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| Hevea brasiliensis |
leaflets obovate, apically acuminate, entire, basally acute, penninerved, 10–15(-50) cm long, 3–6(-15) cm broad, elliptic-lanceolate in outline; flowers numerous, monoecious, creamy, yellow or green, in axillary pubescent panicles, sweet-scented, small; female flowers apical, the more numerous male flowers lateral in the inflorescence;petals absent; fruit a 3-lobed, 3-seeded ellipsoidal capsule, each carpel with 1 seed; seeds ellipsoidal, variable in size, 2.5–3 cm long, mottled brown, lustrous, weighing 2–4 g each. Seeds collected July–September in India. Hevea brasiliensis, the Pará rubber tree, often simply called rubber tree, is a tree belonging to the family Euphorbiaceae and the most economically important member of the genus Hevea. It is of major economic importance because its sap-like extract (known as latex) can be collected and is the primary source of natural rubber.
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| Hevea brasiliensis |
Chemistry
Per 100 g, the poisonous seed is reported to contain 8.5 g H2O, 17.6 g protein, 48.5 g fat, 22.9 g total carbohydrate, 2.5 g ash, 120 mg Ca, and 430 mg P. Leaves contain a- and g-tocopherol, and plastochromanol-S. Ubiquinone 9 and 10 heveaflavone, vitexin, and isovitexin are also reported. The latex contains 60% water, 37% caoutchouc, 0.34% protein, 1.45% quebrachitol, 0.25% sugar, 0.53% ash, and 0.34% undetermined substances. Arachidylacohol, r, a-, b-, g-, and D-tocotrienol, hevein, L-inosit-2-methylether, b-indolylaceticacid, trigonelline, ergothioneine, and hercynine. Bark contains D-apiose (C5H10O5). Seeds contain the toxin linamarin (C10H17NO6). The seed oil (ca 40%) contains 7% palmitic-, 9% stearic-, 0.3% arachidic-, 30% oleic-, 30–50% linoleic-, and 2–23% linolenic-acids.
Per 100 g, the poisonous seed is reported to contain 8.5 g H2O, 17.6 g protein, 48.5 g fat, 22.9 g total carbohydrate, 2.5 g ash, 120 mg Ca, and 430 mg P. Leaves contain a- and g-tocopherol, and plastochromanol-S. Ubiquinone 9 and 10 heveaflavone, vitexin, and isovitexin are also reported. The latex contains 60% water, 37% caoutchouc, 0.34% protein, 1.45% quebrachitol, 0.25% sugar, 0.53% ash, and 0.34% undetermined substances. Arachidylacohol, r, a-, b-, g-, and D-tocotrienol, hevein, L-inosit-2-methylether, b-indolylaceticacid, trigonelline, ergothioneine, and hercynine. Bark contains D-apiose (C5H10O5). Seeds contain the toxin linamarin (C10H17NO6). The seed oil (ca 40%) contains 7% palmitic-, 9% stearic-, 0.3% arachidic-, 30% oleic-, 30–50% linoleic-, and 2–23% linolenic-acids.
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| Hevea brasiliensis |
The Pará rubber tree initially grew only in the Amazon Rainforest. Increasing demand and the discovery of the vulcanization procedure in 1839 led to the rubber boom in that region, enriching the cities of Belém and Manaus. The name of the tree derives from Pará, the second largest Brazilian state, whose capital is Belém.
These trees were used to obtain rubber by the Olmec people of Mesoamerica as early as 3600 years ago. The rubber was used, among other things, to make the balls used in the Mesoamerican ballgame. There had been an attempt made, in 1873, to grow rubber outside Brazil. After some effort, twelve seedlings were germinated at the Royal Botanic Gardens, Kew. These were sent to India for cultivation, but died. A second attempt was then made, some 70,000 seeds being smuggled to Kew in 1875, by Henry Wickham, at the service of the British Empire. About 4% of these germinated, and in 1876 about 2000 seedlings were sent, in Wardian cases, to Ceylon, and 22 sent to the Botanic Gardens in Singapore. Once established outside its native country, rubber was extensively propagated in the British colonies. Rubber trees were brought to the botanical gardens at Buitenzorg, Java in 1883. By 1898, a rubber plantation had been established in Malaya, and today most rubber tree plantations are in South and Southeast Asia and some also in tropical West Africa. Efforts to cultivate the tree in South America (Amazon) were unsatisfactory, because of blight.
These trees were used to obtain rubber by the Olmec people of Mesoamerica as early as 3600 years ago. The rubber was used, among other things, to make the balls used in the Mesoamerican ballgame. There had been an attempt made, in 1873, to grow rubber outside Brazil. After some effort, twelve seedlings were germinated at the Royal Botanic Gardens, Kew. These were sent to India for cultivation, but died. A second attempt was then made, some 70,000 seeds being smuggled to Kew in 1875, by Henry Wickham, at the service of the British Empire. About 4% of these germinated, and in 1876 about 2000 seedlings were sent, in Wardian cases, to Ceylon, and 22 sent to the Botanic Gardens in Singapore. Once established outside its native country, rubber was extensively propagated in the British colonies. Rubber trees were brought to the botanical gardens at Buitenzorg, Java in 1883. By 1898, a rubber plantation had been established in Malaya, and today most rubber tree plantations are in South and Southeast Asia and some also in tropical West Africa. Efforts to cultivate the tree in South America (Amazon) were unsatisfactory, because of blight.
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| Hevea brasiliensis |
Propagated by seeds or vegetatively by buddings or by a combination of both. Fruits burst open when ripe and the seeds are scattered up to 33 m from tree. Seeds gathered and sown fresh as they lose viability rapidly (only 7–10 days), extended to 4–6 weeks, if packed in charcoal powder or sawdust with 15–20% moisture in special containers. Buds collected from seedling trees used for budding. Area to be planted to rubber trees is cleared, then lined and marked for roads and drainage. Planting pits are dug, 75 x 75 x 75 cm, or 90 x 90 x 90 cm, and filled with surface soil and manure. Seedlings are raised in nurseries or directly in the field. Seeds germinate in 1–3 weeks, depending on climatic conditions and freshness of seed. Seedlings are 1–1.3 m tall in 6 months. About 100,000 plants/ha is average for a seedling plot, of which 60,000 to 70,000 should reach standard pulling size in 10–15 months. Then plants are uprooted, the stem cut back to 45–60 cm, the taproot 45–70 cm, and the lateral roots to 10 cm. Seedlings make good cuttings but rubber-bearing trees take very poorly or not at all. Transplanting to field done during monsoon. Tapping stands of 250–300 trees per hectare are recommended, obtained by thinning budwood densities of 375 to 450 or seedling densities of 500 to 600. Wider spacing might be used, intercropping coffee or cocoa, perhaps in conjunction with ipecac. A fodder crop such as Cajanus, might be tried for lac production, instead of the usually recommended covercrops (Centrosema, Calopogonium, Flemingia, Pueraria, Psophocarpus). After a few years under legumes, no N fertilizer may be needed, but phosphorus, magnesium, and potassium may be limiting in some areas. Potassium deficiency is frequent in Vietnam.
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