Prota - Amaranthus blitum

Document Sample
Prota - Amaranthus blitum Powered By Docstoc
					                                             Protabase
                                          Record display

                                              www.prota.org



Amaranthus blitum L.

Protologue
Sp. pl. 2: 990 (1753).


Family
Amaranthaceae


Chromosome number
2n = 34


Synonyms
Amaranthus lividus L. (1753), Amaranthus oleraceus L. (1763).


Vernacular names
Amaranth, wild amaranth, pigweed, purple amaranth (En). Amarante sauvage,
amarante blette (Fr). Amaranto, bredo (Po). Mchicha (Sw).


Origin and geographic distribution
Amaranthus blitum is a cosmopolitan weed, spread over the world from the
tropics to temperate areas such as Japan and Western Europe, in some areas
reported as rather noxious. It probably originates from the Mediterranean region.
It has been recorded for many African countries, and probably occurs throughout
tropical Africa, from Senegal to Ethiopia, South Africa and the Indian Ocean
islands. It is mostly a protected weed in backyards and home gardens, and
sometimes produced for sale at the market. It is cultivated in Central Africa
(Cameroon) and East Africa (Kenya, Uganda). The cultivated type probably
originates from India where it still is an important vegetable. It is a popular home
garden vegetable in south-eastern Europe, e.g. in Greece where it is used as a
substitute for spinach (Spinacia oleracea L.) during the hot dry summer months.


Uses
The main use of Amaranthus blitum is as a cooked leaf vegetable. In most
African countries it is collected as a pot herb from the wild, and is very much liked
for its soft taste. Leaves are sometimes preserved by drying. Vegetable
amaranths in general are recommended as a good food with medicinal properties
for young children, lactating mothers and for patients with fever, haemorrhage,
anaemia or kidney complaints. The leaves are used as a febrifuge and poultice to
treat inflammations, boils and abscesses. In Nigeria Amaranthus blitum is used
as a medicine against lung disorders. It is used as fodder but only as a rather
moderate part of the daily portion.


Production and international trade
Amaranthus blitum is important in East Africa as a frequently collected wild plant
and a popular vegetable in home gardens. The economic value as a market
vegetable is limited, since market growers prefer the more productive
Amaranthus cruentus L. and Amaranthus dubius Mart. ex Thell. No international
trade has been reported, but probably it is occasionally imported as a vegetable
by Western countries from India or East Africa.


Properties
The composition of Amaranthus blitum is comparable to that of Amaranthus
cruentus, samples of the former analyzed in India showing about the same
composition. The moisture content and composition show large variations as a
function of plant age, ecological conditions and cultural practices such as
fertilizing. The composition of Amaranthus leaves per 100 g edible portion (89%)
is: water 88.9 g, energy 75 kJ (18 kcal), protein 3.5 g, fat 0.3 g, carbohydrate 0.3
g, dietary fibre 2.6 g, Ca 270 mg, Mg 130 mg, P 65 mg, Fe 3.0 mg, carotene
1725 μg, thiamin 0.07 mg, riboflavin 0.22 mg, niacin 0.7 mg, folate 85 μg,
ascorbic acid 42 mg (Holland, B., Unwin, I.D. & Buss, D.H., 1991). The dry
matter content is high and ranges from 9–22%; the protein content is also high,
ranging from 20–38%. The amino acids in the leaf proteins include methionine
and other sulphur-containing amino acids. The content of essential
micronutrients, especially calcium, iron, carotene, folate and ascorbic acid, is
high compared with other leaf vegetables. The calcium is partly insoluble and not
taken up in the digestive tract, as it is bound to oxalate. The bioavailability of the
iron is 6–12%. The leaves easily become soft after 5–10 minutes cooking in
lightly salted water. Some types contain much anthocyane, a brilliant red pigment
that dissolves in the cooking water, which is poured off. The leaves and stems
contain the antinutrients nitrate (most in the stems) and oxalate at a level similar
to other green leaf vegetables such as spinach (Spinacia oleracea L.) and
spinach beet (Beta vulgaris L.). Adverse nutritional effects are not likely where
consumption is below 200 g per day. Moreover cooking in ample water removes
these toxic components. The rather high content of hydrocyanic acid and oxalic
acid makes it less suitable for fresh consumption by humans and is a limiting
factor for its use as fodder for animals. Amaranthus blitum seed contains linoleic
acid.


Adulterations and substitutes
In dishes with green leafy vegetables or pot herbs, Amaranthus blitum can be
replaced by any other vegetable amaranth (Amaranthus cruentus is the most
important) or several other dark green leafy vegetables.


