Plant Description:
Dioscorea sylvatica Eckl. var. rehmannii (Baker) Burkill is a twining vine that belongs to the family Dioscoreaceae. It has elliptic to ovate leaves with heart-shaped bases and pointed tips. The plant is known for its large underground tubers, which can grow up to 4 kg in weight.
Origin and Common Names:
Dioscorea sylvatica Eckl. var. rehmannii (Baker) Burkill is native to southern and eastern Africa, where it grows in savannas and forests. It is commonly known as the forest yam or the African potato. In South Africa, it is known as the "inkpot" because of the shape and color of its tubers. In other parts of Africa, it may be called "matoke" or "nduma."
Uses:
The tubers of Dioscorea sylvatica Eckl. var. rehmannii (Baker) Burkill are an important source of food for many communities in Africa. They can be boiled, roasted, or mashed and are often used in stews and soups. In addition to its use as a food crop, the plant has also been traditionally used for medicinal purposes. The tubers are believed to have anti-inflammatory and analgesic properties and may be used to treat fever, rheumatism, and other ailments.
The plant has also been studied for its potential as a crop for sustainable agriculture. The tubers are able to grow in nutrient-poor soils and can be harvested without damaging the plant, making it a good option for small-scale farmers in rural areas.
Light Requirements
Dioscorea sylvatica Eckl. var. rehmannii (Baker) Burkill is a shade-tolerant plant. It grows better under partial shade or filtered sunlight conditions. Direct sunlight exposure can lead to drying of the soil, which can be avoided by providing a partially shaded environment to the plant.
Temperature Requirements
The plant prefers a warm and humid environment for optimal growth. The minimum temperature requirement for the plant is about 20°C, while the maximum temperature should not exceed 35°C. The plant cannot tolerate frost or extreme cold environments and may wither away quickly if exposed to such conditions.
Soil Requirements
The plant requires well-drained soil with good moisture retention. The ideal soil pH should range between 5.5 and 6.5. The plant grows best in soil that is rich in organic matter and has good aeration. Sandy loam soils are the most suitable for the plant, while heavy clay soils may hinder proper growth and development.
Cultivation
Dioscorea sylvatica Eckl. var. rehmannii (Baker) Burkill, commonly known as the Forest Yam, requires a bit of extra care during cultivation. It requires mild temperatures, with an optimal range being between 22°C and 28°C. It grows well in sandy-loamy soils with a pH range of 6.5 to 7.5. The Forest Yam also requires partial shade for optimum growth.
Watering Needs
The Forest Yam needs regular watering to maintain the soil's moisture levels for proper growth and tuber formation. It is imperative to ensure that the soil is consistently moist but not waterlogged. Overwatering can cause the tubers to rot, which can cause significant plant damage.
Fertilization
The application of nitrogenous fertilizer is necessary for optimum growth and tuber formation. The quantity of fertilizer applied depends on the soil type and fertility. It is advisable to apply a balanced dose of nutrients to the soil before planting to ensure healthy tuber formation. Applying organic manure before the planting season can also enhance soil fertility.
Pruning
Pruning is not necessary for Forest Yam. However, removing damaged leaves and branches can help control the spread of diseases and pest infestations. Removing unwanted growth can also help improve air circulation around the plant, leading to healthy growth.
Propagation of Dioscorea sylvatica Eckl. var. rehmannii (Baker) Burkill
Dioscorea sylvatica Eckl. var. rehmannii (Baker) Burkill can be propagated sexually and asexually.
Sexual Propagation
The plant can be propagated through seeds. The seeds must be collected from the mother plant, and sowed immediately as they have a short viability. The seeds are planted at a depth of 1 to 2 cm in fertile, well-drained soil. Regular watering is necessary, and the plant will germinate within two to four weeks. The seedlings can be transplanted after they have grown to a height of about 10 cm.
Asexual Propagation
The plant can also be propagated asexually through vegetative means such as division and stem cutting.
Division: To propagate through division, the tubers are dug up and separated into sections, making sure that each section has a viable bud. These sections are then planted immediately in a well-drained soil mixture and watered regularly. It generally takes about one to two years for the plant to reach maturity.
Stem Cutting: To propagate through stem cutting, select healthy stems with leaves, and trim them to about 10 cm in length. The leaves on the lower half of the stem are removed, and the cutting is planted in a well-drained soil mixture. The cutting is watered regularly, and it takes about two to three weeks for roots to form, and the plant to establish itself.
Disease Management
Dioscorea sylvatica Eckl. var. rehmannii (Baker) Burkill is susceptible to a range of diseases that can cause significant damage if left untreated. Common diseases affecting the plant include:
- Anthracnose: This fungal disease can cause leaf spots, stem blight, and fruit rot. To manage anthracnose, affected plants should be treated with a fungicide containing copper-based products.
- Rust: Rust is a fungal disease that appears as yellow, orange, or brown pustules on the underside of leaves. To prevent rust, maintain adequate spacing between plants to improve airflow and remove any infected leaves and debris from the area.
- Mosaic virus: Mosaic virus affects the overall growth and development of the plant, causing yellow or white patterns on the leaves. There is no cure for mosaic virus, and infected plants should be removed and destroyed to prevent the spread of the disease.
Pest Management
Dioscorea sylvatica Eckl. var. rehmannii (Baker) Burkill is also susceptible to pest infestations that can cause severe damage. Common pests affecting the plant include:
- Whiteflies: Whiteflies are small, winged insects that feed on the sap of the plant, causing wilting and stunted growth. To prevent whiteflies, regularly spray the plant with insecticidal soap, neem oil, or other organic insecticides.
- Spider mites: Spider mites are tiny pests that feed on the plant's sap, causing leaf damage and stunted growth. To prevent spider mites, regularly spray the plant with warm water, neem oil, or insecticidal soap.
- Caterpillars: Caterpillars are the larvae of moths and butterflies that can cause significant damage by feeding on the leaves. To prevent caterpillars, inspect the plant regularly and remove any visible caterpillars by hand or use Bt (Bacillus thuringiensis) insecticides.
