Basella alba
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| Basella alba L. |
Basella alba is a perennial vine, popular as a leaf vegetable in many tropical regions, and only distantly related to spinach. It has been introduced to the English-speaking world under many different names, including Malabar spinach, Malabar climbing spinach, Ceylon spinach, Indian spinach, East-Indian spinach, Surinam spinach, Chinese spinach, Malabar nightshade, broad bologi, vine spinach, Vietnamese spinach, buffalo spinach, Bengali "PUI SAAG". The vegetable is also used in Chinese cuisine, where its many names include "flowing water vegetable" (潺菜, Mandarin chāncài, Cantonese saan choy, shan tsoi), "fallen hollyhock" (落葵 Mandarin luokui, Cantonese lor kwai), "wood ear vegetable" (木耳菜 muercai) and "emperor vegetable" (帝王菜 diwangcai).
It is a fast-growing soft-stemmed vine, reaching 10 m in length. Its thick, semi-succulent, heart-shaped leaves have a mild flavour and mucilaginous texture. Typical of leaf vegetables, it is high in vitamin A, vitamin C, iron, and calcium. It is low in calories by volume, and high in protein per calorie. The succulent mucilage is a particularly rich source of soluble fiber, valued for removing mucus and toxins from the body. The plant is also a rich source of chlorophyll. Among many other possibilities, Malabar spinach may be used to thicken soups or stir-fried with garlic and chile peppers.
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[edit] Introduction to the Plant
Basella (Basella alba syn Basella rubra) is also known as Poi, Ceylon spinach, Malabar spinach, Indian spinach or vine spinach. It is a popular leaf vegetable grown in almost all parts of India and widely grown in North-East and South India. Besides India, it is widely cultivated in tropical Asia and Africa . It is a climbing perennial plant, but is sometimes cultivated as an annual vegetable. The plant is succulent with tender leaves. It is a fast growing, productive leaf vegetable for home gardens and market growers.
[edit] Composition and Uses
Composition Young shoots and leaves of Basella are a rich source of calcium, iron, and Vitamins A and C.
[edit] Uses
Fresh tender leaves and stems are consumed as leaf vegetable after cooking. It is preferable to cook the leaves in soups and stews as half of soluble solids may be lost by boiling in water. Red cultivars contain a colouring matter in leaves, stems and ripe fruits reported to be used as dye and also is used for colouring food. Because of its mucilaginous nature of leaves and stems, it is used as poultice. Juice of leaves is prescribed against constipation, especially for children and pregnant women (Burkill, 1935).
[edit] Origin and Taxonomy
Basella originated in Asia and more particularly in India. Basella belongs to the family Basellaceae and genus Basella. There is only one species Basella alba L. syn. B.rubra L. There are three main types under cultivation. The most common type has dark green, oval or nearly round leaves, which is B. alba. The other less popular type, often referred as B. rubra, has round oval leaves and red stem. The third type less commonly grown, has cordate shaped, dark green leaves and is referred B. cordifolia. Chromosome number of B.alba is 2n=48 and of B.rubra is 2n=44 (Peter, 1998).
[edit] Botany
Basella is a fleshy annual or biennial, twining, much branched herb with alternate, broadly ovate leaves and pointed at apex. Baily (1973) described B.alba as one with narrow leaves, whitish flowers on long peduncled spikes arranged in very close clusters. Haines (1910) described B.rubra as the one with a fleshy twining much branched herb with ovate shiny and rather fleshy leaves and small sessile pinkish flowers on distant spikes.
[edit] Cultivars
Both red- and green leaved cultivars are consumed as vegetables but green leaved cultivars are commercially cultivated and belong to var. alba. Red – leaved and green –leaved cultivars are equally common in West Bengal, Assam and South India, while green- leaved ones are more popular in Uttar Pradesh and Punjab. All the cultivars are trailed on poles, pandals or trellies or grown on ground. Yields among the cultivars vary widely depending upon climatic conditions, hence testing is recommended to identify superior varieties under local conditions. Climate and soil requirements
Basella grows well in hot and humid climates. Low temperatures slow growth rates and result in small leaves. Growth is also limited at altitudes higher than 500 m, due to day/night temperature variations. Partial shading produces larger leaves compared to when grown under full sunlight. Day lengths shorter than 13 hours result in flowering. Although Basella is adapted to many soils, a sandy loam is the most suitable. Ideal soil will be moist, fertile, and well supplied with organic matter. Recommended soil pH is from 5.5 to 8.0.
[edit] Cultivation
[edit] Seeds and Sowing
Basella is commercially propagated through seeds but stem or root cuttings are also practiced. In Northern and Eastern plains of India, seeds are sown from March to May, while in Southern parts it is grown twice, once sown in June and again in October to November. Early summer is the best time for sowing in hills.
