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History of Rubber
Rubber Seeds
Rubber seeds are the planting material for rootstock plants which are grown in poly bags for young budding. The main seed fall in Sri Lanka is around August-September. In relatively dryer parts of the country seed fall is in the dry months of February-March. Since seeds remain viable only for a short period, fresh seeds should be collected and germinated with minimum delay. Seeds with glossy appearance are generally fresh
Seeds are Grown in a Nursery
Germination will start after about 7 days of seed sowing. Seeds should be transferred to the black polythene bags as soon as the tip of the radical has forced its way though the seed coat. Top soil and coir dust is used for filling bags. Water soluble fertilizer is used to achieve the anticipated growth and other agro management practices such as disease control in time are also essential.
Healthy Trees are Selected for Bud Grafting
Selection of healthy trees are to be done prior to the bud grafting. Right selection of healthy seedling plant will give the high successive rate in bud grafting.
Bud Grafting
When the seedlings are grown in the poly bags they can be bud-grafted at the age of 3-4 months. After cleaning the basal portion of the rootstock, two vertical incisions about 5-6cm long and 1-1.5 cm apart are made starting from a point about 1cm above the soil level. The lower ends of these cuts are joined by a horizontal cut. The flap of bark is then gently lifted upwards using the tip of the bud grafting knife exposing the budding panel. The flap is then cut off leaving about 1cm at the top. The prepared bud patch should be gently inserted under the patch and tied in position with a 2 cm wide strip of gauge 150 transparent polythene.
Successful Bud Grafting
Bud patches are examined 14 days after bud grafting. Retention of green color indicates that the grafting is successful. Cutback of the snag can be done at 15cm above the bud patch.
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Bud Grafted Tress are Planted
One hundred percent success in field establishment and uniform growth of the plants could be obtained by using young budding plants. Usually the immature period is 60 months under good management conditions.
5 Year Old Tress Selected for Tapping
In a clearing when 70% of the tress have reached 50cm measured at 125cm from ground level/highest point of the union it could commence tapping.
5 year Old trees are Marked for Tapping
The tapping cut should be marked using a stencil for harvesters to achieve correct angle and length of cut and also to achieve correct bark consumption. As the latex vessels run at an angle of 2.5-70 degrees to the vertical in an anti clockwise manner, a greater number of latex vessels is cut and a greater yield is obtained when cuts are made at 30 degrees to the horizontal sloping from high left to low right.
Year of Tapping
The continuous excision method of tapping developed by Ridley is used to exploit rubber trees for latex. During tapping the original cut is systematically reopened by the removal of a thin shaving of bark from the sloping cut. The special knife used cuts a shallow channel along which the latex flows to a collecting vessel.