Overview
Dolichos angustifolius Eckl. & Zeyh., also known as the narrow-leaved cowpea, is a tropical and subtropical plant that belongs to the family Fabaceae. It is an essential food and forage crop in many parts of Africa, Asia, and South America.
Origin and Distribution
The plant is believed to have originated in Africa and is widely distributed throughout the continent. It has been introduced to many other regions, including Asia, the Americas, and the Pacific Islands. In these regions, it is grown as a food crop, a forage crop, and for soil improvement.
Appearance
Dolichos angustifolius is a climbing or trailing annual plant that reaches a height of up to 2 meters. It has a strong stem with many branches and leaves that are elongated and narrow, measuring about 7-10 cm in length and 1-1.5 cm in width. The flowers are usually white, pink, or purple and form in small clusters at the base of the leaves. The pods are hairy and about 7-10 cm long, containing small seeds.
Common Names
The plant is commonly known by many names across the regions it is cultivated. In Africa, it is known as nyanda, mbaazi, and nduma, among others. In India, it is called sem, while in Australia, it is known as the native bean.
Uses
The plant has several uses, including being a source of food, forage, and nitrogen fixation. The immature pods and leaves are consumed as vegetables, while the mature seeds are used for soups, stews, and curries. The plant is also used as a cover crop and for soil improvement, helping to maintain soil structure and fertility. In addition, it is used as a forage crop for animals such as cattle, goats, and sheep.
Light Requirements
The Dolichos angustifolius plant prefers full sunlight or partial shade for optimal growth. It can tolerate some shade but it may decrease plant productivity.
Temperature Requirements
The plant grows well in temperatures ranging between 15°C and 30°C. However, it is sensitive to frost and does not tolerate temperatures below 10°C.
Soil Requirements
This plant grows best in well-drained soils with pH ranging from slightly acidic to neutral. It prefers sandy loam soils over heavy soils. Additionally, it performs better in soils rich in organic matter. Dolichos angustifolius is relatively tolerant to drought conditions and waterlogging, but performs best with regular watering.
Cultivation of Dolichos angustifolius Eckl. & Zeyh.
Dolichos angustifolius, also known as the sicklepod, is a climbing legume that is easy to grow. It grows best in full sun and well-draining soils with a pH range of 5.5 to 7.5. The plant is adapted to hot and dry environments, and it requires a long growing season of about 100-140 days depending on the variety.
Watering Needs
Dolichos angustifolius requires regular watering to establish healthy plants. The plant thrives well under moderate moisture, therefore, apart from the adequate supply of water, the plant also requires proper drainage. Avoid overwatering as it may lead to root rot.
Pruning
Pruning the Dolichos angustifolius plant is highly recommended to enhance its growth and productivity. The best time to prune is after the main harvesting season. For maximum growth, it is advisable to remove weak and damaged stems or branches to allow for the emergence of new and stronger ones.
Fertilization
The application of fertilizers is an important aspect of Dolichos angustifolius cultivation. Use fertilizers that are rich in nitrogen to enhance growth and yield. The recommended fertilization ratio is 2:1:1, that is, two parts nitrogen, one part phosphorus, and one part potassium. Apply the fertilizer at planting time and again during the growing season.
Propagation of Dolichos angustifolius Eckl. & Zeyh.
Dolichos angustifolius Eckl. & Zeyh. is commonly known as the narrow-leaved white lupin. It is a legume plant that is native to southern and eastern Africa but widely cultivated as a crop in other parts of the world. The propagation of Dolichos angustifolius can be done through various methods such as:
Seed propagation
The most common method of propagating Dolichos angustifolius is through seeds. It involves planting the seeds directly into the soil, either in seedbeds or in the field. The seeds can be sown after the danger of frost has passed and the soil has warmed up, usually in early spring. The planting depth should be about 2-3 cm, and spacing between plants should be around 10 cm.
Before planting, the seeds can be soaked in water for about 24 hours to hasten germination or treated with inoculants to improve plant growth and yield. The seedlings will emerge within a week or two, and they can be thinned or transplanted when they are about 10-15 cm tall.
Cuttings propagation
Dolichos angustifolius can also be propagated through stem cuttings, although this method is less common than seed propagation. The cuttings should be taken from healthy, mature plants during the growing season and should be about 10-15 cm long. The cuttings should be dipped in rooting hormone solution and planted in well-draining soil or compost mix.
The cuttings should be kept moist and warm, preferably in a greenhouse or under a mist system until they root. Rooting may take several weeks, after which the young plants can be transplanted to the field.
Division propagation
Another method of propagating Dolichos angustifolius is through division. This involves separating the plant into smaller sections and replanting them. This method is best suited for established plants that have become too crowded or overgrown.
The division should be done during the dormant season to minimize stress and damage to the parent plant. The separated sections should have a portion of the root system and some stems and leaves. The new plants can be planted in well-prepared soil or compost mix, and should be watered regularly until established.
Disease Management
Dolichos angustifolius is susceptible to various diseases that can affect their growth and productivity. The most common diseases that affect Dolichos angustifolius plants include bacterial blight, Fusarium wilt, and root rot. The following are some strategies that can be employed for managing these diseases:
- Bacterial blight: This disease appears as yellowish or brownish spots on the leaves. It can spread rapidly and cause stunted growth and defoliation. To control this disease, remove and destroy infected plants and avoid overhead irrigation. Also, consider applying copper-based fungicides to protect uninfected plants from getting the disease.
- Fusarium wilt: This disease causes wilting of the foliage and can quickly lead to plant death. It is caused by soil-borne pathogens that can persist for a long time in the soil. Crop rotation and planting disease-free seed are effective ways to manage this disease. Also, avoid excess nitrogen fertilization, which can encourage the disease.
- Root rot: This disease is caused by soil-borne fungi that attack the roots and cause decay. It is favored by wet soil conditions. To control it, avoid overwatering the plants, ensure proper drainage, and use fungicides that contain dimethyl dithiocarbamate.
Pest Management
Dolichos angustifolius can also be affected by various pests that can reduce their productivity. The common pests that attack the plant include aphids, mites, and pod borers. The following are some strategies that can be used for managing these pests:
- Aphids: These are small, soft-bodied insects that suck the sap from the leaves and can cause yellowing and curling of the foliage. To control aphids, apply insecticides that contain imidacloprid or use neem oil. Also, introduce natural enemies like ladybugs and lacewing that feed on aphids.
- Mites: These are tiny, spider-like pests that feed on the underside of the leaves and cause them to become yellowish or bronzed. To manage mites, use insecticides that contain abamectin or apply neem oil. Also, keep the plants healthy and well-watered to reduce their susceptibility to mites.
- Pod borers: These are caterpillar-like larvae that bore into the pods and feed on the seeds. To manage pod borers, remove and destroy infected pods and apply insecticides that contain spinosad or lambda-cyhalothrin. Also, keep the crop weed-free and avoid planting near crops that harbor the pest.
