Please handle this volume with care. The University of Connecticut Libraries, Storrs 3 ^1S3 0imfl7«H Q Digitized by the Internet Archive in 2011 with funding from LYRASIS members and Sloan Foundation http://www.archive.org/details/storagespanishon915hill The Connecticut Agricultural Experiment Station, New Haven Storage and Spanish Onion Trials 1992 BY DAVID E. HILL Bulletin 915 August 1993 SUMMARY In 1992, 15 cultivars of Spanish onions and nine cultivars of storage onions were grown at Windsor in a sandy terrace soil and at Mt. Carmel in a loamy upland soil. Half of each cultivar was grown from bare-rooted transplants and half from transplanted plugs. At Windsor, the average yield of 1 5 Spanish onion cultivars was 669 50-lb bags/A for bare-rooted transplants compared to 556 50-lb bags/A for transplanted plugs. At Mt. Carmel, the average yield of 15 Spanish onion cultivars was 368 50-lb bags/A for bare- rooted transplants compared to 331 50-lb bags/A for transplanted plugs. The root systems of the seedlings in plugs became root bound and early growth was delayed until the roots escaped the root ball. At Windsor, yield of bare-rooted Daytona and Oro Grande exceeded 1000 50-lb bags/A. Yield of Gringo, Hybrid Big Mac, Valiant, and Snow White exceeded the national average of 720 50-lb bags/A. At Windsor, the average yield of nine cultivars of storage onions was 740 50-lb bags/A for bare-rooted transplants compared to 669 50-lb bags/A for transplanted plugs. At Mt. Carmel, the average yield of nine cultivars of storage onions was 536 50-lb bags/A compared to 449 50-lb bags/A for transplanted plugs. Yield of bare rooted Corona and Prince exceeded 1000 50-lb bags/A. Yield of Copra, Wolverine, Early Yellow Globe, and Sweet Sandwich exceeded the national average of 720 50-lb bags/A. Ailsa Craig (22%) and Oro Grande (15%) had the greatest yield of colossal size Spanish onions. Yield of jumbo size Spanish onions exceeded 85% in bare-rooted transplants of Daytona, Gringo, Oro Grande, Ringmaker, Riverside, and White Keeper. Of the storage onions, Prince and Benny's Red had the greatest percentage of jumbo size (73%). In storage, the Spanish onion cultivar Daytona remained dormant for 7 months and was found suitable for late winter and early spring sales. The remaining cultivars of Spanish onions had excessive sprouting losses but were suitable for fall and early winter sales. Among the storage onions, Copra and Wolverine had the least sprouting after 7 months. Treatment with maleic hydrazide (MH30), an antisprouting agent, increased the storage durability of storage onions, but not Spanish onions. A 3; °ils Storage and Spanish Onion Trials 1992 BY DAVID E. HILL The per-capita consumption of onions in the United States has risen from 9.9 pounds in 1970 to 15.2 pounds in 1992 (Unrein 1993). The annual production now exceeds 2.5 million pounds and places onions fourth among all vegetables (Anon 1991). They are available year-round because of their capability of long-term storage supplemented with winter-grown crops from Texas and Mexico. Onions are divided into sweet Spanish types whose bulbs grow to 3-5 inches and the smaller storage types that grow to 2-3 inches whose more pungent taste is abated by cooking. The bulbs of both Spanish and storage types are yellow, white, or red. Historical perspective. The recorded history of onions (Allium cepd) dates back to 3200-2800 BC where they were found in Egyptian tombs. Onion culture spread to India, and then throughout the Greek and Roman empires about 400- 300 BC. By the beginning of the Middle Ages, they had spread to northern Europe (Yamaguchi 1983). Onions were grown in colonial Connecticut with commercial production developing in Wethersfield, Southport, and Westport during the Civil War (Jenkins 1925). Several cultivars, Wethersfield Red, Southport Yellow Globe, Red Globe, and White Globe, were naturally selected by Connecticut growers and remain in commercial production. Current outlook. The relatively recent rapid growth of the food service industry, which