0, 0/0.. Unbound issue rp 2 Does not circulate Special Report 905 November 1992 Jerusalem Artichoke Trials in Southern Oregon Property of OREGON STATE UNIVERSITY Library Serials Corvallis, OR 97331-4503 Agricultural Experiment Station Oregon State University For additional copies of this report, write: John A. Yungen Professor of Agronomy, Emeritus Southern Oregon Experiment Station 569 Hanley Road Medford, OR 97502-1206 Special Report 905 October 1992 Jerusalem Artichoke Trials in Southern Oregon by John A. Youngen Professor of Agronomy, Emeritus Southern Oregon Experiment Station Oregon State University INTRODUCTION The Jerusalem artichoke (Helianthus tuberosa L.) is a member of the sunflower family and a native American plant. It has long been a popular garden crop for its tubers, which can be eaten raw, sliced into salads, or boiled like potatoes. Farmers have used it as a livestock feed, sometimes making silage of the tops but more often feeding the harvested tubers to livestock or simply allowing hogs to root them out of the ground. The plant can easily become a weed, especially in gardens, and wild types are often called wild sunflowers. From America, the crop was taken to Europe by early explorers, and its production spread throughout the continent. In Europe, its use for livestock feed and for human food began in the seventeenth century. In the United States tubers served as a food source for the Huron Indians, and it was used in New England for pottage, a thick soup. Dried stalks were sometimes used for fuel in place of wood. Recently, the Jerusalem artichoke has been mentioned as a promising source plant for the production of industrial alcohol, primarily for blending with gasoline to make gasohol. The tubers contain up to 18 percent sugar, mainly as levulose, and are a good source of inulin, an anhydride of levulose. Trials were conducted in Oregon beginning in the early 1920's, although there was much interest and some production late in the nineteenth century (6). The United States Department of Agriculture conducted trials for several yers beginning in 1931 in Illinois, Minnesota, Oregon, Wyoming, Maryland, and Virginia. One conclusion from that work was that western Oregon had very favorable growing conditions for the crop, resulting in high yields of tops and tulhPrs (1). To obtain information on some agronomic aspects of its production in southern Oregon, field experiments were conducted in 1980, 1981, and 1982. The effect of row and plant spacing, top growth removal, and volunteer stands were measured on fresh and dry weights of top growth, tuhr.r yield, tuber specific gravity, and soluble solids. That information is presented in the first part of this report beginning on page 2. Herbicide tolerance information was obtained from trials conducted from 1982 through 1984. The second part of this report, beginning on page 13, presents data from the herbicide trials which were designed to find chemical means of eradiciating Jerusalem artichoke from a succeeding crop of barley. The information in this publication is provided with the understanding that listing of commercial products, necessary to this research, implies no endorsement by the author or by Oregon State University. Similarly, no criticism or discrimination is intended or implied of products or equipment not listed. -1- Part 1: JERUSALEM ARTICHOKE PRODUCTION TRIALS The trials were conducted on a deep, well-drained Central Point sandy loam soil, described as a coarse-loamy, mixed, mesic, Pachic Haploxerol by the Soil Conservation Service. Irrigation water was applied with high-rise, overhead sprinklers. The Jerusalem artichoke planting stock was the Mammoth French White selection. The design used in each experiment was a randomized complete block with four replications. 1980 Materials and Methods The previous year's crop was spring barley. The experimental area was fertilized with 40 pounds of nitrogen (N), 40 pounds of phosphate (P205 ) and 40 pounds of potash (K50) per acre during seedbed preparation. Trifluralin (Treflan) and EPIC (Eptam) were applied at 0.75 and 2.0 pounds per acre, respectively, as preplant incorporated herbicide treatments on March 19. The two herbicides were registered for use on sunflower, but they were considered experimental for use on Jerusalem artichoke. Small tubers and pieces of titers averaging about two ounces were hand-planted March 21 at a depth of 3 inches. Planting variables included two row spacings, 20 and 40 inches, and spacings of 12, 18, and 24 inches within the rows. The amounts of planting stock used for the different spacings ranged from 