Eleusine coracana (PROSEA)
Eleusine coracana (L.) Gaertner cv. group Finger Millet
- Protologue: Fruct. sem. pl. 1: 8 (1788). Cv. group Finger Millet: name is proposed here.
- Family: Gramineae
- Chromosome number: 2n= 36 (tetraploid)
- Cynosurus coracan L. (1759),
- Eleusine indica (L.) Gaertner f. coracana (L.) Hook.f. ex Backer (1927),
- E. coracana (L.) Gaertner subsp. coracana sensu Hilu & de Wet (1976).
- Finger millet, African millet, koracan (En)
- Eleusine, coracan (Fr)
- Indonesia: jaba (Batak Karo), suket lulangan (Javanese), jampang carulang (Sundanese)
- Malaysia: rumput sambau, ragi
- Cambodia: chë:ng kra:hs, si:ng söng
- Laos: pha:k kh'wa:y
- Thailand: khao-pangsamngam
- Vietnam: mần trầu, cỏmần trầu voi, cỏkê.
Origin and geographic distribution
Finger millet most probably originated about 5000 years ago in the highlands of eastern Africa (from western Uganda to Ethiopia) by domestication of wild weedy forms and is the oldest known domesticated tropical African cereal. From eastern Africa, it was taken elsewhere: to India about 3000 years ago, to southern Africa about 800 years ago. As a cultivated crop, it is at present most important in eastern and southern Africa and in the Indian subcontinent, and is occasionally cultivated elsewhere in the tropics. In South-East Asia, it is grown on a small scale but nowhere reaches commercial importance.
Finger millet grain is used for food, for malting and brewing, and for animal feed. For use as food, the grain is ground and the resulting flour cooked to prepare a thin or thick porridge or baked into a flat (unleavened) kind of bread or pancake. In some parts of eastern Africa and India, it is an important traditional staple food and in many regions it is an important famine food because the grain stores extremely well. The flour is sometimes mixed with other flours (e.g. from cassava, teff, sweet potato), enriched with spices, and the porridge eaten together with meat, pulses, or vegetables. White grain is preferred for use as malt; it is soaked in water for up to 48 hours, germinated, dried, roasted and ground. Home or industrially brewed beer (alcoholic or non-alcoholic) is made by germinating the grain, drying, grinding, mixing with water and adding yeast. Other alcoholic drinks can be distilled from the resulting liquid (e.g. "areki" in Ethiopia). In West Java (Indonesia), young plants are eaten raw or steamed as a vegetable. Finger millet is also used medicinally as a prophylaxis for dysentery. The straw or stover is usually used as forage for cattle, sheep and goats. Old stems have a silky lustre and are used as material for plaiting. Because finger millet tillers strongly it is also a suitable crop to prevent soil erosion.
Production and international trade
The average annual world production of finger millet is about 3.8 million t of grain from 4 million ha. Asia is the largest producer, with 2.9 million t from 3 million ha (mostly from India), followed by Africa with 0.9 million t from 1 million ha (mostly from Uganda, Ethiopia, Zimbabwe and Malawi). Finger millet is usually consumed locally and only surpluses are locally traded. There is hardly any international trade.
Per 100 g edible portion, finger millet grain contains approximately: water 13 g, protein 8 g, fat 1.3 g, carbohydrates 72 g, fibre 3 g, ash 2.7 g. The energy value is 1400 kJ/100 g. The protein content may vary considerably between cultivars, i.e. from 6-14%; it is rich in the amino acids cystine, tyrosine, tryptophane and methionine, but poor in lysine. Finger millet is rich in Ca (up to 0.3%), which may be why it is often recommended as a healthy food for pregnant women, children and sick people. P and Fe contents can also be high. The organic matter in finger millet straw has an in vitro digestibility of about 40-60%. The weight of 1000 grains is about 2.8 g.
- A robust, tillering, tufted, annual grass, up to 170 cm tall with a shallow, branched, fibrous, adventitious root system. Stem erect to ascending, compressed, robust, glabrous, shiny light green, sometimes branching at the upper nodes.