encompasses fast-food chains, school and corporate cafeterias and hospitals, has created a large demand, especially for Spanish onions. A price advantage in late summer and early fall develops before western-grown onions reach the market in October, and creates a profitable opportunity for Connecticut growers. In 1990 and 1991, 1 tested up to 16 cultivars of Spanish and storage onions for yield, quality, and storage durability (Hill 1992). In 1992, to assure maximum bulb growth with subsequent harvest in September, I grew onions using plugs to eliminate transplant shock that often accompanies bare- rooted transplants. Since storage durability of onions, a highly desirable trait, can be prolonged with an antisprouting agent, I tested its effect on the cultivars selected from earlier trials supplemented with several new ones. I report the yield and quality of onions produced by bare-rooted and plug transplants and the effect of MH30 (an antisprouting agent) on storage durability. METHODS AND MATERIALS Soils. Onion trials were conducted at the Valley Laboratory in Windsor on Merrimac sandy loam, a sandy terrace soil with somewhat limited moisture holding capacity, and at Lockwood Farm in Mt. Carmel on Cheshire fine sandy loam, a well drained loamy upland soil with moderate moisture holding capacity. Cultivars. Seeds were obtained from several domestic and foreign seed suppliers. Yellow, red, and white cultivars of Spanish and storage types were included. They are grouped as follows: Yellow Spanish — Ailsa Craig, Burrell's Yellow Valencia, Daytona, Gringo, Hybrid Big Mac, Oro Grande, Ringmaker, Riverside, Sweet Spanish Colorado No. 6, Valiant, Yellow Sweet Spanish Red Spanish — Big Red White Spanish — Snow White, White Keeper, White Sweet Spanish Yellow Storage — Copra, Corona, Early Yellow Globe, Granite, Prince, Sweet Sandwich, Wolverine Red Storage — Benny's Red, Red Man Culture. Three rows of seed were sown March 6-9 in shallow trays, 21x1 1x2.5 inches, and in each unit of 162- pack propagation trays, 1x1.5 inches, all filled with Promix Connecticut Agricultural Experiment Station Bulletin 915 BX in a greenhouse maintained at 50-70F. The seedlings in the trays were lightly thinned to avoid overcrowding after reaching 1-1.5 inches height. The seedlings in the propagation trays were also thinned to one seedling/plug. After 5 weeks, the seedlings were moved to a cold frame for hardening 14 days before planting in the field. Water soluble 20-20-20 fertilizer (1 tbsp/gal) was added to the seedlings 1 week before transplanting. On May 6-12, the seedlings were transplanted at both sites in paired 30-foot rows 12 inches apart with 24 inches between cultivars. In one row, seedlings with bare roots were transplanted from flats, and the other row transplanted with plugs from the propagation trays. Spanish onion transplants were set 6 inches apart within rows; storage onions, 4 inches apart. At Mt. Carmel, the transplants were irrigated about 1 week after planting, and at Windsor, 5 weeks. Fertilizer amendments. The soils were fertilized with 1200 lb/A 10-10-10 and limed to attain a pH of 6.5 before planting. In early June, the crops at each site were sidedressed with 90 lb/A ammonium nitrate at the 5-leaf stage. At Windsor, after heavy rains leached the soil in early June, an additional 45 lb/A ammonium nitrate was applied mid June and again in late June. Total fertilization supplied about 1 80 lbN/A to the growing crop at Windsor and 150 lbN/A at Mt. Carmel. Weed and insect control. At Mt. Carmel, weeds were controlled with Dacthal 75 W (10 lb/ A) applied immediately after transplanting. Weeds that emerged between trans- planting and the 3-leaf stage of growth were controlled with Goal 1 .6E (3 oz/A). At Windsor, weeds were controlled with light applications of Goal 1 .6E (3 oz/A) up to July 1 . Root maggots were controlled with Lorsban 4E (1.1 oz/1000 ft of row), applied as a soil drench, immediately following transplanting. Foliar damage by onion thrips was controlled with Diazinon AG500 (1 pt/A). Harvest