Copyright © 1997. All rights Reserved. Quotation from this document should cite and acknowledge the contributors.
Lentil (English), Adas (Arabic), Mercimek (Turkey), Messer (Ethiopia), Masser (India), heramame (Japanese)
Species: Lens culinaris Medic.
Lentil is a nutritious food legume. It is cultivated for its seed and mostly eaten as dhal. Dhal is seed that is decorticated and split. The primary product is the seed which has a relatively higher contents of protein, carbohydrate and calories compared to other legumes and is the most desired crop because of its high average protein content and fast cooking characteristic in many lentil producing regions (Muehlbauer et al., 1985). It can be used as a main dish, side dish, or in salads. Seeds can be fried and seasoned for consumption; flour is used to make soups, stews, purees, and mixed with cereals to make bread and cakes; and as a food for infants (Williams and Singh, 1988). Even though lentils are considered to be highly nutritious, they contain antinutritional factors such as, trypsin inhibitors, hemagglutinins, and oligosaccharides that cause flatulence. These problems can be greatly reduced by heating and germination (Jambunathan et al., 1994). Williams et al. (1994) reported that lentils have the least while faba bean generally have the highest concentrations of these antinutritional factors. Tannins are present in high concentrations in the seed coat; however tannins can be removed by processing (Williams et al., 1994), most often to remove the seedcoats. Husks, dried leaves, stems, fruit walls and bran (residues), can be fed to livestock. Lentil residues contain about 10.2% moisture, 1.8 % fat, 4.4% protein, 50% carbohydrate, 21.4% fiber, and 12.2% ash (Muehlbauer et al., 1985). According to Muehlbauer et al. (1985), when production of forage crops fall below the level required in the market, lentil residue commands an equal or a better price than lentil seeds in some Middle Eastern countries. Green plants make valuable green manure. Seeds are a source of commercial starch for textile and printing industries (Kay, 1979).
Protein concentration of lentils reportedly range from 22-34.6%, and 100 g of dried seeds contain 340-346 g calories, 12% moisture, 20.2 g protein, 0.6 g fat, 65.0 g total carbohydrate, about 4 g fiber, 2.1 g ash, 68 mg Ca, 325 mg P, 7.0 mg Fe, 29 mg Na, 780 mg K, 0.46 mg thiamine, 0.33 mg riboflavin, 1.3 mg niacin (Adsule et al., 1989; Muehlbauer et al., 1985). Among the cool season legume crops, lentil is the richest in the important amino acids (lysine, arginine, leucine, and sulpher containing amino acids) (Williams et al., 1994). The starch content ranges from 35-53% in the seed and 42% in dry matter while amylose varies from 20.7 to 38.5% of the seed starch (Huisman and van der poel, 1994; Hulse, 1994). "One hundred grams of decorticated lentil seed contain 344 calories, 9.9 % moisture, 25.8 g protein, 1.8 g fat, 58.8 g total carbohydrate, 0.9 g fiber, 3.7 g ash, 24 mg Ca, 271 mg P, 10.6 mg Fe, 0.47 mg thiamine, 0.21 mg riboflavin, and 1.5 mg niacin. Lentils are a good source of B vitamins, containing per 100 g: 0.26 mg thiamine, 0.21 mg riboflavin, 1.7 mg nicotinic acid, 223 mg choline, 107 mg folic acid, 130 mg inositol, 1.6 mg pantothenic acid, 13.2 mg biotin, and 0.49 mg pyridoxine. Vitamins, except folic and pantothenic acids, increase markedly during sprouting. Dry lentil husks contain 11.1% protein (1.3% digestible), 0.7% fat, 47.5% carbohydrate, 25.6% fiber, and 3.1% ash" (Duke, 1981). "About 90% of lentil protein is found in the cotyledons with albumins and globulins being the major fractions. Digestibility coefficients for lentil are relatively high and range from 78-93%, while biological values range from 32-58%. Oleic, palmitic and linoleic are the dominant fatty acids" (Hulse, 1994).
Lentils are supposed to remedy constipation and other intestinal afflictions. "In India, lentils are poulticed onto the ulcers that follow smallpox and other slow-healing sores" (Duke, 1981). In the 6th century, chickpeas were believed to be an aphrodisiac; while curiously enough, lentils were considered to have the opposite effect, and this was probably the reason why the lentil was included in the diet in monasteries on meatless days (Van der Maesen, 1972).
