ONION PRODUCTION FROM TRANSPLANTS IN THE TREASURE VALLEY

Clinton C. Shock, Erik B. G. Feibert, and Lamont D. Saunders
Malheur Experiment Station
Oregon State University
Ontario, OR, 2003

Introduction


The objective of this trial was to evaluate whether yellow, white, and red onion varieties planted as transplants would have adequate bulb yield and quality when grown in the Treasure Valley.

Methods


The 2003 trial was conducted on an Owyhee silt loam with 1.2 percent organic matter and a pH of 7.4. The field had previously been planted to wheat. In the fall of 2002, the wheat stubble was shredded, and the field was disked, irrigated, ripped, moldboard-plowed, roller-harrowed, fumigated with Telone C-17 at 20 gal/acre, and bedded. Soil analysis indicated the need for 100 lb P2O5/acre, 150 lb K /acre, 6 lb Mn/acre, 2 lb Cu/acre, and 1 lb B/acre, which was broadcast in the fall.

Onion seed of 19 varieties was planted in flats with a vaccum seeder at 72 seeds/flat on January 30, 2003. The seed was sowed on a 1-inch layer of Sunshine general purpose potting mix. The seed was then covered with 1 inch of potting mix. The flats were watered immediately after planting and were kept moist until emergence on February 7. On March 18 and 19 the seedlings were transplanted to the field. The seedlings were manually planted in double rows on 22-inch beds. The spacing between plants in each single row was 6 inches, equivalent to 95,000 plants per acre. The seedlings had one to two true leaves at the time of transplanting. The field was furrow irrigated on March 20. Plots of each variety were 20 ft long by four double rows wide arranged in a randomized complete block design with four replicates.

The onions were managed to avoid yield reductions from nutrient and irrigation deficiencies, weeds, pests, and diseases. The field had 100 lb N/acre applied on April 22 as water-run urea during an irrigation. Weeds were controlled with an application of Goal at 0.12 lb ai/acre, Buctril at 0.12 lb ai/acre, Poast at 0.38 lb ai/acre on April 16, and Prowl at 1 lb ai/acre on May 22. After lay-by the field was hand weeded as necessary. Thrips were controlled with one aerial application of Warrior on June 5 and two aerial applications of Warrior and Lannate (July 16 and August 4). Warrior was applied at 0.03 lb ai/acre and Lannate was applied at 0.4 lb ai/acre.

The trial was furrow irrigated when the soil water potential at 8-inch depth reached -20 kPa. Soil water potential was monitored by six granular matrix sensors (GMS, Watermark Soil Moisture Sensors Model 200SS, Irrometer Co., Riverside, CA) installed on June 10 below the onion row at 8-inch depth. Sensors were automatically read three times a day with an AM-400 meter (Mike Hansen Co., East Wenatchee, WA).

On July 9 and again on July 22, 9.5 ft of the middle two rows in each plot were topped and bagged. Decomposed bulbs were not bagged. The onions were put in a barn at room temperature for 3 days. After 3 days the onions were graded. Bulbs were separated according to quality: bulbs without blemishes (No. 1s), split bulbs (No. 2s), neck rot (bulbs infected with the fungus Botrytis allii in the neck or side), plate rot (bulbs infected with the fungus Fusarium oxysporum), and black mold (bulbs infected with the fungus Aspergillus niger). The No. 1 bulbs were graded according to diameter: small (<2¼ inches), medium (2¼-3 inches), jumbo (3-4 inches), colossal (4-4¼ inches), and super colossal (>4¼ inches). Bulb counts per 50 lb of supercolossal onions were determined for each plot of every variety by weighing and counting all super colossal bulbs during grading. Varietal differences were compared using ANOVA and protected least significant differences at the 5 percent probability level, LSD (0.05).

A subjective evaluation of exterior bulb quality (sprouting, bulb shape, softness, and appearance) was made soon after grading for bulbs from all plots. Ten randomly chosen bulbs from each plot from the July 22 harvest were shipped on August 1 via UPS ground to Vidalia Labs International in Collins, GA. The bulb samples were analyzed for pyruvic acid content on August 11. Bulb pyruvic acid content is a measure of pungency with the unit being micro mols pyruvic acid per gram of fresh weight. Onion bulbs having a pyruvate concentration of 5.5 or less are considered sweet according to Vidalia Labs sweet onion certification specifications.

