Overview
Dioscorea nummularia Lam., also known as the Indian potato or coin-leaf yam, is a plant species in the genus Dioscorea. This plant is commonly found in Africa, Asia, and Australia, in tropical rainforests, savannas, and foothills areas.
Description
The Dioscorea nummularia Lam. plant is a twining vine that can grow up to 10 meters long. It has a tuberous root system with roots that are up to 60 centimeters long and 20 centimeters wide. The leaves are heart-shaped, measuring 6 to 20 centimeters long and 5 to 15 centimeters wide. The plant produces small, greenish-white flowers in clusters on separate male and female plants.
Common Names
Dioscorea nummularia Lam. is known by various common names, depending on the region. In India, it is commonly known as Ghuiyan, Chhota Ghuiyan, or Choti Ghuiyan. In Myanmar, it is known as Biliam, while in Cambodia it is known as Preab Kra Biet. In Vietnam, it is known as Cây Su Su Nh?.
Uses
The tubers of Dioscorea nummularia Lam. are rich in starch and are a valuable food source in many parts of the world. They are used in soups, stews, curries, and in the same way, potatoes are used. The leaves and roots of this plant have also been used in traditional medicine for various ailments, including fever, diarrhea, and stomach problems.
Additionally, Dioscorea nummularia Lam. is being studied for its potential as a biofuel crop due to its high starch content.
Light Requirements
Dioscorea nummularia requires full sunlight to partial shade for optimal growth. It can tolerate shade, but the quality and quantity of the tubers will be significantly reduced. Therefore, it is recommended to plant the species in areas with at least 6-8 hours of direct sunlight per day.
Temperature Requirements
The plant grows well in warm, humid conditions, and can tolerate temperatures between 20-30°C. It cannot survive in areas with frost or extreme cold temperatures, and it is susceptible to diseases and pests during the rainy season. Thus, it is preferable to plant the species during the dry season when the weather is less humid and the temperatures are warmer.
Soil Requirements
Dioscorea nummularia does well in well-drained soils with good organic matter content, but it can grow in a variety of soil types, including sandy, loamy, and clay soils. The ideal pH range for it is between 5.5 and 7.5. A neutral pH is optimal for the best growth and yields. Additionally, the plant is drought-tolerant, so it can grow in arid areas provided that the soil is deep enough to allow the roots to reach groundwater levels. It is important to note that the soil should be fertile to ensure that the plant has all the necessary nutrients for optimal growth.
Cultivation Methods:
Dioscorea nummularia Lam. can be grown through stem cuttings or planting tubers. Planting is recommended in the early rainy season when soil moisture is ideal. The plant thrives in well-drained, loamy soil, rich in organic matter. A pH level of 6-7.5 is ideal for the plant's growth. The site should receive partial to full sunlight exposure, with a temperature range of 27-35°C.
Watering Needs:
The plant requires adequate watering during the growing season, which is seven to nine months. Watering should be done thoroughly, but care should be taken not to waterlog the soil. The soil moisture should be kept at a moderate level, with the plant receiving 900-1100 mm of rainfall annually. In regions experiencing dry spells, irrigation should be done once or twice per week, depending on the soil moisture level.
Fertilization:
Dioscorea nummularia Lam. requires high levels of nitrogen, phosphorus, and potassium for good yields. Soil fertility should be enhanced through the application of farmyard manure. Inorganic fertilizers such as NPK (nitrogen, phosphorous, and potassium mix) can be applied at a rate of 80:80:60 kg per hectare. Application of foliar fertilizer is essential during the vegetative growth stage to supplement soil fertility.
Pruning:
Pruning is essential in managing plant growth and maintaining plant form, especially when grown as ornamentals. Pruning can be done during the dormant season by cutting the old shoots. In some cases, the plant may require support structures as it grows taller and heavier. Care should be taken during the pruning process to avoid causing plant damage, which can lead to stunted growth or disease development.
Propagation of Dioscorea nummularia Lam.
Dioscorea nummularia Lam. is a perennial plant propagated through various methods, such as by seed, tubers, and stem cuttings.
Propagation by Seed
The seeds of the plant are small, light brown, and triangular in shape. They should be sown in well-draining soil at a depth of 1-1.5 cm. The seedlings emerge in about two weeks and are ready for transplanting after 4-6 weeks.
Propagation by Tubers
The tubers of Dioscorea nummularia Lam. are the primary method of propagation. The parent plant produces small tubers in the soil around it. These tubers need to be dug up carefully and stored in a cool, dry place until the next planting season. The tubers are planted in furrows or pits in the field, usually at a distance of 60-90 cm.
Propagation by Stem Cuttings
Propagation by stem cuttings is another method that can be used for Dioscorea nummularia Lam. It involves taking cuttings of young shoots and planting them in a rooting medium. The cuttings should be treated with a rooting hormone to encourage quick root development. After rooting, the cutting can be transplanted into the field.
Overall, Dioscorea nummularia Lam. can be propagated by seed, tubers, or stem cuttings. Each method has its own advantages and disadvantages, and the choice of the propagation method depends on the grower's resources, experience, and the plant's growing conditions.
Disease and Pest Management for Dioscorea nummularia Lam.
Dioscorea nummularia Lam., commonly known as the coin-leaf yam, is a tropical tuber crop grown for its edible underground tubers. Like all crops, it is susceptible to various pests and diseases that can cause significant damage if left uncontrolled. Here's a look at some of the common diseases and pests that can affect D. nummularia, and ways to manage them.
Common Diseases
Anthracnose: This is a fungal disease that can cause leaf spots, stem cankers, and rotting of the yam tubers. To manage it, ensure that the planting material is healthy, and practice crop rotation to reduce the build-up of the pathogen. Applying fungicides can also help prevent the spread of this disease.
Yam mosaic virus: This virus can cause yellowing of the leaves and stunted growth of the plant. It is transmitted by aphids and other sucking insects. To manage it, control the insect vectors by spraying insecticides, and remove and destroy any infected plants.
Root knot nematodes: These are microscopic worms that infest the roots of the plant, causing galls to form, leading to stunted growth. They can be managed by planting resistant cultivars, practicing crop rotation, and applying nematicides.
Common Pests
Moths: The larvae of various moth species can bore into the yam tubers, causing severe damage. To manage them, use pheromone traps and insecticides to prevent the adult moths from laying eggs on the plant.
Termites: These pests can cause significant damage to the yam tubers by tunneling through them. To manage them, apply insecticides to the soil around the plant to kill the termites before they can infest the tubers. Using resistant cultivars can also help reduce termite damage.
Yam beetle: This is a key pest that can cause defoliation and yield loss. To manage it, use pheromone traps and apply insecticides to control the adult beetles before they lay eggs on the plant. Using resistant cultivars can also help reduce damage from this pest.
In conclusion, managing pests and diseases is crucial for the successful cultivation of Dioscorea nummularia Lam. Implementing integrated pest and disease control measures can help ensure a healthy yam crop and maximize yields.
