Overview of Dioscorea dumetorum (Kunth) Pax var. lanuginosa A.Chev.
Dioscorea dumetorum (Kunth) Pax var. lanuginosa A.Chev., commonly known as Bitter Yam, is a perennial and climbing vine that belongs to the family Dioscoreaceae. This plant is usually found in tropical regions in West and Central Africa, in countries such as Nigeria, Cameroon, Congo, Ghana, Uganda, and Sierra Leone.
General Appearance of Dioscorea dumetorum (Kunth) Pax var. lanuginosa A.Chev.
The Bitter Yam is a robust plant that can grow up to three meters in length. It has heart-shaped leaves that are about 10-15 cm in length and width. The plant produces a dense cluster of small, greenish-yellow flowers which develop into fleshy, cylindrical fruits that are about 6-8 cm long and 3-4 cm in diameter. The outer surface of the fruit is hairy and has a hard shell that encloses up to 40 seeds.
Common Names of Dioscorea dumetorum (Kunth) Pax var. lanuginosa A.Chev.
Dioscorea dumetorum (Kunth) Pax var. lanuginosa A.Chev. is known by different common names across the regions it is found in. In Nigeria, it is called Bitter Yam, Ako in Cameroon, Nwankasi in Igbo, and Ijesu or Ijenu in Yoruba. In Sierra Leone, it is known as Kakara or Kakra, while in Uganda, it is called Nyakatunguru.
Uses of Dioscorea dumetorum (Kunth) Pax var. lanuginosa A.Chev.
Bitter yam has many medicinal uses, and different parts of the plant are used to treat various ailments. The roots and tuber of the plant are used to treat fever, constipation, and stomach pains, while the leaves and stem are used to treat skin infections and wounds. In some regions, the plant is used to make soap, and the mashed tubers are used as a traditional contraceptive.
Bitter yam is also used as food, although the tubers require special processing to remove the bitter taste before they become edible. The tubers are cooked, pounded, and washed in water several times to remove the bitterness. Once processed, the tubers are used to make porridge, soup, or added to other foods for nutritional balance.
In conclusion, Dioscorea dumetorum (Kunth) Pax var. lanuginosa A.Chev.is a significant plant in West and Central Africa, with a variety of medicinal and nutritional uses.
Light Requirements
Dioscorea dumetorum (Kunth) Pax var. lanuginosa A.Chev. typically thrives in locations with partial shade to full sun exposure. Having too little light can stunt the plant's growth and cause it to become leggy, whereas excessive sunlight can damage the foliage.
Temperature Requirements
The plant grows best in warm, tropical environments with temperatures between 20°C and 35°C (68°F to 95°F). The roots can tolerate temperatures slightly below freezing, but the leaves and stem are sensitive to frost. In areas with cold winters, it's best to grow the plant indoors.
Soil Requirements
The plant prefers well-draining, fertile soils with a pH between 5.5 and 6.5. Clay and loamy soils are also suitable, provided they are rich in organic matter. The soil should be kept moist but not waterlogged, as excessive moisture can promote fungal growth and damage the roots. Adequate drainage is crucial to prevent waterlogging.
Cultivation
When cultivating Dioscorea dumetorum var. lanuginosa A. Chev., it is important to note that it prefers a well-draining, fertile soil that is rich in organic matter. The plant also requires a warm and humid climate with plenty of sunlight. It can be grown in regions with enough rainfall or irrigated areas.
The plant is usually propagated through tubers. Before planting the tubers, they should be treated with a fungicide or ash to prevent rot. Plant the tubers about 8 to 10 cm deep into the soil with their sprouts facing upward. It takes about 4 to 6 months to harvest the tubers after planting.
Watering Needs
Dioscorea dumetorum var. lanuginosa A. Chev. requires regular watering to produce optimal yields. The plants should be watered regularly, especially during the dry season. However, too much water can cause root rot, and it is crucial to ensure that the soil is well aerated.
Fertilization
Fertilizers can improve the yield of this plant. It is advisable to use organic manure. Apply a layer of compost on the soil to improve the nutrient content of the soil. Alternatively, apply a balanced NPK fertilizer before planting. Use approximately 100 grams of NPK fertilizer per hole during planting and another 100 grams for cadastral measurement.
Pruning
Pruning is an essential practice in Dioscorea dumetorum var. lanuginosa A. Chev. cultivation. It is recommended to remove the stems of the plant that have grown along the ground to promote upward growth and improve light penetration. Additionally, removing the dead stems and leaves of the plant promotes healthy plant growth.
Pruning should be done after the final harvest when the plant enters dormancy.
Propagation of Dioscorea dumetorum (Kunth) Pax var. lanuginosa A.Chev.
Dioscorea dumetorum (Kunth) Pax var. lanuginosa A.Chev. can be propagated through different methods:
Tissue Culture Propagation
Tissue culture propagation is the most common form of propagation for Dioscorea dumetorum (Kunth) Pax var. lanuginosa A.Chev. In this method, small pieces of plant tissue, such as the shoot tip, are taken from a mother plant and then placed onto a culture medium. The tissue then grows into a new plant that is genetically identical to the mother plant.
Seed Propagation
Another method of propagation for Dioscorea dumetorum (Kunth) Pax var. lanuginosa A.Chev. is through seed propagation. The seeds are obtained from flowering plants and then sown in a well-prepared seedbed. The seedbed should be moist and warm to facilitate germination. The seeds will germinate after a few weeks, and the seedlings are then transplanted into individual pots or directly into the field.
Cuttings Propagation
Dioscorea dumetorum (Kunth) Pax var. lanuginosa A.Chev. can also be propagated through cuttings. A stem cutting about 20-30 cm long is taken from a healthy plant and then planted in a well-prepared soil mixture. The cutting should be kept moist and placed in a shaded environment to encourage rooting. After a few weeks, the cutting should have developed roots and can be transplanted into a larger pot or field.
Disease Management
One of the common diseases that can affect Dioscorea dumetorum is anthracnose caused by Colletotrichum gloeosporioides. This disease leads to the formation of black lesions on stems and leaves, eventually causing the plant to die. To manage anthracnose, it is advisable to remove and destroy all infected plant parts and use fungicides such as copper oxychloride or mancozeb.
Another disease that can affect Dioscorea dumetorum is yam mosaic virus, which causes yellowing of leaves and stunted growth. It is transmitted by aphids and can be controlled by using resistant cultivars, practicing good hygiene, and removing and destroying infected plants.
Black rot, caused by the fungus Ceratocystis fimbriata, also affects Dioscorea dumetorum. It causes the stem to rot, leading to wilting and death. To manage black rot, it is essential to remove and dispose of all infected plant debris and use fungicides such as copper-based products.
Pest Management
Aphids are a common pest of Dioscorea dumetorum, and their infestation can cause stunted growth and reduced yield. They can be controlled by using insecticides such as neem oil or soap sprays. In addition, companion planting with plants such as marigold or dill can repel aphids.
The sweet potato weevil, Cylas puncticollis, is another pest that can cause significant damage to Dioscorea dumetorum. It feeds on the leaves and stems of the plant and can cause wilting and death. To manage infestations, it is advisable to use integrated pest management strategies such as crop rotation, intercropping with non-host crops, and using a combination of chemical and biological control measures.
