HORT410 - Vegetable Crops
Onion and its Relatives - Notes
Common name: onion.
Latin name: Allium cepa L.
Family name: Amaryllidaceae (Liliaceae, Alliaceae) [Liliaceae Images].
Diploid (2n = 16).
Harvested organ: swollen base of the stem (bulb) with numerous fleshy leaves.
Economically most important bulb vegetable.
Cultivated by the Egyptians, Greeks and Romans.
Brought to N. America by the Spaniards.
Long considered of medicinal value.
Onion history (TAMU).
Distinctive flavor and odor of Allium species occurs when plant tissue is bruised, cut or macerated
Enzyme alliinase (cysteine sulfoxide lyase) catalyzes the conversion of alliins to allicins.
These flavor compounds have antimicrobial activity.
Onion divided into 3 main groups:
1. The common onion
Major diseases of onions in the Midwest:
Insect pests of onions in the Midwest:
Onion seed production industry has moved away from open-pollinated types to hybrid production systems
Cytoplasmically inherited male sterility factor (S) and a nuclear encoded gene (Ms) which can normally override the male sterility or "restore" the plant to a normal fertile phenotype
When this "restorer" gene is in the homozygous recessive condition only in the S cytoplasm does male sterility result
- bulbs are formed as single plants
- inflorescence does not form bulbets
- biennial, often grown as an annual
- most important commercially
- propagated in the main from true seeds
- sometimes planted as transplants
- small bulbs (sets) are produced from thickly planted seed
- when sets are replanted, these bulbs reach maturity rapidly
- cultivars vary for bulb shapes, dry scale color (white, yellow, and red), pungency (ranging from mild and sweet to pungent), soluble solids, adaptation to different day lengths
- when harvested early they produce spring or bunching onions
- mature bulb onions are usually dried before marketing
2. The aggregatum group
- with many lateral bulbs or shoots
- inflorescences lacking bulbets
- sterile seed production
- propagation by vegetative means
- includes the potato
onion or multiplier onion, ever-ready onions, and shallots
- shallots are sometimes called scallions, a source of confusion because A. fistulosum is also called scallions
3. The proliferous (proliferum) group
- ground bulbs are sometimes poorly developed
- infloresence bears bulbets
- true seed is usually lacking
- reproduction is by vegetative infloresence and bulbets
- not commercially cultivated
- almost exclusively for home gardening
- includes tree onions, top-set onions, and Egyptian onions
S msms ( = sterile)
Onion is insect (bee) pollinated
In hybrid production important to have both parental lines flowering at the same time
Ratio of 8 female : 2 male rows commonly used.
Three-way hybrids prepared by crossing an S msms F1 hybrid (male sterile) to a third inbred parent
Similar male sterility system in chives (A. schoenoprasum)
In chives, male sterility caused by the S cytoplasm is reversed by the dominant restorer gene X
Plants only with the genetic constitution Sxx are male sterile
Five major genes determine onion bulb color:
S Msms ( = fertile)
S MsMs ( = fertile)
N msms ( = fertile) (N msms plants are known as maintainers)
N Msms ( = fertile)
N MsMs ( = fertile)
I- inhibits the production of color and the bulbs are white (the expression of red, yellow or chartreuse pigments requires that the plant be ii)
Over 600 Allium species known.
Related alliums used as vegetables and/or herbs include:
C locus conditions the production of colored bulbs
all iicc bulbs are white
plants with a dominant allele at the C locus and homozygous recessive rr at the R locus are yellow to brown in color
red bulbs are conditioned by dominant alleles at both the C
and R loci (iiC-R-)
a dominant allele at the G locus conditions a golden color without pink
chartreuse bulbs are homozygous recessive at the G locus
L conditions a red pigment when the plant has the genotype iiC-rrG-L-
A. schoenoprasum L., chive; slender hollow leaves; used as a flavoring for salads; bulbs narrow.
A. fistulosum L., Japanese bunching onion, scallions or Welsh onion; like large and very coarse chives; hollow evergreen leaves; almost no bulb at the base; not clear how this onion came to be associated with Wales (origin = China); may be derived from the German welsche = foreign.
A. sativum L., garlic, grown for its bulb with a distinctive and strong flavor; propagates only vegetatively; a bulb consists of up to 10 cloves.
A. ampeloprasum L. var. porrum (syn. A. porrum), leek; commonly grown for its thickened and overlapping leaf bases; generally white; self-compatible outbreeding tetraploid.
(see: ID-56: Midwest Vegetable Production Guide for Commercial Growers 2003 - Onions (Bulb and Green) (PURDUE) [pdf] for onion crop recommendations (varieties, spacing and seeding, fertilizing, disease, weed and insect control) recommendations for the Midwest)
Sources of information:
Davis, M.K., Grafius, E., Cranshaw, W., Royer, T. Onions. In "Vegetable Insect Management With Emphasis on the Midwest" (ed. R. Foster, B. Flood), Meister Publishing Co., Willoughby, Ohio, pp. 139-146 (1995).
Nonnecke, I.L. "Vegetable Production", Van Nostrand Reinhold, NY (1989).
Phillips, R., Rix, M. "The Random House Book of Vegetables", Random House, NY (1993).
Lorenz, O.A. Onion. In "The Software Toolworks Multimedia Encyclopedia", Version 1.5, Grolier, Inc. (1992).
Tatlioglu, T. Chive, Allium schoenoprasum L. In "Genetic Improvement of Vegetable Crops", (ed. G. Kalloo, B.O. Bergh), Pergamon Press, Oxford, U.K., pp. 3-13 (1993).
Batchvarov, S. Garlic, Allium sativum L. In "Genetic Improvement of Vegetable Crops", (ed. G. Kalloo, B.O. Bergh), Pergamon Press, Oxford, U.K., pp. 15-27 (1993).
Pink, D.A.C. Leek, Allium ampeloprasum L. In "Genetic Improvement of Vegetable Crops", (ed. G. Kalloo, B.O. Bergh), Pergamon Press, Oxford, U.K., pp. 29-34 (1993).
Havey, M.J. Onion, Allium cepa L. In "Genetic Improvement of Vegetable Crops", (ed. G. Kalloo, B.O. Bergh), Pergamon Press, Oxford, U.K., pp. 35-49 (1993).
Ford-Lloyd, B.V., Armstrong, S.J. Welsh Onion, Allium fistulosum L. In "Genetic Improvement of Vegetable Crops", (ed. G. Kalloo, B.O. Bergh), Pergamon Press, Oxford, U.K., pp. 51-58 (1993).
Midwest Vegetable Production Guide for Commercial Growers, ID-56, eds. R. Foster, D. Egel, E. Maynard, R. Weinzierl, H. Taber, L.W. Jett, B. Hutchinson, Purdue University Cooperative Extension Service, 2003.
Warade, S.D., Kadam, S.S. Onion. In "Handbook of Vegetable Science and Technology: Production, Composition, Storage, and Processing", (ed. D.K. Salunkhe, S.S. Kadam), Marcel Dekker, Inc., NY, pp. 373-396 (1998).
Warade, S.D., Shinde, K.G. Garlic. In "Handbook of Vegetable Science and Technology: Production, Composition, Storage, and Processing", (ed. D.K. Salunkhe, S.S. Kadam), Marcel Dekker, Inc., NY, pp. 397-413 (1998).
Warade, S.D., Shinde, K.G. Other Alliums. In "Handbook of Vegetable Science and Technology: Production, Composition, Storage, and Processing", (ed. D.K. Salunkhe, S.S. Kadam), Marcel Dekker, Inc., NY, pp. 415-431 (1998).