Voandzeia Subterranea (l.) Dc. - >>vigna Subterranea

Overview of Voandzeia subterranea

Voandzeia subterranea, also known as Bambara groundnut, is a herbaceous plant that belongs to the Fabaceae family. It is a unique and less known legume crop that grows underground despite having a visible foliage above the ground.

Appearance of Voandzeia subterranea

The plant has aerial stems that can reach up to half a meter long with triple leaves of elliptic shape. Underground, its tuberous roots can stretch to a depth of half a meter, developing small-sized nuts that are about 1-3 cm dimensionally. It has a rough beige-colored skin encapsulating the decorticated nuts, which appear tan color with speckles.

Origin and Distribution of Voandzeia subterranea

The origins of Voandzeia subterranea can be traced to Africa, particularly West Africa. Currently, the cultivation of the plant is widespread in different African countries, India, and other tropical regions. Voandzeia subterranea is viewed as an undervalued species and used predominantly as a subsistence crop in the areas in which it is grown.

Uses of Voandzeia subterranea

The bean and tuberous roots of Voandzeia subterranea are popular ingredients in traditional dishes of Africa, Asia, and South America. They serve as a critical source of nutrients and protein. The crop is also useful for soil conservation, owing to its deep-ranging roots that enhance soil structure and fertility. Besides, Voandzeia subterranea has shown potential in treating and preventing several diseases, such as diabetes, cancers, and hypertension.

In conclusion, Voandzeia subterranea is an unusual plant with remarkable attributes worthy of appreciation. Its underground growth and various uses make it a valuable crop to the people of West Africa and other tropical regions.

Light Requirements

The plant Voandzeia subterranea (L.) DC. requires minimum sunlight exposure of six hours. It grows well in bright and indirect sunlight, which helps in its growth rate. Too much exposure to direct sunlight can be harmful to the plant, leading to wilting of the leaves. Therefore, it is essential to ensure that it is not exposed to direct sunlight for prolonged periods.

Temperature Requirements

The plant requires a warm climate for proper growth. The optimum temperature range for Voandzeia subterranea (L.) DC. growth is between 20 to 28°C. The plant cannot withstand freezing temperatures, and temperatures below 10°C may affect the growth rate. Therefore, it is important to protect it from extreme temperatures by planting it in a greenhouse or growing it indoors.

Soil Requirements

Voandzeia subterranea (L.) DC. can grow in a wide range of soil types, including sandy, loamy, and clay soils. However, it grows best in moderately fertile, well-draining soil. The plant prefers a slightly acidic to neutral pH (around 6.0-7.0). It is essential to ensure that the soil is not waterlogged, as this can hinder proper growth or lead to root rot. Therefore, it is recommended to water the plant moderately and avoid excessive watering.

Cultivation Methods for Voandzeia subterranea (L.) DC.

Voandzeia subterranea (L.) DC., also known as Bambara groundnut, is cultivated mainly for its edible seeds which are high in protein content. The plant is grown in tropical and subtropical regions and can adapt to different soil types, from sandy to heavy clay soils. The cultivation of Bambara groundnut involves the following steps:

• Choose a well-drained site that receives full sun exposure for at least 6 hours a day.
• Sow seeds directly into the soil at a depth of 3-5 cm and 10-15 cm apart.
• Water the soil immediately after planting to promote germination.
• Thin out the seedlings when they reach a height of 10-15 cm to reduce competition for nutrients.
• Mulch the soil to conserve moisture and suppress weed growth.

Watering Needs for Voandzeia subterranea (L.) DC.

Bambara groundnut requires a consistent supply of moisture for optimum growth and high yield. The watering needs of the plant depend on the soil type, weather conditions, and stage of growth. Some tips for watering Voandzeia subterranea (L.) DC. are:

• Water the plant deeply and infrequently to encourage deep root growth.
• Avoid overwatering which can lead to waterlogging and root rot.
• Water the plant in the early morning or late evening to reduce evaporation losses.
• Use drip irrigation or a soaker hose to deliver water directly to the plant roots while minimizing water wastage.
• Monitor soil moisture levels regularly and adjust watering frequency as needed.

