Taro

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Project experiments for 1998 / 1999

Taro Links

• Thailand
• IPGRI
• University of Florida
• University of Hawaii
• GPPIS (FAO)
• Purdue University, Indiana
• botany.com

Species: Colocasia esculenta

Family: Araceae

Crop status: New

Varieties

Two distinct botanical varieties are recognised; Colocasia esculenta var. antiquorum (eddoe type) and var. esculenta (dasheen type) (Masalkar and Keskar 1998).

Seed is available from Earthcare Enterprises. Different varieties exist for paddy and upland cultivation (Larkcom 1991).

Of the 134 000 t of seed produced in 1997, 75 000 t were produced in Cyprus and another 31 000 in Japan. The Philippines and Egypt were also major producers (FAO 1998).

(A)

(B)

Figure 1: High and low prices (A) and throughput (B) of taro at Flemington Markets during 1996 (green), 1997 (blue) and the first half of 1998 (red) (Flemington Market Reporting Service, NSW Agriculture).

Production

Taro is grown commercially in NSW, NT and Vic (Lee 1995). Some producers have small plots in NT but an industry has not emerged, possibly due to problems with termites and water requirement (Melinda Gosbee 1999, pers. comm.). Opportunities exist to grow taro in tropical and sub-tropical Australia, for domestic sale (Bourke 1996).

Growth model: A crop growth simulator has been developed (Singh et al. 1998, see DSSAT).

Mixed cropping: Taro is among the most shade tolerant terrestial food crops (Johnston and Onwueme 1998, O'Hair 1990), though shading may increase the incidence of leaf blight.

Climate: Tropical or subtropical is best, with long warm summers and a season of at least 200 days (Larkcom 1991). Excessive wind can cause damage to the large leaves (Follett 1996).

Season: Planting in southen climates is limited by soil temperature to mid-late spring. Earlier production can therefore be achieved by sprouting under cover or in a hot house (Follett 1996).

Temperature: Best growth occurs at 25-35°C and a mimimum temperature of 15°C is required for sprouting (Follett 1996). Must be frost free (Larkcom 1991) but can grow in a subtropical environment with average temperatures of 20°C (Masalkar and Keskar 1998).

Soil: Rich, loamy, well drained soil is preferred (Splittstoesser 1990) but the crop also responds to well manured heavy soils (Waters et al. 1992).

Salinity: Hydroponic experiments indicated that salinity of 4.9 mM NaCl and above would retard growth of cultivar 'Bun long' (Hill et al. 1998).

pH: Optimum is 5.5-7.0 (Masalkar and Keskar 1998). Taro can tolerate highly acidic soils but growth is reduced (Follett 1996).

Propagation: Plants are reproduced asexually since the plant seldom flowers (Waters et al. 1992). Healthy daughter and granddaughter tubers of about 30-60g are taken from healthy parent plants and dusted with fungicide (Follett 1996). Using about 1 cm of the corm tip with 15-20 cm petiole may produce better yields than planting the corm alone. Cormels may be used if there are problems with storage until next season (Masalkar and Keskar 1998). A simplified bioreactor system for mass propagation of corms is described by Akita and Ohta (1996). In vitro propagation has been successfully trialled by a number of researchers (Mixwagner 1993, Ebida 1995, McCartan et al. 1996, Chand et al. 1999).

Sowing: Sow into 15 cm deep trenches and cover with 5-8 cm soil (Larkcom 1991). Planting is labour intensive (O'Hair 1990). Incorporate fertiliser into the base of the trench before sowing (Follett 1996).

Plant density: Recommended spacing varies from 30 x 30 (Mehla et al. 1997) to 40 x 40 cm apart (Larkcom 1991), to 30-50 x 100-120 cm spacing (Follett 1996). The latter requires approximately 1.5 t/ha of corms (Follett 1996).

Plant maintenance: Soil can be mounded up around the plants to encourage corm swelling, but too much mounding may induce corm elongation (Follett 1996).

Water: Taro requires a lot of water during growth (Larkcom 1991) as the plant is shallow rooted (Splittstoesser 1990), and can withstand waterlogging (Masalkar and Keskar 1998). Dry conditions cause lower yields, cracked corms and rots during storage or in the field. Water fluctuations can also lead to cracked corms (Follett 1996).

