Malheur Experiment Station
|
Information for Sustainable Agriculture
|
2006 ONION VARIETY TRIALS
Clinton C. Shock, Erik B. G. Feibert, and Lamont D. Saunders
Malheur Experiment Station
Oregon State University
Ontario, OR
Lynn Jensen
Malheur County Extension Service
Oregon State University
Ontario, OR
Krishna Mohan
University of Idaho
Parma, ID
Introduction
The objective of the onion variety trials was to evaluate yellow,
white, and red onion varieties for bulb yield, quality, and single
centers. Eight early season varieties (six yellow, two white) were
planted in March and were harvested and graded at the end of
August. Forty-three full-season varieties (33 yellow, 6 red, and 4
white) were planted in March, harvested and weighed in September
2006, and were graded and fully evaluated out of storage in January
2007. Each year, growers and seed industry representatives have
the opportunity to examine the varieties at our annual Onion
Variety Field Day and during onion grading in early January.
Methods
The onions were grown on an Owyhee silt loam previously planted to
wheat. In the fall of 2005, the wheat stubble was shredded, and
the field was irrigated and disked. Soil analysis indicated the
need for 100 lb phosphate/acre, 100 lb sulfur/acre, 2 lb
copper/acre and 1 lb/acre of boron, which were broadcast in the
fall of 2005 after disking. The field was then moldboard-plowed,
groundhogged, roller-harrowed, fumigated with Telone® C-17 at
20 gal/acre, and bedded.
A full-season trial and an early maturing trial were conducted
adjacent to each other. Both trials were planted on March 23 in
plots 4 double rows wide and 27 ft long. The early maturing trial
had 8 varieties from 3 seed companies (Table 1) and the full-season
trial had 43 varieties from 10 seed companies (Table 3). The
experimental designs for both trials were randomized complete
blocks with five replicates. A sixth nonrandomized replicate was
planted for demonstrating onion variety performance to growers and
seed company representatives.
Seed was planted in double rows spaced 3 inches apart at 9 seeds/ft
of single row. Each double row was planted on beds spaced 22
inches apart with a customized planter using John Deere Flexi
Planter units equipped with disc openers. The onion rows received
3.7 oz of Lorsban 15G® per 1,000 ft of row (0.82 lb ai/acre),
and the soil surface was rolled on March 24. Onion emergence
started on April 14. On May 15, alleys 4 ft wide were cut between
plots, leaving plots 23 ft long. From May 17 through May 19, the
seedlings were hand thinned to a plant population of two plants/ft
of single row (6-inch spacing between individual onion plants, or
95,000 plants/acre).
The onions were managed to try to avoid yield reductions from
weeds, pests, diseases, water stress, and nutrient deficiencies.
Weeds were controlled with an application of Prowl® at 1 lb
ai/acre on April 28. On May 9, Goal® at 0.1 lb ai/acre,
Buctril® at 0.3 lb ai/acre, and Select® at 0.25 lb
ai/acre were applied. On May 17, Goal at 0.2 lb ai/acre and
Buctril at 0.3 lb ai/acre were applied. On May 30, Goal at 0.2 lb
ai/acre, Buctril at 0.3 lb ai/acre, and Select at 0.25 lb ai/acre
were applied. After lay-by the field was hand weeded as necessary.
Thrips were controlled with aerial applications of the following
insecticides: June 12, Warrior®; June 18, Warrior plus
Lannate®; July 1, Carzol®; July 17, Warrior plus
Mustang®; July 24, Carzol; July 29, Warrior plus MSR; August
10, Warrior plus Lannate. Carzol was applied at 0.69 lb ai/acre,
Warrior at 0.03 lb ai/acre, Lannate at 0.45 lb ai/acre, Mustang at
0.05 lb ai/acre, and MSR at 0.5 lb ai/acre.
The trial was furrow irrigated when the soil water tension at
8-inch depth reached 25 cb (1 cb = 1 kPa)(Shock et al. 2005).
Starting in mid-June, soil water tension was monitored by six
granular matrix sensors (GMS, Watermark Soil Moisture Sensors Model
200SS, Irrometer Co. Inc., Riverside, CA) centered at 8-inch depth
below the onion row. The sensors were automatically read three
times a day with an AM-400 meter (Mike Hansen Co., East Wenatchee,
WA). The last irrigation was on August 23.
