Overview
Dioscorea sagittifolia Pax var. sagittifolia is a perennial climbing plant that belongs to the family of Dioscoreaceae. It is commonly known by different names such as water yam, lesser yam, winged yam, and arrowleaf elephant ear. It is primarily cultivated for its edible tubers, which serve as food for humans and animals. The plant has its origin in West Africa and has spread to different parts of the world due to its economic and nutritional value.
Appearance
The plant has a large tuberous root system that produces annual shoots that grow up to 4 meters in height. The stem is usually slender, round, and could be green, brown, or purple. The leaves are arrowhead-shaped, alternate and heart-shaped at the base. The leaves grow up to 20 cm in length and 15 cm in width, with prominent veins that run through them. The flowers are small, yellowish-green, and grow in clusters. The fruits are capsules that contain triangular seeds.
Uses
The tubers of Dioscorea sagittifolia Pax var. sagittifolia are the major part of the plant that is of economic importance due to its numerous uses. The tubers have a high starch content which makes them a good source of food for humans and animals. The tubers are cooked, roasted, or fried and used in soups, stews, and different dishes. The leaves are also used as vegetables in some parts of the world. The plant is also used for medicinal purposes, where the tubers and leaves are believed to have antioxidant, anti-inflammatory, and immune-boosting properties. The plant is also grown as an ornamental plant, due to its attractive and unique appearance.
Light Requirements
Dioscorea sagittifolia Pax var. sagittifolia thrives in partial shade to full sun. It requires bright light for photosynthesis which is essential for plant growth and development.
Temperature Requirements
The ideal temperature range for Dioscorea sagittifolia Pax var. sagittifolia is between 10°C to 30°C. Temperatures below 10°C may cause the plant to become dormant and slow down growth. On the other hand, prolonged exposure to temperatures above 30°C may lead to dehydration and harm the plant.
Soil Requirements
The plant prefers fertile, well-draining soil. Soil with a pH range of 5.5 to 6.0 is ideal for growth. It also requires moderate soil moisture to maintain healthy growth. The use of organic matter such as compost or manure during soil preparation can improve soil fertility, water-holding capacity, and the availability of nutrients to the plant.
Cultivation
The Dioscorea sagittifolia Pax var. sagittifolia plant is commonly grown in West and Central Africa and is a hardy perennial that can be easily cultivated. It grows well in warm temperatures and requires good soil. The plant can propagate through seeds, stem cuttings or tubers.
When planting stem cuttings or tubers, ensure that the soil is suitable - rich in nutrients and well-draining. The plant prefers slightly acidic to neutral soil pH values ranging between 6.0-7.5. Plant the tubers or stem cuttings firmly and deeply in the soil, with the buds facing up and water well.
Watering needs
The Dioscorea sagittifolia Pax var. sagittifolia plant thrives well when the soil is moist but not waterlogged. During the rainy season, the plant can be watered twice a week but, during the dry season, watering should be more frequent. The aim is to keep the soil consistently moist.
Fertilization
The Dioscorea sagittifolia Pax var. sagittifolia plant is a heavy feeder that requires a steady supply of nutrients. Adding organic fertilizers to the soil helps in meeting the plant's nutritional needs. During planting, mix farmyard manure, compost or any other organic fertilizer into the soil. For established plants, a balanced NPK (Nitrogen, Phosphorus, and Potassium) fertilizer or any other organic fertilizer can be added, once every three months.
Pruning
Pruning the Dioscorea sagittifolia Pax var. sagittifolia plant is not a mandatory task as the plant is known to grow naturally without any need for pruning. However, if some shoots start to get unruly, it is okay to prune them. Prune dead, diseased, or damaged stems and leaves as soon as possible to prevent the spread of the disease. Pruning can also help with better air circulation and light penetration into the plant.
Propagation of Dioscorea sagittifolia Pax var. sagittifolia
Dioscorea sagittifolia Pax var. sagittifolia, also known as the five-fingered yam, can be propagated by various methods.
Propagation by Cuttings
Propagation by cuttings is a common method for propagating Dioscorea sagittifolia Pax var. sagittifolia. The cuttings should be taken from the mother plant during the dormant season when the plant has stopped growing. The cuttings should be around 30cm long and 1-2cm thick. The cuttings should be treated with a rooting hormone before planting in a well-draining potting mix. The cutting should be planted in a pot and kept in a shady spot until new growth appears.
Propagation by Tuber Division
Dioscorea sagittifolia Pax var. sagittifolia can also be propagated by tuber division. The tubers should be dug up during the dormant season and separated into individual pieces. Each piece should have at least one eye or bud. The tuber pieces should be planted in well-draining soil with the eye or bud facing upwards. The tuber pieces should be planted at a depth of 5-10 cm and watered regularly until new growth appears.
Propagation by Seeds
Dioscorea sagittifolia Pax var. sagittifolia can also be propagated by seeds. The seeds should be harvested from mature fruits and sown immediately. The seeds should be sown at a depth of 2-3 cm in well-draining soil. The seeds should be watered regularly, and the seedlings should be transplanted to their permanent location after 6-8 months.
Propagation of Dioscorea sagittifolia Pax var. sagittifolia can be done by cuttings, tuber division, and seeds. Each method has its advantages and disadvantages, and the choice of propagation method will depend on the availability of plant material and the desired outcome.
Disease Management
Dioscorea sagittifolia Pax var. sagittifolia is susceptible to a number of diseases that can negatively impact its growth and yield. These diseases include:
- Anthracnose: A fungal disease that causes circular, sunken lesions on the leaves, stems, and fruits of the plant. It can be managed by applying fungicides and removing infected plant parts.
- Fusarium wilt: A soil-borne fungal disease that causes wilting and yellowing of the leaves, eventually leading to plant death. It can be managed by planting disease-resistant varieties and practicing crop rotation.
- Bacterial leaf spot: A bacterial disease that causes small, water-soaked lesions on the leaves, which can coalesce and lead to defoliation. It can be managed by applying copper-based fungicides and avoiding overhead irrigation.
To effectively manage these diseases, it is important to practice good cultural practices such as maintaining proper irrigation and fertilization, removing infected plant parts, and keeping the area around the plant clean and free of debris.
Pest Management
Dioscorea sagittifolia Pax var. sagittifolia is also susceptible to a number of pests that can cause damage to the plant. These pests include:
- Aphids: Small, soft-bodied insects that feed on the sap of the plant, causing stunted growth and distorted leaves. They can be managed by spraying the plant with insecticidal soap or neem oil.
- Cutworms: Larvae of various moth species that feed on the stems of the plant, causing wilting and death. They can be managed by handpicking them off the plant or applying a Bacillus thuringiensis (BT) insecticide.
- Spider mites: Tiny spider-like pests that feed on the undersides of the leaves, causing stippling and discoloration. They can be managed by spraying the plant with a strong jet of water or applying a miticide.
Again, good cultural practices such as removing plant debris and maintaining proper irrigation and fertilization can help prevent pest infestations. Additionally, planting companion plants that deter pests can be an effective means of pest management.
