biology of economic agriculture

1. RUBBER CULTIVATION
Many plant species produce natural
rubber.
Considerations of quality and
economics, however, limit the source
of natural rubber to one species,
namely Hevea brasiliensis.

2. Introduction
• It is a native of the Amazon basin and
introduced from there to countries in the
tropical belts of Asia and Africa during late
19th century.
• It can be termed as the most far reaching
and successful of introductions in plant
history resulting in plantations over 9.3
million hectares, 95 per cent of it across
the globe in Asia.

3. Botanical Description
Hevea brasiliensis, also known as the
Para rubber tree after the Brazilian port of
Para, is a quick growing, fairly sturdy,
perennial tree of a height of 25 to 30
metres. It has a straight trunk and thick,
somewhat soft, light brownish gray bark.

4. The young plant shows
characteristic growth pattern of
alternating period of rapid
elongation and consolidated
development. The leaves are
trifoliate with long stalks. The tree
is deciduous in habit. Re-foliation
is quick and copious flowering
follows (pengeluaran bunga yg lebat).

5. Flowers are small but
appearing in large clusters.
Fruits are three lobed, each
holding three seeds, (quite like
castor seeds in appearance
but much larger in size). The
seeds are oil bearing.

6. The rubber tree may live for a
hundred years or even more. But its
economic life period in plantations,
on general considerations is, only
around 32 years, i.e. 7 years of
immature phase and 25 years of
productive phase.

7. Germination of Seeds
Rubber seeds lose viability
very rapidly if left in the field.
The seeds are therefore
picked up daily during the
seed fall season and quickly
transported to nurseries for
germination and planting.

8. For germination, raised level beds
(tapak semaian) with a 5 cm thick
layer of river sand, 90 cm wide
and of convenient lengths are
used. Partial shade in order to
prevent strong sun is necessary.

9. The seeds are sown in a single
layer touching one another and
germination beds are kept moist,
but not wet, by evenly sprinkling
water during morning and
evening. The seeds are covered
with loosely woven coir matting
(sabut) or gunnies.

10. • Germination starts 6 to 7 days after
sowing. Seeds sprouted each day
should be picked and planted in
nursery beds or in the field as the
case may be. Germinated seeds
will have young roots emerging first.
That is the ideal stage for nursery
planting.

11. • The sproutings are tender and
require careful handling. Usually,
germinated seeds are carried to
nursery beds in buckets half filled
with water.
• About 75 percent germination is
considered good. Pickings are done
for about 21 days after sowing

12. 1. Nurseries
Nurseries are required for raising
seedlings, budded stumps and
budwood.
Open and level land should be
selected for raising nursery. Water
should be easily available for
irrigation. The soil should be deep,
well drained and fertile.

13. 2. Nursery Establishment
• Nurseries are established and maintained for
raising various propagation materials for
planting. These include seedling stumps,
budded stumps and advanced planting materials
like polybag plants, etc.
• Mother plants or source bushes for the
multiplication of budwood are also grown in
nurseries. Raising of plants is easier and
cheaper in nurseries than in the main field.
• Moreover, nurseries offer an opportunity for
selection of vigorous and uniform plants

14. The land should be dug to a depth
of 75 cm and all stumps, roots, and
stones should be removed. Nursery
beds should be prepared with 60 to
120 cm width and convenient
lengths and with pathways laid in
between to facilitate manuring
(fertilizing), watering, weeding etc.

15. Planting distances should vary
according to the type of planting
materials to be raised in the nursery.
The ideal spacing for (a) seedlings is
30 cm X 30 cm, (b) budwood
nurseries, the plants may be at
distances of 60 X 90 cm or 60 X 120
cm or 90 X 90 cm

16. 3. Nursery management
• Nursery management aims at the most
rapid production of standard healthy
planting materials. More intensive care
can be exercised in a nursery than in a
field. Plants which are unsuitable can be
eliminated at an early stage.
• Mainframe operations for nursery include
weeding, mulching, irrigation during dry
months, manuring and disease and pest
control.

17. Planting materials for establishing
rubber plantations are generated
in:
–Seedling nurseries,
–budwood nurseries and
–polybag nurseries.

18. Bud Grafting
• The principle involved in bud grafting
(budding) is the replacement of the shoot
system of a plant with that of another more
desirable plant. In this process, a patch of
bark of the seedling plant (stock) is
replaced by a patch of bark with a dormant
bud (bud patch) taken from the clone to be
multiplied. The bud patch gets attached to
the stock permanently and becomes a part
of it.