The field was sidedressed with 100 lb of nitrogen/acre as urea and
cultivated on May 25. On June 21, the field was sidedressed with
100 lb N/acre as urea. An onion root tissue analysis on July 14
showed the need for potassium. On July 21, potassium at 20 lb/acre
was water run during a routine irrigation.
Onions in each plot were evaluated subjectively for maturity by
visually rating the percentage of onions with the tops down and the
percent dryness of the foliage. The percent maturity was
calculated as the average percentage of onions with tops down and
the percent dryness. The early maturing trial was evaluated for
maturity on August 7 and August 21 and the full-season trial on
August 22 and September 7. The number of bolted onion plants in
each plot was counted.
Onions in each plot of the full-season trial were evaluated
subjectively for severity of symptoms of iris yellow spot virus
(IYSV) on August 22. Each plot was rated on a scale of 0 to 5,
where 0 = no symptoms and 5 = over 80 percent foliage dried out
due to symptoms.
After grading of the early maturing trial, 10 randomly chosen bulbs
from each plot were shipped via UPS ground to Vidalia Labs
International in Collins, Georgia. The bulb samples were analyzed
for pyruvic acid content on September 6. 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.
In early September, bulbs from one of the border rows in each plot
of both trials were rated for single centers. Twenty-five
consecutive onions ranging in diameter from 3.5 to 4.25 inches were
rated. The onions 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 less than 1.5 inches, "intermediate
double" had diameters from 1.5 to 2.25 inches, and "blowout" had
diameters greater than 2.25 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."
Onions from the middle two rows in each plot in the early maturity
trial were lifted, topped by hand, and bagged on August 21. On
August 23 the onions were graded. The onions in the full-season
trial were lifted on September 8 to field cure. Onions from the
middle two rows in each plot of the full season trial were topped
by hand and bagged on September 13. The bags were put in storage
on September 18. Before being placed into storage each bag was
weighed. The storage shed was ventilated to maintain air
temperature as close to 34°F as possible. Onions from the
full-season trial were graded out of storage on January 3 and 4,
2007.
During grading, 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 (<2.25 inches),
medium (2.25-3 inches), jumbo (3-4 inches), colossal (4-4.25
inches), and supercolossal (>4.25 inches). Bulb counts per 50
lb of supercolossal onions were determined for each plot of every
variety by weighing and counting all supercolossal bulbs during
grading. The red varieties were evaluated subjectively during
grading for exterior thrips damage during storage. The bulbs from
each red variety plot were rated on a scale from 0 (no damage) to
10 (most damage) for damage on the bulb surface, without removing
the outer scales.
Varietal differences were compared using ANOVA and least
significant differences at the 5 percent probability level, LSD
(0.05). Regression analyses of yield against IYSV ratings were
conducted on both the data from 2005 (Shock et al. 2006) and the
current year's data.
Results
Both environmental stress and pest stress limited onion performance
at Ontario in 2006. The weather was cooler than normal, with fewer
growing degree days than average until May 20. After May 20 the
weather was warmer than average. Heat for the season exceeded
norms, especially in July. A heat wave had maximum air
temperatures equal to or greater than 100°F from July 21 to
July 29. Thrips and IYSV were particularly damaging during the
2006 season.
Varieties are listed by company in alphabetical order. The LSD
(0.05) values at the bottom of each table should be considered when
comparisons are made between varieties for significant differences
in performance characteristics. Differences between varieties
equal to or greater than the LSD value for a characteristic should
exist before any variety is considered different from any other
variety in that characteristic.
Since 2003, several experimental varieties were named. In 2004
Nunhems 'SX 7000ON' and 'SX 7002ON' were named 'Bandolero' and
'Montero', respectively. Global Genetics '6001' was named
'Maverick'. In 2005, Seminis 'XP5646' was named 'Orizaba',
'XP5813' was named 'Affirmed', and 'EX5843' was named 'Monarchos'.
In 2006, D. Palmer 'DPS 1405' was named 'Generation X', 'DPS 1406'
was named 'Evolution', and 'DPS 3052' was named 'Shiraz'. Nunhems
'NUN7004ON' was named 'Arcero', 'NUN7200ON' was named 'Grand
Coulee', and 'NUN7008ON' was named 'Joaquin'. Varieties are all
listed by name in the results. The experimental numbers are useful
for comparing results from previous years.
