Overview
Dioscorea bulbifera L. var. sativa Prain is a herbaceous climber that belongs to the Dioscoreaceae family. It is often referred to by its common names, including aerial yam, bulbil-bearing yam, air potato, and potato yam. This plant is widely known for its edible tubers and has been traditionally used in different regions for medicinal purposes.
Origin
Dioscorea bulbifera L. var. sativa Prain originated in the tropical regions of Africa and Asia. It can be found throughout Africa, Asia, North and South America, the Caribbean, and the Pacific Islands. This plant is commonly grown as a food crop in different countries, including India, China, and Nigeria.
Appearance
The Dioscorea bulbifera L. var. sativa Prain is a fast-growing, perennial vine that can reach up to 20 meters in length. The stem is usually cylindrical, woody, and has a reddish-brown color. The plant has heart-shaped leaves that grow alternately on the stem. It produces bulbils, which are small, potato-like structures, in the leaf axils. The tubers of the plant are oblong or cylindrical in shape and can be up to 50 cm long and 15 cm wide.
Uses
Dioscorea bulbifera L. var. sativa Prain has been traditionally used as a food crop in different regions around the world. The tubers of the plant are rich in starch and can be prepared in various ways, including roasting, boiling, frying, or baking. The bulbils are also edible, and they are commonly used as a vegetable in some parts of Africa and Asia. This plant is also used in traditional medicine to treat various ailments, such as arthritis, hypertension, and digestive disorders.
Light Requirements
Dioscorea bulbifera L. var. sativa Prain thrives in a partial shade environment. It requires a minimum of 50% shade to develop properly. Direct sunlight may cause the leaves to scorch and dry out, thereby inhibiting growth.
Temperature Requirements
The optimal temperature range for Dioscorea bulbifera L. var. sativa Prain growth is between 25°C and 30°C. The plant does not tolerate temperatures below 10°C or above 35°C. Temperatures below 10°C may cause the plant to become dormant, while temperatures above 35°C may cause leaf drop, wilt, or even death.
Soil Requirements
The soil requirements for Dioscorea bulbifera L. var. sativa Prain are not very strict. It grows well in a range of soils, but prefers well-drained soils that are rich in organic matter. A slightly acidic (pH 5.5 to 6.5) to neutral (pH 6.5 to 7.5) soil pH level is the most suitable for growth. It can also grow in sandy, loamy, or clay soils.
Cultivation methods for Dioscorea bulbifera L. var. sativa Prain
Dioscorea bulbifera L. var. sativa Prain is commonly cultivated in tropical and subtropical regions for its edible tubers. It can be propagated through vegetative methods such as bulbil separation or stem cuttings. The plant requires well-drained soil with a pH range of 5.5-6.5. It also requires partial shade, as exposure to direct sunlight can damage its foliage.
Watering needs for Dioscorea bulbifera L. var. sativa Prain
The watering needs of the plant depend on the climate and the moisture content of the soil. Over-watering can cause root rot, while under-watering can lead to stunted growth and poor tuber development. The plant requires regular watering during the growing season, but the frequency should be reduced during the dormant period.
Fertilization for Dioscorea bulbifera L. var. sativa Prain
Dioscorea bulbifera L. var. sativa Prain requires adequate nutrition for healthy growth and high tuber yield. The plant responds well to organic fertilizers such as compost and manure. It also requires a balanced fertilizer with a higher ratio of potassium to phosphorus for the development of larger tubers. Fertilizers should be applied at the onset of the growing season and during the flowering stage.
Pruning for Dioscorea bulbifera L. var. sativa Prain
Pruning is not commonly performed on Dioscorea bulbifera L. var. sativa Prain. However, removing the lower leaves of the plant can help to improve air circulation and reduce the incidence of fungal diseases. Bulbils can also be removed for propagation purposes to maintain plant density and encourage optimal tuber development.
Propagating Dioscorea bulbifera L. var. sativa Prain
Dioscorea bulbifera L. var. sativa Prain, commonly known as Chinese yam, is propagated through various methods such as tubers, bulbils, stem cuttings and seeds. Each of these methods has its advantages and disadvantages.
Tubers
The most common method is propagating through tubers. This method is similar to propagating potatoes. To propagate using this method, you will need to select mature tubers that are free of diseases and have buds. Once selected, the tubers are usually cut into smaller pieces, each having one or two buds. The pieces are then planted about 10cm deep and 30-40cm apart in a well-drained soil. The best time to plant the tubers is during spring when the soil is warm enough to allow the tubers to sprout. Within weeks after planting, the sprouts will emerge.
Bulbils
Bulbils are small aerial (above ground) tubers that grow at the axils of the leaves. Bulbils propagate quickly and can be used as a substitute for seed propagation. To propagate through bulbils, select healthy plants and remove the bulbils using a sterilized knife. Once removed, the bulbils are planted in a well-drained soil at a depth of about 5cm. The best time to plant the bulbils is during May or June. Within weeks after planting, the bulbils will develop roots and shoots, and the new plants will emerge in about two to three months.
Stem Cuttings
Propagation of Chinese yam can also be done through stem cuttings. This method is best done during spring or early summer. Select a healthy plant and cut a 10-15cm long stem. Remove the leaves from the lower half of the stem and dip the cut end in rooting hormone powder. Plant the stem cutting about 5cm deep in well-draining soil and keep it moist by misting it regularly with water. The cutting should root within four to six weeks, and new shoots will emerge after about three months.
Seeds
Propagation of Chinese yam through seeds is quite rare. Seeds are produced by the plant, but they take a long time to germinate and, therefore, are not widely used for propagation purposes. If you choose to propagate using seeds, you should start them indoors during spring under controlled conditions. Soak the seeds in water for 24 hours to soften the seed coat before planting them in a well-draining soil. Keep the soil moist and warm by covering it with a plastic bag. Seed germination may take up to one month, and the young plants will take another six to twelve months to mature.
Disease Management
Dioscorea bulbifera L. var. sativa Prain is susceptible to various diseases that can cause a significant yield loss. Here are some common diseases that might affect Dioscorea bulbifera L. var. sativa Prain and ways to manage them:
Dioscorea Root Rot
Dioscorea Root Rot is a fungal disease caused by different species of fungi. It causes the rotting of the tubers and a significant loss of yield. The best way to manage this disease is by planting disease-free tubers in well-drained soil. Also, avoid over-fertilization, which can damage the roots and lead to infection.
Leaf Spot
Leaf Spot is a fungal disease that affects the leaves, causing yellow or brown round spots. The infected leaves eventually die off, leading to a significant loss of yield. To manage this disease, it is advisable to remove and burn the infected leaves to prevent spreading the disease to other plants. Also, apply fungicides regularly to protect the plant from infection.
Pest Management
Dioscorea bulbifera L. var. sativa Prain is also susceptible to different pests that can cause significant yield loss. Here are some common pests that might affect Dioscorea bulbifera L. var. sativa Prain and ways to manage them:
Yam Beetle
Yam beetle is a significant pest that feeds on the leaves and stem of the plant, causing a significant loss of yield. To manage this pest, handpick the beetles from the plant and destroy them. You can also use insecticides to control the yam beetle population.
Mealybugs
Mealybugs are also a significant pest that affects Dioscorea bulbifera L. var. sativa Prain. They feed on the leaves, causing yellowing and eventual leaf drop. To manage this pest, it is advisable to use insecticides to control the population. Alternatively, you can use biological controls such as parasitic wasps, which feed on the mealybugs.
