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United States Department of Agriculture

Agricultural Research Service

Title: Harvesting Small Plots of Guayule for Laboratory Analyses

Authors
item Coffelt, Terry
item Nakayama, Francis

Submitted to: Association for the Advancement of Industrial Crops Conference
Publication Type: Proceedings
Publication Acceptance Date: April 22, 2004
Publication Date: May 15, 2004
Citation: Coffelt, T.A., Nakayama, F.S. 2004. Harvesting small plots of guayule for laboratory analyses. Association for the Advancement of Industrial Crops Conference. p. 10

Technical Abstract: Guayule (Parthenium argentatum Gray) is the best potential source of hypoallergenic latex to replace latex products made with Hevea (Hevea brasiliensis (A. Juss.) Muell.-Arg.) latex that cause Type I allergies. Breeding programs in the past have focused on screening germplasm and developing improved lines with higher rubber and/or resin contents. Thus, previous harvesting protocols have not had to deal with the problem of latex loss as plant material is being processed. A new protocol that allows harvesting of various amounts of plant material in a manner that minimizes latex loss is needed by guayule researchers. A standardized protocol will also allow better comparison of research results from various areas of the world where guayule research is being conducted. The objective of this study was to develop a protocol that could be used to harvest various amounts of plant material from agronomic and breeding tests for laboratory analyses. A six step protocol was developed that could harvest from 1 kg to over 20 kg of plant material from field plots in a form suitable for laboratory analyses with minimal latex loss. Step one was to cut the plants in the field as close as possible to ground level (. 50 mm). Step 2 was to transport the plants from the field to the chipping area as soon as possible in bags that kept plant samples separate. Step 3 was to obtain a fresh weight for each sample. Step 4 was to process the sample through the chipper and obtain a fresh weight of the chipped material. After weighing and prior to chipping the bag(s) containing the plant material to be chipped was emptied onto a plastic sheet to minimize sample loss during the chipping process. After the larger plant parts had been chipped, the plastic sheet was carefully picked up and the smaller plant materials remaining on the plastic sheet were dumped into the chipper/shredder. Step 5 was to add antioxidant solution (0.2% sodium sulfite in distilled water at a pH of about 11) so that fresh weight of plant material collected and antioxidant solution are in a 1:1 ratio. Step 6 was to thoroughly mix the antioxidant solution with the plant material by stirring the plant material after the antioxidant solution was added. Steps 2 - 6 were done in less than 3 hours to minimize latex loss. The mixture was stored at 4 to 10E C prior to laboratory analysis for latex. While this mixture can be stored under these conditions up to five weeks without loss of latex, samples used in our studies were processed within 3 - 5 days after harvest. The proposed protocol was evaluated by processing samples harvested using this protocol for latex content. If samples harvested using the proposed protocol could be processed for latex using the recommended laboratory protocol without additional preparation prior to using the laboratory protocol, then we considered the proposed harvesting protocol acceptable. Additionally, the proposed protocol should provide samples that could be used for rubber, resin, and other laboratory analyses. This basic protocol has been used for over five years to successfully analyze guayule plant material from plants of various ages and sizes for latex, rubber, and resin concentration. This protocol will be of use to other researchers around the world who are now beginning to conduct research on guayule.

Last Modified: 10/24/2014
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