Hopen, Herbert John

Peterson, C.E.

English

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Seeding rates, cultivars, and planting methods for small processing onions (Alium cepa L.)

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630,7I6bno. 749cop. 8UNIVERSITY OFSeeding Rates,Cultivars, andPlanting Methods forSMALL PROCESSING ONIONS (Mum cepa uBy H. J. Hopenand C. E. PetersonUNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGNCOLLEGE OF AGRICULTUREAGRICULTURAL EXPERIMENT STATIONContentsMaterials and Methods 3Results and Discussion 4Summary 10Literature Cited . .10This bulletin was prepared by H. J. Hopen, associate professor,Department of Horticulture, University of Illinois, and C. E. Peter-son, Horticulturist, Agricultural Research Service, U.S. Depart-ment of Agriculture, Madison, Wisconsin. The assistance ofWalter Staszak, Drug and Horticulture Station, University ofIllinois, and of Onion Specialties of South Holland, Illinois, aregratefully acknowledged.Urbana, Illinois November, 1974Publications in the Bulletin series report the results of investigations made or sponsoredby the Experiment Station.The Illinois Agricultural Experiment Station provides equal opportunitiesin programs and employment.3M 11-74 29216SEEDING RATES, CULTIVARS, AND PLANTING METHODSFOR SMALL PROCESSING ONIONSThe majority of small processing onions (Allium cepa L.) consumedin the U.S. are imported from Holland or Italy (3). Processing of smallonions in the U.S. is located primarily in the traditional onion-set pro-duction areas. Greater domestic production of small processing onionsappears to be possible. Modern field and processing technology andequipment has been developed by a small group of growers and grower-processors. Crystal Wax was the cultivar of comparison, as it is themajor commercial cultivar used in the production area of NortheasternIllinois and Southeastern Wisconsin, which was the area in which thestudies were conducted.It is known that short days promote top growth and inhibit bulbformation. Long days induce early bulb formation and better bulbgrowth at early stages, while simultaneously inhibiting leaf growth (2,7) .Leaf emergence ceases immediately after the onset of bulbing (2). Thecritical photoperiod for bulbing usually varies between 12 and 16 hoursof light per day, depending on the cultivar (6). Manuel and Velasco (7)found that bulbs from plants that received short days (9 hours) weresmaller and weighed less than bulbs from plants receiving 12 or 15hours of light.The size and shape of the onion determines if it is used for mixedvegetable products, cocktail onions, pickle products, or soups and stews.The ideal small to intermediate size of processing onion is white, globe-shaped, and with a small neck and root zone (3). To obtain small bulbsfor processing, seeds are planted at a uniform, high rate (3). Short-daycultivars are used under northern U.S. conditions since they will bulbsooner than long-day cultivars if planted in April or early May when longdays prevail (6). It has been established that the bulbing of Allium cepaL. is determined by the interaction of photoperiod, age of plant, and afavorable temperature for bulb induction (8) .Numerous studies on optimum plant populations for dry bulb onions(over 5 cm in diameter) have been reported (3,5). In the only studylocated on pickling onions (in Venezuela), Crystal White Wax andCrystal Wax had the best confirmation of six cultivars evaluated. WhiteGranex and White Granex PRR had the greatest yields (/).Materials and MethodsExperiments were conducted for three years, 1970 to 1972, to evalu-ate the range of onion sizes and types that could be grown for thedomestic market and to determine the influence of plant population,depth, and method of planting on size, shape, and total yield. Thesestudies were conducted at the University of Illinois Drug and Horticul-ture Experiment Station at Downers Grove on a Drummer silty clayloam soil.Split-plot randomized designs with three to five replicates were usedin 1970 and 1971, with single-row plots 3.08 m long and 25 cm betweenrows. Cultivars were main-plot treatments, and seeding rates were split-plots. Preliminary studies on a grower's field in 1969 are not reportedhere. Cultivars evaluated in 1970 were Crystal Wax, Barletta, Konigen,Queen, Pompei, and Gladalin White. Cultivars in 1971 were CrystalWax, Pompei, and Gladalin White. Seeding rates in 1970 were 44.2,67.2, 89.6, and 112.0 kg/ha. Only the three lower rates were evaluatedin 1971. The theoretical number of seeds per m were 380, 565, 750, and945 at 44.2, 67.2, 89.6, and 112.0 kg/ha respectively. The usual commer-cial seeding rate is about 40 kg/ha. One pound (454 g) of onion seedscontains about 152,000 seeds (4). Individual cultivar counts variedslightly, but were in general agreement with the published figure.All planting was with a V-belt seeder at a depth of about 2 cm,except in 1972. In 1972 Crystal Wax at 67.2 kg/ha was seeded in a rowat 7.5, 2.5, and both 7.5 and 2.5 cm depths. Seeds at the same depthswere also scattered to a 7.5 