LARGE CARDAMOM CULTIVATION IN INDIA
Botanical name of large cardamom is Amomium subulatum. Large cardamom is an important spice and a powerful flavoring agent. It has been used in Ayurveda since time immemorial because of its medicinal properties. It acts as carminative, stomachic, diuretic, an effective cardiac stimulant and is a remedy for throat and respiratory troubles. India is a major producer, consumer and exporter of this spice crop. Large cardamom is mainly grown in the sub-Himalayan hills of Sikkim and Darjeeling. India produces about 4,200 tons of cured cardamom annually.
Large cardamom is a seophyte, i.e a shade-loving plant. It is a crop of humid sub-tropics and a semi-evergreen plant. It is naturally found in the steep hills of eastern sub-Himalayan region which receive a well-distributed rainfall spread around 200 days with a total of about 3,000–3,500mm/year. Large cardamom grows up to 600–2,350m above mean sea level. Large cardamom is commercially cultivated in lower altitudes of cooler areas and higher altitudes of warmer areas. Cardamom plants remain dormant during winters and it can withstand up to 2°C but the plant is susceptible to frost injury. The flower bud differentiation occurs from August in lower altitudes to October in higher altitudes. The initiation of flower buds occur before winter on lower elevations but further development takes place only after the lapse of cold period in early-March. On the other hand, in higher elevations, the flower-bud initiation and development occurs post-winter in Arpil–May resulting in late flowering by at least 2–3 months compared to plants grown at lower elevations. Rains during flowering is detrimental, as it hampers foraging activity of the pollinating bees, affecting the sensitive flowers and resulting in poor capsule setting and barren spikes.
Large cardamom requires moist but well-drained, loose, slightly acidic, sandy loam to loamy soils. Ideal pH is 4.5–6.0.
Drought tolerant variety of large cardamom; resistant to foorkey viral infection; capsules are medium to bold in size; seeds contain 2% essential oil.
Tall variety of large cardamom; plants grow very tall up to 2.8m; yields big, bold and elliptic capsules; 15–20 capsules per each spike and 40–60 seeds per each capsule. It yields 500kg of cured capsules/ha. Essential oil in seeds is 2.5%.
Self-shaded, less vigorous growing variety of large cardamom; grown at low and mid elevations; clump size is smaller with less number of tillers and hence suited to close spacing; capsules are bold, roundish with reddish-brown to dark-pinkish and slightly echinated; consistent performer though not a heavy yielder; immune to chirkey but not to foorkey disease; susceptible to fungal leaf-spot disease; on an average, capsules contain about 40–55 seeds; volatile oil content of the seeds is 2–3.0%.
Tall and vigorous; capsules are dark pinkish, uniform and medium-bold in size having 25–35 seeds each; seeds contain 2.2–3% volatile oil content; moderately tolerant to chirkey but susceptible to foorkey disease.
Tall, vigorous, slanting with drooping leaves; suited to higher altitudes as well as on steep slopes, occupying a major area under cultivation in Sikkim and Darjeeling; Capsule size is small with less number of seeds (16–30), the colour being reddish-brown to maroonish. The essential oil content in seeds is about 1.5–1.8% on volume by weight basis; susceptible to chirkey and foorkey especially at lower altitudes.
Vigorous-growing with maroonish to greenish-brown leafy stems slightly tapering towards apex; adapted to low, mid and high altitudes of Sikkim and Darjeeling; capsules are reddish-brown to maroonish, variable in size from medium to bold with volatile oil content of 1.8–2.5%; plants are susceptible to both viral and leaf-spot and spike-rot diseases; heavy yielder
Vegetative propagation by suckers is commercially practiced.
Cultivation of Large Cardamom
Main field should be near to the irrigation source and a permanent curing shed should be erected within the main field. It is necessary to establish shade plants well ahead of planting in the main field. Important shade trees are Utis or Himalayan alder; chillowne, Schima wallichi, panisaj, pipli, Bucklandea populnea, Malato, Macaranga dentalata and Edgeworthia gardeneri. The shade trees are planted at a spacing of 7–10m between plants for uniform shade on plantations.
The suckers and bare-rooted seedlings are planted in shallow pits with stakes, whereas polybag seedlings do not require stakes as they have well-established roots.
Weeding, mulching, irrigation and shade regulation should be done regularly
Weed trashing is carried out twice a year, once during the onset of monsoons (May–June) and before harvesting.
Mulching is done by covering fallen leaves around the collar region of the clumps during November–April.
Irrigation is necessary during summer months as large cardamom plants do not tolerate drought. Constant maintenance of optimum soil moisture level ensures early fruit bearing. Irrigations are done once in every 10 days during December–April. Drip irrigation or sprinkler irrigation is most efficient.
Tall-growing trees are pruned regularly at a height of 4–5m to encourage spreading habit with renewed vegetative vigour to provide a uniform shade.
Gap filling is done by removing the damaged and diseased plants and replacing them with healthy ones. This also helps maintain an effective plant population. The ideal time for gap filling is May–July.
Major fertilizer application is done during April – May. Provide forest soil or leaf litter @ 5kg mixed with low graded composite NPK fertilizer (15:10:12) @ 0.2kg/plant during this time. Fertilizer mixture consisting of 20g DAP (di-ammonium phosphate) and 15g MOP (muriate of potash) dissolved in 2 liters of water may be drenched twice around each plant during April–May and October–November. Drenching of fertilizer mixtures @ 3–5 liters along with 10–15kg leaf litter/plant is very effective. Earthing up around the clump, once, soon after harvesting, also ensures better management of available nutrients in the soil apart from acting as mulch.
Harvesting and Postharvest Management
Fruit bearing clumps are cleaned by removing diseased and damaged shoots. Afterwards, the fruit bearing spikes are harvested using a sharp-edged knife. Generally, harvesting is done during August–September at low and mid altitudes and November–December at high altitudes.
Large cardamom plants are ready for harvesting within two or three years after planting in the main field. But plants start heavy yield from fourth year onwards. An average yield of about 450kg dry or cured capsules may be obtained from a hectare of crop during fourth to tenth year. Sustained yields are normally expected up to fifteenth year from planting. However, constant replanting by replacing the old and degenerated clumps every year in the plantation along with optimum shade and nutrition may keep them productive for many more years.
Raw capsules contain up to 85% moisture and hence are of poor keeping quality. Therefore they are immediately cured to retain only about 10–13% moisture on dry-weight basis. The retention of natural colour and flavour during curing is most important. The flavour constituents are highly volatile and are easily lost due to direct heat and higher temperatures (>55°C). Therefore it is necessary to adopt appropriate curing techniques.
Curing of Raw Cardamom
Curing process involves indirect heating of the raw capsules at an optimum temperature range of 50–55°C which is followed by rapid air circulation within and afterwards exhaustion of moist air from the curing unit.
Packing of Cured Cardamom
Packing is done in insect-proof bags. Coal-tar coated and polythene lined gunny bags are effective against insects during storage. Curing of capsules up to a moisture level of 10% and packing them in air-tight containers also ensure protection against insects.