On August 22 the onion bulbs were rated for single centers. The onions from each plot were cut equatorially through the bulb middle and, if multiple centered, the long axis of the inside diameter of the first single ring was measured. These multiple-centered onions were ranked according to the diameter of the first single ring: "small double" had diameters <1½ inch, "intermediate double" had diameters from 1½ to 2¼ inches, and "blowout" had diameters >2¼ inches. Single-centered onions were classed as a "bullet". Onions were considered functionally single centered for processing if they were a "bullet" or "small double".

Results


Plant establishment was very good. There were no significant differences in plant population between varieties in 2003 (Tables 1 and 2). Plant population averaged 88,000 plants per acre at harvest.

On July 9, total yields ranged from 910 cwt/acre for 'XON-0101' to 523 cwt/acre for 'Everest' (Table 1). Variety XON-0101 had the highest total yield on July 9. The super colossal yields of varieties XON-0101, 'Candy', 'T-803', 'XON-0103', 'Stanza', 'EX6876', and 'Rumba' were among the highest on July 9. Varieties 'Electric', 'Alabaster', Rumba, Stanza, and T-803 were among the best in total exterior bulb quality rating for the July 9 harvest (Table 3).

On July 23, total yields ranged from 1,186 cwt/acre for XON-0101 to 170 cwt/acre for Everest (Table 2). Varieties XON-0101 and 'Renegade' had the highest super colossal yields on July 23. Total exterior bulb quality rating for the July 23 harvest ranged from 5 for Rumba to 12 for 'Mesquite' (Table 3).

'Cometa' had the highest percentage of "bullet" single-centered bulbs (Table 4). Cometa and 'Ranchero' had the highest percentage of functionally single-centered bulbs.

Varieties Renegade, Rumba, Electric, Stanza, 'Golden Spike', and 'Dawn' had bulb pyruvate concentrations low enough (< 5.5) to be classified as sweet onions (Table 4). Renegade had the lowest pyruvate concentration.

Transplanted onions were more productive in 2003 than in 2002 (Table 5). Plant populations were lower in 2002, possibly because of very cold weather immediately after transplanting. Varieties Candy and Renegade were among the highest yielding of marketable bulbs and super colossal bulbs in both 2002 and 2003. The pyruvate concentration of Renegade was among the lowest in 2002 (Table 6) and was the lowest in 2003.

Discussion

Growing onions for transplant produced early high yields. Onion quality was adequate for marketing some of the varieties and lines tested. The costs and returns of transplanting for early harvest were not thoroughly examined, so the economic viability of the practice is unknown. Promising varieties such as Renegade might require special handling for successful harvest and packing. The ideal date to start seedlings in the greenhouse was not determined. An earlier date in January might be beneficial.

Vidalia Labs suggested that onions be shipped overnight as soon as harvest was completed, so that bulb pyruvate would not increase between harvest and analysis. Instead we chose to have the bulbs evaluated 2 weeks after harvest after shipping by ground, a realistic time interval between bulb harvest and delivery to a retail outlet or end user.

Table 1. Performance data for experimental and commercial onion varieties grown from transplants and harvested on July 9, 2003, Malheur Experiment Station, Oregon State University, Ontario, OR.




 
 
Marketable yield by grade Marketable yield by grade Marketable yield by grade Marketable yield by grade Marketable yield by grade Marketable yield by grade Small
Plant population



Total-yield Total
>4¼ in >4¼ in 4-4¼ in
3-4 in
2¼-3 in

Company
Variety 
Bulb color cwt/acre cwt/acre
#/50 lb cwt/acre
cwt/acre
cwt/acre
cwt/acre
cwt/acre
plants/acre
American-Takii T-803 Y
819.4
817.5
40
49.4
203.9
553.9
10.3
2.0
89,613
Bejo
Electric
R
574.0
573.6
0
0.0
11.0
513.8
48.8
0.4
82,274

Stanza
Y
811.2
809.5
34
40.8
316.0
440.3
12.4 1.7
84,652
Crookham
XPH97H27 Y
638.4
632.7
52
14.8
38.3
559.1
15.9
4.7
88,993
D. Palmer Mesquite Y 579.3
573.0 46
16.9
23.5 480.4 52.2
6.2
89,303

Tequila Y 557.5 553.0 44 3.5 7.1 496.2 46.2 4.5 86,822
Sakata  XON-0101 Y 910.3 905.5 46 63.9 391.3 442.1 8.1 4.9 91,784

XON-0103 Y 765.6 765.4 54 48.4 212.9 496.8 7.3 0.1 87,442
Shamrock Dawn F1 Y
797.7 797.7 43 26.5 246.3 514.1 10.9 0.0
86,202
Seminis
Candy Y 833.3 830.5 45 57.9 312.1 457.1 3.4 2.8
87,132

