Synonym is A ilium sativum L.
Common names are Welsh Onion, Green Bunching Onion, Japanese bunching onion, spring onion, two-bladed onion, Chinese small onion (Eng.); ciboule (Fr.); cebolla, ceboletta (Sp.); riihtenlauch (Ger.); pijplook, bieslook (Neth.); taai ts’ung (China); kikiyu onion (E.Afr.)
Widely grown in many tropical areas, particularly tropical Asia and Africa.
Widely grown in tropical Asia (Indonesia, Malaysia, the Philippines, China); East and West Africa.Grown as an annual herb, rarely producing bulbs, basal lateral buds develop to form many offshoots. Roots: adventitious, fibrous. Leaves: hollow, circular in cross-section, 15-30 cm in length. Flowers: borne in an umbel on a hollow scape 40-80 cm in height; perinatal segments 6-8 mm in length, yellow; flowers open from tip of umbel downwards.
Well-drained barns, with a high level of organic material are generally suitable. The plants are adapted to a wide range of temperature but rarely thrive in lowland areas with temperatures greater than 25C. Seeds are sown in containers or in a seedbed and the seedlings are transplanted, when 15-20 cm in height, to prepared beds with rows 24-30 cm apart, plants 15-20 cm apart in the row, or in square planting at 20 cm X 20 cm. Seed requirement: 4 kg/ha to give a density of 300 000 plants/ha.
Most cultivars are easily propagated by division of the basal shoots produced by the parent plant. These are detached and plan
Fertile, well-drained sand or silt loam soils, with good moisture retaining properties give good results; heavy clay soils are likely to produce malformed bulbs. The major elements should be available to the crop during growth but a surface dressing of nitrogen as bulbing begins is often beneficial. Potash may be required in some areas. Relatively high temperatures up to 30C are required for optimum bulb development but cooler conditions in the early stages favor vegetative growth. Flower initiation does not appear to be directly linked with low temperatures; some clones do not flower. Excessive humidity and rainfall are detrimental to both vegetative growth and bulb formation. The crop is therefore normally grown in low rainfall areas with irrigation, if required, during the early vegetative growing stage when the rate of water intake by the plant is relatively high and is approximately the same as that of onion. In most areas, elevations from 500-2000 m provide suitable growing conditions, particularly during dry periods. Long days favor bulb development. In areas where there is a seasonal variation in length of day, it is preferable to plant during short photo periods so that maximum use will be made of this for vegetative growth. The total yield depends on the amount of vegetative growth made before bulbing begins.
Plants are normally mature enough for harvesting 60-120 days from planting, depending on the characteristics of the cultivar. An average yield of 20 t/ha may be obtained. Seeds are rarely produced in short days and high temperatures. The leaves should be crisp, clean and free from discoloration. The roots should be trimmed, without damaging the condensed stem base, before the plants are tied into bunches.
The bulbs should be mature 90-120 days from planting, when the leaves turn brown and dry out. Leaves required for flavoring can be cut before they become mature. Yield: Within the range of 5-10 t/ha, depending on the cultivar characteristics. Seed production: Plants do not normally produce fertile flowers.
Plants are propagated either from seed or division of existing clumps. Seeds, rarely formed in the lowland tropics, are normally sown in rows 30 cm apart. The leaves are often blanched by being covered. The young inflorescences, as well as the leaves, are used for seasoning.
The leaves should be crisp, clean and free from discoloration. The roots should be trimmed, without damaging the condensed stem base, before the plants are tied into bunches. The leaves and bulbs are used as flavoring in soups, or eaten raw as a salad vegetable.
