(Reuters) - Tire makers such as Bridgestone Corp and Continental AG are spending millions of dollars on the development of new rubber-yielding crops such as dandelions to reduce their reliance on rubber-tree plantations in Southeast Asia.
Here are key facts about the rubber trade and the research into new sources of natural rubber.
Rubber is a polymer with the property of elasticity. There are two categories of rubber: natural rubber currently obtained from the rubber trees, or Hevea brasiliensis; and synthetic rubber derived from petrochemicals.
The tire industry consumes about two-thirds of natural rubber produced globally. Natural rubber is also used to make gloves, condoms and thousands of other products for industries such as transport, construction, health, mining and weapons.
The Russian dandelion, or Taraxacum kok-saghyz (TKS), is a type of dandelion native to Kazakhstan that can grow on marginal soil in temperate world regions.
Its taproot produces a milky fluid, which is similar to the fluid taken from the bark of the rubber tree.
Guayule, a desert shrub native to the southwest United States and Mexico, is also being explored as an alternative source in dry regions of the world.
* Dandelion and guayule could provide relief if the South American Leaf Blight, a tree-killing fungus, ever strikes rubber-tree plantations in the main growing region of Southeast Asia. The pathogen emerged in the early 20th century in Brazil, where the rubber tree is originally from. It has rendered large-scale rubber farming in South America almost impossible.
* Dandelions can be harvested within a year of sowing while new rubber-tree plantations need to be left growing for about seven years before they can be tapped. This lead time has contributed to massive swings in the rubber price.
* Dandelions can be grown in temperate regions of North America, Europe and Asia, even on marginal land not suitable for food production. This could accommodate further growth in tire demand.
* Thailand, Indonesia, Vietnam, India, China and Malaysia currently account for almost the entire global natural rubber output. The land available for further expansion is limited and tropical rainforests could be at risk.
* For every ounce of rubber, dandelions yield more than two ounces of inulin, a carbohydrate that can be used as a food additive or as a precursor material for plastics or biofuels. Rubber trees do not yield any inulin.
Reporting by Ludwig Burger; Editing by Pravin Char