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Allium cepa var. cepa

Authority Family Liliopsida:Liliidae:Asparagales:Alliaceae Synonyms Common names Onions (bulb) Editor Ecocrop code 551

Notes
BRIEF DESCRIPTION A herb producing a bulb at the base. All parts produce a strong onion odour when crushed. Inflorescence may reach a height of 30-100 cm. Onions vary considerably in size, shape, color, and flavor. USES It is grown for its edible, pungent bulbs, which are rich in calcium and riboflavin (vitamin B2). The bulbs can be eaten raw or cooked and they are often used for flavoring. GROWING PERIOD Biennial, normally grown as an annual, growing 85-175 days. Requires two seasons to produce seeds. COMMON NAMES Onion, Common onion, Bulb onion, Oignon, Cebolla, Speise-zwiebel, Ui, Sibuyas, Yeung ts'ung tau. FURTHER INF Onion is probably indigenous to the mountain lands of central Asia where Afganistan, Iran and Pakistan meet. High temperatures encourage bulb formation, but flower formation and seed production are only possible where the bulbs are subjected to low temperatures. In the tropics, flower and seed formation will therefore only occur at higher elevations. The production of bulbs is controlled by the photoperiod, the critical day-length varies from 11-16 hours, depending on the cultivar. A long, dry period is required for bulb ripening after the leaves have withered. A cool period promotes early leaf production. Moist soil is required throughout the growing period, but excessive soil water and high humidity encourage diseases. Bulb yields of up to 5-10 t/ha or 0.5-1 kg/m˝ can be obtained. Mentioned as a useful agroforestry species.
Sources
SOURCES (A. cepa L. var cepa) Sims D 1993 (pers. comm.) Dube P 1982 pp 25 Maas E 1990 pp 278 Rice R 1990 pp 305-307 [FER, PH, RAIN, PHO] Tindall H 1983 pp 20-23 [FER, TEXT, PH, TEMP, PHO, RAIN] Rehm S 1991 pp 134-135 [PHO, USE] Doorenbos J 1979 pp 109 Kassam A 1976 pp 82 Landon J 1984 pp 282 285 290 301 [TEXT, DRA, DEP, PH, FER, SAL] Roecklein J 1987 pp 497 [USE] Eswaran H 1986 Hackett C 1982 pp 42 [FER, PHO, DEP, PH, TEXT, TEMP] Hartmann T 1981 pp 577-580 [TEMP, PHO, TEXT, PH] Kernick M 1961 pp 421 Purseglove J 1972 pp 38-50 [RAIN, TEMP, TEXT, DRA, FER, PH, PHO] Duke J 1982 pp 14 Langer R 1991 pp 33 OMM 1991 pp 1-5