Lentils probably originated in the Near East and rapidly spread to Egypt, central and southern Europe, the Mediterranean basin, Ethiopia, Afghanistan, India and Pakistan, China and later to the New World including Latin America (Cubero, 1981; Duke, 1981; Ladizinsky, 1979). It is probably the oldest of grain legumes to be domesticated (Bahl et al., 1993). It is now cultivated in most subtropical and also in the Northern hemisphere such as Canada and Pacific Northwest regions.
The botanical features of Lens culinaris (cultivated lentil) can be described as annual bushy herb, slender almost erect or suberect, much-branched, softly hairy; stems slender, angular, 15-75 cm height (Duke, 1981; Muehlbauer et al., 1985). Ten to sixteen leaflets are subtended on the rachis (40-50 mm); upper leaves have simple tendrils while lower leaves are mucronate (Muehlbauer et al., 1985). "The leaves are alternate, compound, pinnate, usually ending in a tendril or bristly; leaflets 4-7 pairs, alternate or opposite; oval, sessile, 1-2 cm long; stipules small, entire; stipules absent; pods oblong, flattened or compressed, smooth, to 1.3 cm long, 1-2-seeded; seed biconvex, rounded, small, 4-8 mm × 2.2-3 mm, lens-shaped, green, greenish-brown or light red speckled with black; the weight of 100 seeds range from 2 to 8 g; cotyledons red, orange, yellow, or green, bleaching to yellow, often showing through the testa, influencing its apparent color" (Kay, 1979; Duke, 1981; and Muehlbauer et al., 1995). Flowers are small, pale blue, purple, white or pink, in axillary 1-4-flowered racemes; 1-4 flowers are borne on a single peduncle and a single plant can produce upto 10-150 peduncles each being 2.5-5 cm long (Muehlbauer et al., 1985). Flowering proceeds acropetally. The size of seeds increase from the types grown in eastern regions to western types. Two types, namely; macrosperma, found mainly in the Mediterranean region and the New World (seed size ranging from 6 to 9 mm in diameter and yellow cotyledons with little or no pigmentation), and microsperma (2 to 6 mm with red orange or yellow cotyledons) found on the Indian subcontinent, Near East and East Africa, respectively, are known (Hawtin et al.,1980; Muehlbauer et al, 1985). The first one includes the Chilean or yellow cotyledon types while the latter includes the small seeded Persian or red cotyledon lentils (Kay, 1979). Germination is hypogeal and this keeps the developing seedlings below ground level which reduces the effects of freezing and other desiccating environmental conditions (Muehlbauer et al.1985).
"Seeds will germinate at temperatures above freezing but best at the range of 18-21°C; temperatures above 27°C are harmful; optimum temperatures for growth and yields are around 24°C. Lentils are grown as a cool weather or winter crop in the semi-arid tropics, cultivated from sea level to 3,800 m, but are not suited to the humid tropics. They are less damaged by drought than by waterlogging. In Bulgaria, small-seeded cultivars are more drought-resistant than large-seeded. Lentils thrive on a wide range of soils from light loams and alluvial soil to black cotton soils, best on clay soils; tolerate moderate alkalinity. Salt tolerance is higher during germination than during subsequent development. At 20.0 mmhos/cm salinity, seed yields are reduced 50%. Greenhouse studies suggest that tolerance to 3.9 mmhos is more realistic. Lentils are quantitative long-day plants, some cultivars tending to be day-neutral. Lentil is reported to require environments ranging from cool temperate steppe to wet through subtropical dry to moist forest life zones. It tolerates annual precipitation of 2.8-24.3 dm annual mean temperature of 6.3-27.3°C and pH of 4.5-8.2". (Kay,1979; Duke, 1981)
Lentil is propagated by seed. Fields should be plowed and harrowed to a fine texture. Well drained soils on south-and east-facing slopes because these slopes get warmer during the early part of the growing season and as a result crop emergence will be faster (Muehlbauer et al., 1981; Muehlbauer et al., 1985). Seed may be either broadcast, or sown in drills at the rate of 25-90 kg/ha, in rows 20-30 cm apart. Muehlbauer et al. (1981) reported that in the United States lentils are often planted with small grain equipment in rows spaced 15-18 cm apart. Lentils are a cool season legume species and as such are grown as a summer annual in temperate climates and as a winter annual in subtropical climates. In India, planting starts late in November when sown in monoculture. Two intercultivations are usually sufficient for weed control during establishment. A 2-3-1 NPK mixture is applied at planting time, followed by a top-dressing of ammonium sulfate at flowering. In India, lentils may be intercropped with barley, castor, mustard, and rice; while in other areas, lentil is rotated with other crops, especially wheat, barley, tef, or other cereals depending on the region.
