Overview
Crotalaria subcapitata De Wild. var. subcapitata is a species of flowering plant in the Legume family, Fabaceae. It is native to Africa, ranging from Senegal to Tanzania, as well as Madagascar and the Comoro Islands. The plant is characterized by its upright form, green foliage, and yellow flowers. It is also commonly known as Sunn hemp or Bengal hemp.
Appearance
The Crotalaria subcapitata De Wild. var. subcapitata plant grows up to 2 meters in height, with erect stems that vary in color from green to brown. The leaves of the plant are simple, alternate, and ovate, measuring approximately 6–14 cm long and 3-8 cm wide. The flowers are bright yellow in color and are arranged in short dense racemes that are up to 10 cm long. The fruits of the plant are cylindrical pods that are covered in minute hairs.
Uses
Crotalaria subcapitata De Wild. var. subcapitata has several uses in traditional medicine and agriculture. The plant is known for its strong root system, which helps to prevent soil erosion and improve soil fertility. It is commonly used as a cover crop in intercropping systems and as a green manure crop to increase soil organic matter. Additionally, some Crotalaria species are used in traditional medicine to treat various ailments, such as fever, malaria, and coughs.
However, it is important to note that some Crotalaria species contain toxic alkaloids that can be harmful to livestock if ingested. Therefore, caution should be taken when using Crotalaria subcapitata De Wild. var. subcapitata as a forage or cover crop.
Growth Conditions of Crotalaria subcapitata De Wild. var. subcapitata
Light: Crotalaria subcapitata De Wild. var. subcapitata prefers full sun to partial shade. It requires a minimum of six hours of direct sunlight per day to grow and thrive. If grown in partial shade, it will still grow but may not produce as many flowers.
Temperature: This plant grows well in warm temperatures. It can tolerate temperatures as low as 10°C and as high as 35°C. However, the ideal temperature range for its growth is between 20°C and 30°C. It is important to note that frost can kill the plant, so it is not suitable for areas that experience frost.
Soil: The soil for Crotalaria subcapitata De Wild. var. subcapitata should be well-drained and fertile. A pH range of 5.5 to 7.5 is ideal for optimal growth. The plant can tolerate moderately acidic soils but will not grow well in alkaline soils. Adding organic matter to the soil, such as compost, can improve its fertility and drainage.
Water: This plant requires regular watering throughout the growing season. The soil should be kept moist but not waterlogged as this can lead to root rot. During dry spells, it may need watering more frequently to prevent wilting and damage to the plant.
Fertilizer: Fertilizer is not always necessary for Crotalaria subcapitata De Wild. var. subcapitata, as it can fix nitrogen from the air and add it to the soil. However, if the plant appears to be lacking nutrients, adding a balanced fertilizer once every six weeks during the growing season can help improve its growth.
Cultivation Methods for Crotalaria subcapitata De Wild. var. subcapitata
Crotalaria subcapitata De Wild. var. subcapitata is a versatile plant that can grow in a variety of soil types, including sandy and loamy soils. It requires full sunlight to grow optimally and can be cultivated in both pots and open fields.
Before planting, the soil should be properly prepared by loosening it and adding compost or well-rotted manure to improve soil fertility. The seeds should be planted directly in the soil or in seed trays, 2-3cm deep, and covered with soil. Germination usually occurs within 7-14 days.
Watering Needs for Crotalaria subcapitata De Wild. var. subcapitata
Proper watering is important for the growth and development of Crotalaria subcapitata De Wild. var. subcapitata. The plant should be watered regularly, especially during dry seasons, to prevent the soil from drying out.
The frequency of watering will depend on factors such as temperature, humidity, and soil type. Generally, the plant needs to be watered every 2-3 days, but this may vary depending on the above factors. It is important to ensure that the soil is moist, but not waterlogged, to prevent root rot.
Fertilization of Crotalaria subcapitata De Wild. var. subcapitata
Crotalaria subcapitata De Wild. var. subcapitata requires adequate nutrients to grow optimally. Fertilize the plant once a month during the growing season using a balanced fertilizer (NPK 10-10-10) or an organic fertilizer such as compost or well-rotted manure.
Avoid over-fertilization, as this can lead to the accumulation of salts in the soil, which can damage the roots of the plant.
Pruning of Crotalaria subcapitata De Wild. var. subcapitata
Pruning is not necessary for Crotalaria subcapitata De Wild. var. subcapitata, but it can be done to promote bushier growth and prevent legginess. It can also help to remove any dead or damaged leaves and branches.
Prune the plant during the growing season using clean and sharp pruning shears. Cut at a 45-degree angle just above a leaf node to promote new growth.
Propagation of Crotalaria subcapitata De Wild. var. subcapitata
Crotalaria subcapitata De Wild. var. subcapitata can be propagated through both sexual and asexual methods.
Sexual Propagation
The seeds of Crotalaria subcapitata De Wild. var. subcapitata can be collected from the mature pods and can be used for propagation. The seeds must be stored in a dry and cool place until they are sown.
The sowing can be done directly in the field or in the nursery. If done directly in the field, the seeds must be sown in shallow furrows at a spacing of about 15cm between rows. The furrows must be covered with a thin layer of soil and watered regularly. The seeds will germinate within 7 to 14 days.
If sown in a nursery, the seeds must be sown in seedling trays filled with a well-draining potting mix. The trays must be watered regularly and placed in a warm, well-lit area. The seedlings must be transplanted to the field when they reach a height of about 10cm.
Asexual Propagation
Crotalaria subcapitata De Wild. var. subcapitata can also be propagated asexually through stem cuttings.
The stem cuttings must be taken from healthy plants and must be about 10cm in length. The lower leaves must be removed, and the cutting must be dipped in a rooting hormone before it is planted in a well-draining potting mix.
The cuttings must be watered regularly and placed in a shaded area. Rooting will occur within 2 to 3 weeks, and the plants can be transplanted to the field once the roots have established.
Disease and Pest Management for Crotalaria subcapitata De Wild. var. subcapitata
Crotalaria subcapitata De Wild. var. subcapitata, commonly known as sunn hemp, is a popular cover crop due to its numerous benefits such as nitrogen fixation, weed suppression, and soil improvement. However, sunn hemp is still susceptible to various diseases and pests that can reduce its growth and productivity. Here are some common diseases and pests that affect sunn hemp and ways to manage them:
Diseases
Fusarium Wilt - This is a soil-borne fungal disease that causes yellowing of leaves and wilting of the plant. To manage this disease, it is essential to rotate sunn hemp with non-host crops and use resistant varieties. Avoid planting sunn hemp in areas where soil-borne diseases have affected the previous crops.
Leaf Spot - This fungal disease causes small, black, circular spots on leaves. Regularly monitor the crop and remove infected plant parts to prevent spreading. Apply fungicides to manage severe cases and promote plant health.
Pests
Aphids - These are small, pear-shaped insects that suck sap from the plant, causing stunted growth and yellowing of leaves. Encourage natural predators such as ladybugs and lacewings to control aphids. Alternatively, use insecticides such as neem oil or pyrethrin to manage severe infestations.
Soybean Cyst Nematode - This is a microscopic soil pest that causes root damage, stunted growth, and yellowing of leaves. To manage this pest, rotate sunn hemp with non-host crops, use resistant varieties, and apply nematicides as a last resort.
Implementing good cultural practices such as proper irrigation, crop rotation, and timely harvesting can also go a long way in preventing diseases and pests. Regularly scout the crop and promptly manage any signs of diseases or pests to maximize the benefits of sunn hemp as a cover crop.
