This edible corm of a sedge, botanical name Eleocharis dulcis, has long been valued throughout the Orient as a vegetable delicacy and as a source of medicine and starch (Ref 1). Presently unavailable as a fresh product in Australia, a significant commercial opportunity exists in the growing of this pond plant. It will also be of interest to those involved in self-sufficiency.
ORIGIN AND DISTRIBUTION
Eleocharis dulcis grows wild in many parts of India, South East Asia and Polynesia. Indeed it is native to Australia, and the logs of the explorer, Leichardt, refer to it. In the explorer's opinion, it was the tastiest native food offered to him by the Aborigines.
Water chestnuts were first cultivated in South East China in humid monsoon areas and is now also grown commercially in Japan, Hong Kong, the Philippines, Hawaii and other PACIFIC Islands, India and the southern USA. In 1988, a commercial planting occurred in Caboolture in Queensland, and to the author's knowledge this was the first commercial crop in Australia.
DEMAND - USES
A strong demand exists for this product, especially in the fresh state when it has a characteristic sweet taste and crispness similar to a cross between a coconut and apple. It has the ability to remain crisp even when cooked, thereby imparting a highly desired texture to Chinese dishes.
The Chinese also utilise the vegetable in traditional medicine, and believe that regular eating of fresh corms aid in the prevention of stomach problems, including cancer. The juice extracted from the corms was shown in 1945 (Ref.1) by Chinese university researchers to contain an antibiotic principle, puchin, which resembled penicillin in its action. Even if matai has no curative powers, it tastes great and parents have no problems getting their children to eat this vegetable. The result of all this is a demand, particularly from our immigrants with Asian backgrounds, for the vegetable.
Temperature - a long warm growing period is required. At least 220 frost free days, and a soil temperature of 14-15. 5°C is necessary for germination of the corms.
Water supply - the plant is aquatic and thrives in areas where a continuous water supply is available.
Soils - for optimum yields a rich clay or pretty soil with a pH of 6.9 to 7.3 is best. However, the plant is robust and will tolerate a variety of conditions. It was grown in soil at pH 5.8 in Caboolture. Why? Because we did not know any better. However, this does show that land of little value for other crops can be utilised in the growing of water chestnuts.
Yield - the literature reports a variety of yields ranging from 20 to 40 tonnes per hectare in China and 28 tonnes per hectare in Florida. Our experience indicates that 3 kg per square metre is the expected yield.
Return - the price achieved for good quality product, greater than 3 cm in diameter, has been $7 per kg and for small quantities $10 per kg.
Growing period - a total of six to seven months is required for corms to reach maturity.
Harvesting - has traditionally been performed dry. The paddies or ponds are normally drained three to four weeks before harvesting and the corms dug out by hand to avoid damage. Slightly more mechanised methods are employed in the USA. Harvesting may be delayed for considerable periods as the corms do not deteriorate in the soil. At Caboolture, harvesting commences in June and is still proceeding in September. We are not slow, just lazy.
Secondary and waste products - the dry stems of the plant can be used for cattle feed, mulching, and as a packing material for horticultural products and, it is claimed, for weaving.
Seed material - seed material is available as a result of the successful growing at Caboolture.
W.H. Hodge, Economic Botany, circa 1955, pages 49-65.
DATE: July 1989
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