Lentil flowers in 6-7 weeks after planting with early cultivars ready to harvest in 80-110 days, late cultivars reach maturity in 125-135 days. In traditional agricultural systems plants are cut to ground level or pulled by hand when they turn golden yellow and left to dry for 5-10 days before being threshed and winnowed. Low moisture is desirable at harvest. In the United States, lentils are harvested with swathers that cut and windrow the crop for drying. After a 5-10 day drying period, the lentil crop is harvested by combine. Harvesters used for cereals but with slower cylinder speeds are used for lentils. Also, in USA, the lentil crop is cleaned by air and sieves and other seed processing equipment to remove inert materials and produce graded products. For red lentils, 50% of the product should remain on a 4.35 mm round hole perforated screen and 100% to remain on a 3 mm screen, while for the yellow lentils they should remain on 7 mm and 5 mm screens (Muehlbauer et al., 1985). In Russia, problems with mechanical harvesting were overcome by intercropping with a fiber plant Camelina that served as a support. Lentils are usually stored in bulk bins or elevators.
Seed yields range from 450-675 kg/ha in dry areas, may increase to 2000 kg/ha with irrigation, and yields over 3,000 kg/ha have been recorded. The straw-to-seed ratio in one cultivar was about 1.2:1 and in studies conducted on 28 cultivars in New Delhi, India, pulse yields ranged from 558 to 1,750 kg/ha, while dry matter yields ranged from 2,667 to 3,550 kg/ha (Duke, 1981). The major producer of lentils in the world is India, with about 1,160,000 hectares producing 850,000 MT in 1994; while World production was 2.875 million MT on about 3.36 million hectares during the same year (FAO, 1994). Other important producers are USA, Australia, Canada, Pakistan, Syria, Argentina, Chile, Turkey, Ethiopia and Spain. In these countries, yields have ranged from 637 to 1263 kg/ha while the highest yield, 5000 kg/ha was recorded in Germany (FAO). World production of lentil increased by about 65% over the past 25 years (FAO, 1996). In developing countries alone, lentil production and yield rose by 60% (Hulse, 1994). Major production increases have been recorded in Turkey and Canada. In the USA, lentil occupies about 60,000 ha, and from 1984 to 1993, 65, 000 tons of lentil have been produced (Muehlbauer, 1996). Among the agronomic problems, pod shedding, pod shattering, lodging, and the spreading growth habit are important constraints in production (Robertson et al, 1996). Close to 80-85 % of lentil production in the USA is exported (Muehlbauer et al., 1995 and Muehlbauer, 1996). Canada, Turkey and the USA are major exporters of lentil.
