Plant family Amaryllidaceae is famous for its economically important edible plant containing the genus Allium. Onion is named Allium cepa. Cepa has a Latin origin meaning onion. Carl Linnaeus defined onion in its taxonomic classification of binomial nomenclature in 1753.
Onion (Allium cepa) is the most cultivated species of the family and genus as well. Farmers can have two harvestings per year, characteristics of the biennial plant. But it usually grows as an annual plant in many regions of the world.
For 7000 years, onion is being cultivated and used as an important kitchen ingredient. There are thousands of dishes around the globe that are incomplete without onion.
A volatile chemical is released during the processing or cutting of onion named syn-propanediol-S-oxide. It is responsible for eye irritation and activates lacrimal glands producing tearsBrodnitz, M.H. and J.V. Pascale, Thiopropanal S-oxide: a lachrymatory factor in onions. Journal of Agricultural and Food Chemistry, 1971. 19(2): p. 269-272. Read.
There are many subspecies of varieties associated with Allium cepa such as var. cepa, var. aggregatum, and some hybrids of A.cepa. Onion flies, bulb nematodes, and eelworms are important insect pests of onion. Fungal wilt is also an emerging issue that is decreasing onion production and export. Neck rot and grayish-white mycelia have also been observed when not stored properlyBrewster, J.L., Onions and other vegetable alliums. Vol. 15. 2008: CABI. Read.
Grow Onion from Seed
Propagation of onion is done with old sprout cuttings, buds, and seeds. Onion seeds are easily available in the local market. Two major steps are included in the propagation of onions.
1. Preparation of seeds
To grow onion from seed, the seeds are prepared by soaking in slightly warm water for 24 hours. The seeds are then drained to remove water. Seeds are not immediately sown. They are kept for 3 days in the open air before sowing. A small nutrition-rich land or patch of land is selected for sowing seeds at less distance, between each sowing seed.
These seeds will later be transferred and sown on some larger prepared land. A small tray filled with healthy soil can also be used to sow seeds if one is doing it for house garden purposes. It will take almost 7-8 days when seeds will show sprouting. Small roots and shoots will appear and one needs to take care of small seedlings.
2. Preparation of land for sowing onion saplings
The land is prepared with fertilizers or sometimes with animal urine or manure (e.g. cow dung). Soil is watered and small onion seedlings are carefully removed from the soil of a small bed or tray from where the seeds were sown. Make sure to plant each seedling almost 15 to 20 cm apart.
This distance will help bulbs to grow well and one plant bulbs will not be able to disturb the bulbs of the onion plant sown next to itRumpel, J. and K. Felczyński, Effect of plant density and cultivar on yield responses in onions (Allium cepa) grown from seeds. Acta Agrobotanica, 1997. 50(1-2): p. 221-229. Read. Harvesting is done in 4 to 5 months after sowing in beds in a row.
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The plants are harvested mostly when the bulb starts appearing above the soil surface. Carefully pull the bulbs from the soil holding the bunch of leaves above bulbs. The leaves are cut 2-3 cm above the bulb. Leaves are also used to cook when driedGloberson, D., A. Sharir, and R. Eliasi. The nature of flowering and seed maturation of onions as a basis for mechanical harvesting of the seeds. in Symposium on Vegetable and Flower seed Production … Continue reading.
Care of onion plant
- Water plant regularly when soil becomes dry. Overwatering of closely planted onion plants may face leek rust (a fungal disease condition due to over moisture content in the soil and air) characterized by yellow to orange rusty spots on leave and bulb.
- Bulbs can be damaged easily when one uses machines for weeding. It is preferred to do hand weeding in the case of onions.
- Watering is not recommended with onions having pale r yellow leaves.
- Flower spikes are immediately and carefully removed if seen.
- Fungicides are used to clear the fungal infections.
- Insecticides and insect nets are sometimes used to avoid Allium leaf miners and onion fliesOnions, C., Retaining foster carers during challenging times: the benefits of embedding reflective practice into the foster care role. Adoption & Fostering, 2018. 42(3): p. 249-265. Read.
|↑1||Brodnitz, M.H. and J.V. Pascale, Thiopropanal S-oxide: a lachrymatory factor in onions. Journal of Agricultural and Food Chemistry, 1971. 19(2): p. 269-272. Read|
|↑2||Brewster, J.L., Onions and other vegetable alliums. Vol. 15. 2008: CABI. Read|
|↑3||Rumpel, J. and K. Felczyński, Effect of plant density and cultivar on yield responses in onions (Allium cepa) grown from seeds. Acta Agrobotanica, 1997. 50(1-2): p. 221-229. Read|
|↑4||Globerson, D., A. Sharir, and R. Eliasi. The nature of flowering and seed maturation of onions as a basis for mechanical harvesting of the seeds. in Symposium on Vegetable and Flower seed Production 111. 1980. Read|
|↑5||Onions, C., Retaining foster carers during challenging times: the benefits of embedding reflective practice into the foster care role. Adoption & Fostering, 2018. 42(3): p. 249-265. Read|