Malheur Experiment Station Information for Sustainable Agriculture

2004 ONION VARIETY TRIALS

Clinton C. Shock, Erik B. G. Feibert, and Lamont D. Saunders

Malheur Experiment Station

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. Five early season yellow varieties and one early season white variety were planted in March and were harvested and graded in August. Forty-three full season varieties (33 yellow, 5 red, and 5 white) were planted in March, harvested in September 2004, and evaluated in January 2005.

Methods

The onions were grown on an Owyhee silt loam previously planted to wheat. Soil analysis indicated the need for 60 lb nitrogen (N)/acre, 100 lb phosphate (P₂O₅)/acre, 70 lb sulfur/acre, 2 lb copper/acre, 7 lb zinc/acre, and 1 lb boron/acre, which was broadcast in the fall. In the fall of 2003, 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. A soil sample taken on May 20, 2004 showed a pH of 7.3, 2 percent organic matter, 8 ppm nitrate-N, 37 ppm phosphorus, and 461 ppm potassium.

A full season trial and an early maturing trial were conducted adjacent to each other. Both trials were planted on March 19 in plots four double rows wide and 27 ft long. The early maturing trial had 6 varieties from 3 companies (Table 1) and the full season trial had 43 varieties from 10 companies (Table 2). The experimental design for both trials was a randomized complete block 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 20. The field was irrigated on March 25. On March 31 the field was sprayed with Roundup^® at 24 oz/acre. Onion emergence started on April 5. On May 4, alleys 4 ft wide were cut between plots, leaving plots 23 ft long. From May 5 through 8, 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 field was sidedressed with 100 lb of N/acre as urea and cultivated on May 12. On June 9 the field was sidedressed with 100 lb N/acre as urea.

The onions were managed to avoid yield reductions from weeds, pests, and diseases. Weeds were controlled with an application of Prowl^® at 0.75 lb ai/acre on April 12 and on May 12, and an application of Goal^® at 0.12 lb ai/acre, Buctril^® at 0.12 lb ai/acre, and Poast^® at 0.28 lb ai/acre on May 25. After lay-by the field was hand weeded as necessary. Thrips were controlled with aerial applications of Warrior^® on June 12, Warrior (0.03 lb ai/acre) plus Lannate^® (0.4 lb ai/acre) on June 25, Warrior (0.03 lb ai/acre) plus MSR^® (0.5 lb ai/acre) on July 17, and Warrior (0.03 lb ai/acre) plus Lannate (0.4 lb ai/acre) on July 31.

The trial was furrow irrigated when the soil water potential at 8-inch depth reached -25 kPa. Soil water potential was monitored by thirteen granular matrix sensors (GMS, Watermark Soil Moisture Sensors Model 200SS, Irrometer Co. Inc., Riverside, CA) installed in mid-June below the onion row at 8-inch depth. Six sensors were automatically read three times a day with an AM-400 meter (Mike Hansen Co., East Wenatchee, WA). Seven sensors were automatically read hourly with a Watermark Monitor (Irrometer Co., Inc.). The last irrigation was on August 20.

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 10 and the full season trial on August 24. The number of bolted onion plants in each plot was counted.

Onions in each plot were evaluated subjectively for damage from iris yellow spot virus on August 11. Each plot was rated according to the number of leaves with symptoms per plant: 0 = no symptoms, 5 = at least 3 leaves with symptoms per plant.

Onions from the middle two rows in each plot in the early maturity trial were lifted on August 13, and topped by hand and bagged on August 17. On August 20 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 15. The bags were put in storage on September 22. The storage shed was managed to maintain an air temperature as close to 34°F as possible. Onions from the full season trial were graded out of storage on January 11 and 12, 2005.

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 the damage that was apparent on the bulb surface, without removing the outer scales.

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."

Varietal differences were compared using ANOVA and least significant differences at the 5 percent probability level, LSD (0.05).

Results

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.

A few experimental varieties were named in 2004. Nunhems' 'SX 7000ON' and 'SX 7002ON' were named 'Bandolero' and 'Montero', respectively. Seedworks' '6001' was named 'Maverick'. Varieties are all listed by name in the results. The experimental numbers are useful for comparing results from previous years.

Iris Yellow Spot Virus Rating

Subjective rating of damage from iris yellow spot virus for the early maturing varieties ranged from 0.68 for 'Renegade' to 1.84 for 'XON-0101' (Table 1). Subjective rating of damage from iris yellow spot virus for the full season varieties ranged from 0.82 for 'T-433', 'Delgado', and 'PX 5299' to 1.92 for 'Export 151' (Table 3).