Early Maturing Trial
The percentage of "bullet" single centers averaged 30.0 percent and
ranged from 4.0 percent for 'Western Giant', to 66.6 percent for
Montero (Table 1). The percentage of onions that were functionally
single centered averaged 49.8 percent and ranged from 14.0 percent
for Western Giant to 87.8 percent for Montero.
Total yield at harvest in September 2006 ranged from 496 cwt/acre
for 'EX7106' to 727.5 cwt/acre for 'Exacta' (Table 1). Exacta,
'Ovation', and 'Spanish Medallion' were among the varieties with
the highest total yield.
Marketable yield out of storage ranged from 466 cwt/acre for EX7106
to 691 cwt/acre for Exacta (Table 2). Colossal yield ranged from
9.7 cwt/acre for Montero to 166 cwt/acre for Exacta.
Full-season Trial
The percentage of "bullet" single centers averaged 43.4 percent and
ranged from 3.3 percent for 'White Wing', to 89 percent for
Generation X (Table 3). The percentage of onions that were
functionally single centered averaged 66.6 percent and ranged from
13.3 percent for 'Snowflake' to 97.3 percent for Generation X.
Generation X, 'Ruby Ring', 'Cometa', Grand Coulee, 'Ringleader',
Arcero, and 'Koala' had higher than 90 percent functionally
single-centered bulbs.
Total yield at harvest in September 2006 ranged from 377 cwt/acre
for Shiraz to 834.8 cwt/acre for 'Tequila' (Table 3). Tequila,
'T-433', 'Ranchero', 'Harmony' and 'Charismatic' were among the
varieties with the highest total yield.
Total yield out of storage ranged from 288.9 cwt/acre for Shiraz to
771 cwt/acre for OLYS05N5 (Table 4). Varieties OLYS05N5, Tequila,
Joaquin, Charismatic, and Harmony were among the varieties with the
highest total yield. Marketable yield ranged from 163.8 cwt/acre
for Shiraz to 714 cwt/acre for Joaquin. Varieties Joaquin, EX5819,
Harmony, and Charismatic were among the varieties with the highest
marketable yield. Supercolossal onion yield ranged from 0 cwt/acre
for many varieties to 28 cwt/acre for Tequila. Varieties Tequila,
Joaquin, Evolution, Harmony, and 'Sweet Perfection' were among the
varieties with the highest super-colossal yield. Colossal onion
yield ranged from 0 cwt/acre for several varieties to 184 cwt/acre
for Joaquin. Varieties Joaquin, Charismatic, Tequila, Evolution,
and OLYS05N5 were among the varieties with the highest colossal
yield.
Iris Yellow Spot Virus (IYSV)
Subjective ratings of IYSV symptom severity for the full-season
varieties, on a scale from 0 to 5, ranged from 1.6 for Joaquin and
OLYS05N5 to 4.1 for Generation X (Table 3). Average total onion
yield by variety was closely related to the average IYSV symptom
severity in 2005 and 2006 (Figs. 1 and 2). In general, varieties
with a lower severity rating had higher total yield. Clearly, the
relative onion variety tolerance to the effects of IYSV has become
a major factor in onion productivity.
References
Shock, C.C., R. Flock, E. Feibert, C.A. Shock, A. Pereira, and L.
Jensen. 2005. Irrigation monitoring using soil water tension.
Oregon State University Extension Service EM 8900.
Shock, C.C., E.B.G. Feibert, L.D. Saunders, L. Jensen, and K.
Mohan. 2006. 2005 Onion Variety Trials. Oregon State University
Agricultural Experiment Station Special Report 1070:42-53.
Table 1. Onion multiple-center rating and pyruvate concentration
for early maturing varieties, Malheur Experiment Station, Oregon
State University, Ontario, OR, 2006.