and storage. Maleic hydrazide (MH30 at 2.5 lb/A), an antisprouting agent, was applied to green plants in one-half of each row as they began to topple. After half of all plants toppled; those remaining erect were bent over. After the tops began to wither, the bulbs were uprooted and air dried for 7-10 days. The bulbs were weighed and graded by diameter according to USDA and commercial standards as follows: Colossal 4.0"+ Jumbo 3.0-4.5" Medium 2.0-3.5" Small 1.0-2.25" After weighing and grading all onions, 25 bulbs treated with MH30 and 25 untreated bulbs from each cultivar were randomly sampled, placed in wire baskets, and stored at 32F and 70% humidity. After 20 weeks, cold storage was terminated and the temperature rose to 55F. After 3 weeks at 55F, losses due to rotting and sprouting were measured. YIELDS Spanish onions. At Windsor, the average yield of 15 cultivars was 669 50-lb bags/A for bare-rooted transplants compared to 556 50-lb bags/A for transplanted plugs (Table 1). Higher yield from bare-rooted transplants compared to transplanted plugs was due to increased average bulb weight (13.0 vs 1 1.7 oz) and average percent harvested (69 vs 63). Yield of bare-rooted Daytona and Oro Grande exceeded 1000 50-lb bags/A by virtue of heavy bulbs and high percentage harvested. Yield of Gringo, Hybrid Big Mac, Valiant, and Snow White were above the national average of 720 50-lb bags/A (USDA 1990). For plug transplants, yield of Oro Grande, Daytona, Valiant, Hybrid Big Mac, and Ailsa Craig also exceeded the national average. Among the white cultivars, Snow White had the greatest yield for bare-rooted and plug transplants. White Keeper neared the national average for bare-rooted transplants only. At Mt. Carmel, the average yield of 15 cultivars was 368 50-lb bags/A for bare-rooted transplants compared to 33 1 50-lb bags/A for transplanted plugs (Table 2). The higher average yield for bare-rooted transplants compared to transplanted plugs was due to heavier bulbs (8.8. vs 8.0 oz). The higher average yield at Windsor, compared to Mt. Carmel, for bare-rooted transplants and plugs is due to a 43-48% increase in bulb weight and a 6-12% increase in bulbs harvested. Although Valiant and Oro Grande had the highest yield from bare-rooted transplants and plugs, they were below the national average. Among the white cultivars, White Sweet Spanish had the greatest yield from bare-rooted transplants and plugs, but was well below the national average. Storage onions. At Windsor, the average yield of nine cultivars was 740 50-lb bags/A for bare-rooted transplants compared to 669 50-lb bags/A for transplanted plugs (Table 1). The higher yield of bare-rooted transplants compared to plugs was due to increased average bulb weight (9.2 vs 8.6 oz). Yield of bare-rooted Corona and Prince exceeded 1000 50-lb bags/A. Yield of Copra, Wolverine, Early Yellow Globe, and Sweet Sandwich also exceeded the national average of 720 50-lb bags/A because of a high percentage of marketable bulbs. For plug transplants, yield of Corona exceeded 1000 50-lb bags/A; Prince, Copra, and Sweet Sandwich exceeded the national average. Marketable bulbs ranged between 80-90% for these cultivars. Bulb weight of the red cultivars, Benny's Red and Red Man, was average among all storage cultivars, but only 32% of the bulbs from bare-rooted and plug transplants were marketable. The average yield of bare-rooted storage cultivars was 1 1% greater than bare-rooted Spanish cultivars and 20% greater for storage cultivars than Spanish cultivars grown from plugs. Although bulb weight of Spanish cultivars is 40% greater than bulb weight of storage cultivars, higher Spanish and Storage Onion Trials 1992 Table 1. Yield of Spanish and storage onions grown from bare-rooted and plug transplants at Windsor, 1992. SPANISH TYPES STORAGE TYPES Harvested % Bare Rooted Plugs Avg bulb wt. oz Bare Rooted Plugs 50-lb bags No./A Bare Rooted Plugs Ailsa Craig Daytona Gringo Hyb. Big Mac Oro Grande Ringmaker Riverside Sw. Sp. Colorado #6 Valiant Yellow Sweet Sp. Yel. Valencia