Early Maturity Trial, Five Yellow Varieties, One White Variety

The percentage of "bullet" single centers averaged 20.6 percent and ranged from 0 percent for 'XON-209W', a white variety, to 76.4 percent for Montero (Table 1). The percentage of onions that were functionally single centered averaged 45 percent and ranged from 14.7 percent for XON-0101 to 95.2 percent for Montero. Montero had the highest percentage of bullet and functionally single-centered bulbs in this trial.

Total yield averaged 849 cwt/acre and ranged from 721 cwt/acre for Montero to 971.4 cwt/acre for 'Exacta' (Table 2). Exacta, XON-0101, and Renegade were among the highest in total yield. Supercolossal-size onion yield averaged 25.6 cwt/acre and ranged from 9.2 cwt/acre for XON-209W to 47.2 cwt/acre for Exacta. Exacta and XON-0101 were among the highest in yield of supercolossal bulbs. Not considering supercolossals, colossal-size onion yield averaged 235 cwt/acre and ranged from 109.5 cwt/acre for Montero to 371 cwt/acre for Exacta. Exacta and XON-0101 had the highest colossal bulb yields.

Full Season Trial, 33 Yellow Varieties

The percentage of "bullet" single centers averaged 33.7 percent and ranged from 4 percent for Delgado to 82 percent for '6011' (Table 3). Varieties 6011, Bandolero, 'SX 7004 ON', and 'Sabroso' were among the highest in percentage of onions with "bullet" single centers. Varieties 6011, SX 7004 ON, Montero, Bandolero, Sabroso, 'Granero', 'Varsity', 'Vaquero', '4001', and 'SVR 5819' were among the highest in percentage of onions that were functionally single centered.

Marketable yield out of storage in January 2005 ranged from 439.9 cwt/acre for Export 151 to 1,025.7 cwt/acre for 'Ranchero' (Table 4). Ranchero, 'Sweet Perfection', and 'OLYS97-24' were among the varieties with the highest marketable yield. Supercolossal-size onion yield ranged from 2.3 cwt/acre for Sabroso to 245.6 cwt/acre for 6001. 6001, 'PX 2599', 'PX 5299', 'Harmony', 'Harvest Moon', and Ranchero were among the varieties with the highest supercolossal yield. The number of bulbs per 50 lb of super colossal onions ranged from 29.8 for 'XPH95345' to 58.0 for Sabroso. Eight yellow varieties had supercolossal bulb counts above the acceptable range (average size too small, because almost all bulbs are at the small end of the size range) for marketing as super colossals (28-36 count per 50 lb). None of the varieties had supercolossal counts below the acceptable range (averaged too big) for marketing as supercolossal. Not counting supercolossals, colossal-size onion yield ranged from 48.5 cwt/acre for Export 151 to 500.8 cwt/acre for Ranchero. Ranchero, 'Torero', PX 5299, PX 2599, OLYS97-24, Harmony, and Sweet Perfection were among the highest in colossal bulb yields.

Decomposition in storage ranged from 1.5 percent for 'Daytona' to 9 percent for 'Tequila'. No. 2 bulbs ranged from 5 cwt/acre for SX 7004ON to 100.3 cwt/acre for Harvest Moon. Bolting averaged 0.04 bolted onions per plot and occurred in only seven varieties.

Full Season Trial, Five Red Varieties

The percentage of "bullet" single centers averaged 25 percent and ranged from 10.8 percent for 'Mercury' to 46.4 percent for 'Salsa' (Table 2). The percentage of functionally single-centered onions averaged 44.6 percent and ranged from 24.2 percent for Mercury to 64.8 percent for Salsa.

Total marketable yield ranged from 389.4 cwt/acre for 'Red Fortress' to 538.8 cwt/acre for Mercury (Table 4). Colossal-size onion yield ranged from 19.4 cwt/acre for 'Red Zeppelin' to 71.7 cwt/acre for Mercury. Decomposition in storage ranged from 1.5 percent for 'Redwing' to 13.9 percent for Salsa. No. 2 bulbs ranged from 10.6 cwt/acre for Redwing to 146.1 cwt/acre for Red Fortress.

Subjective evaluation of thrips damage to red onions in storage ranged from a rating of 1.4 for Red Fortress to 3.8 for Salsa.

Full Season Trial, Five White Varieties

The percentage of "bullet" single centers averaged 22.9 percent and ranged from 15.3 percent for 'Gladstone' to 33.3 percent for 'SVR 7106' (Table 2). The percentage of functionally single-centered onions averaged 55.7 percent and ranged from 44.7 percent for 'Oro Blanco' to 76.0 percent for SVR 7106.

