Leek
Synonym is Allium cepa L. var. cepa.
Common names are Leek (Eng.); Poireau (Fr.); Puerro (Sp.); Breitlauch, Lauch, Porree (Ger.); Prei (Neth.); Kutsai, Kau Ts’ung, Taai Suen, Taai Ts’ung (Chin.); Kutsai (Philipp.).
In most areas, local cultivars have been selected.
A cultigen, not known in the wild state, possibly originating in the Mediteraranean region from Allium ampeloprasum L. Diploid chromosome number: 217 = 32.
Tropical Asia (India, Malaysia, the Philippines, China); Central, East, North and West Africa.
A biennial, negligible bulb formation. Leaves: flattened, variable in length, from 40-100 cm X 1.2-2.5 cm. Flowers: numerous, borne in a large terminal umbel, pink, anthers exserted.
Tolerant to a wide range of soils with a pH of 6.0-7.0. Loose, sandy soils with a high level of organic content are preferable, although silt-clay loams are often used. Bulb size and the number of cloves formed can often be increased by additional applications of nitrogen and potash after planting. Plants are very tolerant to high temperatures up to 30C and relatively high temperatures encourage bulb development in most cultivars. Bulbs are not formed at temperatures lower than 20C. Flowers are rarely produced at high temperatures and in short-day conditions. Yields are liable to be reduced during heavy rainfall, partly due to the incidence of disease. A dry period is required for ripening of mature bulbs and drying the leaves. Most cultivars grow well at altitudes varying from sea level to 2500 m. Larger bulbs are formed in day lengths of 12 hours than of 10 hours. Although the shallot can be regarded as requiring long days for maximum bulb development, most tropical cultivars will form bulbs of an adequate size in relatively short day lengths.
Seeds are rarely used; propagation is mainly by mature bulbs (setts), formed in clusters from the base of parent bulbs which have completed their dormant period by being stored for at least 6 weeks after harvesting. The clusters are separated and individual bulbs planted, two-thirds below the surface, on prepared beds with a well-consolidated surface. Spacing is usually 15 cm X 22 cm, or in rows 25-30 cm apart and 12-15 cm between bulbs. Approximately 1500 kg of bulbs are required for a population of 400 000 plants/ha. An average bulb diameter of 4-6 cm is common, but size is related to planting density. Time of planting is not dependent on climatic conditions, although bulbs are normally planted towards the end of a wet period. Shallots respond particularly to potash and phosphate but soils should also be well supplied with organic material before planting. Excessive nitrogen may lead to delayed bulb formation. Irrigation is essential during dry periods.
Mature plants may be harvested 120-150 days from transplanting by which time they will have grown to 25-30 cm in length and have a diameter of 4-5 cm. Yield: Often variable, but average yields are estimated to be in the region of 20 t/ha. Seed production: Seeds are rarely produced in tropical regions, except at very high elevations, since long days and relatively low temperatures are required for flower initiation and flower stalk elongation.
These are, in general, similar to the requirements of onion although storage in a controlled environment is rarely required if the bulbs are adequately cured.
The swollen, overlapping bases of the leaves are cooked; the upper portions of the leaves are rarely used.