- Leaves numerous, distichous, sheath flattened, overlapping, split along the entire length, glabrous except for some hairs along the edges; ligule short, fimbriate; blade linear, 30-75 cm × 1-2 cm, often folded, recurved, scabrous above, dark green.
- Inflorescence a terminal cluster of 3-6(-26) dense sessile spikes ("fingers"), the cluster consisting of a terminal digitate whorl, often with 1-2(-7) additional spikes 2-4 cm below this whorl; spikes 3.5-15 cm long, up to 1 cm in diameter, straight and spreading or variously incurved and compact, unbranched or branched.
- Spikelets ovoid-elliptical, up to about 1 cm long, awnless, flattened, containing 6-12 florets arranged alternately in two parallel rows on a zigzag rachilla; florets hermaphrodite but terminal ones may be sterile or male; lemma deeply boat-shaped, 2-5 mm long; palea about three-quarters of the length of the lemma; stamens 3; ovary with 2 free styles with plumose stigmas.
- Fruit a utricle, 4-7 per spikelet, globose, 1-2 mm in diameter, smooth or rugose, varying from orange to red, red-brown, dark brown to black or white; pericarp remains distinct during development and at maturity appears as a papery structure surrounding the seed.
Growth and development
Seed of finger millet has no dormancy and its viability drops to about 50% after 2 years of appropriate storage. Young seedlings are very susceptible to drought and competition. It takes finger millet 3.5-6 months to mature, depending on cultivar, photoperiod and temperature. On average, cultivars need about 80 days to 50% flowering but variation is great. An inflorescence flowers about 8-10 days with a maximum number of florets opening on the third day. Flowering proceeds from the top to the bottom of the inflorescence, from the bottom to the top in the spikelet. Self pollination is normal; about 1% cross pollination by wind may occur. Heavy rain at flowering reduces grain setting.
Other botanical information
Botanically, finger millet is part of a complex formed by Eleusine indica (L.) Gaertner (fowl-foot grass), E. africana Kennedy-O'Byrne and E. coracana. E. indica is a diploid (2n= 18) wild grass of Old World origin but at present widespread throughout the tropics and warm temperate regions of the world. It is often a troublesome weed, but sometimes it is used as fodder, the grain as famine food and dried culms for plaiting. E. africana is a tetraploid (2n= 36) wild grass confined to the eastern and southern African highlands, with similar uses as E. indica. Although in older literature finger millet is thought to have been derived from E. indica and considered a form or variety of it, more evidence exists for a closer relationship with E. africana which in turn could have been derived from E. indica (cf. the synonymous name E. indica (L.) Gaertner subsp. africana (Kennedy-O'Byrne) S.M. Phillips). E. coracana and E. africana cross readily and produce fertile hybrids, and are quite similar vegetatively. Therefore they are also considered as being one species, E. coracana, with wild (subsp. africana (Kennedy-O'Byrne) Hilu & de Wet) and cultivated (subsp. coracana) representatives. This view is followed here but it is proposed to classify the cultivated forms not as subspecies but as the cultivar group Finger Millet. Finger millet differs from its wild progenitor primarily in having spikelets that do not shatter at maturity.
Many cultivars and landraces of finger millet exist, with different ecological requirements (e.g. highland or lowland, rainfed or irrigated land) and many varying characteristics like height, colour, degree of tillering, type of inflorescence, length of spikes and number of spikelets per spike, site of glumes, colour and yield of grains, susceptibility to diseases). Well-known cultivars include "Engenyi" from Uganda, "EC593" from India, "25C" from Zimbabwe and "Lima" from Zambia.
The cultivars have been grouped into 5 major cultivar subgroups based on the inflorescence morphology (especially the branches or "fingers"):
- cv. subgroup Compacta (other names: race Compacta, cockscomb finger millet): Main inflorescence branches 4-14, incurved, larger than in subgroup Vulgaris and always branched again, forming a large fist-like inflorescence. Indian cultivars have one branch inserted lower than the other branches (not in African cultivars). Grown in north-eastern India, Kenya, Ethiopia and Uganda.
- cv. subgroup Coracana (other name: race Coracana): Inflorescence branches 5-19, slender, straight, 6-11 cm long, all cultivars with a well-developed central inflorescence branch. Cultivars resemble the wild subsp. africana. Grown throughout the finger millet range in Africa and India.
