Vanilla (Extension Pamphlet)
Contributors
M. Anandaraj, J. Rema, B. Sasikumar and R. Suseela Bhai
Editors
P. Rajeev and R. Dinesh
Publisher
V. A. Parthasarathy, Director, Indian Institute of Spices Research January 2005.
Cover
A. Sudhakaran
Printed at
Printers Castle, Kochi
Natural vanillin is obtained from the cured pods (fruits) of the vanilla plant Vanilla planifolia (Family: Orchidaceae). Vanilla is a perennial climbing orchid with sessile leaves and succulent green stems, producing aerial roots (velamen roots) at the nodes.
The important vanilla growing countries are Madagascar, Indonesia, Mexico, Comoro and Reunion. Indonesia is the largest producer of vanilla in the world. Vanilla is a native of Mexico and was introduced to India as early as 1835. The estimated area under vanilla in India is about 2,545 hectares with a production of 92 tonnes (2002-03). Karnataka has the largest area under vanilla in the country.
There are three important cultivated species of vanilla namely, Vanilla planifolia (Mexican vanilla), V. pompona (West Indian vanilla), and V. tahitensis (Tahitian vanilla). V. planifolia is predominantly cultivated for production of vanillin. V. tahitensis and V. pompona also yield vanillin, but of inferior quality.
Climate and soil
Vanilla is adapted to a wide range of soils rich in humus and having good drainage. Clayey soils and water logged areas are not suitable for the plant. It thrives well in humid tropical climate with an annual rainfall of 200-300 cm from sea level to 1500 m above sea level. A warm humid climate with temperature ranging from 21 to 32°C is ideal The rainfall should be well distributed for a period of 9 months and there should be a dry period of 3 months for flowering. In India, parts of Kerala, Karnataka and Tamil Nadu, north eastern region and Andaman and Nicobar islands are suitable for vanilla cultivation.
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.
Propagation
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 can be raised either as monocrop or intercrop in coconut and areca nut gardens. It is usually trained on trellies or on low branching, rough barked trees like Clyricidia maculata, Plumeria alba, jack (Artocarpus heterophyllus), Erythrina spp., etc. or on dead standards. In some places areca nut is also used for trailing vanilla. The standards have to be planted well in advance at a spacing of 1.2-1.5 m within rows and 2.5-3.0 m between rows. Approximately 1 600 to 2000 standards can be accommodated in a hectare. If dead standards are used, shade should be provided to the vines initially by planting banana or suitable plants. The vanilla plants should be allowed to trail horizontally on poles/trelIies tied to trees after trailing to a height of 1.5-2.0 m or coiled around the branches so as to facilitate pollination and harvesting. Flowering will not occur as long as the vines climb upward. The shade trees should be regularly pruned to maintain a light shade. The pruned leaves and branches can be applied as mulch.
Planting of cuttings should be taken up preferably during September-November in shallow pits, filled with humus and mulch. The cuttings should be planted with two nodes below the soil surface and at the rate of two cuttings per standard. Care should be taken to ensure that the basal cut end of the cutting is kept just above the surface of the soil to prevent rotting. It is advisable to provide adequate shade to the newly planted cuttings. A thick mulch of leaves should be provided immediately after planting. The cuttings sprout within 4-8 weeks.
Inter-cultivation is not generally recommended in vanilla plantations. However, occasional slashing of weeds is beneficial. Care should be taken not to disturb or damage the roots during cultural operations since they are mainly confined to the surface layer of the soil. Regular mulching combined with irrigation during summer enhances growth and yield.
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 vermicompost, 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 available. As in the case of other orchids, vanilla also responds to foliar feeding. A 1 % solution of 1 7:1 7:1 7 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
Vanilla usually starts flowering in the third year of planting; however, it depends on the size of the original cutting used for planting. Maximum production of flowers occurs during the 7-8th year. Vanilla flowers during December to February and each flower lasts for only a day. Pinching off the top 7.5 to 10.0 cm of the vine, 6-8 months before the flowering season encourages flower production. Similarly, pruning off the older branches (which bore fruits the previous year) also encourages flower production. The flowers are borne in axillary racemes and each inflorescence consists of 15-20 flowers. The flowers are to be artificially pollinated (hand pollination) for fruit set. Since the flowers last only for a day pollination must be done on the same day. The remaining flower buds are nipped off. About 10-12 inflorescences may be pollinated in a vine. In hand pollination method, a pin or needle or small piece of pointed wood or a tooth pick is ideal to apply pollen on the stigma of the flower. The pollen of the vanilla flower is produced in a mass called pol-linia, and is covered by hood or anther cap. The stigma is protected with a lip known as 'rostellum' or 'labellum'. For pollination, the stamen cap is removed by a needle exposing the pollinia. Then the flap like rostellum is pushed up and the pollinia are brought into contact with the stigma. The ideal time for pollination is 6 am to 1 pm. An efficient worker can pollinate 1500-2000 flowers a day.