|
|
|
|
Multiple
center
|
|
Single
center
|
|
|
Seed
company
|
Variety
|
Bulb
color
|
Blowout
|
Intermediate
double
|
Small
double
|
|
Functionala
|
Bullet
|
Pyruvate
concentration
|
|
|
|
|
------------------------------- %
---------------------------------
|
µmoles/g
FW
|
|
Nunhems
|
Renegade
|
Y
|
60.7
|
17.3
|
12.7
|
|
22.0
|
9.3
|
6.3
|
|
|
Montero
|
Y
|
8.0
|
4.2
|
21.2
|
|
87.8
|
66.6
|
7.3
|
|
Sakata
|
Ovation
|
Y
|
34.6
|
18.8
|
17.0
|
|
46.7
|
29.7
|
6.9
|
|
|
Spanish
Medallion
|
Y
|
25.3
|
16.0
|
23.3
|
|
58.7
|
35.3
|
7.0
|
|
|
Western
Giant
|
Y
|
61.3
|
24.7
|
10.0
|
|
14.0
|
4.0
|
7.6
|
|
Seminis
|
Exacta
|
Y
|
43.3
|
22.0
|
21.3
|
|
34.7
|
13.3
|
7.5
|
|
|
Orizaba
|
W
|
13.3
|
20.0
|
30.7
|
|
66.7
|
36.0
|
6.6
|
|
|
EX7106
|
W
|
18.7
|
13.3
|
22.0
|
|
68.0
|
46.0
|
6.4
|
|
LSD
(0.05)
|
|
|
16.3
|
NS
|
11.1
|
|
14.3
|
10.6
|
NS
|
aBullet + small double.
Table 2. 2006 performance data for early maturing varieties,
Malheur Experiment Station, Oregon State University, Ontario, OR,
2006.
|
Variety
|
Bulb
color
|
Total
yield
|
Marketable yield by
grade
|
Bulb counts >4¼
in
|
Non-marketable
yield
|
Maturity on Aug.
21
|
|
|
|
|
Total
|
>4¼
in
|
4-4¼
in
|
3-4
in
|
2¼-3
in
|
|
Total
rot
|
No.
2s
|
Small
|
|
|
|
|
--- cwt/acre
---
|
----------- cwt/acre
------------
|
#/50
lb
|
%
|
-- cwt/acre
--
|
%
|
|
Renegade
|
Y
|
602.1
|
516.3
|
3.1
|
72.7
|
417.0
|
23.4
|
33.1
|
0.6
|
71.3
|
11.14
|
67
|
|
Montero
|
Y
|
502.1
|
483.4
|
0.0
|
9.7
|
451.4
|
22.4
|
---
|
0.6
|
0.75
|
15.1
|
62
|
|
Spanish
Medallion
|
Y
|
693.3
|
674.8
|
2.7
|
135.2
|
512.4
|
24.5
|
38.9
|
0.3
|
8.54
|
7.97
|
52
|
|
Ovation
|
Y
|
700.5
|
685.7
|
0.0
|
102.4
|
555.0
|
28.3
|
---
|
0.1
|
3.28
|
11.14
|
48
|
|
Western
Giant
|
Y
|
596.5
|
548.8
|
1.6
|
51.0
|
470.7
|
25.5
|
31.5
|
0.3
|
36.88
|
9.2
|
65
|
|
Exacta
|
Y
|
727.5
|
691.0
|
8.1
|
165.6
|
497.1
|
20.2
|
29.4
|
0.8
|
21.39
|
9.41
|
63
|
|
Orizaba
|
W
|
591.9
|
563.1
|
0.0
|
31.5
|
489.2
|
42.4
|
---
|
1.2
|
10.59
|
11.07
|
34
|
|
EX7106
|
W
|
496.0
|
465.9
|
0.0
|
16.0
|
378.1
|
71.7
|
---
|
1.0
|
4.9
|
20.18
|
27
|
|
LSD
(0.05)
|
|
140.0
|
146.9
|
NS
|
42.3
|
NS
|
19.8
|
NS
|
NS
|
14.9
|
NS
|
8.9
|
Table 3. Total yield at harvest, bulb multiple-center rating, and
iris yellow spot virus rating for long season varieties, Malheur
Experiment Station, Oregon State Univ., Ontario, OR, 2006.
|
|
|
Bulb
color
|
Multiple
center
|
|
Single
center
|
Iris yellow spot virus
ratingb
|
|
Seed
company
|
Variety
|
|
Blowout
|
Intermediate
double
|
Small
double
|
|
Functionala
|
Bullet
|
|
|
|
|
|
--------------------------- %
--------------------------
|
0 -
5
|
|
A.