Golden-Spike
Y 740.3
738.2
54 29.2 92.0 589.9 27.1 2.2
92,714

Santa Fe Y
663.3 661.9
73
2.8
73.0
561.2
24.9
1.4
88,476

EX 6876
Y
781.9
780.5
44
35.1
210.5
530.4
4.4
1.4
87,753
Sunseeds
Alabaster
W
667.2
664.4
55
5.9
99.1
547.1
12.2
2.9
83,411

Cometa
W
552.5
538.8
151
1.0
15.3
476.4
46.1
13.6
87,132

Ranchero
Y
622.3
614.5
56
8.3
48.4
513.1
44.6
7.8
90,233

Renegade
Y
744.4
741.4
51
29.8
228.5
474.8
8.2
3.1
85,272

Rumba
R
660.4
654.7
47
34.6
63.4
510.1
46.8
5.7
90,543
US Agriseeds
Everest
W
523.2
513.4
0
0.0
13.4
461.4
38.7
9.8
83,928
Average


697.0
693.0
49.3
24.7
137.2
506.2
24.7
4.0
87,562
LSD (0.05)


70.7
72.3
13
33.4
77.0
83.9
18.4
5.9
ns

Table 2. Performance data for experimental and commercial onion varieties grown from transplants and harvested on July 22, 2003, Malheur Experiment Station, Oregon State University, Ontario, OR.





Marketable yield by grade Marketable yield by grade Marketable yield by grade Marketable yield by grade Marketable yield by grade Marketable yield by grade Small
Rot
Plant population


Total-yield
Total
>4¼ in
>4¼ in
4-4¼ in
3-4 in
2¼-3 in


Company
Variety
cwt/acre
cwt/acre #/50 lb   cwt/acre cwt/acre cwt/acre cwt/acre cwt/acre cwt/acre plants/acre
American-Takii
T-803 909.8
908.4
31
50.8
355.7
490.5
11.3
0.0
1.4
91,669
Bejo
Electric
645.5
639.7
0
0.0
69.5
543.4
26.8
2.6
3.2
91,018

Stanza
1,007.7
1,004.7
30
190.7
511.6
298.9
3.5
1.1
1.9
86,517
Crookham
XPH97H27 871.5
867.0
29
47.2
354.6
457.1
8.1
2.3
2.2
94,176
D. Palmer Mesquite
762.2
756.0
29
51.5
295.8
398.7
10.1
1.4
4.8
91,627

Tequila
835.2
828.1
36
20.9
325.2
471.0
10.9
4.3
2.8
91,836
Sakata  XON-0101
1,186.5
1,183.8
30
347.4
629.9
201.6
4.9
1.0
1.7
91,780

XON-0103 1,089.0
1,087.8
31
255.9
511.9
315.8
4.2
0.0
1.2
88,393
Shamrock
Dawn F1
1,016.1
1,012.4
29
98.7
497.3
408.0
8.5
1.9
1.8
91,998
Seminis Candy 1,112.6
1,109.1
30
200.3
565.1
339.5
4.1
1.4
2.1
92,920

Golden-Spike 966.4
962.7
32
93.7
433.6
430.2
5.2
2.4
1.3
91,540

Santa Fe 865.6
863.0
33
109.7
463.4
285.1
4.9
0.1
2.5
78,218

EX 6876
985.8
980.1
32
200.2
517.6
258.8
3.5
2.9
2.8
86,213
Sunseeds
Alabaster
771.4
763.2
30
17.2
251.2
480.9
14.0
4.7 3.5
88,973

Cometa
806.9
802.1
34
35.5
281.8
470.8
13.9
1.9
2.9
91,844

Ranchero
944.9
942.4
32
70.7
459.3
400.3
12.1
0.2
2.3
92,072

Renegade
1,027.2
1,023.5
30
269.8
504.8
239.8
9.2
1.0
2.6
89,833

Rumba
853.9
845.0
30
16.1
319.9
501.5
7.5
8.2
0.7
87,193
US Agriseeds
Everest
169.5
158.3
0
0.0
12.1
134.5
11.7
0.0
11.3
77,467
Average

885.7
880.9
28
109.3
387.4
375.1
9.2 2.0
3.0
89,226
LSD (0.05)

120.7
122.0
3
88.8
120.1
113.7
ns
ns
2.6
ns

Table 3. Subjective rating of exterior bulb quality: 0-10, 1 = least and 10 = most for sprouting, torpedo shape, and softness; 1 = best and 10 = worst for appearance; 1 = best and 10 = worst for total subjective rating; Malheur Experiment Station, Oregon State University, Ontario, OR, 2003.



