Stachys sieboldii (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Stachys sieboldii Miquel

Protologue: Ann. mus. lugd. bat. 2: 112 (1865).

Family: Labiatae

Chromosome number: 2n= 66-70

S. affinis Bunge (1883, nomen, non Fresenius), S. tuberifera Naudin (1887).

• Chinese artichoke, Japanese artichoke, spirals (En). Crosne du Japon (Fr)
• Malaysia: cordyceps, tung-tung chow
• Thailand: thua-duang (northern). China: gan-lu-zi. Japan: chorogi.

Chinese artichoke is indigenous to China; there and in Japan it has been cultivated since ancient times. At the end of the 19th Century some tubers were introduced into France and planted successfully near the village Crosne (hence the French name). Since then Chinese artichoke has been cultivated on a small scale in France, and due to the research attention it has received since 1977, cultivation is increasing. In the 1980s, the crop was introduced into Malaysia by Chinese farmers, especially in the Cameron Highlands where cultivation has been commercialized. Occasionally the crop is also cultivated in other countries in Asia and Europe.

The edible parts of Chinese artichoke are the tubers; they can be prepared variously and are eaten raw in salads, cooked or fried, and have a delicate taste. In Japan, they are appreciated for traditional dishes of New Year's Day. In China and Japan, the tubers are often pickled. Before preparing, the tubers have to be washed and, if necessary, carefully scrubbed to remove any adhering soil. They do not have to be peeled. The plant also has ornamental value. In China, extracts of the plant are used to cure lung diseases.

Chinese artichoke is cultivated on a small scale. In France cultivation is limited to a few hectares (about 150 ha in 1986), often to supply exclusive restaurants. In the Cameron Highlands of Malaysia, the tubers are a common product on the local markets. Production statistics are not available.

Per 100 g edible portion tubers of Chinese artichoke contain: water 78.0 g, protein 4.3 g, fat 0.2 g, carbohydrates 14.6 g and ash 1.0 g. The energy value is 320 kJ/100 g. The main carbohydrate is the tetrasaccharide stachyose (gal-gal-sucrose), which is exclusively localized in the vacuoles. In dormant tubers 80% of the dry weight is stachyose (18% of the fresh weight). Other carbohydrates present are sucrose, raffinose and verbascose.

Erect, hairy, perennial, stoloniferous herb, up to 120 cm tall. Tubers produced by thickening of the top part of the stolons, 5-8 cm × 1-2 cm, constricted at the internodes into rows of rounded segments, whitish, often in great numbers just below the soil surface. Stem quadrangular with opposite leaves; petiole 1-3 cm long; blade ovate to ovate-lanceolate, 3-12 cm long, cordate at base, margin obtusely dentate, roughly hairy at both sides. Inflorescence consisting of whorls of 6 flowers on upper 5-15 cm part of the stem and branches; bracts linear, pubescent; calyx with 5 triangular teeth, about 1 cm long, 10-veined; corolla bilabiate, 12 mm long, upper lip erect, lower lip 3-lobed, pinkish, purplish or whitish. Fruit composed of 4 nutlets, enclosed within the persistent calyx.

Stolons and tubers are formed 5-7 months after planting in the same way as in Irish potato ( Solanum tuberosum L.). Tubers are formed at the end of the stolons when temperature drops. In temperate regions, tubers are dormant during winter time and start sprouting in spring. The plant rarely flowers, flowering and stolonization possibly being antagonistic processes.

Chinese artichoke is cultivated mainly in temperate climates but cultivation in tropical highlands is also possible. It is not sensitive to frost, in China it occurs up to 3200 m altitude. Long days are required for stolonization. A light, loose and sandy fertile soil is needed for good tuber formation and to facilitate harvesting. For vegetative growth a day temperature of 23°C is optimal, for tuberization 15°C. At higher temperatures, the tubers will become more elongated.

Usually, propagation is by tubers and rarely by cuttings. Propagation by seed is also possible but seed is scarce. Large tubers of the last harvest are planted 2-3 together in upright position, 2-15 cm deep, directly in the field or first in pots. Planting distances vary from 15-40 cm in the row and from 30-80 cm between the rows. Wide spacing gives more tubers per plant. In Malaysia, Chinese artichoke is planted on beds after cabbage or in rotation with other tuber crops such as potato and yam. Until the canopy covers the soil it should be kept weed-free or covered by mulch or black poly-ethylene. The crop responds well to fertilizer. When the plants are 30-60 cm tall they are earthed up around the base of the stem. In Europe, Chinese artichoke can be infected by several viruses known from other crops. Aphids and caterpillars can also cause problems. The crop is very sensitive to Rhizoctonia solani . No information is available on diseases and pests on the crop in Asia. Harvesting is done manually 6-8 months after planting. Tubers are small and grow dispersed in the soil making harvesting rather time-consuming. All tubers must be removed, otherwise the plant can become a weed. Under optimal conditions a plant may form 40-220 tubers depending on the planting material. The yield is 8-20 t/ha. Cultivation trials in Switzerland gave maximum yields of 43 t/ha. Tubers dry and discolour in the open air and should therefore be marketed soon after harvesting. They can be stored in moist sand at 0-2°C or frozen at -18°C. For a short period they can be stored in a refrigerator, wrapped in paper.

There are no germplasm collections. Selection work on Chinese artichoke is carried out mainly in France and Japan. Tissue culture techniques are applied successfully to ensure fast propagation and virus-free plant material. Breeding objectives are focused on the improvement of quality and productivity.

Chinese artichoke is a minor crop, not suitable for large-scale cultivation because of the laborious harvest and relatively low return. However, it has potential to broaden the vegetable assortment. In France, the demand seems to exceed the supply. Little is known about its cultivation in China, Japan and the tropics. Its cultivation in the Cameron Highlands shows that the crop has potential in the tropics. More research and dissemination of knowledge is needed.

• Boccon-Gibod, J., 1980. Régénération du crosne du Japon (Stachys sieboldii Miq.) par culture de méristèmes: multiplication et conservation in-vitro des clones [Regeneration of Japanese artichoke (Stachys sieboldii Miq.) through meristem culture: in-vitro multiplication and conservation of clones]. In: Dore, C. (Editor): Application de la culture in-vitro à l'amélioration des plantes potagères [Application of in-vitro culture in breeding of vegetable crops]. Symposium Eucarpia, Versailles, France, 16-18 April 1980. Institut National de la Recherche Agronomique (INRA), Versailles, France. pp. 31-41.
• Herklots, G.A.C., 1972. Vegetables in South-East Asia. George Allen & Unwin, London, United Kingdom. pp. 470-471.
• Larkcom, J., 1991. Oriental vegetables. The complete guide for garden and kitchen. John Murray, London, United Kingdom. pp. 66-67.
• Perko, J., 1990. Essai de diversification en culture maraîchère: le crosne du Japon (Stachys sieboldii Miq., Labiacées) [Diversification trial in vegetable growing: Japanese artichoke (Stachys sieboldii Miq., Labiatae)]. Revue Suisse de Viticulture, d'Arboriculture et d'Horticulture 22(5): 295-297.
• Peron, J.Y., 1986. Culture in-vitro innovations phytotechniques et technologiques, base de la réémergence actuelle du crosne du Japon (Stachys sieboldii Miq.) [In-vitro culture, phytotechnical and technological innovations, basis of the present reemergence of Japanese artichoke (Stachys sieboldii Miq.)]. Bulletin Technique d'Information 407: 125-133.

M.H. van den Bergh