!ntroductionRubber tree (Hevea bras

!ntroduction
Rubber tree (Hevea brasilliensis Muell.)
is indigenous to the Amazon basin of South
America. During the nineteenth century,
Brazil was the main supplier of hevea latex,
a milky colloid produce in lactiferous tissue
of the bark, which was collected through
tapping of tree in the natural forest. Until
now rubber tree is cultivated as economic
plants (1). There are several varieties that
produce latex or timber and both of two
productions (2,3). Many high-yielding clones
have been developed for commercial
planting. These clones yield more than 2,500
kg of dry rubber per hectare per year (400
kg rai-1), when they are grown under
appropriate condition (4).
Rubber plantation are found in
several countries in the tropic from its native
habitat in Amazon basin to Guatamala and
Mexico in the America; Nigeria, Liberia,
Cameroon and lvory Coast in West Africa
and continental and insular Southeast Asia
and The lndian sub-continent. (2). Rubber
plantation areas in Asia occupy approximately
94 % o'f the world total, 5.1 % in Africa and
1.2 % in America (2). ln Southeast Asia
Thailand, lndonesia and Malaysia rang first
among the world rubber cultivators, They
contribute more than 90 % of the world total.
Other countries in Asia with relatively minor
rubber plantation are lndia, Vietnam, China,
Sri Lanka, Philippines, Burma, Lao and
Cambodia (1). Plantation area in Thailand is
approximately 2.79 million hectares