Description
Annual herb, small and stunted to rather tall and erect, up to 100 cm tall; stem
simple or branched, glabrous. Leaves arranged spirally, simple without stipules;
petiole 1–10 cm long; lamina angular ovate, 1–10 cm × 0.5–6 cm, shortly cuneate
at base, notched at apex, entire, glabrous, green or more or less purple,
pinnately veined. Inflorescence an axillary many-flowered cluster, forming a false
spike at apex of plant, with male and female flowers intermixed; bracts up to 1
mm long. Flowers unisexual, subsessile, with 3(–5) tepals up to 1.5 mm long;
male flowers with 3 stamens opposite tepals; female flowers with superior, 1-
celled ovary crowned by (2–)3 stigmas. Fruit a subglobular to broadly ovoid-
ellipsoid capsule c. 2 mm long, indehiscent or bursting irregularly, crowned by
stigmas, 1-seeded. Seed lenticular, up to 1.5 mm in diameter, glossy dark brown
to black.


Other botanical information
The genus Amaranthus comprises about 70 species, including at least 17
species with edible leaves. Many local types and cultivars of Amaranthus blitum
occur. Cultivated types are larger, more erect and more succulent than weedy
types. Mediterranean cultivated types are robust, erect, simple or little-branched
plants, up to 1 m tall, with large leaves. The African or Asian (Indian) cultivated
types are generally much smaller, up to 50 cm, strongly branched and erect or
prostrate. Some cultivated and wild types have dark red inflorescences and a
large brown-red spot of anthocyane in the centre of the leaf blade, hence the
name ‘purple amaranth’. In most African floras the name Amaranthus lividus is
used instead of Amaranthus blitum. The names Amaranthus blitum L. and
Amaranthus lividus L. have been published simultaneously. The correct name
depends on the author who first combined the taxa, accepting one of them. J.D.
Hooker (1885) seems to be the first to unite them and did so under the name of
Amaranthus blitum.


Growth and development
Emergence of the seedling takes place 3–5 days after sowing. Vegetative
development is fast. Like maize and sugar cane, the genus Amaranthus is
characterized by the C4-cycle photosynthetic pathway, which means a high rate
of photosynthesis at high temperature and radiation. Flowering may start 4–8
weeks after sowing, making the plant less suitable for consumption. Pollination is
effected by wind but the abundant pollen production, especially in the flowers in
the upper part of the plant, causes a high rate of self-pollination. Insect pollination
also takes place. The first seed matures after 2 months. The plants continue
growing for several months before dying.


Ecology
Vegetable amaranths grow well at day temperatures above 25°C and night
temperatures not lower than 15°C. Shade is disadvantageous except in cases of
drought stress. Amaranth is a quantitative short-day plant, which is an advantage
in the subtropics where the generative stage is retarded during summer.
Amaranths like fertile, well-drained soils with a loose structure. The mineral
uptake is very high. Amaranthus blitum is fairly resistant to adverse climate and
soil conditions.


Propagation and planting
The seed of Amaranthus blitum is larger than the seed of most other Amaranthus
species with about 1000 seeds/g. In the wild and in home gardens the seed of
flowering plants scatters and gives rise to new plants automatically. In the dark,
the seed may remain dormant for several years. It germinates when it comes at
the surface or in the upper soil layer of less than 3 cm. For market production
Amaranthus blitum is normally grown as a sole crop on beds. It is also found in
intercropping systems with food crops and in home gardens. The common
practice in Uganda and in Western Kenya is to sow directly, broadcast or in rows
15–20 cm apart, with a seed rate of 2–5 g/m2. The plants are uprooted after 4–5
weeks. Another cultivation method is sowing in a seedbed (nursery) 3–10 g/m2
and transplanting after 2–3 weeks. From a nursery, the grower gets up to 1000
plantlets per m2 for transplanting. A plant density of 100–200 plants/m2 can be
used for a once-over harvest whereas 25 plants/m2 are appropriate for repeated
cuttings. In Kenya, Amaranthus blitum is sown in a mixed cropping with other
indigenous vegetables like Corchorus olitorius L., in rows 30 cm apart; the seed
is mixed with sand for easier sowing.