Weeds: Early and uniform sprouting of corms will reduce time to development of the crop canopy, inhibiting weeds and thus increasing yields (Waaijenberg and Aguilar 1994).

Nutrition: Apply fertiliser before planting and again when plants reach 60 cm high (Splittstoesser 1990). Good plant vigour in the early stages will discourage disease and insect infestation (Masalkar and Keskar 1998) but too much can cause excessive foliar growth and inhibit corm swelling (Follett 1996). The crop requires more K than N or P (Masalkar and Keskar 1998).

Harvest: The plant reaches maturity in approximately 200 days (Waters et al. 1992) and can be harvested after leaves have yellowed and almost died. Tubers can be left in the soil until needed, unless there is a possibility of frosts (Larkcom 1991). It is usually harvested by hand (Waters et al. 1992) but a potato harvester can be modified for the job (Follett 1996, O'Hair 1990). Soil is removed by shaking and corms are left on the ground to dry (Follett 1996). The main harvest in New Zealand is from mid March to May, but may be as early as February with early production techniques (Follett 1996).

Yield: Average 1997 yield around the world was 6.2 t/ha, but USA and Japan reached 13.8 and 11.6 respectively, and Egypt reported yields of 34.9 t/ha (FAO 1998). Early yields in New Zealand have averaged 25 t/ha, or 2.7 kg/plant (Follett 1996).

Figure 2: High and low prices of taro leaf at Flemington Markets during 1996 (none was traded in 1997 or the the first half of 1998), recorded on a half monthly basis (Flemington Market Reporting Service, NSW Agriculture).

Figure 3: Japanese production of taro (MAFF 1999).

Postharvest

Refer to GAIN.

Handling: Mechanisation is required for sorting and the removal of harts and contusions to make it more profitable. Tubers must be cooked before eating to remove calcium oxalate (Vinning 1995).

Temperature: Tubers are stored at room temperature for a few days to cure bruises, then at 7-10°C with good ventilation for long term storage (Splittstoesser 1990).

Shelf life: 4-5 months if care is taken during harvest and handling (Masalkar and Keskar 1998).

Leaves: Taro leaves that are packed in low density polyethylene bags with the tops folded, and stored at 10°C can last for 2 weeks. Unpackaged leaves turn brown-yellow after 8 days and lose more weight due to the lower humidity. Chilling injury was observed as browning discolouration after 12 days at 3°C (Sankat et al. 1995)

Quality assessment

Aim at producing smaller size tubers, about the size of a golf ball (Vinning 1995). Japanese rate taro according to size, with smaller being a higher quality. A good size is 60-100 g and a diameter of 6-9 cm (Vinning 1995).

Pests and diseases

Few during production, but rots can be a problem during storage (Follett 1996). Potential viruses are listed at Plant viruses online (Brunt et al. 1996).

See Hawaiian pests & diseases. Diseases in India are described in Masalkar and Keskar (1998).

Domestic market

There is an unsatisfied demand for taro in eastern Australia (Bourke 1996). Australian consumption could rapidly increase with marketing. Melbourne is supplied mostly from Fiji, with some from Queensland. Taro shoots are supplied from Victoria at prices mostly between $0.80 to $1.20/bunch (Chew and Morgan 1996).

Figure 4: World production of taro 1990-97 (FAO 1998).

Export market

(click here for exchange rates).

Taro was rated a priority Asian vegetable for developing a fresh export market by workshop members reported in Lee (1996) and also by Vinning (1995). It can be sold as a dessert, after peeling, packing and freezing (Vinning 1995). Taro is produced commercially in 43 countries worldwide (FAO 1998).

