Vanilla is native of the Atlantic coast from Mexico to Brazil. It is grown on a plantation scale in Java, Mauritius, Madagascar, Tahiti, Seychelles, Zanzibar, Brazil and Jamaica and other islands of the West Indies. Malagasy Republic grows 70 to 80 per cent of the world’s crop of Vanilla bean followed by Reunion. U.S.A. is the largest importer. This spice was introduced to India as early as 1835. Its commercial cultivation is now restricted to Wayanad of Kerala and Nilgiris of Tamil Nadu. Recently, the demand for natural vanilla is on the higher side.
It is an orchid, belonging to the family Orchidaceae. There are two important species of vanilla viz. V.planifolia and V.pompana. The former species produces short thick pods whereas the latter one has the largest pods. V.planifotia has opposite, sessile leave of 10 to 23 cm long which are oblong in shape.
CLIMATE AND SOIL
Vanilla requires a warm climate with frequent rains and prefers an annual rainfall of 150-300 cm. Partially un-cleared jungle lands are ideal for establishing vanilla plantations. In such locations, it would be necessary to retain the natural shade provided by lofty trees which allows penetration of sunlight to the ground level and to leave the soil or the rich humus layer on the top undisturbed. However, vanilla is cultivated in varied types of soils from sandy loam to laterites.
PREPARATION OF LAND
When cultivation of vanilla is taken up in virgin areas, the land should be cleared by cutting all shrubs and unwanted trees. Vanilla can also be cultivated in open lands by providing adequate shade plants. The cleared land should be prepared by two rounds of ploughing or digging followed by leveling. It is advisable to incorporate green leaves and forest soil in the cleared land. A gentle slope is ideal for cultivation of vanilla.
Vanilla is usually propagated by stem cuttings. Cuttings of 60- 120 cm length can be selected as planting material for direct planting in the field. Cuttings less than 60 cm should not be used directly for planting. Such cuttings have to be rooted and raised in the nursery before planting. The stem cuttings after collection should be washed thoroughly and dipped in Bordeaux mixture 1% or copper oxychloride 0.2% for killing pathogenic fungi. The cuttings are then stored in a cool shaded place for 2-3 days for partial loss of moisture, a process which enhances rooting. The cuttings can also be stored up to 10 days if required. Plants raised from mature lengthy cuttings flower early. Tissue cultured plantlets can also be utilized for planting. However, sufficiently grown up plantlets should be used.
PLANTING AND AFTER CARE
Vanilla is generally planted at a time when the weather is not too rainy or too dry. The months of August-September are ideal for vanilla cultivation. Cuttings for planting should be collected in advance, and after removing three or four basal leaves, dipped in one per cent Bordeaux mixture and kept in shade to lose moisture for about a week. Since establishment of cuttings is almost cent per cent, planting of single cutting per support is enough.
The defoliated part of the vine is laid on the loose soil surface and covered with a thin layer of about two to three cm soil. The basal tip of the cutting should be kept just above the soil to prevent rotting. The growing end is gently tied to the support for climbing by the aerial roots. The cuttings are shaded with tall dry grass, palm fronds or with other suitable materials. In dry soil, a light sprinkling of water helps for early establishment of cuttings. It takes about four to eight weeks for the cuttings to strike roots and to show initial signs of growth. Vanilla can also be planted as an intercrop in coconut and areca nut plantations.
MANURING AND FERTILIZER APPLICATION
The quantity of fertilizers to be applied may vary based on the fertility status of the soil. However, 40-60 g of N, 20-30 g of P2O5 and 60-100 g of K2O should be given to each vine per year besides organic manures such as vermi-compost, oil cakes, poultry manure, wood ash, etc. Organic manures can be applied during May-June and NPK in 2-3 splits along with leaf mulch during June-September on the topmost layer of the soil when sufficient moisture is avail- able. As in the case of other orchids, vanilla also responds to foliar feeding. A 1% solution of 17:17:17 NPK mixture can be sprayed on the plant once a month for boosting growth and flower production. A need based spray of micronutrient mixture can also be taken up.