Big Red Snow White White Keeper White Sweet Sp. 75 93 65 80 92 68 53 92 92 75 48 27 80 72 28 60 82 60 77 90 68 67 78 100 68 30 23 60 53 27 18.4 17.3 15.8 13.6 16.6 13.8 14.4 13.8 15.8 15.2 13.6 13.4 13.6 10.4 7.4 9.9 12.5 10.6 11.8 9.3 6.9 5.8 9.1 8.3 13.0 11.8 13.0 12.0 12.6 10.9 1003 1071 786 840 1054 673 521 495 832 648 238 178 755 680 256 752 812 600 772 989 661 510 558 764 461 126 138 515 468 213 Copra 93 94 8.8 8.3 891 845 Corona 99 98 9.6 9.8 1043 1027 Early Yellow Globe 84 71 8.5 9.0 834 696 Granite 61 72 8.6 7.8 580 613 Prince 98 94 9.8 9.1 1039 932 Sweet Sandwich 80 71 8.5 9.8 801 755 Wolverine 81 67 9.8 7.7 862 567 Benny's Red 33 34 9.8 8.5 350 313 Red Man 31 32 9.1 7.8 309 273 Connecticut Agricultural Experiment Station Bulletin 915 average yield of storage cultivars is attained because of a higher planting density than for Spanish cultivars (87,120 vs 58,080 plants/A). At Mt. Carmel, the average yield of nine cultivars was 536 50-lb bags/A for bare-rooted transplants compared to 449 50-lb bags/A for transplanted plugs (Table 2). The higher yield of bare-rooted transplants compared to plugs was due to increased average bulb weight (6.9 vs 6.0 oz). Yield of bare-rooted Prince, Copra, and Red Man exceeded 630 50-lb bags/A, but none exceeded the national average. Copra had the greatest percentage of marketable bulbs, and Prince had the highest bulb weight. For plug transplants, yield of Prince and Copra exceeded 500 50-lb bags/A. Average yield of bare-rooted storage onions was 46% greater than for bare-rooted Spanish onions and 36% greater for plug transplants due to greater planting density. SIZE GRADES Spanish onions. At Windsor, fully 80% of all Spanish onions, grown from bare-rooted transplants, exceeded 3 inches diameter and were graded jumbo (76%) or colossal (4%) compared to 73% for onions grown from plugs (jumbo 70%, colossal 3%) (Table 3). Ailsa Craig and Oro Grande had the greatest yield of colossal size for bare-rooted transplants and plugs. Yield of jumbo onions exceeded 85% in bare-rooted transplants of Daytona, Gringo, Oro Grande, Ringmaker, Riverside, and White Keeper. For plug transplants, Daytona, Gringo, Hybrid Big Mac, and Oro Grande exceeded 85% jumbo size. At Mt. Carmel, 47% of all Spanish onions grown from bare-rooted transplants exceeded 3 inches diameter and were graded jumbo (45%) and colossal (2%) compared to 38% jumbo size for onions grown from plugs (Table 4). Ailsa Craig had the greatest yield of colossal size. No cultivars yielded at least 85% jumbo size. Yield of jumbo onions was greatest for Hybrid Big Mac and Snow White. At Mt. Carmel, the predominant grade size was jumbo for bare- rooted transplants and medium for plug transplants. Storage onions. At Windsor, 56% of all storage onions, grown from bare-rooted transplants, attained jumbo size compared to 51% for transplanted plugs (Table 3). Prince had the greatest yield of jumbo size for both bare-rooted and plug transplants. The yield of Corona, Benny's Red, and Red Man exceeded 64% jumbo size for bare-rooted transplants. Corona and Sweet Sandwich also had high yields of jumbo size for plug transplants. Despite a few cultivars with a high percentage of jumbo sizes, the dominant size for storage onions at Windsor was medium. At Mt. Carmel, 33% of all storage onions grown from bare-rooted transplants attained jumbo size compared to 20% for transplanted plugs (Table 4). Medium sizes dominated the onions grown from both bare-rooted and plug transplants. Prince had the highest yield of jumbo onions for both types of transplants but the yield of jumbo size was 35-65% less than Windsor. STORAGE DURABILITY Stored onions are the mainstay of winter and early spring sales. Although Spanish onions are generally sold soon after harvest, they can be kept 1-3 months. Under proper conditions of temperature and humidity, some storage onions can be stored nearly a year. In these trials, both types of onions were placed in cold storage for 21-29 weeks and then at 55F for an additional 3 weeks. Table 5 shows the