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Sweet Onion Variety Trial, Spring 2004

Sweet (short-day) onions are a relatively minor crop in Florida. Production exists as both dry bulbs (mature) and green tops (immature). Limited production has existed throughout the state. The biggest deterrent for increased production is from competition from established markets in south Texas and middle Georgia areas. However, the potential exists for expanding production, especially in the areas of local sales and direct marketing.

The objective of this trial was to evaluate the performance of sweet onion varieties under northwest Florida conditions.

The transplants for this trial were produced from field beds at the NFREC-Quincy. Twenty entries were seeded on 9 Oct 2003. Seed were planted at rate of about 30 seed per ft into rows spaced 12 inches apart. Preplant fertilization of seedbeds was 30-40-40 lbs/A of N-P₂O₅-K₂O. Dacthal W 75 was applied was applied over the top at 10 lb/A after seeding. Seedbeds were top dressed once with 34 lbs N/A. Entries were transplanted into the production field on 7 Jan 2001. Soil type was an Orangeburg loamy fine sand. Preplant fertilization was 60-80-80 lbs/A of N-P₂O₅-K₂O. Production scheme was 3 rows spaced 15 inches apart under a 6 ft tractor and in-row spacing was 4 inches (65,340 plants/A). Goal 2XL at 2 pts/A was applied on soil surface before transplanting and Dacthal W 75 at 9 lbs ai/A was applied over the top after transplanting. Nitrogen was applied twice during the season at 50 lbs N/A each time. One top dressing of 60 lbs/A as KCl was made during the season. Registered pesticides were applied as needed to control pests.

Entries were harvested as they matured, where mature is defined as when about 25% of the tops of an entry had fallen down naturally. Bulbs were lifted, allowed to dry for a few hours and tops and roots removed. Bulbs were then placed in bushel baskets and dried for 72 hours at 100^o F in large drying rooms. After drying time was complete, onions were removed, allowed to cool down and graded. Grading consisted of discarding culls (small onions, splits, off color and decayed) and sizing into medium (1.5-2 inches), large (2-3 inches) and jumbo (>3 inches) categories. Bulbs were then weighed and counted.

Harvest occurred from the period of 29 April to 21 May. Total yields ranged from 896 50 lb bags/A for ‘Sweet Melissa’ to 302 50 lb bags/A for ‘Safari’ (Table 1). Three other entries produced yields as high as ‘Sweet Melissa’. Yields were excellent to good in 2004. Growing conditions were good and disease was not a problem. ‘Tanya’ produced the largest bulb at 14.5 oz and ‘SSC 1600’ produced the smallest at 5.7 oz. Percent marketable bulbs ranged from a low of 78.5 % for ‘Century’ to a high of 100 % for ‘SSC 1600' and ‘SSC 1535'. Percent bolting level was very low (<2%) on all entries except ‘Sugar Belle’ at 9.3 % and ‘SSC 6372' at 11.8 %. Days to harvest from transplanting ranged 113 days for SSC 1535', ‘Georgia’, ‘SSC 33076' and ‘Georgia Pride’ to 135 days for ‘Tanya’, ‘EX 19013', ‘Granex 33', ‘Yellow Granex 1380' and ‘Century’.

(Steve Olson, NFREC-Quincy, Vegetarian 04-06)