Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2010
Publication Date: 5/1/2010
Citation: Pearson, C., Cornish, K., Mcmahan, C.M., Rath, D.J., Brichta, J.L., Van Fleet, J.E. 2010. Agronomic and Natural Rubber Characteristics of Sunflower as a Rubber-Producing Plant. Industrial Crops and Products. 31:481-491. Interpretive Summary: Thousands of plants produce natural rubber (NR), and development of domestic sources of natural rubber would benefit from annual rubber-producing crops with well-defined agronomic practices. Sunflower is native to North American and produces natural rubber in its leaves. The objective of this study was to explore genetic variation for biomass partitioning, NR yield and NR quality for various sunflower cultivars. The potential for increasing latex production in sunflower appears possible, given that current NR levels are low and reasonable advances in NR production in sunflower plants might be achieved through plant breeding and genetic engineering.
Technical Abstract: Sunflower (Helianthus annuus L., Asteraceae) is a genus native to North American and is a potential natural rubber (NR) producing crop. The objectives of the study were to: 1) evaluate commercial sunflower cultivars to determine biomass production and how they partition biomass into leaves, stems, and head, 2) determine how removing the head affects biomass partitioning, 3) determine latex concentration and yield in commercial sunflower cultivars and a diversity of genetic sunflower material, and 4) characterize several quality factors pertaining to the latex produced by commercial sunflower cultivars and a diversity of genetic sunflower material. Field performance tests were conducted at the Western Colorado Research Center at Fruita, Colorado for three growing seasons (2001, 2002, and 2003). Latex was found almost entirely in the leaves of young and mature sunflowers. No latex was found in mature stems or in the pappus of the flowers. On average, sunflower partitioned biomass into 18% leaves, 38% stems, and 44% heads. With the head removed, sunflower partitioned biomass into 33% leaves and 67% stems. Sunflower cultivars exhibited considerable genetic variation for biomass partitioning and also for NR yield and quality. Sunflower synthesized NR with 95-97% being low molecular weights ranging from 66,000 to 74,000 g/mol and a small, remarkable percentage (~5%) of NR being higher molecular weight (~600,000 g/mol). The potential for increasing latex production in sunflower appears possible, given that current NR levels are low and reasonable advances in NR production in sunflower plants through plant breeding and genetic engineering might be achieved. Based on the genetics of the sunflower cultivars included in our study, it appears that some cultivars would be more responsive to plant breeding for increased leaf mass than others. The development of sunflower cultivars suitable for commercial production of NR will require significant improvements in the quantity and quality of NR produced in the plant.