Research report from OSU's North Willamette Agricultural Research and Extension Center
Delbert Hemphill
OSU Dept of Horticulture, NWREC
Extremely high quality leeks are being produced on a small scale in the Willamette Valley. The crop is usually seeded in early spring, matures in autumn, and can be held through the winter for harvests until the following spring. Very few varieties are grown commercially and the highest quality plants have been transplanted and grown in trench culture. The most lucrative market is the restaurant trade, which demands long, thick, blanched stems. Healthy foliage can also be used decoratively in presentation of restaurant dishes. This trial had two purposes: to evaluate a number of varieties in a late spring planting for autumn and overwinter harvest, and to evaluate several winter hardy varieties in a late planting for overwinter harvest. Growers would benefit if planting of the overwinter crop could be delayed, allowing the possibility of double cropping with a short season crop and reduced weed control problems. Only the early harvests from the spring-sown crop are reported here. The late planting (July 31 transplant) had not produced marketable leeks at this writing (1/5/85).
Methods
Nine varieties were seeded in flats on a greenhouse bench on March 23, 1984. The plot area received a broadcast application of 1,000 pounds/acre of 10-20-10, followed by formation of raised beds with 18 inch tops, 40 inches furrow to furrow, and about 7-inch height. Seedlings were transplanted on May 31 into holes dibbled approximately 4 inches deep on 6 inch spacing, with two rows/bed. A single plot consisted of 20 feet of bed (80 plants). Treatment (varieties) were replicated 3 times in randomized block design. Propachlor herbicide was applied at 4 pounds/acre after planting and was reapplied on June 29, July 31, and October 8. The plots were also hand-hoed twice. An additional 25 pounds N/acre as nitroform was applied on July 6 and again on August 31. Twenty plants were harvested from each plot on August 24 and again on October 8. Plants were topped approximately 2 inches above the base of leaves.
Results and Discussion
At the first harvest, all varieties were somewhat immature and did not differ significantly in weight/plant, blanched stem length, or stem width (Table 1). Often there appeared to be more variation between blocks than between cultivars. Stem length did vary significantly with cultivar, with Conqueror and Acadia the shortest and Tivi the longest. All stems were slightly bulbed at the root end; color was light blue-green for all cultivars.
At the second harvest, all varieties had produced mature, marketable plants. Mean leek weight did not vary greatly except that Conqueror was lighter and Argenta, heavier, than most other varieties (Table 2). Stem length varied considerably among varieties with Tivi, Bluvetia, and Kilima producing longer stems, Conqueror and Electra shorter stems. Blanch length did not vary significantly and appeared to be mostly controlled by transplanting depth. Stem width also varied little among cultivars, with great variability within a variety.
Differences in growth habit and foliage color were very evident by the second harvest. Acadia and Conqueror had the darkest blue foliage; Argenta, Bluvetia, Kilima, and Tivi had pale green foliage, with the other three varieties intermediate in color. Tivi plants were tall and upright; Electra and Kilima plants were taller than average but with less upright foliage. Alaska and Conqueror had the shortest leaves. All cultivars were judged of acceptable quality, with the blue-foliage plants more attractive.
Table 1. Leek size on August 24, 1984, 85 days after transplanting Variety Stem wt. Stem lengthZ Blanched lengthY Stem widthX ______________________________________________________________________ oz. -------------------inches------------------- Acadia 4.3 3.3 2.2 1.2 Alaska 3.6 3.5 2.3 1.0 Alberta 4.4 4.0 2.8 1.2 Argenta 4.7 3.8 2.8 1.2 Bluvetia 4.6 4.0 2.2 1.2 Conqueror 4.0 3.2 2.0 1.0 Electra 4.9 3.5 2.0 1.3 Kilima 4.9 3.7 2.1 1.3 Tivi 5.1 4.3 2.5 1.3 LSD(0.05) NS 0.7 NS NS ZMeasured from base of bulb to point of leaf branching. YMeasured from base of bulb to mean extent of white area. XMeasured just above the bulb. NSNo significant differences. Table 2. Leek size on October 8, 1984, 130 days after transplanting Cultivar Stem wt. Stem length Blanched length Stem width oz. ---------------------inches------------------- Acadia 7.9 4.7 2.5 1.5 Alaska 7.4 3.9 2.4 1.4 Alberta 8.4 3.9 2.6 1.4 Argenta 9.9 4.5 2.9 1.6 Bluvetia 8.2 5.2 2.1 1.4 Conqueror 6.4 3.3 2.5 1.4 Electra 7.6 3.5 2.5 1.5 Kilima 9.1 5.1 2.1 1.6 Tivi 8.4 5.2 2.6 1.4 LSD(0.05) 2.1 0.6 NS NS