Japanese production of taro has decreased in recent years (254 000 t in 1996, Figure 3) largely because it is labour intensive to harvest (JETRO 1994). Taro consumption has increased due to use in Japanese style restaurants, a consumer interest in dietary fibre (JETRO 1994), and a sharp increase in the use of Japanese style frozen vegetable mixes (JETRO 1996a). Consumption is currently about 3 kg/person/year (Otsubo 1996). Imports have therefore increased and are expected to increase further (JETRO 1994). In the past, Kyushu was the main producing district for frozen taro, but production has increasingly shifted to China (JETRO 1996a). China supplied 99% of imports in 1992 (JETRO 1994). There is potential for Australian exports (Vinning 1995, Lee 1996), but Japanese taro (sato imo) is a different, smaller variety to the Pacific type available in Australia.

It is usually sold whole and unpeeled, but can also be peeled and packed in a liquid (Vinning 1995). Taro accounts for 0.3% of fresh cut vegetable production (Pan 1995). Taro is used primarily in Japanese-style dishes that are boiled and seasoned in sugar and soy sauce. Frozen taro is imported not only as a separate item but also in Japanese-style mixes. When the latter is taken into account, the volume of imports is thought to be substantial (JETRO 1996a). Prices are highest in summer, especially May, and annual average prices are trending upward. Imports must carry a certificate stating them free of pests generally, and Radopholus similis specifically (Vinning 1995).

Figure 5: US imports of fresh taro (US Census Bureau, via the Government Information Sharing Project, Oregon State University). Note that FAO (1998) figures show a similar trend, but value and price is around 25% higher.

Figure 6: Chinese exports of fresh taro (FAO 1998).

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(B)

Figure 7: Japanese imports of fresh (A) and frozen (B) taro. Domestic production of frozen taro is small at 3 000 t in 1995 (Ministry of Finance via JETRO 1995, 1996a, Japan Frozen Food Association via JETRO 1996b).

Taiwanese market throughput is decreasing but prices are increasing, reaching NT$27/kg in 1994. Prices are highest from August to December (Vinning 1995). There is potential for Australian exports (Lee 1996).

Chinese exports have been increasing in volume and price (Figure 6). 83 000 ha were planted in 1994 (FAO 1998). The main suppliers are based in Shandong province, where Japanese-affiliate firms are boosting their production capacity (JETRO 1996a).

Prices to the US have been increasing steadily to 1997 (Figure 5). There is distant future potential for Australian exports to Indonesia, Malaysia and Singapore (Lee 1996). Minor vegetable in South Korea and not currently viable for export (Lee 1996). Thailand exports around 1 000 t/year at low prices, averaging US$0.37/kg in 1997 (FAO 1998).

References

Akita, M. and Ohta, Y. (1996). Development of a system for mass propagation of Colocasia esculenta in large scale without forced aeration. Acta Horticulturae No(440): 554-559.

Bourke, R. M. (1996). Opportunities for growing Melanesian food crops in Australia. First Australian New Crops Conference, The University of Queensland Gatton College, Rural Industries Research and Development Corporation.

Brunt, A.A., Crabtree, K., Dallwitz, M.J., Gibbs, A.J., Watson, L. and Zurcher, E.J. (eds.) (1996 onwards). `Plant Viruses Online: Descriptions and Lists from the VIDE Database. Version: 16th January 1997.'

Chand, H., Pearson, M. N. and Lovell, P. H. (1999). Rapid vegetative multiplication in Colocasia esculenta (L) Schott (taro). Plant Cell Tissue & Organ Culture 55(3): 223-226.

Chew, M. and W. Morgan (1996). Melbourne retail Asian vegetable survey. Melbourne, Agriculture Victoria 143 pp.

Ebida, A. I. A. (1995). In vitro propagation and in vivo establishment of the Egyptian taro, Colocasia esculenta var. esculenta (L) Schott (Araceae). Alexandria Journal of Agricultural Research 40(3): 457-474.

FAO (1998). FAOSTAT statistics database.

Follett, J. (1996). Japanese taro - an Asian vegetable. Crop Facts. Crop & Food Research NZ.

Hill, S., Abaidoo, R. and Miyasaka, S. (1998). Sodium chloride concentration affects early growth and nutrient accumulation in taro. Hortscience 33(7): 1153-1156.

JETRO (1994). Frozen Vegetable. Japan External Trade Organisation, Market Report.

JETRO (1995) Fresh Vegetables: Access to Japan's Import Market - Mini Report 1995 August. Japan External Trade Organisation, Market Report.

