Curcuma zedoaria (PROSEA)
Curcuma zedoaria (Christm.) Roscoe
- Protologue: Trans. Linn. Soc. London 8: 354 (1807).
- Family: Zingiberaceae
- Chromosome number: 2n= 63 (64, 66) (triploid)
- Amomum zedoaria Christmann (1779),
- Amomum latifolium Lamk (1783),
- Curcuma pallida Lour. (1790),
- Curcuma zerumbet Roxb. (1810). Note: "zedoaria" is often erroneously spelled "zeodaria".
- Long zedoary, round zedoary, zedoary, kua (En)
- Zédoaire (Fr)
- Indonesia: koneng tegal (Sundanese), temu putih (Malay, Jakarta)
- Malaysia: kunchur, temu kuning, temu lawak (Peninsular)
- Philippines: alimpuyas (Cebu Bisaya), barak (Tagalog), tamahilan (Bikol)
- Burma (Myanmar): thanuwen
- Cambodia: prâtiël prèah 'ângkaôl
- Laos: 'khmin2khai
- Thailand: khamin khun (northern), khamin oi (central)
- Vietnam: nghệ den, nga truật, ngải tím.
Origin and geographic distribution
The origin of C. zedoaria is not known exactly, but it is possibly in north-eastern India. It has been cultivated for a very long time throughout South and South-East Asia, China and Taiwan and it easily runs wild in this area, thus occurring wild and cultivated all over. Occasionally, it is cultivated elsewhere (e.g. in Madagascar).
The rhizomes of C. zedoaria are the source of "shoti" starch, which is easily digestible and valued as an article of diet, particularly for infants and people with digestive problems. The heart of young shoots is used as a vegetable (raw or cooked) in Indonesia, where also young rhizome parts (tops) are eaten raw and inflorescences cooked. Leaves are used for flavouring foods in India and Indonesia, and in India the rhizomes are used in perfumery.
Rhizomes are widely used as stimulant, stomachic, carminative, diuretic, anti-diarrhoeal, anti-emetic, anti-pyretic and depurative, the latter especially after childbirth, but also to clean and cure ulcers, wounds and other kinds of skin disorders. Rhizomes are also chewed against bad breath, and a decoction is drunk against stomach-ache, indigestion and colds.
Production and international trade
Zedoary is primarily produced and traded locally. Until the Middle Ages the rhizomes were also popular in Europe and were an article of commerce. At present, international trade is negligible but no statistics on local production are available either.
Fresh zedoary rhizomes contain approximately: water 70%, starch 12%, other materials (including essential oil, cellulose) 18%. Per 100 g edible portion "shoti" starch contains approximately: water 13 g, starch 83 g, ash 1 g, other materials 3 g. The starch grains have an average size of 1.6-4.2 μm and are ellipsoidal or ovoid.
The essential oil present in the rhizomes (1-2%) is light yellow-greenish, smells like ginger oil mixed with camphor; at 30 °C it has a specific gravity of 0.9724 and it contains d-α-pinene, d-camphene, cineol, α-camphor, d-borneol, sesquiterpenes, sesquiterpenols and sesquiterpene alcohols.
- Robust, perennial, erect, strongly tillering herb, 1(-3) m tall.
- Rhizome a fleshy complex with an erect broadly ovoid structure (primary tuber) at the base of each aerial stem, ringed with the bases of old scale leaves and when mature bearing numerous lateral rhizomes which are again branched; primary tuber up to 8 cm long, 4-6 cm in diameter, lateral rhizomes usually smaller, up to 10 cm long and 3 cm in diameter, outside grey, inside pale yellow-white to bright yellow.
- Roots numerous, fleshy and terete, at the apex usually swollen into a subellipsoidal tuber of 2-15 cm × 1-2.5 cm and white inside.
- Leaf shoots bearing up to 8 leaves, surrounded by bladeless sheaths which form a pseudostem; sheath 40 cm long or longer; petiole 3-12 cm long, its apex passing gradually into the blade; blade elliptical-oblong or oblong-lanceolate, 35-75 cm × 10-20 cm, above dark green with a more or less intensely reddish-brown central streak 1-2.5 cm wide, light green below with a narrower central streak, the streak fading in older leaves.
- Inflorescence lateral, sprouting from the rhizome next to the leaf shoot, spike-like; peduncle about 22 cm tall, covered with 3 sheaths; flower spike cylindrical, 10-16 cm long, 5-12 cm in diameter, provided with 16-30 bracts arranged spirally, each of which contains 4-5 flowers (arranged in a cincinnus) except the 5-6 upper ones; bracts in their lower half adnate to each other, the basal parts thus forming closed pockets, the free upper parts more or less spreading; lowest bracts entirely green, middle ones tipped with a purple spot, uppermost 5 entirely purple with 4 bracts below them streaked white and pale green at the base and purple at the tips; bracteoles small, membranous, surrounding the flowers.
