Detailed Explanation of Water Chestnut Planting Methods and Technical Key Points

Water chestnut (scientific name: Eleocharis dulcis (Burm. f.) Trin.), also known as horseshoe, water chestnut, black taro, water nut, etc., belongs to the monocotyledonous family Cyperaceae and is a perennial herbaceous plant with persistent roots. It has slender creeping rhizomes, and tubers grow at the tips of the creeping rhizomes, commonly called water chestnut. The culms are numerous, clustered, erect, cylindrical, with many transverse septa; after drying, the culm surface shows nodes, but they are not obvious, grayish-green, smooth and hairless. Leaves are absent, with only 2-3 leaf sheaths at the base of the culm; the sheaths are nearly membranous, greenish-yellow, purplish-red or brown. The spikelet is terminal, cylindrical; at the base of the spikelet there are two scales that are hollow and flowerless, clasping the base of the spikelet for one circle; all the remaining scales are fertile; it is one and a half times longer than the achene, with barbed bristles; stigmas 3.

Cultivation Techniques

1. After the water chestnut seedlings are planted, a relatively high soil temperature is required to facilitate green return and tillering, so shallow water should be irrigated to stabilize the seedlings. As tillering and ramet formation increase, transpiration increases, so the water layer should be gradually deepened to promote the formation of the aboveground stem population. After the rows close, irrigate deeply to control tillering and ramet formation, promote early corm formation, and increase and enlarge corms, but the amount of nitrogen fertilizer should be controlled to prevent excessive growth. Water chestnut cannot lack water throughout the entire growth period. If there is no excessive growth, the field should not be drained and dried, especially during the corm expansion period, when water shortage is even more unsuitable.

2. Water chestnut has many and large clumps, and during the corm formation period it also requires many various nutrients and assimilated substances, so the base fertilizer must be sufficient. During the tillering and ramet stages, sufficient nitrogen fertilizer is required, and fertilizer shortage is even less acceptable, to ensure that water chestnut has enough seedlings and sufficient plants. After entering the corm formation stage, nitrogen should no longer be applied; otherwise, excessive growth will occur, causing lodging, affecting corm formation, and increasing the occurrence of diseases. Potassium plays an important role in improving corm quality, promoting the synthesis of amino acids and proteins, and the transport and accumulation of sugars and starch. In addition to being used as a base fertilizer, potassium should also be applied as a topdressing during the water chestnut growth period. In addition, sufficient potassium fertilizer can also improve the disease resistance of the plants. Phosphate fertilizer has a similar effect on water chestnut. Therefore, when planting water chestnut, the three major elements of nitrogen, phosphorus, and potassium fertilizers must be combined, especially phosphorus and potassium fertilizers around the early flowering and corm formation stages. At this time, if foliar fertilizer or potassium dihydrogen phosphate, etc. can be sprayed, the effect of larger corms and increased yield can be achieved.

   

1. Seedling stage: The period from after seedling establishment to before tillering and ramet formation is called the seedling stage. Water chestnut is an aquatic crop, and during the seedling stage a shallow water layer of 3-5 cm should be maintained. Water chestnut begins to grow 10-15 days after planting. When the old leaves of the water chestnut seedlings wither and die, combine with weeding by treading the yellowing culms, rotten seed corms, and dead weed leaves into the field, which is beneficial for the seed corms to grow new roots. At this time, urea can be applied once as a topdressing, generally 10-15 kg of urea per mu, to promote earlier tillering and ramet formation of water chestnut.
2. Nutritional period: During the tillering stage, carry out 2-3 times of inter-row weeding and cultivation in the water chestnut field, and combine weeding with the second topdressing, applying 5-10 kg of urea per mu to promote corm formation. From the Autumn Equinox to Cold Dew, during the vigorous growth period of the corms, the water layer should be deepened, and it is best to keep the water layer within the range of 6-9 cm. During this period, water chestnut culm blight and water chestnut white stem borer often occur. For water chestnut culm blight, 40 kg of a 500-1000 times solution of 50% carbendazim wettable powder plus an 800 times solution of 70% thiophanate-methyl can be sprayed per mu for control. The control method for the white stem borer is to use 100 g of 98% cartap and mix it with 50 kg of water for spray control.
3. Maturation stage: During the corm maturation stage, that is, about 20 days before harvest, irrigation should be stopped so that the leaves turn yellow and gradually dry up, preparing for harvest. There is no other management during this period; it is only necessary to prevent damage by livestock.

1. Harvest time: The water chestnut harvest period can begin from Frost's Descent and last until the Spring Equinox of the following year. Corms harvested early have tender flesh, mild taste, and thin skin, and are not suitable for storage. From the Winter Solstice to Minor Cold, the skin color of the corms turns reddish-brown, and the taste is sweetest, which is the period with the highest sugar content, making this the most suitable time for harvest. Afterward, the sugar content of the corms gradually decreases, the skin thickens, the skin color deepens and becomes dark brown, and a layer of yellow coating forms under the skin, deteriorating the quality, so commercial corms should be harvested before overwintering.
2. Harvesting method: Generally, the field water is drained one day before harvest. Because the corms are mainly concentrated in the 9-20 cm soil layer, first remove the upper 8-9 cm of soil, then remove the lower layer of soil, and carefully pinch out the corms by hand (commonly known as "feeling for water chestnuts"). If rushing to plant the next crop (such as rapeseed stubble or wheat stubble), drain and dry the field 10-15 days before harvest, and dig them out with a fork.