JETRO (1996a) Frozen Vegetables: Access to Japan's Import Market-1996. Japan External Trade Organisation, Market Report.

JETRO (1996b) Process Vegetables: Your Market in Japan-1996. Japan External Trade Organisation, Market Report.

Johnston, M. and Onwueme, I. C. (1998). Effect of shade on photosynthetic pigments in the tropical root crops: yam, taro, tannia, cassava and sweet potato. Experimental Agriculture 34(3): 301-312.

Larkcom, J. (1991). Oriental vegetables: the complete guide for garden and kitchen. London, John Murray 232 pp.

Lee, B. (1995). Audit of the Australian Asian vegetables industry. RIRDC Research Paper No. 95/13. Canberra, Rural Industries Research and Development Corporation 97 pp.

Lee , B. (1996). Assessment of economic benefits for Asian vegetables. RIRDC project CON-4A review meeting 14 November 1996.

MAFF (1999). Abstract of statistics on agriculture, forestry and fisheries. Statistics and Information Department, The Ministry of Agriculture, Forestry and Fisheries of Japan.

Masalkar, S. D. and Keskar, B. G. (1998). Other roots, tubers and rhizomes. In: Handbook of vegetable science and technology: production, composition, storage and processing. (Ed; Salunkhe, D. K. and Kadam, S. S.). New York, Marcel Dekker 141-170.

McCartan, S. A., Staden, J. and van Finnie, J. F. (1996). In vitro propagation of taro (Colocasia esculenta). Journal of the Southern African Society for Horticultural Sciences 6(1): 1-3.

Mehla, C. P., Ram, M. and Singh, J. (1997). Effect of spacing and fertilizer levels on growth and yield of colocasia (Colocasia esculenta L.). Agricultural Science Digest 17(3): 205-208.

Mixwagner, G. (1993). Invitro-multiplication of yam (Doiscorea rotundata poir) and taro (Colocasia esculenta L.) for planting material production [German]. Landbauforschung Volkenrode 43(2-3): 93-100.

Nguyen, V. Q. (1998). Report on the study tour to Japan on pickling of Asian vegetables and attendance at an international symposium on vegetable quality in Seoul, Korea 1997. Gosford, Horticultural Research and Advisory Station. 96 pp.

O'Hair, S. K. (1990). Tropical Root and Tuber Crops. Advances in new crops. Ed.: J. Janick and J. E. Simon. Portland, Oregon, Timber Press: 424-428.

Otsubo, M. (1996). Asian vegetables into Japan: export potential, opportunities and myths. In: Proceedings of an Asian Food Industry Conference (Ed; Lee, B. and Prinsley, R.). RIRDC Research Paper No. 96/9: 22-28.

Pan, C. (1995). Market opportunities for fresh and processed Asian vegetables. RIRDC Research Paper No. 95/14. Canberra, Rural Industries Research and Development Corporation 117 pp.

Sankat, C. K., Maharaj, V. and Lauckner, B. (1995). The effect of temperature and packaging on the storage of dasheen (Colocasia esculenta) leaves. Asean Food Journal 10(1): 3-9.

Singh, U., Matthews, R. B., Griffin, T. S., Ritchie, J. T., Hunt, L. A. and Goenaga, R. (1998). Modeling growth and development of root and tuber crops. Understanding options for agricultural production. Dordrecht, Netherlands, Kluwer Academic Publishers: 129-156.

Splittstoesser, W. E. (1990). Vegetable growing handbook, organic and traditional methods. 3rd Ed. Melbourne, Thomas Nelson Australia 362 pp.

Vinning, G. (1995). Market Compendium of Asian Vegetables. RIRDC Research Paper No. 95/12. Canberra, Rural Industries Research and Development Corporation 386 pp.

Waaijenberg, H. and Aguilar, E. (1994). Production and partitioning of dry matter in eddoe (Colocasia esculenta var. antiquorum). Tropical Agriculture 71(1): 49-56.

Waters, C. T., Morgan, W. C. and McGeary, D. J. (1992). How to identify, grow and use oriental vegetables. Melbourne, Agmedia 128 pp.