Overview
Dioscorea thonneri De Wild. & T.Durand, also known as the Bitter yam or Ugwu Ebule, is a perennial climbing vine that belongs to the family Dioscoreaceae. It is native to West and Central Africa, particularly in Nigeria, Cameroon, and Congo.
General Appearance
The plant produces long stems that can grow up to 15 meters in length. These stems are supported by twining, coiling tendrils that help the plant climb up other plants or any available support. The leaves are alternate, heart-shaped, and have pointed tips. The flowers are small, white, and grow in clusters, while the fruits are thin-walled capsules that contain numerous winged seeds.
Common Names
Dioscorea thonneri is commonly known as Bitter yam or Ugwu Ebule in Nigeria, while in Cameroon, it is known as Mugumang, Mukwemosi, and Edebe. In Congo, it is called Tshiungu and Omoumou.
Uses
The tubers of the Bitter yam are edible but bitter, with a similar taste to that of the bitter cola. However, the plant is not commonly used as food due to its bitterness. In traditional medicine, the tubers are used to treat various ailments such as fever, stomach aches, and diarrhea. Additionally, the plant's leaves are sometimes used as fodder for animals, while the stem is utilized for weaving baskets and making ropes.
Typical Growth Conditions for Dioscorea thonneri De Wild. & T.Durand
Dioscorea thonneri De Wild. & T.Durand is a perennial, twining vine species commonly found in savanna and forest margin areas in West Africa. To cultivate this plant in a garden or agricultural setting, it is essential to mimic the plant's typical growth conditions closely.
Light Requirements
Dioscorea thonneri requires a moderate to the high amount of sunlight to grow well. The plant prefers bright indirect light to direct sunlight, which can scorch its leaves. A shaded environment is also acceptable, but the plant may grow more slowly and produce fewer tubers. Therefore, it is essential to ensure that the plant receives at least four hours of direct sunlight daily.
Temperature Requirements
Dioscorea thonneri needs a warm and humid environment to thrive. The plant grows best with daytime temperatures ranging from 24 to 32°C (75 to 90°F) and nighttime temperatures between 16 and 22°C (60 to 72°F). These temperature ranges provide ideal conditions for the plant to grow its leaves and tubers. It is crucial to note that the plant is not frost-tolerant and requires a warmer, frost-free environment to survive year-round.
Soil Requirements
Dioscorea thonneri prefers well-drained, rich, loamy soil with a pH range of 5 to 7. The soil should be deep, friable, and rich in organic matter to support the plant's growth and tuber development. The ideal soil texture should be moderately loose and suitable for root development. Additionally, the soil should be adequately watered, but not waterlogged.
In conclusion, cultivating Dioscorea thonneri De Wild. & T.Durand in a garden or agricultural setting requires providing it with a warm and humid environment with moderate to high sunlight and well-drained, nutrient-rich soil. By providing these ideal growing conditions, the plant can grow healthy foliage and tubers.
Cultivation methods for Dioscorea thonneri De Wild. & T.Durand
Dioscorea thonneri De Wild. & T.Durand, commonly known as "African yam," is a tropical plant native to Africa. Cultivating this plant requires a warm and humid environment.
The best time to plant Dioscorea thonneri De Wild. & T.Durand is during the rainy season when the soil is moist. The plant should be planted in well-drained and loamy soil that is rich in organic matter.
It is advised to plant the yam in mounds or ridges as it helps in moisture retention, and prevents water-logging. The plants require support as they grow, so staking the plants is essential.
Watering needs of Dioscorea thonneri De Wild. & T.Durand
Dioscorea thonneri De Wild. & T.Durand requires moist soil for optimal growth and development. The plant should be watered regularly, especially during the dry season, to keep the soil consistently moist.
However, care must be taken not to overwater the plant as it can lead to water-logging and root rot. Watering the plant once or twice a week should suffice, depending on the weather conditions.
