Bulb onions

Bulb onions can be grown on a wide range of mineral and peat soils provided that they are well drained, have a good available-water capacity, a pH of 6.5 or mote and can provide a good seedbed. Bulb onions eanbe grown in marty parts of the UK, but do best in the eastern and south-eastern counties where it is often drier at harvesting time, which helps promote skin quality. 

Onions develop best in loose, well-stractiued soil. Ideally the land should be deep ploughed and disced before planting. Capping soils should be avoided. In some fields destoning may be needed to remove large stones that could alFect onion development and harvesting. 

Onions are planted by precision drill in shallow double rows, 1-2 em deep. A bed system is used with the seed spacing dictating bulb size. A target of 5-7 em bulbs would require 50-100 plants/ml Sets are planted at similar spaeings using specialist planters. 

Onions (and other albums) should not be grown more often than one year in fom, and ideally one year in six in the same field, because of the risk of nematode, onion fly and white rot disease. 

The following can affect bulb onions leaf blotch, downy mildew, onion white rot, neck rot, onion fly, cutworms, bean seed fly, thrips and bulb and stem nematode. 

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Onions for storage Once harvested, bulb onions need to be kept in a warm, dry, airy environment for a week or two to "harden" their skins so that they will store well. In sunny weather you can leave them on the soil surface (see also p.271). 

Bulb onions and leeks respond well to variations in plant spacing (see pp.256-259), which can be used to control the size of the plants. A crop of baby leeks, for example, can be grown as close as 2 in (5 cm) apart. 

Bulb onions illustrate the influence of spacing on size. For large bulbs, an equidistant spacing of 8 x 8 in (20 x 20 cm) is ideal. By... 

Potatoes are always grown from tubers. Always buy certified seed potatoes from a reliable source. They usually grow better if chitted before planting (see panel, opposite). Bulb onions and shallots can be grown from seed, but most... 

Melander, B. and Rasmussen, G. 2001. Effects of cultural methods and physical weed control on intrarow weed numbers, manual weeding and marketable yield in direct-sown leek and bulb onion. Weed Research 41(6) 491-508. 

Polysaccharides that exclusively contain D-fructose are known as fructans and there are two known kinds, inulin and levan. Inulin is a polysaccharide containing -D-fructofuranose linked (2 1) [118]. Inulins are found in the roots and tubers of the family of plants known as the Compositae, which includes asters, dandelions, dahlias, cosmos, burdock, goldenrod, chicory, lettuce, and Jerusalem artichokes. Other sources are from the Liliacae family, which includes lily bulbs, onion, hyacinth, and tulip bulbs. Inulins are also produced by certain species of algae [119]. Several bacterial strains of Streptococcus mutans also produce an extracellular inulin from sucrose [120]. 

On the other hand, protected edible parts of plants like seeds, tubers (potatoes), bulbs (onions), roots (radish and carrots) show hardly any increase in lead. It s an evidence that lead salts are immobile in the soil and largely unavailable to plant s roots. 

Lee, S., et al. (2014). Comparison study on soil physical chemical properties, plant growth, yield nutrient uptake in bulb onion from organic conyentional systems. HortScience, 49(12), 1563-1567. 

Perennial weeds should, wherever possible, be controlled in the previous year. Bulb onions are not very competitive and grass weeds can be a problem. 

A perennial or biennial herb with hollow leaves and a taller and thicker scape (flowering stem), also hollow up to about 1.2 m high generally considered to be native of western Asia has long been cultivated worldwide and much varied. Part used is the fleshy bulb onion oil is obtained by steam distillation. 

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