Chinese Waterchestnut

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WARNING: The information on this page has been gathered from both published and unpublished material, and contains comments and opinions from people working in the field. CQUniversity cannot guarantee all the information, and we stress that it is necessary to CHECK WITH THE SOURCE of the information, before using it to make a business decision. Please read our disclaimer.

Family: Cyperaceae

Species: Eleocharis dulcis (Burm.f.) Trinius ex Henschel. There are three main genera known as Chinese waterchestnut; Sagittaria spp., Eleocharis spp., and Trapa spp., each with many species. However, Eleocharis dulcis is the most commonly traded (Vinning 1995) and is the true Chinese waterchestnut (David Midmore 1998, pers. comm.). Each genus is distinctive in corm size, sweetness, coconut flavour and harvest time (Lodge 1998). The origin of Eleocharis dulcis ranges from India , through south east Asia to Polynesia, with one variety native to northern Australia. This variety is small but quite sweet (Earthcare Enterprises 1998). The cultivated forms originate from China, and were developed through selection for size, sweetness and juiciness (Midmore 1998). Work with RAPD's indicated that morphological variation across Australia is more likely due to different environments than varieties (Li and Midmore 1999).

Seed corms of Chinese origin are available from Earthcare Enterprises.

Production

About 10 growers across Australia (Lodge 1998), producing about 20 t/year. Most is grown in Mackay, and most of the rest in Victoria and NSW (Midmore 1998) but it has also been produced in NT (Lee 1995). Current producers have formed the Australian Aquatic Vegetable Development Corporation (AAVDC), which aims to establish quality assurance and grading, and confront marketing issues such as opportunities and coordinated planting and production (Midmore 1998). Research is being conducted in agronomic and postharvest issues to extend the season (Lodge 1998).

Mixed cropping: Eleocharis dulcis is a dominant weed in rice fields of the Malaysian eastern coastal states (Li and Wang 1986) and the Andaman Islands (Li and Wang 1987). It can be used to remove excess nutrient from fish ponds (McCord and Loyacano 1978).

Climate: Usually cultivated in warm to subtropical climates (Lodge 1998). Corms grown in NSW and Victoria are much sweeter than those grown in Queensland, but the reason for this is not yet known (Li et al. 1998).

Season: It is harvested from June to November in Australia (Midmore 1998). Corms are initiated during shorter days (<12.5 hours) and the reeds (stems) senesce as days get cooler (Lodge 1998).

Temperature: The plant prefers high temperatures, optimally 30-35° C during the growing period and 20-25 ° C when the corms are forming (Larkcom 1991) but 15-25° C is fine. The plant requires a 220 day frost free period (Midmore 1998).

Photoperiod: Under short photoperiods a higher proportion of synthate is allocated to the roots and corms, but total dry matter is unchanged. There appears to be a critical day length for corm formation, somewhere between 13 and 16 hours, but shorter photoperiods increase the effect. Hence, it is possible to manipulate corm formation for out of season production (Li et al. 1998).

Soil type: A clay based soil that holds water is best for production, but too much clay content increases the difficulty of harvest (Midmore 1998). Therefore a rich, friable soil is preferred that is high in nutrient and free of stones, wood or other debris that could obstruct harvesting (Earthcare Enterprises 1998). Soil can be mixed with sand or sugar mill byproduct (mill mud) if clay content is too high (Earthcare Enterprises 1998). Sandy or otherwise porous soils are unsuitable, as they must be lined with polyethylene sheets to retain water (Midmore 1998). Soil should be at least 30 cm deep (Loughrey 1998).

pH: ideally between 6.0 and 7.5 (Earthcare Enterprises 1998).

Nutrition: Total fertiliser required per hectare is approximately 200-350 kg N, 120 kg P 2 O 5 and 170 kg K 2 O, but is very site-specific. Nitrogen is best applied as ammonium as this is more easily absorbed by the plant, and less easily leached. Apply one third to one half before planting (see 'soil preparation') and the rest at 8-10 weeks after planting, as secondary plants appear just before corms begin to form (Midmore 1998). Apply extra fertiliser if the stems yellow during the growing season (Loughrey 1998).

