Origin
Vigna sinensis (L.) Hassk., commonly known as cowpea or southern pea, is native to West Africa and has been cultivated for over 5,000 years for its nutritious seeds and leaves. It was introduced to the Americas during the transatlantic slave trade and has since become an important food crop in many countries.
Common Names
The cowpea has many common names such as black-eyed pea, China bean, Southern bean, southern cowpea, yardlong bean, crowder pea, and California blackeye.
Uses
The cowpea serves both as a food and animal feed. Its seeds are rich in protein, fiber, and essential amino acids, making it a valuable dietary staple in many parts of Africa, Asia, and the Americas. Cowpea leaves are also edible and can be used as a vegetable. In addition to its nutritional value, cowpea plants are used in animal feed and for soil improvement due to their ability to fix nitrogen in the soil.
General Appearance
The cowpea is an annual, climbing or trailing vine that can reach up to 2 meters in length and produces pods that can be up to 25 cm long. The leaves are trifoliate with two large lateral leaflets and a smaller terminal leaflet. The flowers are small and white to lavender in color. The seeds are oval-shaped, flat, and vary in color from white, cream, green, brown, and black.
Light Requirements
Vigna sinensis requires a lot of light to grow. Therefore, it is an excellent plant that can thrive in full sun or partial sun. Providing the plant with at least six hours of direct sunlight each day allows for healthy plant growth. If grown in partial shade, the plant may not produce as much fruit as it would under full sun conditions.
Temperature Conditions
Vigna sinensis requires warm temperatures to grow and produce fruit. The plant prefers a temperature range between 20°C to 30°C (68°F to 86°F). The plant can tolerate temperatures as low as 10°C (50°F), but it will not grow or produce fruit in these colder conditions.
Soil Requirements
Vigna sinensis prefers well-drained soils with a pH ranging from 6.0 to 7.5. The plant can grow in a variety of soil types, including sandy loam, clay loam, and loamy soils. The soil should also be rich in nutrients, especially nitrogen, phosphorous, and potassium, to ensure healthy plant growth and fruit production.
Cultivation Methods
Vigna sinensis is an annual or perennial climbing vine with tendrils that attaches itself to supports. It requires warm temperatures, sunlight, and well-drained soils with a pH of 6.0-6.5. It can be propagated via seed, which should be sown directly into the soil after the last frost. The spacing between the plants should be 15-20 cm with rows 30-45 cm apart.
Watering Needs
Vigna sinensis requires continuous moisture to grow healthily. During the growing season, it requires regular watering. Care must be taken not to overwater, as waterlogging can lead to root rot. Irrigation should only be carried out during the early mornings or late afternoon to prevent excessive evaporation.
Fertilization
The vine requires adequate nutrients for optimal growth. Therefore, it benefits from the application of organic and inorganic fertilizers. The fertilizer application should be done in two phases. The first phase is when the plant is just starting to grow. The second phase is during flowering and pod formation. A balanced NPK (nitrogen, phosphorus, and potassium) ratio of 20:10:20 is recommended.
Pruning
Pruning is necessary for a healthy and productive Vigna sinensis. Remove the lateral shoots to encourage upward growth, and pinch off the growing tips to control the plant's size. Prune regularly to remove dead, diseased, or damaged parts of the vine. After harvesting, cut back the plant to 10 cm above the ground to prevent the spread of diseases.
Propagation of Vigna sinensis (L.) Hassk.
Vigna sinensis (L.) Hassk., commonly known as yard-long bean or asparagus bean, is a legume crop widely grown for its tender and delicious pods. Propagation of yard-long bean is commonly done by seeds, but various vegetative methods can also be employed.
Propagation by Seeds
Seeds are the main method of propagating Vigna sinensis. The seeds can be collected from mature pods after the pods have dried on the vines naturally. The seeds should be stored in a cool, dry place until planting. The seeds must be sown in the garden after the danger of frost has passed. The soil must be fertile, well-drained, and in full sun position. Yard-long beans grow best in warm soil, so it is recommended to warm the soil before planting by covering it with black plastic for several days.
Propagation by Cuttings
Propagation by cuttings is another method used to propagate yard-long bean. The cuttings should be taken from young, healthy plants that are actively growing. The cuttings should be about 10 cm long and taken from the stem tips. After removing the leaves from the lower part of the stem, the cuttings should be planted in a pot filled with sand and peat moss, kept moist, and placed in a shaded location. The cuttings should root in about two weeks and can then be transplanted into the garden.
Propagation by Layering
Propagation by layering is a simple vegetative propagation method used for yard-long beans. Layering is done in the late spring or early summer. A healthy, strong stem should be chosen, and a shallow trench should be dug around the plant. The stem should be bent down to touch the soil in the trench, and the stem should be secured in place with wire or wooden pegs. The soil should be pressed down firmly over the trench. Roots should develop from the part of the stem in contact with the soil, and the new plant should be cut free from the parent plant and transplanted to a new location after two to three months.
Propagation by Grafting
Grafting is another vegetative propagation method that can be employed for Vigna sinensis. Grafting involves attaching the stem of one plant to the root system of another plant, creating a new variety with desirable traits. The rootstock of the plant should be chosen for its vigorous growth and disease resistance. The scion should be chosen for its desirable traits such as high yield or superior quality. The plants should be grown from seed and allowed to reach a height of 10 cm. The plants should then be cut at the stem and grafted using the splice grafting procedure. The grafted plants should then be allowed to grow in a suitable environment while they heal.
Disease management
Vigna sinensis, also known as cowpea, is susceptible to various fungal and bacterial diseases. The common diseases that affect this plant include Anthracnose, Angular leaf spot, Beans blight, and Root rot. To manage these diseases, it is essential to practice crop rotation and avoid planting cowpea in the same location for subsequent years. Keep the field clean and remove any debris and infected plants to prevent the spread of disease. Also, plant resistant varieties and apply fungicides or bactericides to control the spread of diseases.
Pest management
Cowpea is prone to various pest infestations like aphids, thrips, mites, pod borers, and bean beetles. To control aphids and thrips, apply insecticides like imidacloprid or use natural predators like ladybugs and lacewings. Mites feed on the undersides of leaves and can be controlled using acaricides. Pod borers lay eggs on flowers or pods and can be controlled using insecticides like carbaryl or cypermethrin. Lastly, bean beetles can be managed using insecticides or manually picking them off.