percentages of storage losses for MH30 treated and untreated onions. Rotted bulbs include losses from heart rot and bulbs whose outer scales were soft to the touch but whose inner scales were sound. Sprouted bulbs were those whose necks were breached by newly elongating leaves. Storage losses were excessive for the entire crop of Spanish onions. Fully 80% of all Spanish onions were lost in storage (28% rotted; 52% sprouted). For storage onions, 44% were lost in storage (20% rotted; 24% sprouted). Treatment of Spanish onion bulbs with MH30 had little effect on storage durability. Sprouting loss of treated bulbs was 54% compared to 50% of untreated bulbs. For storage onions, MH30 treatment improved storage durability. Only 1 8% of MH30 treated bulbs sprouted as compared to 30% of untreated bulbs. Despite excessive losses of most Spanish onions, the cultivar Daytona had outstanding durability. Losses of both treated and untreated bulbs were only 16%. Their thick, hard outer scales resisted infection and the bulbs remained dormant for 7 months. Oro Grande and Valiant had fair durability with 52-56% losses. Their dormancy period, however, is less than 7 months. All other cultivars had poor durability by virtue of excessive rotting or sprouting. Their durability is probably closer to 1-3 months rather than 7 months. Among the storage cultivars, Copra and Wolverine had the fewest losses and responded well to the MH30 treatment. Their hard outer scales resisted infection. Granite had the best response to MH30 treatment with 6-fold less sprouting in MH30-treated bulbs. MANAGEMENT STRATEGIES Site selection. The data from Tables 1 and 2 suggest that light sandy soils produce greater yields of both Spanish and storage onions than heavier loamy soils. This is consistent with earlier observations at the same sites (Hill 1992). On sandy soils average yield of onions was greater than loamy soils for both bare-rooted and plug transplants. Although yield on loamy soils can be improved 10-15% by addition of 1-inch leaf mold, it seldom reaches the national average of 720 50-lb bags/A. Spanish and Storage Onion Trials 1992 Table 2. Yield of Spanish and storage onions grown from bare-rooted and plug transplants at Mt. Carmel, 1992. SPANISH TYPES STORAGE TYPES Harvested % Bare Rooted Plugs Avg bulb wt. oz Bare Rooted Plugs 50-lb bags No./A Bare Rooted Plugs Ailsa Craig 52 Daytona 57 Gringo 47 Hyb. Big Mac 62 Oro Grande 63 Ringmaker 52 Riverside 53 Sweet Sp. Colorado #6 70 Valiant 87 Yellow Sweet Sp. 68 Yel. Valencia 60 Big Red 52 Snow White 32 White Keeper 53 White Sweet Sp. 48 23 75 68 55 78 65 50 67 88 72 53 52 27 38 37 10.2 10.2 7.7 7.5 8.3 9.6 10.4 8.6 11.0 10.2 9.3 8.6 9.1 6.1 6.6 8.3 11.0 8.3 8.8 7.4 7.0 6.1 6.7 6.4 9.0 9.1 7.5 7.4 9.8 8.6 387 315 284 470 507 348 352 330 696 433 305 207 258 291 342 170 409 471 343 581 404 220 402 530 382 237 239 178 169 232 Copra 93 83 6.7 5.8 680 519 Corona 83 84 6.4 5.1 580 474 Early Yellow Globe 46 62 6.4 6.1 279 410 Granite 82 62 5.6 6.1 496 405 Prince 76 83 8.3 6.1 695 546 Sweet Sandwich 59 57 7.5 6.4 484 394 Wolverine 73 76 6.4 5.8 505 481 Benny's Red 60 58 7.2 5.8 475 368 Red Man 74 62 7.8 6.6 631 440 8 Connecticut Agricultural Experiment Station Bulletin 915 Table 3. Size grades of Spanish and storage onions grown from bare-rooted and plug transplants at Windsor, 1992. Bare Rooted Plugs 4"+ 3-4" 2-3" 1-2" 4"+ 3-4" 2-3" 1-2" % % % % % % % % SPANISH TYPES Ailsa Craig 22 71 7 . 17 83 . Daytona 5 88 7 - 2 88 10 - Gringo 8 90 2 - 8 86 6 - Hybrid Big Mac 8 84 8 - 9 85 6 - Oro Grande 13 87 - - 9 91 - Ringmaker - 95 5 - 5 80 15 . Riverside 9 85 6 - - 60 40 - Sweet Sp. Colorado #6 - 53 47 -' - 68 32 - Valiant - 62 38 - - 69 31 - Yellow Sweet Sp. - 80 20 - - 63 37 - Yel. Valencia . 52 48 . . 