Origin
Dioscorea orbicularis A.Chev. ex De Wild. is a plant species that belongs to the family Dioscoreaceae. It is indigenous to Central Africa, specifically in the Democratic Republic of Congo, Gabon, and Cameroon.
Common Names
The plant is commonly known by different local names. In Cameroon, it is called "Boii" by the Baka people, "Ndolendole" by the Kaka people, "Ndine" by the Maka people, and "Nkoyou" by the Meyomessala people. In Congo, it is referred to as "Mwendo" or "Ndombolo". In Gabon, it is known as "Ndjilo" in Fang language and "Bondjébé" in the Obamba language.
Uses
Dioscorea orbicularis A.Chev. ex De Wild. has different uses. In Central Africa, it is traditionally used to treat various illnesses such as stomach ache, malaria, and fever. The plant is also an important source of food and is commonly consumed as a staple. It is prepared in various ways such as boiling, roasting, or frying. In addition, certain parts of the plant are used for extracting starch that is used in food, textile, and cosmetics production.
General Appearance
The plant is a perennial vine that grows up to a length of 15 meters. It has a cylindrical or slightly flattened stem that can attain a diameter of up to 1.5 cm. The leaves are alternate and heart-shaped with a length of about 15 cm and a width of about 12 cm. The plant produces separate male and female flowers that are borne on the same inflorescence. The fruit is an oval capsule that has a diameter of about 4 cm and contains numerous seeds.
Light Requirements
Dioscorea orbicularis A.Chev. ex De Wild. is a tropical plant native to Central and West Africa. It requires a moderate to bright indirect light to grow properly. Direct sunlight may damage the plant's leaves and hinder its growth, so it's recommended to keep it away from the harsh afternoon sun.
Temperature Requirements
The recommended temperature range for Dioscorea orbicularis A.Chev. ex De Wild is between 20 to 30°C (68-86°F). The plant grows best in warm temperatures and is sensitive to cold temperatures. A sudden drop in temperature can cause the leaves to turn yellow and fall off.
Soil Requirements
The soil for Dioscorea orbicularis A.Chev. ex De Wild should be well-draining and loamy. It can tolerate a pH between 5.5 to 7.5 but prefers slightly acidic soils. Adding organic matter to the soil can also improve the overall growth of the plant. The plant prefers to stay moist but not waterlogged, so the soil should be allowed to dry slightly between watering.
Cultivation Methods
Dioscorea orbicularis A.Chev. ex De Wild., also known as the Chinese yam, is a climbing plant that requires a support structure like a trellis or wall to climb on. The plant grows best in well-draining, fertile soil with a pH range of 5.5 to 6.5. It prefers partial shade to full sun exposure and a warm, humid environment. Plant the tubers in late winter or early spring, with a spacing of 30 cm to 50 cm between plants.
Watering Needs
It is essential to keep the soil moist but not waterlogged for Dioscorea orbicularis A.Chev. ex De Wild. Young plants require regular watering while established plants can survive short periods of drought. Ensure that the watering is done in the morning or evening and not during the heat of the day to reduce water stress to the plant.
Fertilization
Chinese yam is a heavy feeder and requires regular fertilization. You can use an all-purpose fertilizer to feed the plant monthly. Alternatively, use organic matter like well-rotted manure or compost to boost soil fertility. Avoid over-fertilization as it can cause leafy growth at the expense of tuber production.
Pruning
Pruning of Dioscorea orbicularis A.Chev. ex De Wild. is minimal, and it mainly involves the removal of dead, damaged, or diseased vines. Pinch back growing tips of young plants to encourage bushier growth. Regular harvesting of leaves and vines to eat or use for medicinal purposes can also help to keep the plant under control.
Propagation of Dioscorea orbicularis
The propagation of Dioscorea orbicularis A.Chev. ex De Wild. can be done through various methods
Seed propagation
The plant can be propagated through seeds. The seeds should be sown in a mixture of peat, sand, and perlite. The soil should be moist and kept warm (around 25°C) for proper germination. It takes around 10 to 12 weeks for the seeds to germinate. The seedlings can be transplanted to individual pots once they have grown to around 10 cm.
Cutting propagation
Another way to propagate Dioscorea orbicularis is through cuttings. Cuttings should be taken from mature and healthy plants. The cuttings should be around 10 cm long and should have at least three nodes. The cuttings should be planted in well-draining soil with good organic matter. The soil should be kept moist, and the cutting should be kept in a warm and humid environment. The cutting will start developing roots in around 2 to 3 weeks, and it can be transplanted to individual pots once it has grown to around 10 cm.
Tuber division
The plant can also be propagated through tuber division. This method is best done during the dormant period of the plant, which is usually in winter. The tuber should be dug up carefully and should be divided into smaller sections. Each section should have at least one growth point. The sections should be planted in well-draining soil with good organic matter. The soil should be kept moist, and the tubers should be kept in a warm and humid environment. The tubers will start developing shoots in around 4 to 6 weeks.
Disease and Pest Management for Dioscorea orbicularis A.Chev. ex De Wild.
Dioscorea orbicularis A.Chev. ex De Wild. is a wild yam species that is mostly found growing in the tropical regions of Africa. Proper disease and pest management are essential in order to ensure that the yam producing plants remain healthy and productive. Here are some of the common diseases and pests that might affect the plant and suggestions on how to manage them.
Diseases
Anthracnose: This is a fungal disease that affects the plant's leaves and stems, causing them to turn yellow, wilt and eventually die. The infected area usually has small, black spots on it. To manage this disease, it is important to remove any infected plant material and discard it. Also, avoid overhead irrigation to prevent the disease from spreading.
Heart rot: This disease is caused by a bacterium that enters the plant through mechanical damage. The signs of this disease include a soft, brownish black rot in the stem's center. To manage this disease, it is important to handle the plants carefully, being mindful not to cause mechanical damage. Infected material should be removed and destroyed.
Pests
Yam beetles: These insects are the most destructive pest on Dioscorea orbicularis. They have the capacity to cause extensive damage to the leaves, stems, and tubers. To manage this pest, use insecticides and rotate yam crops with non-crop plants.
Termites: Termites are another major pest of Dioscorea orbicularis. They attack young plants and tubers, causing massive damage. To manage this pest, it is important to clear and destroy any dead wood and to use appropriate insecticides. Crop rotation may also be effective in reducing the termite population.
Proper disease and pest management is essential for cultivating healthy Dioscorea orbicularis plants. Regular monitoring and taking appropriate measures as soon as symptoms are detected can help to minimize damage to the crops and ensure the production of high-quality yams.