Soil preparation: Can be grown in rice paddy or in containers (Earthcare Enterprises 1998). Paddy size is determined by harvesting method and machinery. Apply between one third and one half of the total fertiliser before planting, either synthetic, or 12 t/ha of organic (Midmore 1998). If using manure, allow a couple of weeks before planting to avoid rots, which can totally destroy corms (Earthcare Enterprises 1998). Soil is then well watered but not flooded until plants are well established, as flooding tends to lower the temperature. After harvest, ponds can be seeded with Azolla , a nitrogen fixing fern that should reduce fertiliser requirement of the next crop (Midmore 1998).

Propagation: Reproduction is vegetative (Midmore 1998). The cost of planting material is high at present (80 cents per corm) and it is necessary to bulk up supplies of planting material before commercial crops can be marketed (Burt 1995).

Plant density: Approximately 3-5 plants/m 2 , dependent on climate and planting date. More southern climates and later planting require a closer density, as there is less time for rhizome development. Once planted, plant vigour can be governed for that density by fertiliser input (Midmore 1998).

Germination: Sound corms with a viable terminal bud are planted, with the terminal bud face up and covered with not more than 4 cm soil. Corms will sprout when the temperature rises above 13° C, approximately 10 days after planting. Use of larger corms might produce a higher yield (Midmore 1998) but Earthcare Enterprises (1998) use the 20% of corms that are too small to sell for food. As it is reproduced vegetatively there is no genetic demise (Earthcare Enterprises 1998), but plant vigour might be affected.

Transplanting: It is recommended that plants are first grown in a low nutrient nursery plot and transferred when stems are about 300 mm tall (Earthcare Enterprises 1998). This reduces the growth period in ponds by up to 6 weeks, the greatest difference occurring in climates with a larger temperature change. Tops may be trimmed if they are too tall at transplanting (Midmore 1998). Keep seedlings moist but not submerged (Loughrey 1998).

Hydroponics: Water chestnuts may also be grown hydroponically, using buckets and a suitable medium such as permite plus vermiculite. The buckets can be kept topped up with old nutrient solution from other crops (Burt 1995).

Water: Soil should be covered by 100-300 mm of water for the duration of the growing period. Greater depths will affect yield. Can be grown around dams and ponds if the water level is stable, or controlled (Earthcare Enterprises 1998). Shallow flooding is preferred in colder climates as this raises the effective temperature. Water must have salinity levels below 3.3 dS/m to prevent loss of yield (Midmore 1998).

Harvest: Once stems have dried off, drain the water and harvest. Four mechanical harvesters have been developed in Australia and all but one can work through water, enabling them to be used even after rain. Some growers burn the stems first. Harvest period lasts from June to November (Midmore 1998), May to September in WA (Burt 1995). Corms are located 7 to 20 cm under the soil, and will keep well there, provided temperature is below 13° C and frosts are not severe (Midmore 1998). Best harvested in late winter to maximise sweetness (Earthcare Enterprises 1998). The leaves turn brown naturally from May to June and should be removed if the corms are not harvested immediately (Burt 1995).

Yield: Harvests exceed 20 t/ha but marketable yields are less, once corms less than 25 mm diameter are removed. These yields are comparable with those reported from China (Midmore 1998). Approximately 80% of the crop is large enough for sale as food (Earthcare Enterprises 1998). A good yield is 2 kg per plant per year (Burt 1995).

Pests and diseases

Birds can be a serious problem, particularly wild fowl, and netting may be necessary (Earthcare Enterprises 1998).

Grasshoppers can cause minor damage to the stem (Earthcare Enterprises 1998), but insects are generally not a problem (Midmore 1998).

A list of identified diseases is described in Midmore (1998).

Postharvest

Handling: Corms are easily damaged due to their soft peel and high sugar of up to 8% (Lodge 1998). Wash and brush corms, and keep moist to prevent shrivelling (Loughrey 1998). Pack in 250 g punnets with cellophane wrappers (Burt 1995). Mechanical equipment is required for washing, cleaning and grading. Grading sizes will vary with outlet, as does packaging. There is not yet any peeling undertaken on a large scale (Midmore 1998).

