Culture of Long Yam, Using a Tube

Cooperating agency for this topic:
Taoyuan District Agricultural Improvement Station,
Council of Agriculture, Taiwan ROC
Fax: (886 3) 476 0127
Tel.: (886 3) 476 8216 ext. 222, 2002-06-01

Long yam (Dioscorea opposita, or Chinese yam) is a bean-like perennial climber with a long , thin root. This tuber may measure up to 2 meters in length. Long yam is one of about 650 varieties of yam in the world, 60 of which are Asian. The tuber is difficult to harvest because it is so long, growing down deep into the soil. The problem can be solved by growing the yam in a tube. This protects the tuber, so that it is not damaged when it is harvested (Fig. 1).

Importance of Yam

In Africa, long yam is an important food crop. In Taiwan and other Asian countries, long yam is now important because of its health benefits. Yam tubers contain high levels of Vitamin B, Vitamin C, Vitamin K, protein, amino acids, glucose, choline, allantoin and diosgenin.

It is the diosgenin, a plant steroid, which is particularly important. Yams can be eaten directly to relieve arthritis, asthma, eczema and similar conditions. Diosgenin is also the major raw material for the manufacture of medical steroids.

The Techology

• Select a tube which is the right size. Different varieties of long yam have tubers of different sizes. Make sure the tube length matches the tuber length of the variety. The variety of long yam usually grown in Taiwan needs a tube around 10 cm in diameter and 1-2 meters in length.
• When the tubers are planted, the tube should be at a slope of 25%. This helps maintain the optimum soil moisture content in the tube.
• Put the seed tuber in the top of the tube, about
• 5 - 10 cm from the top (Fig. 2).
• Fill the tube with a good soil or growing medium. The medium may be a mixture of sawdust, rice straw, cow manure etc.
• Hoe the soil into a ridge, to make a raised seed bed around 30 cm high (Fig. 3 and Fig. 4).

Index of Images

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  Figure 1 The Tube Makes It Convenient to Harvest Long Yam

• 

  Figure 2 Seed Tuber Placed in the Tube

• 

  Figure 3 Using a Machine to Prepare the Seed Bed Reduces the Labor Cost

• 

  Figure 4 High-Quality Long Yams Grown in Tubes

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