Introduction
Dioscorea rotundata Poir. is a perennial vine belonging to the family Dioscoreaceae. It is commonly known as the white Guinea yam, and it is an important food crop in West Africa.Origin
Dioscorea rotundata Poir. is native to West Africa, particularly Nigeria and Ghana. It is widely cultivated in other countries, including Togo, Benin, Cameroon, and Ivory Coast.Common Names
Besides white Guinea yam, Dioscorea rotundata Poir. has other common names, such as African yam, yam tuber, Dioscorea, and yam.Appearance
The Dioscorea rotundata Poir. plant has a long stem that can grow up to 5 meters in length. It has heart-shaped leaves that are alternate on the stem, and the flowers are small and greenish-white. The tuber is the edible part of the plant, and it is usually cylindrical or round in shape and grows up to 1 meter in length and 10 centimeters in diameter. The outer surface of the tuber is rough, while the inner part is starchy, firm, and white.Uses
The tuber of Dioscorea rotundata Poir. is an essential food crop in West Africa, providing a significant source of carbohydrates. It is a staple food in Nigeria, where it is usually boiled, pounded, and used to make various traditional dishes. The plant also has medicinal properties and is believed to treat various ailments, including fever, asthma, and nausea. Additionally, the Dioscorea rotundata Poir. plant is used in both food and non-food industries for its high starch content. Its leaves and stem are also used for animal feed.Growth Conditions of Dioscorea rotundata Poir.
Light: Dioscorea rotundata Poir. grows best in full sunlight, but can also tolerate partial shade. However, insufficient light can result in reduced yield and poor tuber quality.
Temperature: The optimal temperature range for Dioscorea rotundata Poir. growth is between 25-30°C. Temperatures below 18°C can negatively affect tuber formation and growth, while temperatures above 35°C can cause plant stress and reduced yield.
Soil Requirements: Dioscorea rotundata Poir. prefers well-drained soils with high organic matter content. The optimal pH range for growth is between 5.5-6.5. Soil that is too acidic or alkaline can negatively affect plant growth and tuber development.
Water: Dioscorea rotundata Poir. requires regular and adequate watering throughout the growing season. Waterlogging and insufficient water can negatively affect growth and yield.
Nutrients: Dioscorea rotundata Poir. requires sufficient nutrients for optimal growth and yield. The major nutrients required include nitrogen, phosphorus, and potassium. Micronutrients such as calcium, magnesium, and iron are also important for growth and development.
Cultivation of Dioscorea rotundata Poir.
Dioscorea rotundata Poir., also known as white yam, is a tuberous plant that grows in tropical regions. While it is generally a hardy plant, it thrives in well-drained soils with a pH level between 5.5 and 6.5. Planting should be done in areas with plenty of sunlight, as yields are highest in regions with up to 10 hours of sunlight each day.
The ideal temperature range for the cultivation of Dioscorea rotundata Poir. is between 25 and 30 degrees Celsius. It is important to note that excessive temperatures can harm the plant, so adequate irrigation is necessary to regulate temperature and maintain proper humidity levels.
Watering Needs of Dioscorea rotundata Poir.
Regular irrigation is necessary for the optimal growth and development of Dioscorea rotundata Poir. The plant should be watered at least once a week, and more frequently during periods of drought. Over-watering may cause roots to rot, so it is important to exercise caution when watering the plant.
Fertilization of Dioscorea rotundata Poir.
Applying fertilizer is crucial in promoting the growth and development of Dioscorea rotundata Poir. Cow dung or any other organic fertilizer should be applied during planting and at intervals throughout the growing season. Using mineral fertilizers, including nitrogen, potassium, and phosphorus, is also an effective way to increase yields.
It is essential to conduct a soil analysis to determine the appropriate dosages of fertilizer. Appropriate fertilization not only improves plant growth but also encourages the production of high-quality tubers.
Pruning Dioscorea rotundata Poir.
Pruning helps regulate the growth of Dioscorea rotundata Poir., and It involves the removal of excess leaves, shoots, and vines. Pruning is normally done when the plant reaches a height of approximately 1.5 meters.
Pruning not only helps space the plant and improve air circulation but also increases sunlight penetration and hence leads to higher yields. It is essential to avoid excessive pruning, as this may negatively impact the growth of the plant and reduce tuber yields.
Overview of Dioscorea rotundata Poir.
Dioscorea rotundata Poir., also known as white yam, is an important food crop in West Africa. It is a tuber crop that is widely cultivated for its edible underground tubers, which are rich in carbohydrates and serve as a source of dietary fiber, vitamin C, and antioxidants.
Propagation of Dioscorea rotundata Poir.
The propagation of Dioscorea rotundata Poir. can be done through different methods.
Seed propagation
Dioscorea rotundata Poir. produces viable seeds, but their use is not common due to the long germination period. The seeds can take up to six weeks to germinate, and they require a long warm season to mature.
Vine cuttings
The most common method of propagating Dioscorea rotundata Poir. is by vine cuttings. Vine cuttings are taken from mature vines, and they are planted in a prepared field or nursery. The cuttings should be taken from the middle part of the vine and should be of approximately six feet in length. They should be planted horizontally, and only about one-third of the cutting should be buried in the soil. The cuttings should be covered with soil to a depth of about three inches. The cuttings will produce new shoots and roots, and they will develop into new plants.
Tuber propagation
Dioscorea rotundata Poir. can also be propagated through tuber cuttings. The tubers are cut into pieces, and each piece should have at least one bud. The tuber pieces are planted in a prepared field or nursery. The cuttings should be planted about four inches deep in the soil. The tuber cuttings will produce new shoots and roots, and they will develop into new plants.
Disease Management
Dioscorea rotundata Poir. is susceptible to several diseases, some of which include:
- Anthracnose: This disease is caused by the fungus Colletotrichum gloeosporioides and is characterized by leaf spots, stem cankers, and stem rot. To manage anthracnose, affected plant parts should be removed and destroyed. Fungicides may be applied to protect the plant from further infection.
- Black Rot: This disease is caused by the fungus Diplodia tubericola and is characterized by circular lesions on the leaves, stem, and tubers. The lesions may become sunken and turn black. To manage black rot, affected plant parts should be removed and destroyed. Fungicides may also be applied preventively.
- Yam Mosaic Virus: This viral disease is characterized by yellowing and mosaic patterns on the leaves. It can be spread by aphids and infected planting material. To manage yam mosaic virus, infected plants should be removed and destroyed. Aphids should be managed by applying insecticides or using natural predators like ladybugs.
Pest Management
Dioscorea rotundata Poir. is also susceptible to several pests, some of which include:
- Yam Beetle: This pest feeds on the leaves and stem of the plant and can cause significant damage. To manage yam beetles, planting should be done in areas where the pest population is low. Insecticides may also be applied as needed.
- Yam nematodes: These pests live in the soil and feed on the roots of the plant, causing stunted growth and poor yield. To manage yam nematodes, crop rotation should be practiced, and infected soil should be solarized. Nematode-resistant varieties may also be planted.
- Yam tuber beetles: These pests feed on the tubers, causing significant damage. To manage yam tuber beetles, proper storage of harvested tubers should be practiced. Insecticides may also be applied as needed.