Management
In home gardens, the only care given to Amaranthus blitum plants is selective
weeding. Amaranthus blitum is less fast growing, less susceptible to diseases
and pests and more tolerant to drought than the most commonly cultivated
amaranth Amaranthus cruentus. Because of the rather strong growth of
Amaranthus blitum, which itself displays a weedy character, weeds are not very
troublesome, except sometimes nut grass (Cyperus rotundus L.). If rainfall is not
sufficient, irrigation by sprinkling should be done before the plants reach their
wilting point. Watering every day with 6 mm (6 l/m2) is sufficient. Water shortage
causes early flowering, which reduces the yield and the market quality. Amaranth
is a very high consumer of minerals. Only modest crops can be produced on
poor soils. The mineral uptake and removal calculated for an Amaranthus crop
yielding 25 t/ha is 125 kg N, 25 kg P, 250 kg K, 75 kg Ca and 40 kg Mg. Larger
quantities of N and K are easily absorbed as luxury uptake if these elements are
abundant. Amaranth responds to high rates of organic fertilizer. On poor soils,
the application of 400 kg/ha of NPK 10–10–20 in addition to 25 t of organic
manure is recommended. A split application is recommended during the rainy
season. Nitrate-N is better than ammonium-N. Amaranth does not seem to need
to be rotated with other crops since no serious soilborne disease has been
observed.


Diseases and pests
Stemrot caused by the fungus Choanephora cucurbitarum is the main disease. It
is favoured by wet conditions, poor soil fertility and high nitrogen doses.
Chemical control by repeated spraying with fungicides such as maneb or
carbatene reduces the losses, but is seldom applied. Damping-off caused by
Pythium and Rhizoctonia may be serious in seedbeds. It is controlled by good
drainage. Over-dense sowing should be avoided. Fungicides such as
dithiocarbamates have some effect. No damage by virus diseases has been
reported. Amaranthus blitum is a natural host for turnip mosaic virus and tobacco
leaf curl virus.
Insects are a serious problem for amaranth growers. Caterpillars (Hymenia
recurvalis, Spodoptera litura, Helicoverpa armigera) and sometimes
grasshoppers are the most harmful. The larvae of the stem borer Lixus
truncatulus may cause much damage, sometimes already in the seedbed. The
basal part of the plant containing the pupae swells and the plant growth is much
retarded. Many other insects such as aphids, leafminers, stinkbugs, mole crickets
and mites also attack amaranth but generally cause only minor damage.
Commercial growers spray insecticides to dispel insects instead of the traditional
control method of spreading wood ash.
Amaranth is not very susceptible to nematode damage.


Harvesting
Commercial growers harvest by uprooting or by cutting at ground level. If the
crop was sown directly, the once-over harvest by uprooting or by cutting at
ground level may be done 3–4 weeks after sowing. Some growers obtain a
second harvest 3 weeks later from the regrowth of the smallest plants. When
harvest is by repeated cutting, the first cutting takes place about 3 weeks after
transplanting, and then every 2–3 weeks for a period of one or two months.
Cutting should be done at a height that leaves at least 2 leaves and buds for
regrowth. The height of the first cutting is normally 10–15 cm.


Yield
An uprooted crop of Amaranthus blitum may yield 1.0 kg/m2 at 4 weeks after
sowing. A yield of 1.5 kg/m2 may be obtained from 2–3 cuttings in 2 months from
transplanting date. In an experiment in India, 20 t/ha of foliage was obtained 36
days after planting. The yield of Amaranthus blitum is definitely lower than that of
Amaranthus cruentus or Amaranthus dubius.


Handling after harvest
Harvested plants or shoots are bundled, the roots are washed, and the produce
is packed for transport to the market. In markets and shops, it is sprinkled with
water to keep a fresh appearance. If uprooted, the vegetable can be kept fresh
for some days by putting it in a basin with the roots in the water. It is sold in
bunches or by weight. Some people dry the leaves for use during the dry season.


Genetic resources
Amaranthus blitum is present in Indian collections at the National Bureau of Plant
Genetic Resources (NBPGR), New Delhi (India). Some research institutes in
East and southern Africa have small working collections of local cultivars, e.g.
Kawanda Agricultural Research Institute, Uganda. Evaluation and variability
studies are needed to reveal the amount of exploitable genetic variation.


Breeding
Breeding of Amaranthus blitum as a leafy vegetable has not been reported.