11 72 17 Big Red - 38 62 - - 29 71 - Snow White 2 77 21 - - 69 31 - White Keeper - 91 9 - - 84 16 - White Sweet Sp. - 82 18 - - 75 25 - STORAGE TYPES Copra Corona Early Yel. Globe Granite Prince Sweet Sandwich Wolverine Benny's Red Red Man 54 46 64 36 32 67 38 62 73 27 51 49 56 44 73 27 64 36 51 49 - 73 26 - 52 42 6 22 78 - 76 24 - 66 34 _ 25 75 ■ - 48 45 7 45 52 3 Spanish and Storage Onion Trials 1992 Table 4. Size grades of Spanish and storage onions grown from bare-rooted and plug transplants at Mt. Carmel, 1992. Bare Rooted Plugs r+ 3-4" 2-3" 1-2" 4"+ 3-4" 2-3" 1-2" % % % % % % % % SPANISH TYPES Ailsa Craig 13 36 45 6 - 36 57 7 Daytona - 38 38 24 - 40 40 20 Gringo - 54 21 25 2 47 29 22 Hybrid Big Mac 3 59 32 6 - 45 52 3 Oro Grande 3 55 39 3 2 51 42 5 Ringmaker - 52 45 3 - 52 33 15 Riverside 3 53 28 16 - 17 67 16 Sweet Sp. Colorado #6 - 36 26 38 2 45 33 20 Valiant - 56 44 - - 36 56 8 Yellow Sweet Sp. 3 41 51 5 - 33 58 9 Yel. Valencia 3 28 50 19 . 22 62 16 Big Red - 19 71 10 - 29 55 16 Snow White - 63 21 16 - 38 56 6 White Keeper 6 44 31 19 - 35 56 9 White Sweet Sp. - 48 38 14 - 36 55 9 STORAGE TYPES Copra Corona Early Yel. Globe Granite Prince Sweet Sandwich Wolverine Benny's Red Red Man 30 61 9 32 52 16 29 51 20 28 57 15 48 46 6 40 45 15 26 59 15 33 58 9 36 54 10 12 80 8 21 59 20 18 59 23 11 71 18 27 55 18 25 53 22 19 63 18 19 56 25 27 57 16 10 Connecticut Agricultural Experiment Station Bulletin 915 Table 5. Storage losses of Spanish and storage onions stored at 34F and 70% relative humidity for 21 to 29 weeks and then at 55F for 3 weeks. MH 30 Treated Untreated Cold Rotted Sprouted Rotted Sprouted Storage weeks % % % % SPANISH TYPES* Ailsa Craig 27 76 24 64 24 Daytona 25 12 4 12 4 Gringo 26 16 84 52 36 Hybrid Big Mac 26 48 44 20 64 Oro Grande 26 28 40 24 32 Ringmaker 29 16 68 28 72 Riverside 29 20 80 12 88 Sweet Sp. Colorado #6 25 24 68 12 80 Valiant 29 8 44 12 40 Yel. Sweet Spanish 29 32 52 44 52 Snow White 27 20 52 44 48 White Keeper 27 28 56 44 28 White Sweet Sp. 25 16 80 8 84 STORAGE TYPES Copra 25 4 0 4 12 Corona 25 16 28 0 20 Early Yel. Globe 28 24 12 36 12 Granite 22 24 8 12 48 Prince 22 24 12 20 20 Sweet Sandwich 22 28 32 8 36 Wolverine 21 0 12 4 20 Benny's Red 21 32 24 32 56 Red Man . 21 60 40 16 36 Yellow Valencia and Big Red had insufficient sample for storage. Spanish and Storage Onion Trials 1 992 11 Fertilization and irrigation. Maximum yield of onions requires optimum nitrogen and moisture supplies, especially during bulb formation, which begins when day length reaches 15 hours for long-day cultivars (Splittstoesser 1979). Initial preplant application of 1200 lb/A 10-10-10 fertilizer (120 lb N/A) followed by a sidedressing with 90 lb/A ammonium nitrate (30 lb N/A) at the 5-leaf stage in early June should supply adequate nitrogen. After heavy rains in June, which may leach earlier applications of nitrogen, sandy soils may require additional light applications of ammonium nitrate (45 lb/A) in mid to late June. Soil tests can verify depletion of nitrogen. Onions should receive at least 1 inch of water each week from rainfall or irrigation from transplanting through the completion of bulb formation. Bare-rooted vs plug transplants. From Tables 1 and 2, it is obvious that yield of bare-rooted transplants consistently exceeded the yield from transplanted plugs. Although plug transplants are easier to plant, early growth is hindered by development of a small root ball bound by the container wall. By the time roots escaped the root ball into the surrounding soil, top growth was delayed compared to bare-rooted transplants. At the time of bulb formation, the smaller plants grown from the plugs could only produce smaller bulbs. Larger plugs may have prevented the balling of roots, but transplanting them would have been more difficult. Although transplant shock in bare-rooted transplants caused some delay in growth, the roots became established in a few days, and unimpeded growth ensued. Harvest and storage. Mature bulbs were harvested and field dried for about 10 days. Preferably, they should be protected from the sun to prevent scalding. If left in the field too long, cultivars with short dormancy periods may sprout in the field or shortly after they are placed in storage. Alternatively, anti-sprouting agents, such as maleic hydrazide can be sprayed on the crop a few days