|Root Crops (NRI, 1987, 308 p.)|
LOTUS ROOT, Indian Lotus, Lotus,
Nelumbo nucifera Gaertn. syn. Nelumbium speciosum Willd., Nelumbium nelumbo Druce.
Agyptische bohne (Ger.); Ambuj (Ind.); Baino (Philipp.); Bhen (Ind.); Bua luang (Thai.); Chinese water lily; Gliglio de Nilo (It.); Hasu-n-ne (Japan); Jamaica water lily, Kamal, Kanwal, Kumala (Ind.); Lotier (Fr.); Nilli lili (Ger.); Ninfea d'Egetto (It.); Padma, Pankaja (Ind.); Patma (Mal.); Tarate (Indon.).
A perennial aquatic herb, rooting in mud, with a creeping white globulous rhizome which produces, at intervals, a single leaf and a single flower. Leaves are peltate, 60-90 cm in diameter on very long petioles and are often raised 1-2 m above the surface of the water. They have a wax coating that causes rain water to form large drops that roll off the edges of the blades. The flowers are solitary at the ends of long stems, each with four sepals and numerous petals and stamens: they are large, 15-25 cm across, very showy, variously coloured in shades of pink, and are followed by a somewhat cone-shaped torus, 5-10 cm in diameter, with 10-30 carpers sunk into the upper surface: these carpers mature into ovoid nut-like, edible achenes. The leaves and stems arise from thick spreading rhizomes which radiate out from the original plant and root frequently; the growth of the rhizomes is rapid and new plants are quickly established from buds on the rhizomes.
Origin and distribution
The plant appears to have originated in South-East Asia and possibly Africa and has spread throughout the lowlands of southern Asia and into Australia. It was early introduced into other tropical and subtropical regions and was an important plant of ancient Egypt and other eastern Mediterranean countries. It is now grown mainly as an ornamental in lakes and ponds but also as a source of food in many areas including India, Japan, Malaysia, China, Hawaii, and to a small extent, California.
Although mainly grown in tropical and subtropical regions, lotus root can withstand a considerable degree of frost, and in India may be found from sea level up to 1 800 m. It is grown in lakes, ponds and rivers.
Material - lotus root can be propagated from small pieces of rhizome having at least one eye, or from seed.
Method - a number of methods are described in the literature, among them the following:
(i) Pieces of rhizome are planted with the eyes just above the soil surface and the water level is maintained at about I m of water throughout their growing period.
(ii) Pieces of rhizome are placed horizontally about 15 cm below the soil surface, and water allowed to cover the soil, but with the crown of the developing plant just breaking the surface of the water. The water level is raised as the plant develops.
(iii) A method of planting in a filled pool or pond is to put sprouting pieces in a basket, pot, tub or other suitable container filled with a mixture of soil and compost or FYM, and then place the container in the pool in such a way that the crown of the plant is just above the water surface. The container should be on bricks or stones, and as new growth appears the container is lowered by removal of bricks to maintain the crowns just on or above the water surface.
(iv) When grown from seed, the seedlings are raised in nursery beds and planted out in the ponds after about 2 months in the manner indicated in (ii).
Seed rate - approximately 45 kg of rhizome pieces are used to plant one hectare, or 10-12 kg of seed. Planting density is low because of the very rapid growth of the rhizomes, reported as up to 15 m2 per year.
Pests and diseases
In Japan, rhizome rots have caused a considerable reduction in lotus root production; two organisms have been identified, Bacillus nelumblii and Fusarium bulbigenum Wr. nelumbicolum, and are associated with iron deficiency, especially on light sandy soils. Rice root worm, Donacia provostii, also affects the crop in some areas, but effective control is reported to be obtained by a pre-planting application of aldrin at the rate of 1-2 kg/ha. In countries where aldrin is not permitted carbofuran at 5 kg/ha or chlorpyrifos at 2-5 kg/ha should be effective.
The rhizomes mature to a suitable stage for eating in approximately 6-9 months, though if not harvested will continue growing until checked by competition with their neighbours.
Harvesting and handling
The roots are normally dug by hand after the ponds are drained just before harvesting, but a mechanical harvesting system is being developed in Japan.
Rhizomes - the fleshy starchy rhizomes when harvested at 6-9 months can measure 60-120 cm in length and 5-10 cm in diameter, and resemble the links of large sausage, each individual link being about 7.5-15 cm long and weighing from about 150 g to 1.2 kg. A cross-section reveals one central air passage surrounded by several smaller ones and the flesh can vary in colour from white or grayish-white to pink or orange-buff. They are very fibrous and when freshly cut they exude a mucilaginous juice.
In India the crop is reported to yield 3.5-4.5 t/ha.
The fresh rhizomes are eaten after roasting; dried slices are fried as chips or used in curries. The rhizomes may also be pickled and quick frozen, but must be eaten young otherwise they are very tough and fibrous.
The rhizomes can be used as a source of a starch, similar to that of arrowroot.
Secondary and waste products
Carpels - the carpers are regarded as a delicacy and are eaten after the removal of the outer skin and the embryo, which is intensely bitter. They are eaten raw, roasted, boiled, candied or ground into a flour.