[edit] Field Preparation
Basella requires a well-prepared seed bed for good germination and seedling growth. With plough or mechanical bed shaper, beds that are 20 cm high during dry season and 30cm or higher during wet season have to be prepared. Distance between centers of two adjacent furrows is about 150 cm with a bed width of 90cm. Flat beds may also be used but will be more subjected to flood damage.
[edit] Planting
Basella is planted either by direct seeding, transplanting, or using rooted or unrooted cuttings. Choice of planting method depends on availability of seed and labor, and may also vary with growing season. Direct seeding is appropriate when plenty of seeds are available, labor is limited, and during dry season when frequency of flooding is less. Transplanting or using cuttings are preferred when there is limited amount of seed, plenty of labor, and during wet season when heavy rains and flooding are likely to occur.
[edit] Direct seeding
When direct seeding is to done, seeds are sown in rows on well-prepared seedbeds. Make furrows of 1.0–1.5 cm deep and space them 10–15 cm apart on bed. Sow seeds 5 cm apart in rows. Cover seeds with a layer of compost. After they develop two to three true leaves, thin seedlings to stand 10–15 cm apart. For this method, on a commercial scale, with a density of 50,000 plants/ha, 10 kg/ha of seed will be required.
[edit] Transplanting
There are two steps in transplanting seedling production and planting seedlings in field. Seedling production. Seedlings can be grown in divided trays or in seedbeds. First method is preferred since there is less damage to seedlings when they are pulled for transplanting. Plastic seedling trays can be used for growing containerized transplants. Seedling trays vary in sizes. For Basella, cell trays with cells 3–4 cm wide and deep are recommended (size 100–128). Seedling trays have to be filled with a potting mixer with water-holding capacity and good drainage like peat moss, commercial potting soil, or a potting mixer prepared from soil, compost, rice hulls, vermiculite, and/or sand. A mixture of 66% peat moss and 34% coarse vermiculite is recommended. If non-sterile components are to used, potting mixture is to sterilized by autoclaving or baking at 150°C for 2 hours. Two or three seeds are sown per cell at 1.0–1.5 cm depth. Thinning is done to one seedling after seedlings develop two to three true leaves.
If seedlings are raised in seedbed, soil should be partially sterilized by burning a 3–5 cm thick layer of rice straw and other dry organic matter on bed. This also adds minor amounts of P and K to soil, which helps in better establishment of seedlings. Sow seeds in furrows of 0.5–1.0 cm deep, spacing seeds 3–5 cm apart in furrows spaced 5 cm apart. Cover with soil. Cover seedbeds with insect-proof nets or sow seeds inside a greenhouse or screen house. This provides shade and protects seedlings from heavy rain and pests. Water seedlings thoroughly every morning or as needed (moist, but not wet), using a fine mist sprinkler or watering can to avoid soil splash and plant damage. If seedlings are grown in shade, harden them off by gradually exposing to direct sunlight during the 4–5 days just prior to transplanting. On first day, expose them to 3–4 hours of direct sunlight. Increase duration until they receive full sun on fourth day. Seedlings are ready for transplanting when they have five true leaves.
[edit] Planting seedlings in field
Recommended spacing varies depending on variety and harvest method. Narrow spacing is used for once-over harvest. Wider spacing is used, if plants are allowed to produce long vines with multiple harvests or cuttings. For once-over harvest, raised beds that are 20–30 cm high with bed tops about 90 cm wide are recommended. Rows are spaced 10–15 cm apart with 15cm between plants within rows. Transplant in late afternoon or on a cloudy day to minimize transplant shock. Place transplants in holes that are 10cm deep, cover the roots with soil, and lightly firm. Irrigate immediately after transplanting to establish good root-to-soil contact. Transplanting can be done manually or by machine.
[edit] Using stem cuttings
Stem cuttings from an existing Basella crop can be used for planting when seeds are not available or insufficient. Stem cuttings of 20–25 cm length with three to four internodes are soaked in water overnight before transplanting. In some cases, stem cuttings are soaked in water for 1–3 days to develop roots before transplanting in field. Wider spacing is required when stem cuttings are used. Dig holes of 5–10 cm depth and plant two or three stem cuttings per hole. Spacing between rows is 20–30 cm and plants within rows are spaced 15–20 cm apart. Irrigate immediately after planting.
[edit] Fertilization
Basella thrives under conditions of moderate soil fertility, but is quite responsive to nitrogen fertilizer. It also responds to application of organic manure. A combination of both inorganic and organic fertilizers improves yield and maintains soil fertility. Recommended fertilizer rates and application schedules for Basella are given below (Palada and Chang, 2003).