July 9 harvest
July 9 harvest July 9 harvest July 9 harvest July 9 harvest July 22 harvest July 22 harvest July 22 harvest July 22 harvest July 22 harvest
Variety
Sprouting
Torpedo shape
Softness
Appear.
Total
Sprouting
Torpedo shape
Softness
Appear.
Total
T-803
1.0
4.0
2.0
2.8
9.8
1.0
2.5
1.3
1.8
6.5
Electric
1.0
2.0
1.0
2.0
6.0
1.0
1.0
1.3
2.0
5.3
Stanza
1.0
2.8
2.8
2.5
9.0
1.0
1.5
1.3
1.5
5.3
XPH97H27 5.5
6.8
5.0
6.3
23.5
2.5
3.3
1.7
3.3
11.0
Mesquite
6.5
7.3
5.8
7.0
26.5
3.3
3.5
2.0
3.5
12.3
Tequila
5.3
5.8
5.0
6.0
22.0
2.5
3.0
1.8
3.0
10.3
XON-0101
1.3
3.5
2.5
3.0
10.3
1.0
2.0
1.5
1.5
6.0
XON-0103
2.8
5.5
4.5
4.8
17.5
1.3
3.3
1.8
2.5
8.8
Dawn F1
2.0
3.5
2.0
2.8
10.3
1.5
2.5
1.5
2.0
7.5
Candy
1.0
3.0
5.5
3.8
13.3
1.0
1.3
2.5
1.0
5.8
GoldenSpike
2.3
5.3
4.8
4.8
17.0
1.0
3.0
1.3
2.3
7.5
Santa Fe
4.3
4.7
5.7
4.7
19.3
2.7
2.7
2.3
3.0
10.7
EX 6876
2.0
4.0
3.3
3.5
12.8
1.3
2.0
2.0
1.5
6.8
Alabaster 1.3
3.0
2.0
2.3
8.5
1.3
2.0
1.0
2.0
6.3
Cometa
2.5
5.0
3.5
4.0
15.0
1.3
2.3
1.3
2.5
7.3
Ranchero
5.0
6.0
4.5
5.3
20.8
1.3
2.5
2.0
2.3
8.0
Renegade  1.0
3.3
3.5
3.3
11.0
1.0
2.0
2.3
2.0
7.3
Rumba  1.0
2.7
2.3
2.7
8.7
1.0
1.3
1.0
1.7
5.0
Everest
1.0
3.0
1.7
3.7
9.3
1.0
1.7
1.3
5.7
9.7
Average
2.5
4.3
3.5
3.9
14.2
1.5
2.3
1.6
2.4
7.7
LSD (0.05)
1.5
1.6
1.5
1.4
4.3
0.9
1.2
ns
1.2
2.5

Table 4. Pyruvate concentration on August 11, 2003 in bulbs from July 22 harvest, and multiple center rating, Malheur Experiment Station, Oregon State University, Ontario, OR.


Company
Entry-name
Pyruvate concentration
"Blowout"
"Intermediate double"
"Small double"
"Bullet"
Functionally single centered "small double + bullet"


µmoles/g FW %
%
%
%
%
American-Takii
T-803
5.7
5.0
36.0
55.0
4.0
59.0
Bejo
Electric
5.0
70.7
24.0
4.0
1.3
5.3

Stanza
5.3
59.0
28.0
12.0
1.0
13.0
Crookham
XPH97H27
5.8
27.0
33.0
21.0
19.0
40.0
D. Palmer
Mesquite

24.0
48.0
11.0
17.0
28.0

Tequila

15.0
33.0
17.0
35.0
52.0
Sakata XON-0101
5.9
27.0
39.0
33.0
1.0
34.0

XON-0103
5.7
31.0
41.0
17.0
11.0
28.0
Shamrock
Dawn F1
5.4
34.0
34.0
29.0
3.0
32.0
Seminis
Candy
6.0
18.0
47.0
28.0
7.0
35.0

GoldenSpike
5.3
22.0
22.0
38.0
18.0
56.0

Santa Fe
6.0
10.7
26.7
28.0
34.7
62.7

EX 6876

17.0
39.0
26.0
18.0
44.0
Sunseeds
Alabaster
6.1
27.0
44.0
28.0
1.0
29.0

Cometa
5.6
2.0
2.0
11.0
85.0
96.0

Ranchero
5.7
6.0
12.0
47.0
35.0
82.0

Renegade
3.9
17.0
51.0
28.0
4.0
32.0

Rumba
4.8
25.3
36.0
32.0
6.7
38.7
US Agriseeds
Everest

38.7
21.3
29.3
10.7
40.0
Average

5.5
25.1
32.5
26.0
16.4
42.5
LSD (0.05)

0.6
14.1
19.2
16.4
9.4
14.6

Table 5. Performance data for experimental and commercial onion varieties grown from transplants and harvested on July 23, 2002 and July 22, 2003, Malheur Experiment Station, Oregon State University, Ontario, OR.




