Overview: Vigna unguiculata (L.) Walp. var. unguiculata
Vigna unguiculata (L.) Walp. var. unguiculata, commonly known as cowpea, is a leguminous plant species belonging to the Fabaceae family. It is an annual crop that is widely cultivated in African, Asian, and Latin American countries and holds significant cultural and economic importance in those regions.
Origin and Distribution
The exact origin of cowpea is unknown. However, it is believed to have originated from West Africa and is one of the oldest crops in the continent. Cowpea cultivation gradually spread to other parts of the world, including Asia, Americas, and Europe.
Cowpea is now widely grown in warm, tropical, and subtropical regions across the world that have suitable growing conditions. It is an important crop in Africa, where it is widely cultivated for its high protein content, ability to tolerate drought, and capacity to fix nitrogen in soil.
Common Names
Cowpea has several common names across different regions of the world. It is known as black-eyed pea, southern pea, yardlong bean, niebe, chawli, and lobio in different areas where it is grown.
Appearance
Cowpea is a bushy plant that can grow up to 2 meters in height. It has a tap root system and produces branched stems with trifoliate leaves that are green in color. The leaves are alternate and petiolate, with elliptical to ovate leaflets that are about 2 to 8 cm long and 1 to 6 cm wide.
The flowers of cowpea come in different colors, including white, cream, yellow, and purple. They are arranged in racemes and have an irregular shape. The fruits of the plant are pods that are about 10 to 20 cm long and 1 to 2 cm wide and contain 5 to 15 seeds.
Uses
Cowpea is a highly nutritious crop that is rich in protein, fiber, and vitamins. The crop is used in various ways, including as food, animal feed, and forage. The leaves of the plant are also consumed as a vegetable in some regions of the world and are a rich source of iron, calcium, and vitamins A and C.
Due to its ability to fix nitrogen in soil, cowpea is often grown as a cover crop or intercropped with other crops to improve soil fertility. Cowpea is also used in crop rotation to help suppress weed growth and improve soil structure and water retention.
In traditional medicine, cowpea is used to treat various health conditions, including diabetes, hypertension, and inflammation. The plant extract has been found to have antioxidant, antimicrobial, and anticancer properties.
Overall, Vigna unguiculata (L.) Walp. var. unguiculata, or cowpea, is a versatile and important crop that plays a significant role in the agriculture, food, and health sectors of many countries. Its cultivation and use have helped improve the livelihoods of many households, particularly in regions where it is considered a staple crop.
Light Requirements
Vigna unguiculata var. unguiculata prefers full sun exposure for optimal growth and productivity. It can tolerate partial shade but may result in reduced yield and delayed maturity. It is essential to provide at least six hours of direct sunlight per day for efficient photosynthesis and carbohydrate accumulation.
Temperature Requirements
The optimal temperature range for Vigna unguiculata var. unguiculata growth is between 25 and 35°C. It can tolerate a wide range of temperatures from 15 to 40°C, but extreme heat or cold can hinder growth and survival. It is recommended to plant the crop after the last frost in spring and harvest before the first frost in autumn.
Soil Requirements
Vigna unguiculata var. unguiculata can grow in various soil types, including sandy, loamy, and clayey soils. However, it prefers well-draining, fertile soils with a pH range between 6.0 and 7.0. Soil with high organic matter content can enhance water-holding capacity and nutrient availability, leading to better crop growth and yield.
Cultivation Methods
Vigna unguiculata (L.) Walp. var. unguiculata, also known as cowpea, is an annual crop that is easy to cultivate. It can be propagated by seeds, and it thrives in warm climates with well-drained soil. It is also important to ensure that the crop is planted in a location that receives adequate sunlight.
Before planting, the soil should be prepared by removing all weeds and rocks. The depth of planting should be no more than 2-3 centimeters, and it is important to plant the seeds at a spacing of 10-15 centimeters apart. The seeds should be watered immediately after planting to initiate germination.