19. The stock is then cut off above the
budded portion and the grafted bud
develops into a shoot (scion) exhibiting
the characters of the plant from which it
was taken.
The new tree thus formed is a two-part
tree, comprising a root system
belonging to the stock plant and a shoot
system contributed by the donor of the
bud.

20. • Depending on the colour and age of the
buds as well as the age of the stock plants
used, three types of bud grafting are
mainly recognized. These are:
- brown (conventional) budding,
- green budding, and
- young budding.
• In the first method, older buds having
brown colour are used while in the other
two, green tender buds are utilized.

21. Preparation and Packing of
Propagation Materials
• The propagation materials handled by rubber
growers are (a) ungerminated seeds, (b)
germinated seeds, (c) seedling stumps, (d)
brown bud wood, (e) green bud shoot, (f) brown
budded stumps, (g) green budded stumps, (h)
polybag plants and (i) stumped buddings.
• Specific techniques are required for the
preparation of these materials. If not properly
prepared, their quality could be reduced, which
in turn adversely affects the establishment after
planting.

22. Contd/-
• After preparation, these materials may
require storing and/or transportation.
During storage and transit they are likely
to get damaged by loss of moisture or by
breaking, rubbing, bruising, crushing, etc.
To avoid these and to give ample
protection to these materials, certain
specific methods are adopted for packing
and transporting.

23. Soil Type
• Soil in the rubber tract is generally highly
weathered and consists mostly of laterite or
lateritic types. Sedimentary types and non-lateritic
red and alluvial soils are also seen in
some non-traditional areas.
• The laterite and lateritic soils are mostly very
porous, well drained, moderately to highly acidic,
deficient in available phosphorus and varying in
potassium and magnesium content.
• Red soil found in some areas is characterized by
reddish to brown colour and fine loamy
texture. This soil is generally acidic and highly
deficient in available phosphorus.

24. Climatic conditions
• The climatic conditions for optimum growth of
Rubber tree consist of (a) Rainfall of around 250
cm evenly distributed without any marked dry
season and with at least 100 rainy days per
annum (b) Temperature range of about 20°C to
34°C with a monthly mean of 25°C to 28°C (c)
High atmospheric humidity of around 80% (d)
Bright sunshine amounting to about 2000 hours
per annum at the rate of 6 hours per day
throughout the year and (e) Absence of strong
winds.

25. Soil Depth
• Soil for rubber cultivation should have a
minimum depth of one metre without any
intervening hardpan or impenetrable layer.
• Water table should also be well below one
metre so that at least one metre of soil
with good aeration, essential for root
penetration is available.

26. Drainage
• Well-drained soil is essential for optimum
growth and yield of rubber plants.
• In marshy areas, owing to poor physical
properties and waterlogged conditions
growth of rubber is always found to be
very poor.

27. Field Planting
• The success of planting depends on the
prevailing weather conditions, quality of the
planting materials used and the care with which
the planting operation is done. Continuous wet
weather is considered to be ideal for planting
rubber.
• The actual method of planting will depend on the
materials used for planting. Different types of
planting materials used are seeds, seedling
stumps, budded stumps and polybag plants. Of
these, the last two are the most common ones.

28. Intercropping
• During the initial years of a rubber plantation, the
land area is not fully occupied by the rubber
plants and inter spaces are available in the
plantation which receive plenty of sunlight.
• These interspaces can be utilized for growing
intercrops, which will help the farmer to generate
additional revenue. Intercrops should be
planted at least 1.5 m away from plant
bases. Intercrops should be separately and
adequately manured or fertilized.

29. • The topography of the rubber plantations vary
from level lands to gentle, moderate and steep
slopes. The high rainfall in the rubber growing
regions and the undulating topography in many
situations make the soil vulnerable to erosion
hazards.
• Growing of intercrops necessitates soil
disturbing tillage operations of various kinds.
This will predispose the top soil to erosion losses
in steep and undulating lands.

30. • The growing of intercrops, therefore has to
be restricted to level lands and gentle
slopes. Even in such lands it should be
ensured that leguminous cover crops are
established side by side with intercrops or
immediately after the intercropping is
stopped. The general practice of growing
leguminous ground covers has to be
strictly followed in plantations of moderate
and steep slopes.

31. Ground Cover Management
• The undulating topography coupled with
the high rainfall of the traditional rubber
growing region pre-dispose the soil
towards erosion.
• In order to conserve soil and improve soil
fertility cover crops are grown and
maintained. Leguminous ground cover
enhances the growth and yield of rubber.