- cv. subgroup Elongata (other name: race Elongata): Inflorescence branches long and slender, 10-15(-24) cm long, reflexed at maturity This group is the most distinct of the 5 subgroups. Grown in the eastern African highlands and in the eastern Ghats of India. Sometimes again subdivided into 3 subgroups: Laxa (longest open fingers with spikelets arranged in narrow rows), Reclusa (short open fingers, not curving outwards) and Sparsa (open fingers but spikelets arranged in clusters with bare space in between).
- cv. subgroup Plana (other name: race Plana): Inflorescence branches have a flat ribbon-like appearance with large spikelets (8-15 mm long) that are arranged in two more or less even rows along the rachis. In some cultivars the florets are congested and surround the rachis at maturity. Grown in the western and eastern Ghats of India and in Ethiopia, Malawi and Uganda. Sometimes again subdivided into 3 subgroups: Confundere (fertile florets numerous, almost surrounding the rachis at maturity, thus giving a compact appearance to the inflorescence), Grandigluma (glumes large, pointed, and several times longer than the spikelets) and Seriata.
- cv. subgroup Vulgaris (other name: race Vulgaris): Inflorescence branches straight, reflexed or incurved - both forms can usually be found in the same field. This subgroup comprises the most common cultivars in Africa and India and is also grown in Indonesia. Sometimes again subdivided into 4 subgroups: Digitata (inflorescence branches only curved at the top), Incurvata (inflorescence branches incurved), Liliacea (inflorescence branches reflexed) and Stellata (inflorescence branches twisted).
Finger millet is mainly grown in the tropics, from sea-level up to 2400 m altitude (in Nepal up to 3150 m), preferably in areas with the optimum daylength of about 12 hours. It has a C4-cycle photosynthetic pathway. Optimum temperatures are an average maximum of above 27 °C and an average minimum not below 18 °C. It needs about 750 mm rainfall during growth (average annual rainfall usually 900-1200 mm), well distributed during the growing season and without prolonged spells of drought. It is not as drought tolerant as sorghum and pearl millet and, unlike rice and maize, does not grow well with heavy rainfall. At harvesting, a dry period is required. It grows on a wide range of soils, but reasonably fertile, well-drained sandy loams are preferred, with pH 6.5-8. It does not tolerate waterlogging. In South-East Asia, finger millet is grown in semi-arid to subhumid areas.
Propagation and planting
Finger millet is propagated by seed. When irrigated, seedlings are raised in nurseries and transplanted when 3-4 weeks old. This usually gives better results than direct seeding, although transplanting is labour intensive. Under rainfed conditions seed is often broadcast, preferably 1-2 weeks before the onset of the rains. Planting or sowing (2.5 cm deep) in rows facilitates weeding; the usual spacing is about 25 cm between rows, and plants are thinned to 10-12.5 cm apart. Finger millet is planted or sown on ridges where there is a risk of waterlogging. Seed rate depends on the cultivation method and varies from 6-20 kg/ha. Finger millet is mainly a smallholder's crop and is often intercropped, for example, with other cereals (sorghum, maize), legumes (pigeon pea, cowpea, green gram, lupin) or rape seed. Land is prepared by hand or by ox-drawn plough. In Africa, finger millet is often grown in shifting cultivation systems. The "chitemene" system in Zambia is well known: branches from 2.5-4 ha of woodland are piled and burned on about 0.4 ha of land, with finger millet broadcast in the ash, giving a reasonable yield without any further cultivation but requiring a regeneration time of 20-40 years for the woodland.
