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. Planting materials for establishing rubber plantations
are generated in ground and polybag nurseries.
Ground nurseries are established for the production of budded stumps, stumped buddings
Selection of site
Preparation of nursery beds
Seed germination beds
Planting in nursery
Nursery for seedlings and budded stumps
The nursery beds should always be kept free of weeds. Three rounds of weeding are
needed. The first weeding is done just before application of the first dose of fertilizers
and the second weeding before the second dose. The third round of weeding is done
just before commencement of budding during May or June. The first round of manual
weeding can be replaced with the application of pre-emergence herbicides. After
the final preparation of the nursery beds, diuron at the rate of 2.5 kg per ha in
700 L water is sprayed on the beds and germinated seeds planted five days later.
Mulching is an important operation to be followed in seedling nurseries before the
beginning of the summer season and after the second round of fertilizer application.
Natural materials such as tree loppings, dry leaves, undergrowth from forests, grass
cuttings and cut cover crop material are commonly used after they are dried. A single
round of good mulching in December is adequate. Black polythene sheets properly
anchored to the soil to prevent them from being blown away by wind can also be used
for mulching. Spreading a thin layer of soil above the sheet is an effective way
to achieve this.
During the dry period, which usually extends from December to April, the nurseries
should be irrigated. In large nurseries, overhead sprinkler irrigation systems are
ideal. Daily watering is preferred during the initial weeks. Later, the frequency
of irrigation can be reduced to once in two or three days.
Buds required for budgrafting are collected from budwood obtained from plants raised
specifically for this purpose.
Budwood nurseries are of two types:
After cleaning and levelling, soil is first dug to a depth of 45-60 cm. Planting
can be done with polybag plants, budded stumps or seed at stake followed by budding.
For green bud shoot nursery the spacing is 1 m x 1 m or 80 cm x 90 cm. Proper fertilizer
application may be carried out to ensure good growth. Other agronomic practices
such as irrigation, mulching, weeding, shading, protection against diseases and
pests are followed in a similar manner as for seedling nursery.
During the first year of planting, only one shoot is allowed to grow. About 1 m
of brown budwood can be obtained from this after one year.
From the second year, two or three shoots are allowed to develop on a plant depending
on the spacing adopted. To remove the leaves present in the brown-coloured budwood,
the leaflets are first removed by clipping the tip of the leaf stalk. After about
one week, the leaf stalk dries and falls off.
Budwood is then harvested by sawing off, leaving about 15 cm at the base. From this
portion shoots develop in the subsequent season.
Green bud shoot plants are shaped from brown budwood plants. For this, a well-established
brown budwood plant is first cut back at a height of about 75 cm. A number of shoots
emerge below the cut end. Among these, only 3-5 most vigorous ones are retained
and the rest removed. When these shoots have grown and produced brown wood to a
length of about 5 cm, they are pruned at the point where the brown colour ends so
as to produce more branches. Two to three most vigorous branches are retained on
each shoot and the others cut off. When these secondary branches develop brown colour
at the basal 5 cm, they are again pruned. New branches arise from these and give
the budwood plant a bushy appearance. For producing green shoots, all the branches
of a green bud shoot plant (also called source bush) are pruned. The new branches
arising are harvested when one whorl of leaves develop. The harvested budwood is
cut into pieces of convenient length before being taken to the nursery beds for
Planting materials in polybags can be prepared by two different methods.
The roots of budded stumps can be treated with indole butyric acid (IBA), a hormone
that enhances root growth. Dipping root in cow dung slurry before planting enhances
Planting in polybags
Polythene bags of lay-flat dimension 55-60 cm length and 25-30 cm width which can
hold about 8-10 kg soil, are usually used for raising plants up to two to three
whorl stage. For producing plants of 6-7 whorls, larger bags of 65 cm x 35 cm size
and holding about 23 kg soil should be used.
In order to facilitate drainage, sufficient number of holes should be punched on
the lower half of the bags. Low density polyethylene (LDPE) sheet of 400 gauge and
500 gauge thickness are usually used for making small bags and large bags respectively.
Bags made of high density polyethylene (HDPE) sheets can also be used for this purpose.
However, such bags are likely to deteriorate when exposed to sunlight for long periods.
Soils with clay-loam texture, good structure and friability are ideal for this purpose.
The fertile topsoil collected after removing the surface vegetation and leaf litter
is ideal for filling the bags. While filling, the bag should be gently tapped to
ensure compact filling of soil without leaving air spaces. The bag is filled up
to about 2 cm below the brim.
Powdered rock phosphate at the rate of 25 g for small bags and 75 g for large bags
is mixed with the top layer of soil. The filled bags can be kept in the nursery
either in trenches or on the ground supported with wooden poles. After placing the
bag in the trench, the excavated soil is filled in the gap between them. The remaining
soil is mounted around the bags.
Planting of budded stumps or sprouted seeds is undertaken thereafter. When budded
stumps are used, the bud patch should face the footpaths to facilitate growth of
Regular cultural operations like manuring, watering, weeding, shading and plant
protection are adopted. Application of N-P-K-Mg 10-10-4-1.5 mixture is done at monthly
intervals. During the first month, 10 g of the mixture is given per bag which is
gradually increased to 30 g in four months time.
Watering should be done soon after manuring. During dry periods, irrigation should
be done regularly. Watering can be done manually in small nurseries while sprinklers
or drip irrigation system is more economical in large nurseries. Too much watering
should be avoided to prevent waterlogging. During summer months, partial shade may
be provided to the plants by erecting overhead shade. Appropriate prophylactic and
curative measures may be taken against diseases and pests.
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