Several fungal diseases are recorded on lentil, but lentils are not considered to be disease prone. They are seriously affected by fewer diseases than Phaseolus and Pisum. One of the worst diseases in Asia is Fusarium wilt, caused by Fusarium oxysporum f. sp. lentis, which is favored by light and dry soils. Rust, caused by Uromyces fabae, is favored by high humidity and moderate temperatures (17-25°C) and is important in Morocco, Ethiopia, Pakistan and South America. Infection of susceptible cultivars could lead to total failure as observed in Morocco and Ethiopia. Other fungal diseases recorded on lentil include, ascochyta blight, caused by Ascochyta lentis, which is an important foliar disease in many parts of the world including Canada. Resistance sources have been identified in North America and elsewhere, for Fusarium wilt, rust and viruses and is being used extensively in crossing programs. Among the viruses, pea seedborne mosaic virus (PSbMV) is potentially dangerous because it is seedborne and is transmissible by aphids (Muehlbauer et al., 1995). Aphids are serious insect pests on lentil and sometimes cause total failure of lentil production as has been observed in Ethiopia. Lentils are also attacked by a bacterium, Mycobacterium insidiosum; by parasitic flowering plants, Cuscuta sp. and Orobanche sp.; by viruses, pea enation mosaic, bean yellow mosaic; and by nematodes (Kaiser et al., 1994; van Emden et al., 1994). Insects of economic importance in the United States Lygus bugs (Lygus sp.) and aphids. In Southeast Asia, the main insect pests are the gram caterpillar, Heliothis obsoleta; white ants. Clotermes sp.; the gram cutworm, Ochropleura flammatra; and the weevil Callosobruchus analis (Duke, 1981). Other important insect pests throughout the world include Frankliniella spp. (Bud thrips), Bruchus ervi and B. lentis (Bean seed beetle), Callosobruchus chinensis (Adzuki bean seed beetle), Sitonia lineatus (bean weevil), Cydia nigricana (Pea moth), Agriotis spp. (Cutworms), and Heliothis armigera (African bollworm) (van Emden et al., 1994.
The most comprehensive collection of lentil germplasm (about 7407 accessions) is maintained by ICARDA located at Aleppo, Syria (Robertson et al., 1996). The Regional Plant Introduction Station located at Pullman, USA has a collection of 2868 accessions. National programs of other countries also maintain a considerable number of germplasm accessions (Muehlbauer et al., 1995; Robertson et al., 1996). Usually placed in two groups of subspecific rank: Lens culinaris ssp. macrosperma (Baumb.) Barulina include the large-seeded cultivars with large flattened seeds (6-9 mm diameter), flowers large, white or blue. The macrosperma types are important in the northern hemisphere. The smaller seeded L. culinaris ssp. microsperma (Baumb.) Barulina have small flowers that are violet-blue to white or pink convex pods and seeds that range from 2-6 mm. The microsperma are principally found in southwest and western Asia and Africa (Muehlbauer et al., 1985). Lentils may also be classified as summer and winter types. Field rankings for winter hardiness are reported to be higher for lentil and faba bean followed by pea and chickpea (Murray et al., 1994). One wild species of the Near East Lens orientalis (Boiss.) shows close morphological similarities and close genetic affinities to L. culinaris. It is occasionally interconnected to the cultivated lentil by a series of intermediate types and is completely interfertile with cultivated types. On the basis of combined archaeological, botanical, and genetic evidence, Zohary (1973) concluded that L. orientalis is the wild progenitor of cultivated lentil and that the domestication of this pulse took place in the Near East arc. Assigned to the Near Eastern center of diversity, lentil genotypes or cultivars from that center are reported to exhibit tolerance to alkali, disease, fungus, drought, high pH, heavy soil, heat, insects, low salinities, poor soil, slope, and virus (Duke, 1981, Muehlbauer et al., 1985). Some cultivars have high levels of cold tolerance. The passport data for various agronomically important traits including disease and pest resistance, adaptability, growth habit, resistance to lodging, and fruit dehiscence, tolerance to various abiotic stresses, and yielding and biomass production have been partly documented (Robertson, 1996; Muehlbauer, 1996). The core collection comprising 287 accessions of lentil has been developed at the Regional Plant Introduction Station located at Pullman USDA-ARS (Simon and Hannan, 1995) and has been evaluated for resistance to several diseases.
Research geneticist, USDA-ARS
303 Johnson Hall
Washington State University
Pullman, WA 99164-6439
Tel: (509) 335-9521
Fax: (509) 335-7692
Regional Plant Introduction Station
59 Johnson Hall, WSU
Pullman, WA 99164-6402
Tel: (509) 335-1502
Fax: (509) 335-6654
Regional Plant Introduction Station, USDA-ARS
Washington State University, 59 Johnson Hall
Pullman, Washington 99164-6402
Crop Development Center
University of Saskatchewan, Saskatoon,
Saskatchewan S7N 0W0, Canada
Contributors: F.J. Muehlbauer and Abebe TulluCopyright © 1997. All rights Reserved. Quotation from this document should cite and acknowledge the contributors.