Overview
Glycine subterranea L., commonly known as the African groundnut, is a leguminous plant species that belongs to the Fabaceae family. The plant is well-known for its edible seeds, which are often used in cooking, particularly in West African cuisine.
Origin
Glycine subterranea is native to tropical Africa, particularly in the regions of West and Central Africa. It is commonly found in countries such as Ghana, Nigeria, Cameroon, and Senegal. The plant is cultivated for its edible seeds, which can be eaten raw or processed into various food products.
Common Names
Aside from African groundnut, Glycine subterranea is known by several other names depending on the region. In Nigeria, it is called 'Epa', in Ghana, 'Nkatie Burger', in Sierra Leone 'Gbeni', and in Mali 'Belli'.
Uses
Glycine subterranea is primarily grown for its edible seeds, which are rich in protein, oil, and other nutrients. These seeds can be eaten raw or roasted and used in a variety of dishes, including stews, soups, and sauces. The plant's leaves and stems are also used for animal feed production. In addition, the plant is known for its nitrogen-fixing properties, which make it an important crop in sustainable farming practices.
General Appearance
Glycine subterranea is a climbing or trailing plant that can reach up to 1.5 meters in height. It has trifoliate leaves that are dark green in color and ovate in shape. The flowers of the plant are small, white, and purple and appear in clusters on the plant's stems. The edible seeds, which are round and flattened, are housed inside a pod that is buried underground.
Light Requirements
The plant Glycine subterranea L. requires a minimum of 6 to 8 hours of direct or indirect sunlight to grow well. Thus, it is suitable for cultivation outdoors or in a greenhouse where there is adequate light. Insufficient light can lead to stunted growth, yellowing of leaves, and poor yield. Therefore, it is crucial to ensure the plant receives enough light to photosynthesize effectively.
Temperature Requirements
The plant Glycine subterranea L. grows well in warm and humid conditions. It requires a temperature range of about 18 to 27 degrees Celsius (64 to 81 Fahrenheit) to grow successfully. The plant is susceptible to frost, and temperatures below 15 degrees Celsius (59 Fahrenheit) can harm or even kill it.
Soil Requirements
The plant Glycine subterranea L. thrives best in well-drained soils that hold moisture well. The soil pH should be between 6.0 and 7.5, which is slightly acidic to neutral. The plant will not grow well in waterlogged soils, which can result in root rot. Additionally, having enough organic matter in the soil enhances soil quality, improves drainage, and helps with water retention.
Cultivation Methods
Glycine subterranea L. or the African Yam bean is a hardy plant that can grow well in different soil types, including sandy, loamy and clay soil. It can also tolerate both acidic and alkaline soils, with a pH range of 4.5 to 8.0. The plant tends to do well in warm climates with temperatures ranging between 25°C to 30°C.
The seeds should be sown directly in the field because they have a long taproot system that makes them difficult to transplant. Plant them in rows with a spacing of 60cm between rows and 40cm within rows, placing the seeds 5 cm deep into the soil. Establishing the crop with good stand density is crucial to ensure high yields.
Watering Needs
Glycine subterranea L. requires adequate water to develop its taproot system, which can grow up to 2 meters deep. However, overwatering can lead to root rot and other fungal diseases. The plant requires about 600-900mm of rainfall every growing season; however, supplementary irrigation may be necessary during long dry periods.
To avoid overwatering, it is essential to plant the crop in well-draining soil that doesn't hold water for long periods. The use of mulch can also help conserve soil moisture.
Fertilization
Glycine subterranea L. requires adequate nutrients to produce high yields. A soil test should be conducted to determine the soil's nutrient requirements and the appropriate fertilizers to use. A nitrogen, phosphorous, and potassium (NPK) fertilizer with a ratio of 15:15:15 should be applied at planting, and then side-dressed with additional nitrogen and potassium at 4 and 8 weeks after planting.