Avoid watering the plant in the evening as it can increase the chances of fungal diseases.
Fertilization of Dioscorea thonneri De Wild. & T.Durand
For optimal growth and yield, Dioscorea thonneri De Wild. & T.Durand requires regular fertilization. The plant requires a balanced fertilizer rich in potassium, phosphorus, and nitrogen.
The best time to apply fertilizer is during the growing season, and it should be applied in moderate amounts regularly. Overfertilizing the plant can lead to burning of the leaves, which can damage the plant.
Organic fertilizers such as cow dung, poultry manure, and compost can also be applied to the plant.
Pruning of Dioscorea thonneri De Wild. & T.Durand
Pruning is not usually necessary for Dioscorea thonneri De Wild. & T.Durand. However, dead and damaged leaves and stems can be removed periodically to improve the appearance of the plant.
Pruning should be done using sterilized tools to prevent the spread of diseases. It is also crucial to avoid damaging the healthy parts of the plant while pruning.
Removing unwanted leaves and stems can also help in improving air circulation and light penetration, promoting the healthy growth of the plant.
Propagation Methods for Dioscorea thonneri De Wild. & T.Durand
Dioscorea thonneri De Wild. & T.Durand, commonly known as African yam or yellow yam, is a climbing perennial vine that is vegetatively propagated using the following methods:
Tuber Division
This is the most common method for propagating yams as it allows for multiplication of the plant. The tuber is cut into pieces, each with at least one healthy shoot bud. The cut pieces are then treated with a fungicide to prevent infections and planted in rich and moist soil 10-15 cm deep. The tubers should be planted in a location with partial sunlight to avoid scorching the plant.
Stem Cuttings
African yam can also be propagated using stem cuttings. Healthy stem cuttings that are 20-30 cm long with at least one node are selected. The leaves on the lower portion of the cutting are removed, and the cutting is then treated with a rooting hormone to encourage root development. The cutting is planted in well-drained soil, covered with a plastic bag to maintain humidity and placed in partial sunlight. The plastic bag should be removed gradually after the plant has had a chance to establish itself.
Air-layering
Air layering is another method used to propagate Dioscorea thonneri. A section of the stem with a branch is selected and wounded by removing a small section of about 1-2 cm of the bark. The exposed layer is then covered with moist sphagnum moss held in place with a plastic bag. Roots will develop in the moist moss and once roots are established the new plant can be separated and planted in rich and moist soil in a partial shade location.
Disease Management
Dioscorea thonneri De Wild. & T.Durand can fall prey to several diseases that affect the growth and yield of the plant. Some of the common diseases that affect Dioscorea thonneri are:
- Anthracnose: Symptoms of anthracnose include brown spots on the roots, stems, and leaves. To manage anthracnose, remove the affected plant parts and spray with a fungicide that contains copper or mancozeb.
- Bacterial Soft Rot: This disease causes the tissue to rot, and a foul smell is released. To manage bacterial soft rot, remove the affected plant parts and spray with a copper-based fungicide.
- Mosaic Virus: Symptoms of mosaic virus include mottled, chlorotic leaves. To manage mosaic virus, remove and destroy the infected plant parts immediately.
Pest Management
Several pests can attack Dioscorea thonneri De Wild. & T.Durand and cause significant damage to the crop. Some of the common pests that affect this plant are:
- Root-knot Nematode: These are microscopic worms that feed on the roots of the plant, causing them to become knotted and deformed. To manage root-knot nematode, rotate the crop with non-host plants or use organic soil amendments that are rich in beneficial nematodes.
- Scale Insects: These insects suck the sap from the plant, causing yellowing and wilting of the leaves. To manage scale insects, prune the affected plant parts and spray with a horticultural oil or insecticidal soap.
- Caterpillars: These pests can chew the leaves and stems of the plant, causing significant damage. To manage caterpillars, manually remove them from the plant or spray with an insecticide that contains Bacillus thuringiensis.
