Konjac

Overview

Amorphophallus konjac is native to China. This species is being increasingly cultivated for its edible tubers in Japan and China.The tuber is eaten throughout Asia, especially in China, Japan, Indonesia, Thailand, and India. It is added to traditional soups, stews, and similar dishes. It is also cooked by itself in the presence of lime (calcium hydroxide), and the resulting gel is pressed into blocks called konjac tofu. Konjac gel has been a popular traditional Japanese food (konnyaku) for over a thousand years. It is also used to produce noodles and jelly desserts. The studies on the application of konjac glucomannan have been extended greatly from food and food additives (used as an emulsifier and stabilizer) to various fields – such as the pharmaceutical, biotechnological and fine chemical industries, including cosmetics.

Vernacular Names

Ju ruo (Chinese), Konnyaku (Japanese), Gonyak (Korean).

Agroecology

Konjac can be found in forest margins and thickets at elevations of 830 - 1,200 m. It can tolerate a minimum temperature of 15 °C during the growing season, though the optimum range is 20-25 °C. The best crops are produced on deep, fertile, alluvial soils that are slightly acid. Dislikes heavy clay soils. Plants require some shade, especially when young.

Morphology

• Stem/Tuber - a globose tuber having a diameter of 30 cm that produces rhizomatous offsets of 50 cm long and 3 cm thick. 
• Leaves - umbrella-shaped with dull pink type petioles of 1 m in length that are marbled dark green and dotted white, with highly dissected blades of 2 m, divided into many leaflets that are 3–10 cm long and 2–6 cm in diameter. Its peduncle is 1.1 m long, colored in the same ways as its petioles.
• Flowers - produced on spathe, with wavy margins, which is enclosed by a maroon spadix that is narrowly conic, having a length of 0.15–1.1 m.

Cultivation

• Generative propagation is by seed - best sown in containers as soon as it is ripe and the pot sealed in a plastic bag to retain moisture. It usually germinates in 1 - 8 months at 24 °C. When large enough to handle, prick the seedlings out into individual pots and grow them on untill large enough to plant out.
• Vegetative propagation is by division - division of corms when the plant is dormant.

Chemical Constituents

Glucomannan, alginate, xanthan, carrageenan.

Traditional Medicinal Uses

• The root is oxytocic and sialagogue. It is used in the treatment of cancer.
• Helps lower cholesterol and blood glucose levels.
• Help regulate bowel movements, prevent hemorrhoids, and help prevent diverticular disease.