Organic matter such as compost, manure, or legume residues can also be used to enrich the soil with essential nutrients.
Pruning
Pruning is not necessary for Glycine subterranea L. However, removing the plant's terminal buds at about 6 weeks after planting can encourage bushier growth and higher yields. Removing the yellow leaves after pod filling can also help reduce pest and disease incidences while increasing air circulation within the canopy.
Trimming the main stem of the plant to prevent shading is also necessary, especially for plants grown for their foliage. This should be done at about 60-90 cm above the ground to prevent injury to the plant.
Propagation of Glycine subterranea L.
Glycine subterranea L. or the African Yam Bean is propagated mainly by seeds or stem cuttings. The plant can also be propagated through tissue culture methods like somatic embryogenesis and organogenesis.
Seed Propagation
Seed propagation of Glycine subterranea L. is one of the most common methods. The seeds can be sown directly in the field or in seedbeds. The seedlings will emerge within 10 to 21 days after sowing. The ideal time to sow the seeds is at the beginning of the rainy season, as the plant prefers moist soil for germination.
The seedlings should be transplanted carefully to their permanent position when they are about 4 to 6 weeks old. The spacing of the planting holes should be 30 cm x 30 cm or 40 cm x 40 cm, depending on the soil fertility and the cultivar planted.
Stem Cutting Propagation
Glycine subterranea L. can be propagated through stem cuttings which are taken from healthy and disease-free mother plants. The cuttings should be about 20 cm long and should be taken from the middle portion of the stem. The cuttings should be treated with a rooting hormone and planted in a rooting medium.
The rooting medium should be a mixture of sand and soil or sand and sawdust. The cuttings should be placed in the medium about 5 cm deep and watered regularly. The ideal time to propagate through stem cuttings is at the beginning of the rainy season.
Tissue Culture Propagation
Tissue culture methods like somatic embryogenesis and organogenesis can also be used for propagating Glycine subterranea L. In somatic embryogenesis, embryos are developed from somatic cells under controlled laboratory conditions. Organogenesis involves the differentiation of organs from callus cultures.
Tissue culture propagation is advantageous as it allows for the production of large numbers of disease-free plants within a short period. However, this method requires specialized skills and equipment and is also relatively expensive compared to seed and stem cutting propagation.
Disease and Pest Management for Glycine subterranea L. Plants
Glycine subterranea L., commonly known as the underground or African yam bean, is a legume crop that is highly resilient to pests and diseases. However, some common diseases and pests can affect its growth and yield, such as:
Diseases:
Anthracnose: This disease is caused by Colletotrichum gloeosporioides and usually affects the pods and leaves of the plant. Symptoms include lesions on the pods, leaves, and stems, which are often sunken and circular. To prevent this disease, avoid planting infected seeds or in areas where the disease has been reported. Fungicide applications may also be used to control the disease.
Root rot: Root rot is often caused by fungi like Phytophthora and Pythium, which can lead to wilting, stunting, and reduced yield. To manage root rot, proper drainage and soil management should be ensured. Fungicide applications may also be used in severe cases.
Mosaic virus: This virus affects the Glycine subterranea L. plant by causing leaves to turn yellow and small, malformed pods to develop. It is primarily caused by aphid transmission and can be controlled through the use of insecticides.
Pests:
Aphids: Aphids are small insects that feed on plant sap and can cause stunted growth and yellowing of leaves. They can be controlled by using insecticides or introducing natural predators like ladybugs.
Bean Beetles: Bean beetles feed on leaves, causing them to curl and dry out. They can be controlled by handpicking the beetles or using insecticides.
Cutworms: Cutworms are the larvae of moths and feed on the plant stem at the soil level. They can be prevented through proper soil management and by using insecticides.
In conclusion, proper pest and disease management can significantly improve the growth and yield of Glycine subterranea L. plants. Practices like crop rotation, good soil management, and use of resistant varieties can also help reduce pest and disease pressure.