Marketable yield by grade Marketable yield by grade Marketable yield by grade Marketable yield by grade Marketable yield by grade Marketable yield by grade



Total-yield
Total
>4¼ in
>4¼ in
4-4¼ in
3-4 in
2¼-3 in
Small
Rot
Plant-population
Variety cwt/acre cwt/acre #/50 lb cwt/acre cwt/acre cwt/acre cwt/acre cwt/acre cwt/acre plants/acre
2002










XPH97H27
748.5
719.9
33.0
74.2
286.8
320.7
38.2
28.6

68,310
Candy
982.1
973.8
25.7
251.9
424.4
293.8
3.7
8.3

76,230
Santa Fe
794.2
794.2
30.4
196.7
322.6
222.2
52.6
0.0

63,360
Alabaster
549.9
549.9
0.0
0.0
186.2
352.8
10.9
0.0

73,920
Cometa
709.5
677.6
35.7
55.7
201.7
368.3
52.0
31.9

66,330
Ranchero 921.4
921.4
29.1
102.4
327.9
417.2
74.0
0.0

79,200
Renegade 962.5
955.5
27.3
234.0
422.4
285.5
13.5
7.0

72,270
Rumba
742.2
582.2
23.4
42.3
241.7
424.4
33.8
0.0

73,260
Average
801.3
771.8
29.2
136.8 301.7
335.6
34.8
9.5

71,610
LSD(0.05)Variety
ns
ns
16.2
117.3
ns
173.0
48.2
ns

ns
2003









XPH97H27 871.5
867.0
29.0
47.2
354.6
457.1
8.1
2.3
2.2
94,176
Candy 1,112.6
1,109.1
30.0
200.3
565.1
339.5
4.1
1.4
2.1
92,920
Santa Fe
865.6
863.0
33.0
109.7
463.4
285.1
4.9
0.1
2.5
78,218
Alabaster
771.4
763.2
30.0
17.2
251.2
480.9
14.0
4.7
3.5
88,973
Cometa
806.9
802.1
34.0
35.5
281.8
470.8
13.9
1.9
2.9
91,844
Ranchero
944.9
942.4
32.0
70.7
459.3
400.3
12.1
0.2
2.3
92,072
Renegade
1,027.2
1,023.5
30.0
269.8
504.8
239.8
9.2
1.0
2.6
89,833
Rumba
853.9
845.0
30.0
16.1
319.9
501.5
7.5
8.2
0.7
87,193
Average
906.8
901.9
30.9
95.8
400.0
396.9
9.2
2.5
2.3
89,403
LSD(0.05)Variety 120.7
122.0
3.0
88.8
120.1
113.7
ns
ns
2.6
ns
LSD(0.05)Year
84.1
82.0
4.3
ns
54.9
ns
12.3
ns

8,149

Table 6. Bulb pyruvate concentration on August 7, 2002 in bulbs from July 23, 2002 harvest and multiple center rating, Malheur Experiment Station, Oregon State University, Ontario, OR.





Onion multiple center rating Onion multiple center rating Onion multiple center rating Onion multiple center rating Onion multiple center rating
Company
Variety
Pyruvate concentration
"Blowout"
"Intermediate double" "Small double"
"Bullet"
Functionally single centered "small double + bullet"


µmoles/g FW %
%
%
%
%
Petoseed
Candy
6.3
9.7
32.7
31.4
26.1
57.6
Sunseeds
SR4000ON 7.1
1.8
9.1
52.1
37.1
89.1

Renegade
5.4
7.3
34.4
20.8
37.5
58.3

Ranchero
6.2
0.0
0.0
0.0
100.0
100.0

Alabaster
7.2
3.0
41.1
47.8
8.0
55.8

La Nina
7.9
1.6
23.1
33.0
42.3
75.3

SRO-1403
5.9
0.0
3.6
15.5
81.0
96.4

Cometa
5.4
0.0
0.0
0.0
100.0
100.0

Rumba
4.7
2.3
35.7
38.9
23.1
62.0
Average

6.2
2.9
20.0
26.6
50.6
77.2
LSD(0.05)

1.1
9.2
14.9
14.8
14.0
17.3