Hevea brasiliensis (Willd.) Muell.-Arg.
Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.
- Folk Medicine
- Yields and Economics
- Biotic Factors
Source of Hevea or Para Rubber, obtained by tapping the trunks of the trees.
The latex coagulates with the aid of acetic acid, formic acid, and alum. Cured
rubber used for all types of rubber products. Seeds are source of Para Rubber
seed oil, recommended for manufacture of soap. Although poisonous, seeds can
be eaten as a famine food after processing. Boiling removes the poison and
releases the oil which can be utilized for illumination. Seeds are sometimes
eaten off the ground by cattle. Kernels (5060% of the seed) contain 4050% of
a semi-drying pale yellow oil, used in soap making, paints, varnishes, and is
effective against houseflies and lice. Press cake or extracted meal can be
cautiously used as fertilizer or feed for stock (Reed, 1976).
Surprisingly, Duke and Wain (1981) contains no references to folk medicinal
uses of Hevea. Most laticiferous plants have large folk medicinal roles.
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-, 3050% linoleic-, and 223% linolenic-acids (List and Horhammer,
Tree up to 40 m tall, with girth 2.63.3 m; stems smooth and straight; trunk
unbranched up a long way and then with much-branched leafy canopy; bark
grayish; taproot well-developed; leaves alternate, trifoliolate, stipulate,
petioles 7.510(-70) cm long; leaflets obovate, apically acuminate, entire,
basally acute, penninerved, 1015(-50) cm long, 36(-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, 2.53 cm long, mottled brown, lustrous,
weighing 24 g each. Seeds collected JulySeptember in India (Reed, 1976).
Reported from the South American and, secondarily, the Indonesia-Indochina
Centers of Diversity, rubber, or cvs thereof, is reported to tolerate disease,
drought, high pH, insects, laterite, low pH, slopes, virus, and waterlogging
(Duke, 1978). There are many improved varieties and cultivars in areas where
Para Rubber is cultivated commercially. These vary in size, productivity of
latex, and disease resistance (Reed, 1976). (2n = 36, 34,72)
Native to the Amazon region; Brazil, Venezuela, Ecuador, Colombia, Peru, and
Bolivia. Introduced to many other tropical regions of the world, as Indonesia,
Malaysia, Liberia, India, Sri Lanka, Sarawak, and Thailand (Reed, 1976).
Ranging from Subtropical Wet (without frost) to Tropical Dry to Tropical Wet
Forest Life Zones, rubber is reported to tolerate annual precipitation of 10.2
to 42.9 dm (mean of 24 cases = 24.5), annual temperature of 23.1 to 27.5°C
(mean of 24 cases = 25.6), and pH of (4.0) 4.3 to 8.0 (mean of 18 cases = 5.7)
(Duke, 1978). A rain-forest species of the Amazon Basin, rubber is now an
Asian crop, with Asia producing 92% of the world's natural rubber in Malaysia,
Thailand, Sri Lanka, South Vietnam, and Sarawak. Most rubber is between
15°N and 10°S latitude, with hot equable humid climates, evenly
distributed annual precipitation of 19 to 26 dm or more and temperatures
between 23° and 35°C. Tolerates but does not flourish in areas with
pronounced dry seasons and temperature fluctuations. Also tolerates some
waterlogging and a wide pH range (48) but does better in acid soils. Lime is
harmful, and shallow or poorly drained or peaty soils should be avoided.
Thrives best in deep well-drained loamy soil, covered by natural undergrowth or
leguminous cover-crop and protected from erosion (Reed, 1976).
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 710 days),
extended to 46 weeks, if packed in charcoal powder or sawdust with 1520%
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 13 weeks, depending on
climatic conditions and freshness of seed. Seedlings are 11.3 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 1015 months. Then
plants are uprooted, the stem cut back to 4560 cm, the taproot 4570 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 250300 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 (Reed, 1976).
Tapping begins when trees are 58 years old, depending on the area, and
increases every year until a maximum at about 20 years, then yield sustained
for 4050 years or more. Tapping consists of removal by excision of a thin cut
of bark about 1 mm deep at regular intervals, thus opening the latex vessels in
the bark, which are arranged in concentric cylinders and run in
counter-clockwise spirals up the trunk. Usually the cuts run half-way around
the trunk, but may encircle the tree. Several types of cuts are used. Only
the basal part (1.3 m) of the trunk is tapped (most latex vessels develop
here). Special knives are used to cut the proper depth and angle. Latex is
collected through a small spout fixed in the bark in cups placed at end of cut,
large enough to collect one-day's flow. Trees are tapped early in morning when
flow of latex is highest; flow decreases with temperature and usually ceases in
about 3 hours. An average tapper can tap 200300 trees in 3 hours. Then the
tapper starts back through the grove and empties the cups into large pails or
buckets, sometimes adding a few drops of dilute ammonium solution to prevent
coagulation. Rubber yield can be increased treating the bark below the tap
with yield-stimulating mixtures containing plant hormones and selective
weed-killers with hormone properties, as Stimalax, Eureka, 2,4-D, 2,4,5-T in
palm oil (Reed, 1976). Copper sulfate also enhances latex flow (Rogers, 1981).