Total marketable yield ranged from 441.7 cwt/acre for Oro Blanco to 578.4 cwt/acre for 'SVR 5646' (Table 4). Colossal-size onion yield ranged from 80.4 cwt/acre for Oro Blanco to 217.5 cwt/acre for SVR 5646. Decomposition in storage ranged from 6.4 percent for 'Brite Knight' to 21.6 percent for Oro Blanco. No. 2 bulbs ranged from 16.0 cwt/acre for SVR 7106 to 109.6 cwt/acre for Brite Knight.

Table 1. Onion multiple-center rating and iris yellow spot virus rating for early maturing varieties, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

*subjective rating: 0 = no damage, 5 = total damage.

Table 2. Performance data for early maturing onion varieties harvested on August 17 and graded on August 20, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

26

Table 3. Onion multiple-center rating and iris yellow spot virus rating for long season varieties, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

*subjective rating: 0 = no damage, 5 = total damage.

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Table 4. 2004 performance data for experimental and commercial onion varieties graded out of storage in January 2005, Malheur Experiment Station, Oregon State University, Ontario, OR.
				Marketable yield by grade					Bulb counts >4¼ in	Non-marketable yield						Maturity on Aug. 24	Bolters	Thrips damage*
Company	Entry name	Bulb color	Total yield	Total	>4¼ in	4-4¼ in	3-4 in	2¼-3 in		Total rot	Neck rot	Plate rot	Black mold	No. 2s	Small
			--- cwt/acre ---		------------ cwt/acre ------------				#/50 lb	----- % of total yield -----				-- cwt/acre --		%	#/plot
A. Takii	T-433	Y	984.2	821.3	167.9	421.7	216.4	15.3	30.4	7.6	3.2	4.1	0.3	82.3	6.7	24.0	0
	T-439	Y	780.4	717.3	31.5	323.8	351.3	10.7	33.7	3.5	0.3	3.2	0.0	30.8	5.0	59.0	0
	9003G	Y	684.1	627.0	7.8	138.1	454.6	26.6	41.2	3.5	1.0	2.5	0.0	18.5	15.3	56.0	0
Bejo	Daytona	Y	680.0	624.5	8.3	139.5	444.3	32.4	38.0	1.5	0.3	1.0	0.2	32.2	12.8	43.0	0.2
	Delgado	Y	717.4	631.5	9.2	176.9	436.4	9.1	43.4	3.0	0.8	2.2	0.0	59.7	5.8	55.0	0
	Gladstone	W	709.8	548.2	10.1	127.6	391.0	19.5	36.4	12.1	10.1	1.6	0.4	71.8	4.1	46.0	0.4
	Redwing	R	562.2	536.6	1.1	45.2	468.0	22.4	48.3	1.5	0.7	0.8	0.0	10.6	6.7	37.0	0	2.0
	BGS 196 F1	Y	832.3	761.8	43.1	288.1	411.6	19.1	35.5	2.6	0.3	2.3	0.0	41.6	7.5	58.0	0
Crookham	Harmony	Y	1040.6	902.9	221.1	447.9	223.7	10.3	30.9	5.4	3.5	1.8	0.0	77.0	5.2	37.0	0.2
	Sweet Perfection	Y	1072.6	969.8	169.9	439.9	339.9	20.1	30.8	4.6	1.8	2.1	0.8	46.1	7.1	39.0	0
	OLYS97-24	Y	1082.9	927.9	173.9	453.5	281.9	18.6	33.6	6.0	3.7	1.9	0.3	80.7	10.1	25.0	0
	OLYS97-27	Y	964.9	835.6	144.7	397.9	272.7	20.1	32.1	5.7	2.6	2.6	0.5	64.4	9.8	28.0	0
	XPH95345	Y	795.6	613.8	59.3	215.1	321.1	18.4	29.8	10.6	8.9	1.7	0.0	94.7	4.8	33.0	0
Dorsing	Harvest Moon	Y	941.2	786.2	220.8	350.6	206.2	8.7	31.5	5.7	3.4	2.1	0.2	100.3	5.3	29.0	0.2