Watering Needs
Water is essential for the growth of Vigna unguiculata (L.) Walp. var. unguiculata. It is important to ensure that the crop is watered regularly to prevent drought stress. The frequency of watering will depend on the climate and soil conditions in the area. However, it is advisable to water the crop at least twice a week during the growing season.
It is important to water the crop in the early morning or evening to prevent water evaporating in the hot sun and reducing water stress to the plant. The soil should be moist but not waterlogged, as waterlogging can lead to root rot and other diseases.
Fertilization
Vigna unguiculata (L.) Walp. var. unguiculata requires adequate nutrients to grow properly. It is important to fertilize the crop at the right time to ensure maximum yield. Nitrogen, phosphorus, and potassium are all essential nutrients that should be included in the crop's fertilizer.
The crop should be fertilized 3 weeks after planting. Additional applications should be done after 6 weeks and 9 weeks, respectively. The amount of fertilizer applied will depend on the soil fertility, but 20-30 kg/ha of nitrogen, 40-60 kg/ha of phosphorous, and 20-30 kg/ha of potassium are recommended.
Pruning
Pruning is not a necessary practice for Vigna unguiculata (L.) Walp. var. unguiculata. However, removing damaged, diseased, or broken stems and leaves can help to promote healthy growth. It can also help to reduce the spread of plant diseases and pests.
Pruning should be done during the growing season, preferably in the early morning or evening when the plant is cool to avoid stress to the plant. The pruning tools should be disinfected before and after use to avoid spreading diseases to the plant.
Propagation of Vigna unguiculata (L.) Walp. var. unguiculata
Vigna unguiculata (L.) Walp. var. unguiculata is propagated through both sexual and asexual methods. The plant is an annual and has a short growing season. It is primarily grown for its edible seeds, which can be used in a variety of dishes.
Sexual Propagation:
The sexual propagation method for Vigna unguiculata (L.) Walp. var. unguiculata is through seed. The seeds are directly sown in the field after the last frost. The seeds should be planted 2-3 cm deep in well-prepared soil at a spacing of 30-60 cm between rows, depending on the variety and planting system. In general, the seeds will germinate within 7-10 days after sowing. The young seedlings should be thinned to ensure optimal spacing between plants.
Asexual Propagation:
Vegetative propagation is also possible for Vigna unguiculata (L.) Walp. var. unguiculata. The most commonly used propagation method is stem cutting. The stem cuttings for this plant should be taken from mature, healthy plants of the desired variety. The cuttings should be about 10-15 cm long and should be taken from the middle or top section of the plant. The leaves on the bottom half of the cutting should be removed, and the cutting should be allowed to dry for a few hours before planting. The cuttings should be planted in moist soil about 2-3 cm deep and should be protected from direct sunlight until they establish roots. It takes about 2-3 weeks for the cuttings to root and start to grow.
Disease Management
Vigna unguiculata (L.) Walp. var. unguiculata is susceptible to various diseases. Some common diseases that might affect the plant include:
- Anthracnose: This fungal disease appears as small dark spots on leaves, stems, and pods. The spots enlarge, become sunken, and develop a red or brown coloration in the center. Manage it by using fungicides and practicing crop rotation.
- Southern blight: This disease affects the roots and stem base of the plant. It causes the leaves to wilt and the stem to rot. Prevent this disease by planting the crop in well-drained soil.
- Mosaic virus: This virus causes the leaves to become mottled with yellow and green patches. It affects the growth rate of the plant and reduces yield. Practice good insect control to prevent the spread of the virus.
Pest Management
Vigna unguiculata (L.) Walp. var. unguiculata is also susceptible to various pests. Some common pests that might affect the plant include:
- Aphids: These small insects can infest the plant by sucking on the sap from the leaves. They cause the leaves to curl and turn yellow. Use insecticidal soaps to manage the infestation.
- Spider mites: These tiny pests can infest the plant by sucking sap from the leaves. They cause the leaves to become stippled and eventually fall off. Use miticides to manage the infestation.
- Armyworms: These caterpillars can defoliate the plant. They cause the leaves to have ragged edges. Manage the infestation by using insecticides and practicing crop rotation.
