Taro: the plant

Patricia Chay-Prove & Roger Goebel, Department of Primary Industries and Fisheries.

Introduction

Taro belong to the family Araceae and comprise a number of species that produce edible tubers or corms. The "true" taro, which is Colocasia esculenta (L.) Schott, is regarded as one of the main traditional staple food crops in the New Guinea group of islands and the Pacific islands. The names may differ from island to island - cocoyam, dasheen, koko, bari, dalo, wu tau, poi, etc.

The cultivars these names refer to are large corm types.  Another significant grouping are the Jap Taro or small corm types (Colocasia esculenta var. antiquorum).  These are refered to as Sato imo with the cultivar Ishikawa wasse being the dominant variety found and marketed in Japan.  Taro tends to be grown in coastal and tropical areas and because of the large leaf area and subsequent high levels of water loss, it is not suited to hot low humidity environments.

Taro is native to South-central Asia, perhaps India and has been subsequently introduced throughout the Pacific with migrations of Polynesian people from the Malay peninsula through the Sunda Islands and New Guinea. Despite their significance in many of these nations little systematic selection and research have been undertaken.

Malaysians, Indonesians and Chinese fishing off the northern coastline of Australia, well before European settlement probably introduced it into Australia.

Economics/ market

Large corm cultivars are grown for the fresh food market in Australia. The leaf, stalk and corm can be eaten, however, the main part marketed is the corm. The harvested corms are washed and roots discarded prior to packing and sent directly to the major cities or sold to local communities. It has been suggested that growers might market the corms with 5 cm green tops as this could extend shelf life.

There is a potential small corm (Jap taro) market in Japan however this market is yet to be tested.  Due to insufficient production data and a firm idea of market prices, the economics for taro production is not established.

In Australia taro is sold mainly through specialty agents in Brisbane, Sydney and Melbourne with some direct sales to retailers. Taro prices on the wholesale market are generally around the $3-4 kg. Corm weights of around 1-1.5 kg are desirable. although there appears to be an increasing preference for smaller taro.

Fig. 1. Taro corms packed in 10 kg cartons

Botanical description

Taro is a member of the Araceae family which includes plants like the philodendron, anthurium and dieffenbachia. It is an erect and stemless herbaceous plant with large peltate heart-shaped leaves borne on long petioles. The leaves are usually green in colour, sometimes purple. The plant itself, mainly Polynesian types can grow up to two metres high. In taro, the appearance of inflorescences and seed production is infrequent. Because the plant rarely flowers taro is commonly propagated vegetatively.

The bulbous corms are cylindrical-shaped and vary in size, normally 30-40 cm long. A corm is a short upright underground stem that is encircled with rings from where leaves have arisen. These are seen as dark scaly or papery sheaths. The flesh is purple, white, yellow or pinkish in colour depending on the variety and somewhat cheesy or slimy in consistency compared to the humble potato.

The taro plant belongs to the genus Colocasia. Other plants sometimes referred to as taro include the giant taro (Cyrtosperma) which is a taller plant with larger leaves and coarser roots; Xanthosoma grown mainly in Melanesia, has pointed leaves and; Alocasia which is referred to as poor man's taro.

Growth and development

Taro is fast growing and matures in about 6-10 months with time to harvest determined by growth rate. While taro can grow over a range of climatic and soil regimes, the time to reach maturity and attain good yields will vary with temperature, radiation and water. In north Queensland, poor nutrition and inadequate irrigation may delay harvesting by about 2 months. Flowering and seed production rarely occurs. Hence vegetative propagation is the most common method.

Taro nutritional information

The leaves, young shoots and corms are used. The root and leaves have a particular flavour that can give an acrid or sharp taste because of calcium oxalate crystals. Fortunately, cooking destroys the acridity. The main cultivars are relatively free from calcium oxalate crystals. Taro has a range of vitamins and minerals that are listed in Table 1.

The corm may be boiled, baked, fried or barbecued or cooked in curries and in coconut milk. The leaves are generally not eaten but traditional communities cook these like any green vegetable.

Table 1. Nutritional information for taro

Components	per 100 g edible portion
	Corms	Leaves	Petioles
Edible portion (%)	81	55	84
Energy (cal.)	85	69	19
Moisture (%)	77.5	79.6	93.8
Protein (g)	2.5	4.4	0.2
Fat (g)	0.2	1.8	0.2
Carbohydrate (g)	19	12.2	4.6
Fibre (g)	0.4	3.4	0.6
Calcium (mg)	32	268	57
Phosphorus (mg)	64	78	23
Sodium (mg)	7	11	5
Potassium (mg)	514	1237	367
Iron (mg)	0.8	4.3	1.4
Vit A (IU)	Trace	20385	335
Thiamine (mg)	0.18	0.10	0.01
Riboflavin (mg)	0.04	0.33	0.02
Niacin (mg)	0.9	2.0	0.2
Ascorbic acid (Vit C) mg	10	142	8

 

Soils and climate

Taro is quite tolerant of a range of climatic conditions. It is cultivated over a wide range of climatic regimes but appears to do better in wetter regions. It can tolerate waterlogged conditions because of its ability to transport oxygen from the leaves to the root. It is cultivated under both wetland (flooded), as may be found along stream banks.

Taro will grow on a wide range of soil types from heavy clay loams to light volcanic soils. However, taro will only yield well when planted in fertile soil with high water capacity, friable and rich in organic matter. A slightly acid soil in the range of pH 5.5 to 6.5, with moderate clay content is preferred.

Permanently moist soils appear to be most desirable as this condition maximises growth and yield. Moisture stress can be detrimental to growth and supplementary irrigation may have to be applied during dry periods. Optimum yields are obtained in countries with rainfall exceeding 2 500 mm.

Being adapted to high temperatures and humidity, taro performs well between temperatures of 21-27⁰C.

Cultivars

There are a couple of hundred known taro cultivars but only a small proportion is cultivated. Distinction between the different types is based on plant height, corm size, sucker production, leaf shape, leaf and stem colour. Cultivars also differ in crop duration. Currently grown cultivars in the Wet Tropical Coast of north Queensland have a crop duration of around 8-12 months.

Taro can be categorised into hard and soft cultivars. It is important that growers are aware of the basic differences in texture, flavour, appearance, etc. between cultivars as these may influence marketing success. The most commonly marketed taro cultivar in Australia is Pan Long Wu or Bun-long. This cultivar is a soft cooking type desired in Asian cooking.

Most people of Pacific and Torres Strait origin on the other hand, generally prefer the types that retain a firm texture after cooking. Also grown in small areas are cultivars imported from Fiji, Toakula and Vavai Loa. A number of Papua New Guinea cultivars are grown by Torres Strait Islanders but these are mainly consumed locally. Samoan cultivars which are becoming increasingly significant include the pink taro Tausala Ni Samoa (Taro Niue) and Samoan Pink..

Further information

• DPI&F Business Information Centre - phone 132 523 (from within Queensland).
• Taro cultivation in the South Pacific (1982). Lambert, M. (ed.). South Pacific Commission, Noumea, New Caledonia.
• Tropical crops. Monocotyledons 1. (1972). Purseglove, J.W. Longman Group Limited.

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Information contained in this publication is provided as general advice only. For application to specific circumstances, professional advice should be sought. The Department of Primary Industries and Fisheries, Queensland has taken all reasonable steps to ensure the information in this publication is accurate at the time of publication. Readers should ensure that they make appropriate inquiries to determine whether new information is available on the particular subject matter.

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Last updated 04 February 2004