before harvest while the plants are still green. The agent is absorbed by the leaves and translocated to the bulb. Our tests have shown, however, the MH30 had little effect on the sprouting of Spanish onion cultivars. This is probably due to the shorter dormancy of Spanish onions compared to storage onions. The percent of marketable bulbs of storage onions, after 21-25 weeks storage, was improved 12-40% by application of MH30. Bulbs should be stored at 34F and a relative humidity of 50-70% to maintain dormancy. Cultivar selection. Because onions are harvested all at once, most are stored for future winter and spring sales. Thus, selection of cultivars is based not only on yield but also durability under protracted cold storage and return to room temperature. Size distribution is also important because colossal and jumbo sizes are sold at a premium over medium and mixed sizes. Among the yellow Spanish onions, Daytona provided the greatest yield (1071 50-lb bags/A), a high percentage of colossal and jumbo sizes (93%), and a storage durability that exceeded 7 months. This cultivar is well- suited for winter and early spring sales. Yield of Oro Grande and Ailsa Craig also exceeded 1000 50-lb bags/A and 93- 100% colossal and jumbo sizes. Oro Grande, however, had over 50% loss after 7 months storage, thus it is best suited to fall and winter sales. Ailsa Craig has thin outer scales and is easily bruised during harvest and sorting. It is best suited for direct fall sales without storage. Gringo, Hybrid Big Mac, and Valiant also, had over 780 50-lb bags/A, a high percentage of colossal and jumbo sizes, but relatively short durability in storage. These cultivars are best suited to fall and winter sales. Among the white Spanish cultivars, Snow White and White Keeper had the greatest yield, the highest percentage of jumbo size, but low storage durability. These cultivars are best suited for direct fall or early winter sales. Among the yellow storage onion cultivars, the yield of Corona and Prince exceeded 1000 50-lb bags/A. These cultivars also had the highest percentage of jumbo size grown from bare-rooted or plug transplants. Since storage losses after 7 months for both cultivars were over 35%, they would be best suited for fall and winter sales. Although the yields of Copra and Wolverine were somewhat less than Corona and Prince, they are the cultivars of choice for long term storage durability. They are best suited for late winter and early spring sales. Among the red storage onion cultivars, Benny's Red is preferred. Although yield is somewhat low, the percentage of jumbo size is high. Short storage durability, however, limits it to direct fall or early winter sales. REFERENCES Anonymous. 1991. Produce availability and merchandising guide. The Packer. Vance Publishing Company. Overland Park, Kansas. 444p. Hill, D.E. 1992. Onion trials 1990-1991. The Conn. Agr. Exp. Sta., New Haven. Bulletin 906. lOp. Jenkins, E.H. 1925. Connecticut agriculture. In History of Connecticut. States History Company, pp 289-424. Splittstoesser, W.E. 1979. Vegetable growing handbook. AVI Publishing Company. Westport, Connecticut. 298p. Unrein, J. 1993. A meeting of ideas, issues, education. The Packer. Business newspaper. February 27, 1993. Yamaguchi, M. 1983. World vegetables: principles, production, and nutritive values. AVI Publishing Company. Westport, Connecticut. 415p. USDA. 1990. Agricultural statistics 1990. USDA. 517p. en CD ^ CO c&^< sHi • mo^v The Connecticut Agricultural Experiment Station , founded in 1875, is the first experiment station in America. It is chartered by the General Assembly to make scientific inquiries and experiments regarding plants and their pests, insects, soil and water, and to perform analyses for State agencies. The laboratories of the Station are in New Haven and Windsor; its Lockwood Farm is in Hamden. Single copies of bulletins are available free upon request to Pub- lications; Box 1 106; New Haven, Connecticut 06504. ISSN 0097-0905 University of Connecticut Libraries 39153028932772