Temperature: From 1-5° C appears preferable, but 10° C would be better if decay can be controlled, since sugar content increases more at that temperature (Mudahar and Jen 1992). Cool storage is essential in Queensland . During winter in southern states, corms can be stored for short periods without cooling (Midmore 1998). Corms below 2 cm size may exhibit chilling injury at 1° C after 10 days, expressed as internal browning, watersoaking and external decay (Mudahar and Jen 1992).

Humidity: Optimum is 90-98% (Welby and McGregor 1997).

Shelf life: Cool storage is usually limited to 1-2 months (Lodge 1998) but can be extended to 6 months at temperatures of 1-4° C and possibly further by surface sterilising with sodium hypochlorite (Midmore 1998). There are always a few corms that rot during storage, usually where there is damage to the skin, so it is necessary to sort them periodically. They keep very well in cool damp sand, lasting for more than a year for planting material (Earthcare Enterprises 1998). Sugar content increases during the first month of storage, particularly in early harvested corms, larger corms and at higher temperatures (Mudahar and Jen 1992).

Storage in water: If stored in 10% NaCl aerated aqueous solution at 1.5° C, most quality attributes will be retained for six months or more. This treatment increases sodium concentration which is not easily removed, and changes the proportions of sugar types from sucrose to fructose and glucose (Kays and Sanchez 198).

Quality assessment

Larger, sweeter corms are preferable (Lodge 1998). The preferred market size is 3-5cm diameter (Loughrey 1998). A major problem with the crop is that the corms have poor presentation for marketing (Burt 1995).

Domestic market

Development potential was rated as high for the replacement of fresh imports (Vinning 1995). A weekly supply of one ton of fresh water chestnut would eliminate the use of tinned produce in Asian stir-fry mixes and open a weekly domestic market for a conservative value of $5000 (Midmore 1997). However, fresh product is only available from June to November, limiting complete replacement (Midmore 1998).

It is sold fresh, frozen and canned (Midmore 1998) but Australian growers focus on supplying fresh corms for the domestic market (Lodge 1998), sold mostly through supermarkets. The volume of canned imports is not known because the ABS pools data of all chestnut types. Fresh waterchestnuts are sold with their skins but frozen and canned waterchestnuts are peeled (Midmore 1998).

Prices for canned chestnuts vary around $4.00/kg in the supermarkets, but the retail price may be as low as half (Midmore 1998). Price of fresh product appears to have stabilised around $5-6/kg, which is quite competitive with canned imports (Midmore 1998). Prices for some consignments have been as low as $3 to 5 per kilogram in Perth, but good quality produce has returned up to $10 per kilogram. A return of over $8 per kilogram is needed to return a profit, because of the specialist needs of this crop (Burt 1995).

Fresh Chinese waterchestnuts were extremely rare during 1995 in Melbourne (Chew and Morgan 1996) and did not appear in Western Australia until 1994 (Burt 1995).

(A)

(B) 

Export market

(Click here for exchange rates).

Development potential was rated as low for canned exports as competition is fierce and canning reduces the quality of the flavour. Potential would improve with mechanised peeling (Vinning 1995) and improved mechanised harvesting (David Midmore 1998, pers. comm.). Fresh waterchestnuts are used in stir fries, for sweetened drinks and as a dessert syrup. The best Australian product exceeds that of Asian producers, but quality is inconsistent, with some produce tasting starchy and low in sweetness (Midmore 1998).

Taiwan, Thailand and China are traditionally and currently the major producers and exporters (Midmore 1998).

Taiwanese production is decreasing but market volumes and prices are increasing. Production volumes peaked at over 10 000 tons in 1985 (Vinning 1995), but have since fallen to 860 tons in 1995 (Midmore 1998). Throughput and price at the Taipei markets climbed to 210 t and NT$55/kg in 1994. Prices are highest from August to December (Vinning 1995). Taiwan imported 22 t from China in 1997, at NT$22/kg (MarketAg website 1999)

Thailand has recently commenced canning operations (Midmore 1998).

