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VANILLA
(Vanilla planifolia)
Vanilla
is a tropical orchid requiring a warm climate with frequent
rains, preferring an annual rainfall of 150-300 cm. Uncleared
jungle areas are ideal for establishing vanilla plantations.
In such locations, it would be necessary to retain the
natural shade provided by lofty trees and to leave the
soil or the rich humus layer on the top undisturbed. Vanilla
is cultivated on varied type of soils from sandy loam
to laterites. It requires filtered sun light. In the absence
of natural shade, trees should be grown to provide shade.
Preparation
of land
Clear
the land of jungle growth and prepare for planting.
Being a creeper, the plant requires support up to a
height of about 130-135 cm. Cuttings of Plumaria alba,
Erythrina lithosperma, Jatropha carcas and Glyricidia
maculata are suitable as live supports. The growth of
live standard is to be adjusted to make them branch
at a height of 120-150 cm to facilitate trailing of
the vines and artificial hand pollination.
Time
and method of planting
Vanilla is propagated by planting shoot cuttings in
situ. Plant rooted cuttings of 60 cm length. Longer
cuttings bear earlier than shorter cuttings. Rooted
cuttings as well as tissue culture derived plants can
also be used for planting.
Plant
the cutting with the onset of monsoon rains. Set out
the cutting at a spacing of 2.7 m between plants and
1.8 m between rows in pits of size 40 x 40 x 40 cm.
Trail the vines on the live supports and when they attain
a height of 135 cm trail them horizontally on bamboo
poles tied to vertical supports or branches of support
plants in loops touching the ground.
Manuring
Being a surface rooting plant, manuring should be confined
to the surface layer of soil. Provide heavy and frequent
mulching to the vines. Apply 120 g of N in the form of
leaf mould or FYM in two split doses in June-July and
September-October.
Aftercultivation
Vanilla cannot withstand even the slightest root disturbance.
Hence remove weeds from the plant base by hand-weeding
and use them as mulch.
Being
closely planted, no intercrops are raised in a pure
plantation of vanilla. But vanilla can be planted as
an intercrop in coffee, coconut, arecanut etc.
Plant
protection
The
occurrence of a wilt disease caused by Fusarium oxysporum
has been observed. For control of wilt disease adopt
the following measures.
1.
Remove diseased plants along with surrounding soil where
the disease is observed.
2. Remove weeds around the plants.
3. Mulch the base of the vine with dry leaves before
and after monsoon.
4. Avoid injury to roots during cultivation.
5. Drench soil around the base of vine with 1% Bordeaux
mixture.
Fungal
diseases like shoot tip rot, stem and bean rot caused
by Phytophthora sp. as well as immature bean drop are
noticed. The disease-affected portions are to be removed
regularly and 1% Bordeaux mixture should be applied
on the affected plants.
Pollination, harvesting and curing
Flowering of vine commences usually by about the third
year. The inflorescence is produced in the leaf axils.
There is a tendency for some of the vines to maintain
only vegetative growth. A light nipping off or pruning
of the terminal shoots hastens flowering. Due to the peculiar
structure of the flowers, self-pollination is impossible.
Hence hand pollination is adopted for fruit set. Best
time for pollinating the flowers is between 6 a.m. and
1 p.m. and a success of 80-85% can be obtained. Successful
fertilization is indicated by the retention of calyx and
the stigma even after four days of pollination.
The
pods ripen in about 9-11 months time. Before attaining
maturity the fruit is dark green in colour and when
ripe yellowing commences from the tip of the pod. Collect
the pods at this time, as this is the optimum time for
harvesting the pod. If allowed to remain on the vine
further, the pods split. Free vanillin is not present
in the beans when they are harvested. They also do not
have the aroma. Vanillin is developed as a result of
enzyme action on a glycoside occurring during the process
of curing of beans.
Harvested
beans are subjected to curing which is characterized
by four phases.
1.
Killing or wilting beans to arrest the vegetative development
in the fresh beans and initiate the enzymatic reactions
responsible for the production of aroma and flavour.
Killing is indicated by the development of a brown colouration
of the bean.
2. Raising temperature of the killed beans (sweating)
to promote the desired enzymatic reactions and to achieve
rapid drying so as to prevent harmful fermentation.
3. Slow drying at ambient temperature until the beans
have reached about one-third of original weight for
the development of various fragrant substances.
4. Conditioning the beans by storing them in closed
boxes for three months or longer to permit the full
development of desired aroma and flavour.
Curing
of vanilla involves immersing the beans (2-3 days after
harvest) in hot water at a temperature of 63 to 65ºC
for three minutes for the cessation of vegetative life.
After a rapid drying on woolen blankets, when the beans
are still very hot, they are kept in chests lined with
blankets. Next day they are spread out in sun on blanket
for three to four hours and rolled up to retain the
heat. Repeat this for six to eight days during which
beans lose their weight, become supple and can be twisted
on finger without breaking. This is followed by slow
drying in the shade for a period of two to three months.
Properly dried beans are kept in trunks where the fragrance
is fully developed. Finally, they are graded according
to size and bundled and placed in iron boxes lined with
paraffin paper. The vanillin content of properly cured
beans will be about 2.5 per cent.
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