The document discusses the history and cultivation of natural rubber. It notes that rubber trees are native to South America, but were introduced to other parts of the world in the late 1800s. Rubber tree seeds were sent from Brazil to places like Sri Lanka, Indonesia, and Malaysia, which later became a major rubber producer. Commercial rubber cultivation was also established in India and Africa in the early 1900s. The document provides details on rubber extraction, the lifespan and soil requirements of rubber trees, and optimal climatic conditions for growth. It notes that high-yielding clones have been developed that can produce over 2,000 kg of dry rubber per hectare annually under ideal conditions.

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9. •This has been referred to as the first scientific
paper on rubber.
•In England, Joseph Priestley, in 1770, observed
that a piece of the material was extremely good
for rubbing off pencil marks on paper, hence the
name "rubber". Later, it slowly made its way
around England.
•South America remained the main source of the
limited amounts of latex rubber used during much
of the 19th century. In 1876, Henry
Wickham gathered thousands of Para rubber tree
seeds from Brazil, and these were germinated
in Kew Gardens, England

10. •The seedlings were then sent to India, Ceylon (Sri
Lanka), Indonesia, Singapore, and British Malaya.
Malaya (now Malaysia) was later to become the
biggest producer of rubber. In the early 1900s,
the Congo Free State in Africa was also a
significant source of natural rubber latex, mostly
gathered by forced labor. Liberia and Nigeria also
started production of rubber.
•In India, commercial cultivation of natural rubber
was introduced by the British planters, although the
experimental efforts to grow rubber on a
commercial scale in India were initiated as early as
1873 at the Botanical Gardens, Calcutta. The first
commercial Hevea plantations in India were
established at Thattekadu in Kerala in 1902.

12. Rubber latex is extracted from rubber trees. The
economic life period of rubber trees in plantations is
around 32 years – up to 7 years of immature phase
and about 25 years of productive phase.
The soil requirement of the plant is generally well-
drained, weathered soil consisting of laterite,
lateritic types, sedimentary types, nonlateritic red,
or alluvial soils.
The climatic conditions for optimum growth of
rubber trees are:

13. •Rainfall of around 250 cm evenly distributed
without any marked dry season and with at least
100 rainy days per year
•Temperature range of about 20 to 34°C, with a
monthly mean of 25 to 28°C
•High atmospheric humidity of around 80%
•Bright sunshine amounting to about 2000 hours per
year at the rate of six hours per day throughout
the year
•Absence of strong winds
Many high-yielding clones have been developed for
commercial planting. These clones yield more than
2,000 kg of dry rubber per hectare per year, when
grown under ideal conditions.

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28. 105-106
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29. 105-106
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