Organic Cultivation Of Vanilla

By TamilNadu Agricultural University on 03 Aug 2015 | read
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Vanilla is a new spice which received attention for development in the recent years. Though the present production is negligible it may assume sizeable volume when the planted area comes to yielding stage.

Vanilla is a tropical orchid which is cultivated for its pleasant flavour. It requires warm moist conditions. Uncleared jungle land is ideal for establishing vanilla plantation. 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 can be cultivated in varied types of soil from sandy loam to laterite. Vanilla can be cultivated either as a pure crop or as an inter-crop with coffee, coconut, arecanut, pepper etc. Under such cases all the crops should be grown by following organic methods. An isolation distance of 25 m wide should be provided. A period of three years is required as conversion period for existing plantations. For new planting, if vanilla is cultivated in virgin land or in farm where records are available that no chemical inputs are used, this conversion period can be relaxed.

Source of planting material

Vanilla is to be propagated by using cuttings from healthy and vigorously growing plants which are grown organically. However, to begin with they can be obtained from conventional plantations. Tissue culture plants should not be used as planting materials in order to keep integrity with the methods of propagation.

Preparation of land and planting standards

As vanilla requires a support tree for climbing, live standards having low branching habit with rough bark and small leaves may be planted at least six months ahead of planting vanilla cuttings. As many recommended species as possible may be planted to keep bio­diversity.

Vanilla cuttings

Basal 3-4 leaves of cuttings may be stripped off and kept under shade for one week to loose moisture. The defoliated portion of the vine is laid on the loose soil surface and covered with a thin layer of soil. The basal tip is to be kept just above the soil to prevent rotting. The other end is to be tied gently to the support. The plant basin is to be mulched and the plants shaded if necessary.

Cultural practices

The plantation is to be visited regularly to train the vines to grow at a convenient level, to regulate the growth of vines and supports and keep watch for pest and disease incidence if any. Always keep leaf mulch around the vanilla vines. Any operation done in the plantation should not disturb the roots which are mainly confined to the surface layer. Weeding may be carried out if necessary and the materials are to be used for mulching.

The support trees are to be pruned lightly at a height of 125 to 150 cm to induce branching and to develop an umbrella shape for providing adequate light and shade (50%). Pruning is to be done before the commencement of heavy rains and the pruned vegetation used for mulching.

For convenience of cultural operations, the vines are to be allowed to grow only up to a height of 1.2 to 1.5 m and then trained horizontally on the branches of support trees or on bamboo poles tied to two adjacent support trees. Pollinate the recommended number of inflorescences and flowers during the flowering season.

Manuring

Vanilla, being an orchid plant, prefers organic manures. Decomposed organic materials may be applied two to three times a year. Bone meal, well rotten cow-dung, compost or vermicompost @ 4-5 kg/plant/year may be used.

Plant protection

Diseases

Some of the diseases affecting vanilla are rotting of leaf, stem, root, shoot tip and pods and blight caused by Fusarium oxysporum as well as brown spots or anthracnose caused by Colletotrichium gloeosporioides. Regular surveillance and plant sanitation are required for managing the diseases. The disease affected portions are to be removed and burnt. Any injury to roots and other plant parts should be avoided. The plant basins should be kept under mulching. Restricted use of Bordeaux mixture (1%) may be made if necessary.

Pests

No serious pest attacking vanilla is noticed. However, a few caterpillars, earwigs, snails and slugs damage the tender parts of the plant. They may be controlled mechanically.

Harvest and post harvest operations

Immature bean is dark green in colour. When ripe, yellowing commences from the distal end of the bean. This is the optimum time for harvesting the bean. If left on the vine the bean turns yellow on the remaining portion and starts splitting. To avoid this, it is essential that the plantation is visited frequently and beans, which are in the right stage of ripening are harvested. Beans at this stage do not have aroma as free vanillin is not formed in them.
Method of curing involves the following four stages:

Killing the vegetative life of the beans to allow the onset of enzymatic action (Vanillin is developed as a result of the enzyme action on the glucosides during curing)

Raising temperature to promote this action and to achieve rapid drying to prevent harmful fermentation

Slower drying for the development of different fragrant substances

Conditioning the product by storing for a few months

Curing of Bourbon vanilla (produced in Madagascar, Comoro and Reunion), which contributes more than 70 per cent of the world production, is very simple compared to the traditional method practiced in Mexico.

The beans are immersed in hot water of 63 to 65°C for three minutes for the cessation of vegetative life. After rapid drying, when the beans are still very hot, they are rolled in flannel or woolen blanket and kept in chest lined with same material to retain the heat. The beans will acquire chocolate brown colour by the following day. They are then spread out in the sun on dark coloured cotton covers for three to four hours and later rolled up to retain the heat. Usage of raised black net for spreading the beans in sunlight has been observed to give better results.

Sun drying for six to eight days during which the beans loose some weight and become very supple. Later beans are dried by spreading out in trays under shade in an airy location. The duration of drying varies according to the beans, which usually last for two months. Properly dried beans are kept in trunks where the fragrance is fully developed. Finally they are graded according to size, bundled and placed in iron boxes lined with paraffin paper. The vanillin content of properly cured beans will not be less than 2.5 per cent.

 

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