FLOWERING AND POLLINATION
The vines commence flowering in the second or third year depending on the length of cuttings used due to the peculiar structure of the flower, artificial pollination by hand is the rule for fruit setting. The procedure involved is simple and done easily by children and women. Using a pointed bamboo splinter or pin, another is pressed against the stigma with the help of thumb and thus smearing the pollen over it. Generally 85 to 100 per cent success is obtained by hand pollination. The ideal time for pollination is between 6 a. m to 1 a.m., unfertilized flowers fall within two or three days. Normally 5 to 6 flowers per inflorescence and a total of not more than 10 to 12 inflorescences per vine are pollinated. The excess flower buds are nipped off to permit the development of other pods. Pods take six weeks to attain full size from fertilization but takes 4 to 10 months to reach full maturity depending upon the locations.
The beans or pods are ready for harvest 6-9 months after flowering. The beans can be considered as mature when they change from green to pale yellow. At this time, the pods may be 12-25 cm long. It is essential to harvest the pods at the right stage, as immature pods produce an inferior product and over-mature pods split during curing. The right picking stage is when the distal end of the pod turns yellow and fine yellow streaks appear on the pods. Daily picking of mature pods is essential. The pods can be harvested by cutting with a knife. A good vanillery yields 300-600 kg of cured beans per hectare per year. About 6 kg of green pods produce 1 kg of cured beans. The yield of the vine declines after 12-14 years.
Green vanilla beans (pods) contain little vanillin and is odourless and flavourless. It is during curing that the beans undergo enzymatic reaction responsible for the characteristic aroma and flavour of vanilla. Curing should preferably begin immediately after harvesting, but the beans can be stored for 3-5 days. There are different methods of curing but they all consist of more or less four stages:-
- Killing the beans to allow the onset of enzymatic action.
- Sweating, for raising the temperature to promote enzymatic action and enhance rapid drying for preventing fermentation.
- Slow drying for development of fragrance.
- Conditioning the product by storing for a few months in closed boxes.
The important methods of curing vanilla are Mexican Process, Bourbon Process, Peruvian Process and Guiana Process. In the Mexican process, killing is done by exposing the harvested beans directly to the sun for about 5 hours, which produces the optimum percentage of vanillin content. In Bourbon process, bamboo baskets with the beans are immersed in hot water (63-65°C) for 3 minutes. After rapidly draining the water when the beans are still hot, they are kept in wooden boxes lined with blankets. The beans acquire chocolate brown colour the following day. They are then spread in the sun on dark coloured cotton covers for 3-4 hours and later rolled up to retain the heat and stored in wooden boxes. This process is repeated for 6 to 8 days, during which the beans lose some weight and become very supple. Later the beans are dried by spreading them out in wooden trays under shade in an airy location. The duration of drying varies according to the size of the beans and usually lasts for 15-20 days. Properly dried beans are kept in closed containers where the fragrance is fully developed. Finally they are graded according to size and kept in iron boxes lined with paraffin paper. Care should be taken in the early stages of drying to keep the beans straight, because curved beans are considered as inferior in quality. When properly cured and sun dried the vanilla beans will be almost black and supple enough to be bent without breaking and vanillin crystallizes over the beans. Properly cured vanilla beans contain about 2.5% vanillin.
MARKET PRICES AND DEMAND
India is still a very insignificant player in vanilla. It will take some more time before we make our presence felt in the world markets. Presently Indian farmers are getting around Rs.150 per kg of green vanilla beans. The same green beans when they are processed fetch a price of around Rs.1500 per kg. But processing technology in India for vanilla is still very primitive and many farmers are satisfied with just growing and supplying green beans. Considering the fact that cost of production is low, farmers are finding vanilla beans cultivation very attractive. In future more farmers will take up this crop and the production and export figures of vanilla will increase.