cm horizontal width with a hand garden rake.Where seed was placed at both 2.5 and 7.5 cm depths, one-half of theseeding rate was placed at each depth. A randomized complete blockdesign was used in 1972.Two seeding dates were evaluated in each of the three years, withthe initial dates varying because of seasonal variation of soil temperatureand rainfall. Dates of seeding were: 1970, April 23 and May 4; 1971,April 8 and 26; and 1972, April 18 and May 5.In all three years the bulbs from each plot were separated with awooden bar grader into the following diameter sizes: less than 6.5 mm,6.5 to 9.5 mm, 9.5 to 12.5 mm, 12.5 to 15.5 mm, 15.5 to 19 mm, 19 to25.5 mm, and more than 25.5 mm. Total bulb number and weight ineach size range were determined.Results and DiscussionCrystal Wax was later maturing than the other five cultivars grownin 1970 and 1971 (Table 1). There were no significant yield differencesfor cultivars in 1970. However, in 1971 Crystal Wax had the largest totalyields at both planting dates (Table 2). Interactions between seedingrate and cultivar were not significant in 1970 or 1971. The Barletta cul-tivar produced flat bulbs when seeded at the 44.2 kg/ha. Present marketTable 1. Cultivar Maturity at Harvest in 1970 and 19711970" 1971 bUow6S 655IM <*m) o*f loam Row'9 5 tell 5 12 5 '8 15 5 * I* 5 OwrMSTable 3. Average Onion Bulb Weight (g) at Four Seeding Rates... Early plantings Late plantings1970 1971 1970 197144.8...CrootH Si(< (mm) ft, 3 08 m Row' EarlyPIam ingUndr65 65K>95 95tol2S I25lol55 I55tol9 19 to 25 S Our 255 *"'>r iii> Iot o'fSuding Triolmtnl 1iSL, 9Bulb-size distribution for 1972 early planting, and total yields for early and lateplantings, as influenced by seeding depth and by row and scatter methods ofseeding. Mean separation within a size range by Duncan's multiple-range test:capital letters, 1-percent level; lower-case letters, 5-percent level. Seeding treat-ment: 1 7.5 cm (row); 2 2.5 cm (row); 3 7.5 and 2.5 cm (row); 47.5 cm (scattered); 5 2.5 cm (scattered); and 6 7.5 cm and 2.5 cm(scattered). (Fig. 2)which resulted in a slightly larger total yield (Table 6). The 7.5-cmdepth of planting produced comparatively larger total yields, but pri-marily of bulbs 25.5 mm or larger.Scattering the seeds appears to be a more useful practice than varyingplanting depth, as better yield and size distribution were obtained. Scat-tering the seeds would require an increased seeding rate to maintainthe same size distribution.Horizontal seed distribution (scattering) tended to produce a largerbulb than the same seeding rate placed in a row. Further studies areTable 6. Comparison of Yields at Early and Late Planting Dates(extrapolated metric tons/ha)Secdine rate EarlV plantingby variety, plant population, and seed distribution. The cv. Crystal Wax,seeded at 89.6 kg/ha with horizontal distribution (scattered), producedthe most desirable crop, with a high proportion of the sizes in demandfor mixed vegetables, cocktail onions, and pickles.SummaryTen cultivars, with seeding rates of 44.2, 67.2, 89.6, and 112.0 kg/haand vertical and horizontal distribution of seeds, were evaluated in anattempt to alter the size and shape of small processing onions (Alliumcepa L. ) . Crystal Wax, currently the main commercial cultivar, producedthe most desirable shape and yields. As seeding rate increased, bulb sizedecreased, but total yields were not consistently affected by the seedingrate. Horizontal dispersion of onion seeds produced larger bulbs whencompared with identical rates seeded in a row.Literature Cited1. BETANCOURT, L., AND D. RIVAS. 1971. Produccion de bulbitos paraencurtido con variedades blancas de cebolla. (The production of pick-ling onions with white onion varieties.) Proc. Trop. Reg., Amer. Soc.forHort. Sci. 15:132-138.2. HEATH, O. V. S., AND M. HOLDSWORTH. 1948. Morphogenic factorsas exemplified by the onion plant. Sym. Soc. Exp. Biol. 2 : 326-350.3. JONES, H. A., AND L. K. MANN. 1963. Onions and their allies. Inter-science Publisher, Inc. New York.4. KNOTT, J. E. 1962. Handbook for vegetable growers. John Wiley andSons. New York.5. LUCAS, R. E. 1970. Onion spacing and population studies. Mich. StateUniv. Res. Rpt. 115.6. MAGRUDER, R., AND H. A. ALLARD. 1937. Bulb formation in someAmerican and European varieties of onion as affected by length ofday. J. Agr. Res. 54: 719-752.7. MANUEL, F. C., AND J. R. VELASCO. 1962. The effect of photoperiodon the growth and bulb development of onion. Philippine Agr. 46:477-480.8. ROBINSON, J. C. 1971. Studies on the performance and growth ofvarious short-day onion varieties (Allium cepa L.) in the RhodesianLowveld in relation to date of sowing. I. Yield and quality analysis.Rhodesian J. Agr. Res. 9:31-38.9. WARID, W. A., AND M. M. EL-GAMMAL. 1957. Studies on bulb develop-ment of onion varieties in Egypt. Egyptian Soc. of Hort. Mag. 131:3-15.10UNIVERSITY OF ILLINOIS-URBANAQ 630.7IL6BC008BULLETIN. URBANA749197470112019531026

Seeding rates, cultivars, and planting methods for small processing onions (Alium cepa L.)

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