D. Palmer	Mesquite	Y	932.3	810.7	176.2	369.3	246.1	19.2	31.6	4.0	1.6	2.4	0.0	81.8	4.6	20.0	0
	Tequila	Y	1004.4	812.7	184.0	403.3	216.4	9.0	31.3	9.3	4.9	2.9	1.5	93.2	3.5	23.0	0.2
Rispens	Export 151	Y	552.3	439.9	5.2	48.5	369.8	16.4	40.5	3.1	0.7	2.4	0.0	92.8	3.6	43.0	0
	Brite Knight	W	662.7	501.4	4.5	98.3	367.8	30.7	34.8	6.4	5.6	0.8	0.0	109.6	9.3	44.0	0
	Red Fortress	R	557.8	389.4	0.0	25.1	321.8	42.6		1.9	0.6	1.4	0.0	146.1	11.8	47.0	0	1.4
Scottseed	Oro Blanco	W	672.8	441.7	2.8	80.4	337.3	21.2	38.4	21.6	20.5	1.2	0.0	75.0	7.0	55.0	0
Global Genetics	Varsity	Y	655.5	616.0	30.3	195.5	378.6	11.7	35.9	3.9	0.7	3.2	0.0	10.1	5.5	68.0	0
	4001	Y	683.6	638.9	10.7	140.0	464.9	23.3	42.2	3.4	0.3	3.2	0.0	15.0	7.6	69.0	0.2
	Maverick	Y	961.0	869.0	245.6	413.9	195.5	13.9	31.3	6.2	3.1	3.1	0.0	28.6	4.1	30.0	0
	6011	Y	867.7	803.0	130.3	418.0	237.1	17.5	31.6	5.3	2.0	3.2	0.1	15.2	4.7	52.0	0
Seminis	Mercury	R	593.1	538.8	2.6	71.7	437.3	27.2	40.5	5.9	2.7	2.9	0.2	12.8	7.4	80.0	0	3.4
	Santa Fe	Y	904.6	798.4	171.1	374.8	240.8	11.7	30.3	5.9	2.4	3.6	0.0	47.0	6.0	29.0	0
	Red Zepelin	R	518.1	428.2	2.7	19.4	373.8	32.2	56.9	3.3	2.0	1.3	0.0	67.3	5.5	78.0	0	2.6
	PX 2599	Y	945.8	900.7	244.2	464.7	182.3	9.4	31.5	2.5	0.8	1.7	0.0	16.1	5.4	21.0	0
	PX 5299	Y	954.3	895.5	227.9	467.3	193.8	6.4	30.9	2.4	0.8	1.6	0.1	31.8	3.8	33.0	0
	SVR 7106	W	660.8	504.9	8.9	136.7	343.4	15.9	34.4	19.9	15.2	4.7	0.1	16.0	8.1	63.0	0
	SVR 5646	W	767.1	578.4	19.3	217.5	331.1	10.5	37.2	21.1	14.6	6.1	0.4	19.5	6.4	58.0	0
	SVR 5819	Y	950.3	895.3	130.0	440.9	309.5	15.0	31.8	3.6	0.9	2.7	0.0	14.7	7.1	31.0	0
Nunhems	Bandolero	Y	674.7	626.9	3.7	52.2	536.4	34.6	45.5	4.3	1.7	2.5	0.1	8.0	10.6	73.0	0
	Granero	Y	913.1	861.1	71.8	429.1	339.4	20.8	34.3	3.2	1.5	1.6	0.1	14.8	8.8	35.0	0
	Pandero	Y	928.8	884.5	132.7	428.6	310.6	12.6	32.3	1.7	0.2	1.5	0.0	22.0	6.2	23.0	0.2
	Ranchero	Y	1115.0	1025.7	205.8	500.8	302.6	16.5	30.7	5.7	3.2	1.7	0.8	19.1	7.3	49.0	0
	Sabroso	Y	620.5	571.7	2.3	69.6	478.6	21.2	58.0	5.4	2.0	3.4	0.0	6.8	8.7	58.0	0
	Salsa	R	529.7	404.9	0.0	62.4	320.1	22.3		13.9	8.5	5.4	0.0	46.0	6.4	70.0	0	3.8
	Tesoro	Y	749.3	686.3	7.8	202.1	457.8	18.6	39.7	2.5	0.7	1.8	0.0	34.5	10.5	59.0	0.2
	Torero	Y	952.4	889.2	170.5	483.3	223.5	11.9	32.2	4.1	2.3	1.6	0.1	19.1	5.5	40.0	0
	Vaquero	Y	930.1	861.6	65.6	403.4	373.4	19.2	34.2	5.3	2.5	2.8	0.0	11.9	7.4	46.0	0
	Montero	Y	848.1	798.9	45.2	337.3	398.2	18.2	35.7	4.2	2.2	2.0	0.0	7.8	7.7	75.0	0
	SX7004 ON	Y	904.1	856.7	68.3	424.0	356.5	7.8	32.7	4.6	3.1	1.6	0.0	5.0	3.1	50.0	0
Average			810.6	712.4	84.6	273.1	336.4	18.3	36.1	6.0	3.4	2.4	0.1	44.1	7.0	46.3	0.04	2.6
LSD (0.05)			86.0	101.2	46.1	68.9	81.1	16.2	5.5	5.6	4.3	2.2	NS	23.0	NS	8.0	NS	1.2

* Thrips damage: 0 = least damage, 10 = most damage.

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Last updated  Tuesday June 28, 2011.