Takii
|
Ruby
Ring
|
R
|
0.7
|
2.7
|
28.7
|
|
96.7
|
68.0
|
3.7
|
|
|
T-433
|
Y
|
42.4
|
27.2
|
22.4
|
|
30.4
|
8.0
|
2.5
|
|
|
9003G
|
Y
|
16.0
|
34.0
|
30.0
|
|
50.0
|
20.0
|
2.9
|
|
Bejo
|
Calibra
|
Y
|
12.7
|
25.4
|
28.7
|
|
61.9
|
33.2
|
3.0
|
|
|
Crocket
|
Y
|
34.7
|
28.7
|
28.0
|
|
36.7
|
8.7
|
3.4
|
|
|
Snowflake
|
W
|
64.0
|
22.7
|
8.0
|
|
13.3
|
5.3
|
2.1
|
|
|
Red
Bull
|
R
|
23.3
|
21.3
|
27.3
|
|
55.3
|
28.0
|
4.0
|
|
|
Sedona
|
Y
|
30.7
|
20.7
|
29.3
|
|
48.7
|
19.3
|
2.8
|
|
|
Talon
|
Y
|
16.7
|
13.3
|
28.0
|
|
70.0
|
42.0
|
3.4
|
|
|
White
Wing
|
W
|
58.7
|
18.7
|
19.3
|
|
22.7
|
3.3
|
1.9
|
|
Crookham
|
Harmony
|
Y
|
10.7
|
14.7
|
14.7
|
|
74.7
|
60.0
|
2.6
|
|
|
Sweet
Perfection
|
Y
|
20.0
|
27.3
|
20.7
|
|
52.7
|
32.0
|
2.5
|
|
|
OLYS05N5
|
Y
|
12.7
|
14.0
|
24.7
|
|
73.3
|
48.7
|
1.6
|
|
D.
Palmer
|
Mesquite
06
|
Y
|
36.7
|
21.3
|
28.7
|
|
42.0
|
13.3
|
2.5
|
|
|
Tequila
|
Y
|
24.0
|
21.3
|
22.0
|
|
54.7
|
32.7
|
2.0
|
|
|
Generation
X
|
Y
|
1.3
|
1.3
|
8.0
|
|
97.3
|
89.3
|
4.1
|
|
|
Evolution
|
Y
|
3.3
|
9.3
|
17.3
|
|
87.3
|
70.0
|
2.1
|
|
|
Shiraz
|
R
|
41.1
|
17.2
|
23.8
|
|
41.7
|
17.9
|
4
|
|
Global
Genetics
|
Maverick
|
Y
|
21.3
|
18.0
|
28.0
|
|
60.7
|
32.7
|
2.7
|
|
|
Ringleader
|
Y
|
2.7
|
5.3
|
13.3
|
|
92.0
|
78.7
|
2.6
|
|
|
Varsity
|
Y
|
7.3
|
11.3
|
30.7
|
|
81.3
|
50.7
|
2.8
|
|
|
6093
|
Y
|
6.0
|
8.0
|
19.3
|
|
86.0
|
66.7
|
3.5
|
|
Nunhems
|
Cometa
|
W
|
1.3
|
2.0
|
20.0
|
|
96.7
|
76.7
|
2.0
|
|
|
Granero
|
Y
|
10.0
|
18.0
|
23.3
|
|
72.0
|
48.7
|
2.3
|
|
|
Montero
|
Y
|
3.3
|
10.7
|
22.7
|
|
86.0
|
63.3
|
3.0
|
|
|
Pandero
|
Y
|
22.0
|
18.0
|
24.0
|
|
60.0
|
36.0
|
2.5
|
|
|
Ranchero
|
Y
|
14.0
|
12.0
|
28.0
|
|
74.0
|
46.0
|
2.7
|
|
|
Sabroso
|
Y
|
2.7
|
10.0
|
29.3
|
|
87.3
|
58.0
|
3.2
|
|
|
Salsa
|
R
|
40.0
|
15.3
|
22.0
|
|
44.7
|
22.7
|
3.8
|
|
|
Vaquero
|
Y
|
6.0
|
16.0
|
17.3
|
|
78.0
|
60.7
|
2.9
|
|
|
Arcero
|
Y
|
4.0
|
4.7
|
14.0
|
|
91.3
|
77.3
|
3.5
|
|
|
Grand
Coulee
|
Y
|
1.3
|
3.3
|
18.0
|
|
95.3
|
77.3
|
3.9
|
|
|
Joaquin
|
Y
|
6.0
|
10.0
|
20.7
|
|
84.0
|
63.3
|
1.6
|
|
Rispens
|
Solid
Gold
|
Y
|
26.0
|
22.0
|
31.3
|
|