Fertilization of Voandzeia subterranea (L.) DC.

Bambara groundnut responds well to organic fertilizers and requires a balanced supply of nutrients for healthy growth and yield. Here are some tips for fertilizing Voandzeia subterranea (L.) DC.:

• Apply well-rotted compost or manure before planting to enrich the soil with organic matter.
• Top-dress the plants with a nitrogen-rich fertilizer during the vegetative growth stage to promote leaf development.
• Apply a phosphorus-rich fertilizer during flowering and pod formation to enhance seed production.
• Avoid using excessive amounts of fertilizer which can lead to nutrient imbalances and environmental pollution.
• Monitor soil fertility levels regularly and adjust fertilizer application rates as needed.

Pruning Voandzeia subterranea (L.) DC.

Pruning is not necessary for Voandzeia subterranea (L.) DC. as the plant grows as a low-lying groundcover that does not require support. However, some general guidelines for pruning are:

• Remove any dead or damaged leaves and stems to promote plant health.
• Pinch off the tips of young plants to encourage bushy growth.
• Thin out dense areas of the plant to improve air circulation and reduce disease incidence.
• Avoid pruning during the flowering and pod formation stage as this can reduce seed production.

Propagation of Voandzeia subterranea (L.) DC.

Voandzeia subterranea (L.) DC., commonly known as Bambara groundnut, is typically propagated through seeds, which are the primary method of propagation. However, this plant can also be propagated vegetatively through cuttings or by dividing the tubers.

Propagation by seeds

The seeds of Voandzeia subterranea (L.) DC. typically have a germination rate of 80-85%, making them an efficient method of propagation. The seeds should be sown during the rainy season, in well-draining soil that has been enriched with organic matter. It is important to maintain adequate moisture levels during the germination period, which usually takes about 7-10 days. Once the seedlings reach a height of about 10 cm, they can be transplanted to their permanent location.

Vegetative propagation

Voandzeia subterranea (L.) DC. can be propagated vegetatively through cuttings taken from mature plants, particularly those that are about 3 years old. The cuttings, which should be about 10-15 cm long, should be taken from stem tips that are just starting to harden. They should be planted in a well-drained, nutrient-rich soil, and their cut ends should be immersed in rooting hormone. The cuttings should be kept in a humid environment with adequate moisture and should develop roots within 2-3 weeks.

Propagation by tuber division

Propagation by tuber division involves separating the mature tubers of the plant into small segments, each containing a bud. The segments should be planted during the rainy season in well-draining soil that has been enriched with organic matter. Adequate moisture levels should be maintained during the growing period to ensure successful propagation. This method should only be used as a last resort, as it can result in uneven growth and reduced yield.

Disease Management

Voandzeia subterranean is prone to various diseases that affect the plant's growth and overall yield. Some common diseases that may affect the plant include:

• Anthracnose: This fungal disease attacks the plant's leaves, causing yellowing, browning, and spotting. It can be managed by spraying fungicides such as copper-based fungicides or carbendazim.
• Root rot: This is a fungal disease that affects the plant's roots, causing stunted growth, wilting, and eventually death. It can be avoided by growing the plant in well-drained soils and avoiding over-watering.
• Mosaic virus: This viral disease can cause curling, mottling, and discoloration of the leaves. It can spread rapidly among plant populations and is often spread by pests. It can be avoided by planting virus-free seeds and controlling pest infestations.

Pest Management

Aside from diseases, pests can also significantly affect the growth and yield of Voandzeia subterranean. Some common pests that may affect the plant include:

• Aphids: These tiny insects suck sap from the plant's leaves, causing the leaves to wilt and distort. They can be controlled by spraying the plant with soapy water or pesticides such as neem oil.
• Bean fly: The bean seed fly is a pest that lays eggs on the plant's stems and leaves, and the larvae feed on the plant's tissue. It causes wilting, stunted growth, and plant death. Infested plants should be destroyed, and crop rotation should be practiced.
• Cutworms: These pests are nocturnal and feed on the plant's stems, causing breakage and wilting. It can be controlled by applying insecticides such as carbaryl or spinosad to the soil around the plant.