Finger millet does not tolerate competition in its early stages of growth, so weeding and thinning are important and are usually effected when plants are about 5 cm tall. E. indica and wild forms of finger millet that are difficult to distinguish vegetatively from the crop, are serious weeds. In Ethiopia, Guizotia scabra (Vis.) Chiov. and Setaria species are major weeds and sometimes 7-8 ploughings are needed to eradicate them. When rainfall is insufficient, only irrigation can save the crop, but this can hardly be afforded by smallholders. In India, finger millet is usually manured with cattle or sheep dung, applied at sowing or later. In shifting cultivation systems in Africa, finger millet is fertilized with ash and a mulch of the surrounding vegetation. Finger millet responds well to chemical fertilizers. In Zimbabwe, for example, 40-60 kg N, 26-40 kg P and 35-50 kg K are recommended per ha for poor soils; in Kenya, good results were obtained with an application of N and P of 20 kg/ha each; in India, recommendations are 20-60 kg N, 15-25 kg P, and 50 kg K. In practice, however, fertilizers are seldom applied and finger millet should profit from residual soil fertility from previous crops. In shifting cultivation, finger millet is often the first crop in the rotation, often followed by pulses and cassava. In other cropping systems, finger millet is usually intercropped or grown as a sole crop between two major crops (e.g. in Bangladesh between 2 rice crops). Sometimes two crops of finger millet can be grown per year.
Diseases and pests
In general, finger millet suffers from relatively few diseases and pests. Blast (Magnaporthe grisea , syn. Piricularia grisea) can be a serious disease. It provokes brownish lesions on young leaves, black lesions on the inflorescence, and the premature drying of old leaves. Other lesser diseases include leaf blight caused by Helminthosporium nodulosum and Gloeocercospora sp., leaf spot (Cercospora sp.), tar spot (Phyllachora eleusinis) and footrot (Sclerotium rolfsii).
The only serious pest in India is the hairy caterpillar of Amsacta albistriga, but army worms and grasshoppers may cause damage too. In Africa, the phytophagous ladybird Epilachna similis sometimes causes serious damage. Bird damage may occur but is nowhere reported to be serious. Stored grains are hardly attacked by insects and can be kept up to 10 years with little damage.
Harvesting time varies per cultivar from 3.5-6 months after sowing, but may start when grains contain about 10% moisture. Because mixtures of cultivars are often grown, ripening is uneven, making several pickings necessary. Local cultivars are liable to shatter. Harvest is usually by hand and, therefore, very laborious. In Africa, infructescences are cut with a knife with 5-8 cm of the culm attached, then dried, stored, and threshed by beating with sticks when required. In India, usually the entire aboveground plants are cut, stacked for about 2 months and then threshed, either by beating with sticks, trampling with bullocks or using stone rollers. Unthreshed infructescences produce 80-85% of grain. Mechanical threshing is possible with hammer mills.
Grain yields of finger millet are very variable, ranging from 400-2000 kg/ha, averaging 950 kg/ha. In India, the average yield of rainfed crops increased from 700 kg/ha in the 1950s to about 1000 kg/ha in the 1980s. Irrigated finger millet usually reaches double the yield of rainfed crops. Under optimal conditions including fertilizer applications yields can reach about 5 t/ha.
Handling after harvest
Smallholders grind grain to flour between two stones as required. To obtain larger quantities of flour, grain can be ground in grinding mills. The straw is fed to animals, burned, or used as mulch and incorporated in the soil.
Ethiopia, where the largest diversity exists, is considered to be the centre of origin of finger millet. The Plant Genetic Resource Centre of Ethiopia keeps about 1300 accessions. Large germplasm collections are also available in other African countries: Uganda more than 1000, Kenya about 1100, Malawi 1000, Zimbabwe 600 accessions. India is considered as a centre of diversity, and 2500 accessions are available at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).
Numerous cultivars adapted to local circumstances have been developed in countries where finger millet is grown on a larger scale. The potential for finger millet improvement is promising because enough valuable germplasm is available. In general, the major breeding objectives are: higher and stable yield, short growing cycle and resistance to lodging and to blast disease. For grain, white-seeded forms are preferred. New breeding techniques, including mutation breeding and breeding of high-yielding hybrid cultivars with male sterile lines, show promising results.
In Africa and India, finger millet is growing in popularity, unlike other lesser millets. Because of its good storage capacity, finger millet will remain an important crop to overcome periods of famine in areas with unreliable rainfall or other natural calamities. It seems unlikely that it will become a major cereal because labour, capital and research will be diverted to other crops. In South-East Asia, finger millet can be potentially useful, for example, as a short-term off-season catch crop on paddy fields which have been drained and harvested.
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