32. • Advantages of Cover Crops
• Prevent the beating action of rain and effectively
reduces run off
• Increase soil moisture and keep down the
temperature during summer
• Smother weeds
• Add large quantities of organic matter and
improve soil structure
• Fix atmospheric nitrogen resulting in improved
soil fertility

33. Common Leguminous Cover Crops
Grown in Rubber Plantations
• Pueraria phaseoloides
This is a very popular cover crop in rubber
plantations. It is a vigorous twiner and
creeper and forms a dense thick ground
cover when established. It can withstand
strong sun and smother weeds. It is
propagated through seeds and cuttings.
Seed rate about 3.0 to 4.5 kg per ha. A
disadvantage is that it is grazed by cattle
unless afforded protection.

34. • Calopogonium mucunoides
It is a twine and creeper with tolerance for poor
soils. It has a rapid initial growth and dies off
during the dry months and is a prolific seeder.
Seed rate is 3.0 to 4.5 kg. per ha.
• Centrosema pubescens
A perennial climber and creeper that can grow in
shade. It grows slowly and is not tolerant to wet
conditions. It smothers weeds. Seed rate is 3 -
4.5 kg per ha.

35. Mulching, Shading and Whitewashing
• Mulching or covering the plant basin with
dry leaves, cover crop cuttings, grass
cuttings, paddy straw etc is a
recommended practice in rubber
plantations to protect soil in the immediate
vicinity of the plants from direct impact of
heavy rains and sunlight causing soil
degradation.

36. • Benefits of Mulching
* Improvement of water and plant nutrient
holding capacity of the soil
* Maintenance of the soil around young rubber
plants in a cool and moist condition during hot
months
* Multiplication of microbial population of the soil,
ensuring better nutrient availability
* Protection of the soil from beating effect of
heavy rainfall resulting in soil erosion
* Control of weeds around the plant bases

37. Induction of Branches
• It has been observed that to achieve a
high rate of girth increase the rubber plant
should produce branches at a height of
about 2.5 to 3.0 m from the ground. In high
branching trees girth increment has been
found to be poor compared to low
branching trees.

38. • Some plants show a tendency for high
branching, particularly clones like RRIM
600 and GT 1. In such cases branching
has to be induced by encouraging a few
lateral buds to develop.
• The branches thus induced should
develop in different directions in an equally
spaced manner to ensure a well-balanced
canopy.

39. Common Weeds
• Borreria sp. (Button weed),
• Chromolaena odorata (Siam weed),
• Lantana aculeata (Lantana),
• Mimosa pudica (Touch-me-not),
• Clerodendron sp.,
• Mikania micrantha (Mile-a-minute),
• Sida sp.,
• Imperata cylindrica,
• Pennisetum sp. (Napier grass),
• Axonopus sp (Carpet grass),
• Paspalum sp., Digitaria sp. (Tropical crab grass),
Cynodon dactylon (Bermuda grass) etc.

40. Tapping and Stimulation
• Latex is obtained from the bark of the rubber
tree by tapping. Tapping is a process of
controlled wounding during which thin shavings
of bark are removed.
• The aim of tapping is to cut open the latex
vessels in the case of trees tapped for the first
time OR to remove the coagulum which blocks
the cut ends of the latex vessels in the case of
trees under regular tapping.

41. Diseases and Pests
• Crops losses resulting from ravages of
diseases in rubber plantations are
substantial.
• Timely plant protection operations ensure
healthy growth and economic production.
• The major diseases and pests of rubber
are given below.

42. Abnormal Leaf Fall
Shoot Rot
Powdery Mildew
Colletotrichum Leaf Disease
Bird's Eye Spot
Leaf Spot
Pink Disease

43. Patch Canker or Bark Canker
Black Stripe, Black Thread or Black Rot
Dry Rot, Stump Rot Collar Rot or Charcoal
Rot
Brown Root Disease
Poria Root Disease
Scale Insect

44. Mealy Bug
Termite (White Ant)
Cockchafer Grub
Bark Feeding Caterpillar
Mites
Slug and Snail
Rat
Porcupines and Wild Pigs
Cover Crop Pests
Parasitic and Non-Parasitic Maladies

45. Production
Close to 21 million tons of rubber
were produced in 2005 of which
around 42% was natural. Since the
bulk of the rubber produced is the
synthetic variety which is derived from
petroleum, the price of even natural
rubber is determined to a very large
extent by the prevailing global price of
crude oil.

46. • Today Asia is the main source of natural rubber,
accounting for around 94% of output in 2005.
The three largest producing countries
(Indonesia, Malaysia and Thailand) together
account for around 72% of all natural rubber
production.
• Many high-yielding clones have been developed
for commercial planting. These clones yield
more than 1,500 Kilogrammes of dry Rubber per
hectare (or, over 4 tons per acre), per annum,
when grown under ideal conditions