Flowers - the flowers are often used for decorative purposes, especially in religious festivals, and were formerly used as a source of perfume.
Leaves, petioles - these are sometimes eaten as a fresh vegetable. The petiole yields a yellowish-white fibre and the leaves are sometimes used for medicinal purposes.
Rhizomes - figures for composition of the edible portion of the rhizomes have been quoted as: energy 331 kJ/100 g; water 78.3 per cent; protein 1.4 per cent; fat 0.2 per cent; carbohydrate 19 per cent; fibre 0.8 per cent; ash 4 per cent; calcium 4 mg/100 g; iron 0.6 mg/100 g; phosphorus 65 mg/100 g; potassium 500 mg/100 g; thiamine 0.14 mg/100 g; riboflavin 0.2 mg/100 g; niacin I mg/100 g; ascorbic acid 4 mg/100 g.
The starch grains are large, much elongated, 65-100 microns, one end is usually rounded and contains the excentric hilum, the other is usually truncated. The rhizomes are reported to contain approximately 2 per cent aspargine.
Carpels - the dried carpers have the following approximate composition: moisture 10 per cent; protein 17.2 per cent; fat 2.4 per cent; carbohydrate (mainly starch) 66.6 per cent; fibre 2.6 per cent; ash 3.8 per cent; calcium 136 mg/100 g, iron 2.3 mg/100 g, phosphorus 294 mg/100 g. In addition to starch, the carbohydrate content consists of sucrose 4.1 per cent, and reducing sugars 2.4 per cent (as percentages of fresh weight).
Alkaloids - the leaves, carpers and rhizomes are reported to contain alkaloids: nelumbine, which acts as a cardiac poison, has been isolated from the petioles, pedicel and seed embryo, while the leaves contain roemerine, dehydroroemerine, nuciferine, dehydronuciferine, pronuciferine, nornuciferine, N-nornuciferine, armepavine, liriodene, N-methylcoclaurine, anonaine and dehydroanonaine.
In China, a fine white starch, similar in properties to that from arrowroot, is obtained by pulping the clean washed rhizomes and pressing the resultant pulp in a wooden press. The milky extract is collected, mixed with an equal quantity of pure, clean water and the starch left to settle out. It is filtered and then dried on bamboo mats in the sun.
There is a demand for lotus root as an ingredient in Chinese foodstuffs, in Japan and in India, but development outside China has been hampered mainly owing to the high cost of harvesting the crop; however, the development in Japan of a technique for mechanical harvesting may ease this situation.
ANON. 1930. Lotus root flour of Hangchow. Chinese Economic Bulletin, 16 (20), 250-251.
DESHAPRABHU, S. B. (ed.). 1966. Nelumbo nucifera. The wealth of India: Raw materials, Vol. 7 (N-Pe), pp. 7-9. New Delhi, India: Council for Scientific and Industrial Research, 330 pp.
ENDO, S. 1975. [Mechanical harvesting of lotus roots (edible organic herbs.)] Farming Mechanisation, 6, 26-28. (In Japanese).
ESAU, K. 1975. Leaf arrangement in Nelumbo nucifera. A re-examination of a unique phyllotaxy. Phytomorphology, 25 (1), 110-112.
ESAU, K. and KOSAKAI, H. 1975. The phloem of Nelumbo nucifera Gaertn. Annals of Botany, 39 (163), 901-913.
IRVINE, F. R. and TRICKETT, R. S. 1953. Water lilies as food. Kew Bulletin, (3), 363-370.
KUNIMOTO, J., YOSHIKAWA, Y., TANAKA, S., IMORI, Y., ISOI, K., MASADA, Y., HASHIMOTO, K. and INOUE, T. 1973. Alkaloids of Nelumbo nucifera. Phytochemistry, 12, 699-701.
MALIK, H. C. 1961. It pays to grow singhara and bhen. Indian Farming, II (8), 23-24.
MONTALDO, A. 1972. Loto. Cultivo de ras y tubulos tropicales, pp. 262-263. Lima, Peru: Instituto Interamericano de Ciencias Agricolas de la OEA, 284 pp.
NISIKADO, Y. and WATANABE, K. 1953. [On the rhizome rot of lotus, Nelumbo nucifera Gaertn. caused by a new fusarium F. bulbigenum Wr. nelumbicolum Nis. et Wat.] Bericht des Ohara Instituts fdwirtschaftliche, Forschungen, 10, 1-8. (Horticultural Abstracts, 1954, 24 (3), 2977).
OCHSE, J. J. 1931. Nelumbium nelumbo. Vegetables of the Dutch East Indies, pp. 542-544. Buitenzorg, Java: Archipel Drukkerij, 1005 pp.
PORTERFIELD, W. M. (Jr.). 1951. The principal Chinese vegetable foods and food plants of Chinatown markets. Economic Botany, 5, 10-11.
SHEPHERD, A. D. and NEUMANN, H. J. 1958. New processed vegetables may diversify agriculture and diet. Chemurgic Digest, 17(11), 6.
SHUKLA, K. S. 1977. The lotus (Nelumbo nucifera). Indian Horticulture, 22 (1), 21-27.