Table 2. Recommended fertilizer rates (kg/ha) for Basella production Nutrient Preplant Days after sowing/transplanting 10 20 30 Compost 10000 N 48 30 8 8 P2O5 64 8 8 0 K2O 48 15 8 0
[edit] Irrigation
Basella requires plenty of water because of its high succulence. It easily wilts during prolonged dry spells. Water should be applied especially just after sowing or transplanting to ensure good stand. Fields have to be furrow-irrigated every 10 days during cool-dry season, and weekly during hot-dry season. As a rule, plants should be irrigated if wilting occur around noontime. Irrigate thoroughly to maintain vigorous plant growth. Avoid over-irrigation, which may enhance disease development and nutrient leaching. Drip irrigation or micro-sprinkler irrigation is recommended in areas with limited water supply. If sprinkler irrigation to be used, avoid late evening irrigation to prevent diseases. During rainy season, drainage is essential for plant survival and growth. Raised beds, clean furrows, and large drainage canals facilitate quick drainage of excess water after heavy rain.
[edit] Weeds Control
Weeds are controlled through a combination of practices. Thorough land preparation is the first key to effective weed control. Basella seeds are relatively slow to germinate; therefore, early weed control is essential when direct seeding is done. A seedbed free of weed seeds allows Basella seedlings to grow and establish a canopy before weeds emerge. Mulching is recommended to reduce weed competition, soil compaction, erosion, and loss of moisture. Organic mulching materials should be free of weed seeds. Organic mulches can be laid down before or after transplanting and after sowing. Apply a layer of mulch to soil surface. Mulching is easier to apply if Basella is transplanted, but can also be used for row-seeded crops after seedlings reach a height of 10–15 cm.
[edit] Insect pests and diseases control
Insect pests and diseases must be controlled to ensure good yield and quality. Just like any other leaf vegetable, Basella is susceptible to damage by foliar insects, leaf miners and cutworms. Root-knot nematode is sometimes a serious pest. An effective method of controlling many insect pests is to cover bed with fine screen or a fine mesh nylon net (32-mesh or finer). Chemical control of pests should be used mainly as a corrective measure. Choose a pesticide that targets specific insect causing damage and avoid pesticides that kill beneficial insects. Choose pesticides that have short persistence, i.e., their effects last only a few days. Chemical pesticides should be applied in evening, and workers should not be allowed into the field until recommended waiting period (usually 12 to 24 hours) has passed.
A few diseases affect Basella, most notably leaf spot caused by Cercospora, Alternaria or Colletotrichum. Numerous cultural practices reduce incidence of diseases, including crop rotation, field sanitation, and adequate plant spacing, and using furrow rather than overhead irrigation. Chemical fungicides are rarely used unless there is a history of fungal diseases for Basella in the region and conditions favour disease development.
[edit] Harvesting
Basella is usually ready for harvest in 30–45 days after planting. Plants may be harvested once or several times. Once-over harvest is adapted for early maturing and quick growing varieties. Stems or shoots of 15–25 cm long are cut close to ground, washed, and tied in bundles. With multiple harvests, young leaves and shoots are picked at weekly intervals. Frequent harvesting delays flowering and stimulates growth of side shoots. When plants are not regularly harvested, side shoots develop into longer vines. There is need to support long vines with trellis. Leaf vegetables like Basella have large surface to-volume ratio and lose water easily. To reduce water loss, harvest during cooler time of day, such as early morning or late afternoon. Keep produce in a cool shaded place.
[edit] Seed Production
Basella produces seeds freely during spring in North India and during winter in South and East India. Agronomic practices followed for seed production are similar to that for vegetable purpose. Proper isolation distances should be maintained between two cultivars for producing nucleus and foundation seeds. Seeds do not shed from fruit and hence can be left on plant to become fully mature. Ripe fleshy fruits borne in clusters on elongated peduncles are usually collected and seeds extracted. Seeds are then dried and kept in storage.
[edit] Crop Improvement
No systematic work is done for improvement of this crop. Existing germplasm should be properly assessed to identify promising lines. Colchicine induced autopolyploids with 2n=88 are developed. Basella is a short day plant and a day length shorter than 13 hrs induces flowering. Some times even water stress promotes early flowering. Since it is propagated through seeds and stem cuttings, clonal propagation makes it easy for maintenance of vigour observed in plant types. However, larger thick leaves and fleshy stem are main objectives for improving this crop.
To start crop improvement programmes in many under utilized vegetable crops, recently, ICAR started a network project to collect, conserve and select high yielding types of these crops and Basella is one of these crops. Since then systematic collection of Basella germplasm from throughout the country, their characterization and evaluation are started at many centers under this project which might lead to improvement of Basella in near future.
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