- Flowers as long as the bracts or shorter, 3.5-4.5 cm long; calyx very short, up to 1 cm long; corolla up to 4.5 cm long, lower half tubular, upper half much widened, yellow-white, 3-lobed with 2 equal anterior lobes and a larger ventricose posterior one; labellum broadly elliptical, 2-2.5 cm × 1.5-2 cm, weakly 2-lobed, pale yellow with a darker yellow longitudinally furrowed central streak; staminodes 2, large and wide, connate with the base of the stamen, yellow-white; filament 4.5 mm long and wide, anther white, thick, 6 mm long, at the base with divergent curved spurs 3 mm long; ovary 4-5 mm long, pubescent, 3-locular, style filiform, stigma 4-lobed.
- Fruit an ovoid capsule, smooth, dehiscing irregularly.
- Seed ellipsoidal, grey.
Zedoary takes about 2 years to develop fully. It rarely flowers in cultivation, but flowers freely where it runs wild. After flowering the aboveground parts die completely and the plant enters a resting phase which can last a very long time.
C. zedoaria is closely related to C. xanthorrhiza Roxburgh, and some authors consider the two to be conspecific. The main differences are: petals white (yellowish-white) in zedoary, pink in C. xanthorrhiza; flesh of rhizome and root tubers pale yellow to white in zedoary, deep orange in C. xanthorrhiza; the inflorescence of zedoary is smaller and the red-brown central streak on the leaf blade is present on both sides in zedoary, but only on the upperside in C. xanthorrhiza.
Zedoary occurs in a wide range of climatic conditions in tropical and subtropical South and South-East Asia. It prefers areas with an annual rainfall of 900-1250 mm with a pronounced dry season, and is found in shady damp locations, up to 1000 m altitude. It grows on all kinds of soils, but prefers well-drained sandy soils.
Zedoary is propagated from pieces of rhizome. In India, it is planted first on well-manured, hand-watered, shaded nursery beds, and sprouted rhizomes are planted out in the field at the beginning of the rainy season, preferably on flat beds at a planting distance of 25-45 cm. The crop is weeded regularly and after planting in the field the crop receives a thick mulch. Application of fertilizers has been recommended: farmyard manure 25 t/ha, sulphate of ammonia 340 kg/ha, superphosphate 450 kg/ha and muriate of potash 450 kg/ha in two doses, respectively 40 days and 6 months after planting.
When primary tubers are planted (requiring much planting material), harvesting is possible after about 10 months; when lateral rhizome parts are used, the required growing period is up to two years. Harvesting may start when the leaves begin to wither. The rhizome clumps are dug up, roots and remains of leaves removed, and washed. Yield is 7.5-12 t/ha. Planting material is separated. The remaining parts are peeled, shredded into a pulp and steeped for 24 hours in 10 times their volume of water, with frequent stirring. The starch slurry is filtered off, repeatedly washed with clean water, centrifuged and dried at 50¬∞C. Yield of starch is about 80%. When dilute sulphuric acid or alkali is used during the washing process, a starch of about 95% purity can be obtained.
Genetic resources and breeding
Besides the collections available in botanical gardens, no special germplasm collections of zedoary are known to exist. No breeding programmes are known.
Zedoary is an important home garden crop in South-East Asia. More research is needed to improve cultivation methods, to breed better cultivars, and to investigate the feasibility of large-scale production and marketing. Yield improvement is necessary before zedoary can become an important industrial crop. Germplasm collection is needed urgently.
- Burtt, B.L., 1977. Curcuma zedoaria. The Gardens' Bulletin Singapore 30: 59-62.
- Holttum, R.E., 1950. The Zingiberaceae of the Malay Peninsula. Curcuma. The Gardens' Bulletin Singapore 13: 65-72.
- Kay, D.E., 1973. Crop and product digest No 2. Root crops. The Tropical Products Institute, London, England. pp. 135-138.
- Ochse, J.J. & Bakhuizen van den Brink, R.C., 1980. Vegetables of the Dutch East Indies. 3rd English edition (translation of "Indische groenten", 1931). Asher, Amsterdam, the Netherlands. pp. 745-747.
- Valeton, T., 1918. New notes on the Zingiberaceae of Java and the Malayan Archipelago. Bulletin du Jardin Botanique de Buitenzorg, 2nd Series, 27: 57-61, Plate 7, Fig. 1 and Plate 27.
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- Halijah Ibrahim & P.C.M. Jansen
- Trimurti H. Wardini & Budi Prakoso