Chinese prefer the mature, dark corms over the paler immature corms (Larkcom 1991).

Hong Kong imports from Taiwan from December to February, so there is potential for Australia to export to Hong Kong from June to December (Burt 1995).

Japanese production and market throughput are decreasing. Production fell from 1600 tons in 1984 to 1200 tons in 1992 (Vinning 1995). Best prices are gained from September to December, ranging from $9.00 to $30.00/kg (Midmore 1998), and are very sensitive to change in supply (Vinning 1995). Eco-Lodge-Ic aims to supply 250 t/year of fresh corms by 2005 (Geoff Lodge 1998, pers. comm.).

USA imported 34 593 tons of canned Chinese waterchestnut in the year from Oct 1997 - Sept 1998, valued at US$20.8 million (USDA 1999). Approximately 90% of canned waterchestnuts are imported to the US sliced. The country imported a further US$8 million as semi preserved product in 1996 (Midmore 1998). The US Census Bureau treats processed bamboo shoots and Chinese waterchestnuts together (see graphs on the bamboo page) Most Chinese waterchestnut is sourced from China.

Related projects

Geoff Lodge (Duration?). Development of a collaborative grower to processor water chestnut system. RIRDC Project Number LOD-1A.

Geoff Lodge (1 June 1997 to 31 December 1999). Production and postharvest systems for the Chinese water chestnut industry. RIRDC Project Number UCQ-8A.

References

Burt, J. R. (1995). Chinese water chestnuts for the fresh market. Department of Agriculture Western Australia Farmnote (URL: http://www.agric.wa.gov.au/).

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

Kays, S. J. and Sanchez, M. G. C. (1985). Storage of Chinese water chestnut [Eleocharis dulcis (Burm. F.) Trin.] corms. Acta Horticulturae 157: 149-159.

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.

Li, M., Lyall, T., Kleinhenz, V. and Midmore, D. J. (1998). Physiological studies on Chinese water chestnut. Access to Asian Foods 3 : 7. (URL: http://www.nre.vic.gov.au).

Li, M. and Midmore, D. J. (1999). Estimating the genetic relationships of Chinese water chestnut ( Eleocharis dulcis (Burm. F.) Hensch) cultivated in Australia, using random amplified polymorphic DNAs (RAPDs). The Journal of Horticultural Science & Biotechnology 74 (2): 224-231.

Li, Q. X. and L. R. Wang (1986). The dominant aquatic weeds in Peninsular Malaysia. Proceedings, 7th international symposium on aquatic weeds.

Li, Q. X. and L. R. Wang (1987). Ricefield weeds in South Andaman, India. International Rice Research Newsletter 12 (4): 47.

Lodge, G. (1998). Chinese water chestnuts. Access to Asian Foods (2). (URL: http://www.nre.vic.gov.au).

Loughrey, T. (1998). Chinese waterchestnuts. Department of Primary Industries Queensland . DPI note File No. h98040. (URL: http://www.dpi.qld.gov.au)

McCord, C. L. J. and H. A. Loyacano, Jr. (1978). Removal and utilization of nutrients by Chinese waterchesnut in catfish ponds. Aquaculture 13 (2): 143-155.

Midmore, D. J. (1997). Putting the "Australian" into water chestnuts. New Crops Newsletter 8 : 19-20.

Midmore, D. J. (1998). Chinese waterchestnut. The New Rural Industries. Ed.: K. W. Hyde. Canberra , Rural Industries Research and Development Corporation : 181-188.

Mudahar, G. S. and Jen, J. J. (1992). Harvest maturity and storage temperature effects on quality of Chinese water chestnuts (Eleocharis dulcis). Acta Horticulturae No (318): 313-319.

USDA (1999). World horticultural trade and US export opportunities. USDA Trade Report. (URL: http://www.fas.usda.gov)

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

Welby, E. M. and McGregor, B. (1997). Agricultural Export Transportation Handbook. USDA Agricultural Handbook 700, United States Department of Agriculture (URL: http://www.ams.usda.gov/tmd/export/index.htm).