Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/31/2009
Publication Date: 11/14/2009
Citation: Mcmahan, C.M., Himmelsbach, D.S., Brichta, J.L., Chanon, A., Ehrensing, D., Kleinhenz, M.D., Whalen, M.C. 2009. Rapid Field Measurement of Rubber Content in Russian Dandelion. Association for the Advancement of Industrial Crops (AAIC) 2009 International Conference, Termas de Chillan, November 14-19th. Interpretive Summary: Domestic natural rubber from agricultural sources will provide supply security for this critical raw material and reduce dependency on petroleum-based rubber in an environmentally and economically sustainable manner. A 2007 USDA workshop on Domestic Rubber from Russian dandelion (Tks) identified development of a fast, reproducible field method for quantification of rubber content as a rate-limiting step for Tks as a new industrial crop. The collaborators/co-authors in Albany, CA, Wooster, Ohio, Corvallis, Oregon, and Athens, Georgia, worked together to assess the use of NIR (near infrared) spectroscopy to meet this challenge. Both lab bench tests and a field model proved able to quantify rubber content in freshly-cut roots at sufficient precision for practical germplasm screening.
Technical Abstract: Natural rubber is a critical and strategic raw material for industrial manufacturing and national defense. In 2008, 10 million tons of NR were produced for commercial use, most of it from Hevea brasiliensis in tropical countries. The annual US import deficit for NR is approximately $1 billion. Development of a US-based supply of NR is recognized in the Critical Agricultural Materials Act of 1984 (Laws 95-592 & 98-284) and is the subject of expanding research and development in the public and private sectors. Taraxacum kok-saghyz (TKS), Russian dandelion, produces natural rubber, cis-1,4-polyisoprene, in its roots and has been used commercially during times of short supply, especially in Eastern Europe. Evaluation of Russian dandelion as an alternative rubber-producing crop for cultivation in the U.S. requires high-rubber producing lines, as raw material for breeding, processing, and agronomic development. The objective of this work was to develop a fast field method for quantification of natural rubber in fresh TKS roots, to accelerate development of research and development TKS lines. Near-infrared (NIR) spectroscopy is used to measure chemical composition and physical properties of biomass between 750 and 2500 nm, and has been used to quantify rubber content in guayule (ground shrub, bagasse, and latex solutions). Freshly-harvest TKS roots from field plantings in Wooster, Ohio, and Corvallis, Oregon (USA), were shipped overnight to the USDA/ARS QARU Quality and Safety Assessment Laboratory (Athens, Georgia). An axial cut was made across the root and near-infrared spectra acquired using 3 instruments varying in sensitivity. The Polychromix Phazir (MEMS system at 8 nm resolution with 20 co-added scans over range of ~1600-2400 nm) is a handheld instrument that could be used in the field on as is samples. Root tissue were then dried, ground, and rubber content measured by Accelerated Solvent Extraction (ASE). The inulin content of the rubber-extracted roots tissue was determined by colorimetric assay. The rubber content of the roots tested varied from 0-17% dry weight root (dwr), inulin from 0-43% dwr. Results showed no correlation between rubber and inulin levels. NIR chemometric analysis can provide a fast, reproducible method for nondestructive screening of Tks germplasm in the field. The model developed from over 100 plants grown in Ohio and Oregon predicts rubber to within 7-9mg/g, depending on parameters used.