and yield of viable seed: the average number of seeds/g and the weight of 1,000 seeds was determined for each of the above quality class by recording the weight of four replications of 250 seeds each. The June harvests resulted in a greater number of seeds/g and lower 1,000 seed weights as compared to November. However, seed germination was greater in the June harvested seed. The germination of the
3rd quality seed was still acceptable. Germination increased in all lines when seed was conditioned. The 1st quality seed was easier to clean (separate from the trash) and had a greater percentage germination. Seed treatment: Germination of three guayule lines conditioned in 1994 and stored at -20oC was determined in November 2001. The germination of AZ-R2 seed was unchanged after seven years of storage, and surprisingly, the AZ-R3 germination was greater than the original raw germination. The germination of UC-101 seed was only 9% less after 7 years of storage. The germination of guayule line 11591 conditioned in 1988 and stored at -20oC was also determined in November 2001. After 13 years of storage, the germination had decreased 50 and 56% in the raw and conditioned seed, respectively. Spacing/Date of Planting: the spacing/date of planting tests have four lines AZ3, AZ5, AZ1, and 11591. Preliminary latex values at one year of age were almost zero, showing that plants must be at
least one-year of age before producing significant amounts of latex.
Impacts
Significance: data are now available to initiate Special Local Needs herbicide registrations which allow large-scale plantings with private growers. Guayule commercialization cannot proceed until pesticides are registered with the appropriate State Departments of Agriculture. Weed control research will continue on the Texas, New Mexico, and Arizona Agricultural Experiment Stations. Appropriate seed cleaning machinery was identified and will be established at New Mexico State University to provide scale-up studies. Only small differences in germination among the three classes of seed were detected in conditioned seed. All seed classes would be satisfactory for direct seeding when conditioned Spring seed harvests (at least in Texas) will yield the best quality seed. Only rainfall will prevent successful harvests. Conditioned guayule seed can be stored for as much as seven years with little or no loss in viability if the storage temperature is maintained at-20oC.
Realistically, to maintain optimum seed viability, guayule seed should probably not be stored for more than 1-2 years.
Publications
- Published papers: Cornish, K., Chapman M.H., Brichta, J.L., Vinyard, S.H. and Nakayama, F.S. Post-harvest stability of latex in different sizes of guayule branches. Industrial Crops and Products 12: 25-32. 2000.
- Cornish, K., Brichta, J.L., Yu, P., Wood, D.F., McGlothlin, M.W. and Martin J.A. Guayule latex provides a solution for the critical demands of the non-allergenic medical products market. Agro-Food-Industry hi-tech in press 2001.
- Dierig, D. A., D. T. Ray, T. A. Coffelt, F. S. Nakayama, G. S. Leake and G. Lorenz. 2001. Heritability of height, width, resin, rubber, and latex in guayule (Parthenium argentatum). Industrial Crops and Products 13: 229-238.
- Abstracts: Cornish, K., Research and development leading to the commercialization of nonallergenic latex from guayule. 6th International Scientific Workshop on Biodegradable Polymers and Plastics and 9th Annual meeting of the Bio/Environmentally Degradable Polymer Society, Honolulu, Hawaii, December 12-16, 2000. p. 66.
- Cornish, K., Chapman, M.H., Nakayama, F.S. Vinyard, S.H. and Whitehand, L.C. Latex quantification in guayule shrub and homogenate 6th International Scientific Workshop on Biodegradable Polymers and Plastics and 9th Annual meeting of the Bio/Environmentally Degradable Polymer Society, Honolulu, Hawaii, December 12-16, 2000. p. 27.
- Cornish, K., Chapman, M. H., Brichta, J.L. and Scott, D. J. A preliminary crop model demonstrates the effect of post- harvest conditions on the yield of nonallergenic latex from guayule (parthenium argentatum gray). 6th International Scientific Workshop on Biodegradable Polymers and Plastics and 9th Annual meeting of the Bio/Environmentally Degradable Polymer Society, Honolulu, Hawaii, December 12-16, 2000. p. 29.
- Cornish, K., Chapman, M.H. and Brichta, J.L. Purification of nonallergenic latex from guayule (Parthenium argentatum gray) and determination of quality parameters. 6th International Scientific Workshop on Biodegradable Polymers and Plastics and 9th Annual meeting of the Bio/Environmentally Degradable Polymer Society, Honolulu, Hawaii, December 12-16, 2000. p. 28.
- Cornish, K, Brichta, J.L., Nakayama, F.S., Coffelt, T.A. and Vinyard, S.H. Methods optimization for medium-scale guayule latex purification and quality testing of latex from bi-monthly shrub harvests. New Crops and New Uses: Strength in Diversity, Atlanta, Georgia, November 10-13, 2001.Cornish, K.,
- Brichta, J.L., Chapman, M.H., Scott, D.J., Stumpf, D.K. and Ray D.T. A preliminary post-harvest crop model for maximizing latex yield from guayule (Parthenium argentatum gray). New Crops and New Uses: Strength in Diversity, Atlanta, Georgia, November 10-13, 2001.
- Cornish, K., Brichta, J.L., Lytle, C.D., Yu, P.C., and Wood, D.F. Comparative quality testing of allergenic (Hevea brasiliensis), hypoallergenic (Parthenium argentatum) and nonallergenic (synthetic) latex materials. New Crops and New Uses: Strength in Diversity, Atlanta, Georgia, November 10-13, 2001.
- Cornish, K., Brichta, J.L., Yu, P.C., and Wood, D.F. Micro-quantification of latex yield in living guayule using scanning electron microscopy. New Crops and New Uses: Strength in Diversity, Atlanta, Georgia, November 10-13, 2001.
- Foster, M. A. and J. L. Fowler. Comparison of direct-seeded and transplanted guayule. New Crops and New Uses: Strength in Diversity, Atlanta, Georgia, November 10-13, 2001.
- Coffelt, T. A., D. A. Dierig, D. T. Ray and F. S. Nakayama. Regrowth after harvest of one- and two-year old guayule plants. New Crops and New Uses: Strength in Diversity, Atlanta, Georgia, November 10-13, 2001.
- Nakayama, F. S., T. A. Coffelt, S. H. Vinyard, G. S. Leake and A. L. Faber. Seasonal effects on guayule latex content and yield. New Crops and New Uses: Strength in Diversity, Atlanta, Georgia, November 10-13, 2001.
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