A Six Step Harvesting Procedure of Guayule Small Plots for Laboratory Analyses.

Authors: Coffelt, Terry; Nakayama, Francis

Submitted to: Proceedings Assoc for Advancement of Industrial Crops (AAIC) Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 9/14/2006
Publication Date: 10/14/2006
Citation: Coffelt, T.A., Nakayama, F.S. 2006. A six step harvesting procedure of guayule small plots for laboratory analyses.. Proceedings Assoc for Advancement of Industrial Crops (AAIC) Annual Meeting, p. 96.

Interpretive Summary:

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. Harvesting protocols in the past have not had to deal with the problem of latex loss as plant material is being processed. A new protocol allowing harvesting of various amounts of plant material 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 to 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. 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 following harvest to minimize latex loss. The mixture was stored at 4 to 10' 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. In addition, the proposed protocol provided 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.