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As an engineering material, natural rubber combines elasticity with other useful properties of vibration absorption, abrasion resistance, malleability, heat resistance and dispersion, electrical insulation, gas impermeability, and water resistance. It is a unique industrial material that is not mined, but grown. High-yield rubber from the rubber tree Hevea brasiliensis is realized through the extraction of rubber-bearing latex by tapping, which is a non-destructive method of harvesting. High turgor pressure in the laticifer network expels latex from the tapped tree, and its flow ceases when plugs form at the cut ends of the laticifers. At the termination of its rubber producing life, the tree is felled for cultivated timber, yet another renewable industrial material. Events in the year 1876, when the rubber tree was transferred from its native South America to the Orient, were pivotal in its transformation from a jungle tree to a plantation crop plant. After almost a century and a half, rubber productivity has increased sixfold through breeding and selection and the adoption of various agronomic practices (Kadir, Rubber Chem Technol 67:537–548, 1994). Recent advances in genomics have introduced new opportunities for further crop improvement. Breeders can now select genotypes that harbor not just individual desirable genes, but use microarrays to pick sets of genes that control polygenic traits. |