Rubber is produced year round, with great fluctuations month to month. Average
prewar yields for unselected trees was about 300450 kg latex/ha; about twice
that for bud-grafted trees of approved clones, and 7002,000 kg latex/ha for
improved plantings. Average number of tappings per year is 120140 in India,
160 in Malaysia. Some Malayan clones yield 2,250 kg/year, in best years 4,300
kg. Major world supply of natural rubber at present is obtained from Malaysia,
Sumatra, Java, Indochina (Thailand is third largest), and Sri Lanka, with
smaller quantities from Sarawak, India, Burma, and Equatorial Africa, and the
rain-forests of tropical South America. Production in Thailand rose from
97,108 MT in 1953 to 258,000 MT in 1968. World production of Para rubber is
1.92.2 million tons. (Indonesia [38%], Malaysia [33%], Thailand [7%], Sri
Lanka [5%], Indochina [5%], and India [1.2%]). Major consumers are United
States (average 1 kg per capita), United Kingdom, West Germany, and France.
The U.S. rubber products industry employs more than 500,000 people, producing
more than $17 billion worth of goods and consuming 3.4 million MT rubber/yr.
Natural rubber accounts for 1/3 of the world's rubbers, tires and tire
accessories using nearly 3/4 of U.S. natural rubber consumption in 1974
I open my discussion of Hevea as an energy plant with two quotes. Pankhurst
(1983) has higher energetic yields for rubber than I have seen
elsewhere("rubber latex yields equivalent to 62 barrels oil/ha/yr.") Rogers
(1981) says that natural rubber, occupying 6.9 million ha, "ranks as one of our
most important biomass products in today's industrialized world." Such quotes
led me to include rubber in my energy thinking. Some people have equated the
hydrocarbons of latex with petroleum. With yields as high as 68 MT rubber/ha
reported, it is safer to compare this with a sustainable yield of 1520 barrels
of oil per hectare. Rubber is often planted at wide spacing, intercropped with
coffee or cocoa. On small holdings, intercropping is often practiced, but
annuals should be more than a meter away, bananas more than 2 m. In
intercropping situations such as these, there could be 15 MT of prunings, dead
limbs, leaves, etc. per hectare. Assuming that leaf-litter fall in these
simulated forest agroecosystems is equal to that in natural forest ecosystems,
rubber plantations, like other forest plantations, might yield 512 MT/ha/yr.
Five may be a reasonable assumption. Leaf fall values of 5 MT/ha/yr are
reported for San Carlos, Venezuela, 810 in an Ivory Coast Forest, 12 in Khao
Chong Forest in Thailand, 7.410.7 near Belem, Brazil, 6.7 near Manaus. Most
values in tropical forests are greater than 7 MT/ha/yr and several exceed 10.
About 90 species of fungi are known to attack Hevea trees, the most prevalent
ones being the following: Botryodiplodia elactica and B. theobromae,
Colletotrichum heveae (leaf spot), Fomes lamaensis (brown root
rot), Gloeosporium heveae (die-back), Oidium heveae (powdery
mildew), Pellicularis salmonicolor (pink disease), Phytophthora
palmivora (causing fruit rot, leaf-fall, black thread, and die-back),
Polystichus occidentalis and P. personii (white spongy rot),
Sphaerella heveae (rim bright), Sphaerostilbe repens (red rot)
and Ustulina maxima (charcoal rot). It is also attacked by Bacterium
albilineans, and parasitized by Loranthus spp. Nematodes isolated
from Hevea brasiliensis include: Helicotylenchus cavenessi,H.
dihystera, H. erythrinae, Meloidogyne incognita acrita, M. javanica,
Pratylenchus coffeae, P. brachyurus. (Golden, p.c., 1984) Insect pests
include the following species: Scale insects (Aspidiotus cyanophylli and
Parasaissetia nigra). White ants cause serious damage to trees at all
ages. Snails can be serious pests to young trees. Various animals can damage
the trunks (Reed, 1976). The Hevea tree is subject to many types of diseases
that must be controlled for economic production. Three types of root disease,
classified as white, red, and brown, are controlled by cutting away diseased
tissue and applying prophylactic coatings. Panel diseases, classified as black
stripe, moldy rot, and panel necrosis, are minimized by spraying or coating
specific fungicides. Stem disease, consisting of pink disease, stem canker,
and dieback is reduced by brushing on specific fungicides. Leaf disease,
consisting of abnormal leaf fall, Gloeosporium leaf disease, powdery
mildew, and bird's eye spot, is controlled by a variety of sprays, including
copper oxychloride, sulfur dust, and others applied by spray or dusting
techniques (Rogers, 1981).
Complete list of references for Duke, Handbook of Energy Crops
- Duke, J.A. 1978. The quest for tolerant germplasm. p. 161. In: ASA Special
Symposium 32, Crop tolerance to suboptimal land conditions. Am. Soc. Agron.
- Duke, J.A. and Wain, K.K. 1981. Medicinal plants of the world. Computer index
with more than 85,000 entries. 3 vols.
- List, P.H. and Horhammer, L. 19691979. Hager's handbuch der pharmazeutischen
praxis. vols 26. Springer-Verlag, Berlin.
- Pankhurst, E.S. 1983. The prospects for biogasa European point of view.
- Reed, C.F. 1976. Information summaries on 1000 economic plants. Typescripts
submitted to the USDA.
- Rogers, T.H. 1981. Natural rubber. p. 387396. In: McClure, T.A. and Lipinsky,
E.S. (eds.), CRC handbook of biosolar resources. CRC Press, Inc., Boca Raton,
Last update Wednesday, January 7, 1998 by aw