Prospects
Although perhaps best known as a weed, Amaranthus blitum is recognized as an
easy-to-grow, productive, tasty and nutritious vegetable. Research should focus
on optimization of cultural practices (integrated pest management to avoid
pesticide residues, plant nutrition) and on breeding for a better plant habit and a
higher yield.
Major references
• Baquar, S.R. & Olusi, O.O., 1988. Cytomorphological and phylogenetic studies
of the genus Amaranthus from Nigeria. Kromosomo (Tokyo) 2(51–52): 1665–
1674.
• Burkill, H.M., 1985. The useful plants of West Tropical Africa. 2nd Edition.
Volume 1, Families A–D. Royal Botanic Gardens, Kew, Richmond, United
Kingdom. 960 pp.
• Grubben, G.J.H., 1975. La culture de l’amarante, légume-feuilles tropical, avec
référence spéciale au Sud-Dahomey. Mededelingen Landbouwhogeschool
Wageningen 75–6. Wageningen, Netherlands. 223 pp.
• Grubben, G.J.H. & van Sloten, D.H., 1981. Genetic resources of amaranths: a
global plan of action, including a provisional key to some edible species of the
family Amaranthaceae by Laurie B. Feine-Dudley. International Board for Plant
Genetic Resources, Rome, Italy. 57 pp.
• Grubben, G.J.H., 1993. Amaranthus L. In: Siemonsma, J.S. & Kasem Piluek
(Editors). Plant Resources of South-East Asia No 8. Vegetables. Pudoc Scientific
Publishers, Wageningen, Netherlands. pp. 82–86.
• Keskar, B.G., Bhore, D.P., Patil, A.V., Sonone, H.N. & Maslekar, S.R., 1981.
Comparative efficacy of soil and foliar application of nitrogen through urea on
yield of leafy vegetable chaulai (Amaranthus blitum L.) at various seed rates.
Journal of Maharashtra Agricultural Universities 6(1): 68–69.
• Maundu, P.M., Ngugi, G.W. & Kabuye, C.H.S., 1999. Traditional food plants of
Kenya. Kenya Resource Centre for Indigenous Knowledge (KENRIK), Nairobi,
Kenya. 270 pp.
• Schippers, R.R., 2000. African indigenous vegetables. An overview of the
cultivated species. Natural Resources Institute/ACP-EU Technical Centre for
Agricultural and Rural Cooperation, Chatham, United Kingdom. 214 pp.
• Stevels, J.M.C., 1990. Légumes traditionnels du Cameroun: une étude
agrobotanique. Wageningen Agricultural University Papers 90–1. Wageningen
Agricultural University, Wageningen, Netherlands. 262 pp.
• Townsend, C.C., 1985. Amaranthaceae. In: Polhill, R.M. (Editor). Flora of
Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. 136 pp.


Other references
• Holland, B., Unwin, I.D. & Buss, D.H., 1991. Vegetables, herbs and spices. The
fifth supplement to McCance & Widdowson’s The Composition of Foods. 4th
Edition. Royal Society of Chemistry, Cambridge, United Kingdom. 163 pp.
• Leung, W.-T.W., Busson, F. & Jardin, C., 1968. Food composition table for use
in Africa. FAO, Rome, Italy. 306 pp.
• Pal, M. & Khoshoo, T.N., 1973. Evolution and improvement of cultivated
amaranths. VI. Cytogenetic relationships in grain types. Theoretical and Applied
Genetics 43: 242–251.
• Senft, J.P., Kauffman, C.S. & Bailey, N.N., 1981. The genus Amaranthus: a
comprehensive bibliography. Rodale Press, Emmaus, Pennsylvania, United
States. 217 pp.


Sources of illustration
• Stevels, J.M.C., 1990. Légumes traditionnels du Cameroun: une étude
agrobotanique. Wageningen Agricultural University Papers 90–1. Wageningen
Agricultural University, Wageningen, Netherlands. 262 pp.


Author(s)
• G.J.H. Grubben
 Boeckweijdt Consult, Prins Hendriklaan 24, 1401 AT Bussum, Netherlands




Editors
• G.J.H. Grubben
 Boeckweijdt Consult, Prins Hendriklaan 24, 1401 AT Bussum, Netherlands
• O.A. Denton
 National Horticultural Research Institute, P.M.B. 5432, Idi-Ishin, Ibadan, Nigeria
Associate editors
• C.-M. Messiaen
 Bat. B 3, Résidence La Guirlande, 75, rue de Fontcarrade, 34070 Montpellier,
 France
• R.R. Schippers
 De Boeier 7, 3742 GD Baarn, Netherlands
General editors
• R.H.M.J. Lemmens
 PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700
 AH Wageningen, Netherlands
• L.P.A. Oyen
 PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700
 AH Wageningen, Netherlands
Photo editor
• E. Boer
 PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700
 AH Wageningen, Netherlands




wild
1, flowering and fruiting branch; 2, fruit; 3, seed.
Redrawn and adapted by Iskak Syamsudin




broad-leaved form
habit (top view), Uganda




weedy form

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:5
posted:8/9/2012
language:
pages:13