Submitted to: Association for the Advancement of Industrial Crops Conference
Publication Type: Abstract Only
Publication Acceptance Date: 10/1/2003
Publication Date: 10/12/2003
Citation: 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 Conference. p.6.
Technical Abstract: Current guayule commercialization efforts are based upon the production of hypoallergenic latex. However, little is known about the optimal agronomic conditions 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 and between 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 when grown at a density of 22,000 plants per acres, than when grown at 11,000 plant/acre. Also, 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 lessened by April 2003. Rubber particle size also varied slightly. At 11,000 plants/acre the older plants had a larger particle size than the younger plants but this was only seen in AZ-5 at 22,000 plants/acre. 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 latex concentrations - protein concentrations were higher in the latex of younger plants and also in the latex of plants in higher field densities, with 11591 and AZ-3 showing the largest differences. Data from the later harvests is not yet available. 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. No information is yet available on plant size at the different harvests so extrapolations to actual latex yield/acre are not yet possible.