800 to 3,260 pounds per acre. The planting was fertilized with 80 pounds of nitrogen per acre as urea on May 21. Silage-stage sampling was done October 1, 194 days after planting, when the plants were in full bloom. Tuber harvest was done on November 18 from plants that had their tops removed for the silage-stage harvest. Tubers were harvested December 18 from plants whose tops were intact but killed by freezing weather. The tubers were washed and fresh or green weights were recorded after each harvest. Specific gravity was determined on tubers after they were washed. Results and Discussion Excellent stands were obtained, and growth was vigorous throughout the season. By June 5, plants were 18 to 24 inches in height, and there were no weeds. Plants began flowering from buds at the terminals of the upper branches on September 22 (almost 90 days later than oilseed sunflowers growing nearby). Stalks were 10 to 14 feet, and the tallest growth occurred with the highest plant populations and with 20-inch row spacing. With the highest plant population, there was very little branching of the lower part of the plants, but there were many branches a few inches above the crown where plants were spaced 18 and 24 inches apart, especially in the 40-row spacing plantings. -2- The flowers resembled those of sunflowers, but they were numerous and smaller, averaging less than 2 inches in diameter. Fresh weights of top growth ranged from 29.7 to 33.8 tons per acre, and while yields were highest with the 12-inch plant spacing, the differences were not statistically significant (Table 1). Dry matter yields ranged from 7.51 to 9.50 tons per acre. The highest yields were with the 20-inch row spacing, and with the 12-inch hill spacing. Dry matter content averaged 26.9 percent; the 20-inch row spacing, 28.0 percent and the 40-inch row spacing 25.8 percent. The dry matter average yield of 8.56 tons per acre was 91 percent of the yield of 12 field corn hybrids grown on the station. Fresh weights of tubers from plants harvested for silage-stage determination ranged from 14.2 to 17.4 tons per acre (Table 2). Highest yields were obtained with the 12-inch spacing within the row, although differences were not statistically significant. When the tops were left on the plants until the December 18 harvest, tuber yields were more than double that of plants whose tops were removed October 1. The period of rapid tuber expansion of Jerusalem artichoke is after flowering, when sugars stored in the stalks are moved into the tubers. The highest yields were from plants spaced 12 inches apart in both row spacings. Tubers of Jerusalem artichoke vary in shape and size. The type grown produced reasonably smooth tubers, although some knobbiness and pointed ends were present. Tuber weights varied widely, ranging from one half to over 10 ounces, although most were in the two to eight ounce range. The specific gravities of the tubers, comparing tuber weights to that of water (1.000), averaged 1.037 when top growth was removed October 1 and 1.053 when tops were left on the plants until the December 18 harvest (Table 2). Tubers from plants spaced 12 inches apart had the highest specific gravities with both row spacings. 1981 Materials and Methods The experimental area was fertilized with 70 pounds of nitrogen (N) and 80 pounds of sulfur (S) per acre during seedbed preparation. An additional 40 pounds of N was banded along one side of each row on May 27. Small and cut tubers were planted April 3 with 30-inch row spacing and 18-inch plant spacing within the row. Treflan was applied at 0.75 pound of active ingredient per acre as a preplant incorporated treatment. The main variable imposed in 1981 was top growth removal from different plots on a monthly basis from June through October. All top growth was cut at or near ground level, weighed fresh and subsampled for dry matter content. -3- Table 1. Jerusalem artichoke top growth yields as affected by raw and plant spacing variables, Medford, 1980 season Silage-stage yields Spacing variables (inches) (tons per acre) Dry matter Between rows Within rows Fresh wt Dry wt at harvest (%) 20 12 33.8 9.50 28.1 20 18 33.7 9.21 27.3 20 24 30.2 8.66 28.7 40 12 32.3 8.51 26.3 40 18 29.7 7.51 25.3 40 24 30.8 7.95 25.8 Mean 31.8 8.56 26.9 LSD, 5% N.S. 1.19 C.V., % 7.6 9.1 Notes: 1. The planting was made March 21. 2. Silage-stage sampling was done October 1 during the full-bloom stage of plant development. 3. Data are the means of four replications. Table 2. Jerusalem artichoke tuber yield and specific gravity as affected by row and plant spacings and top growth removal, Medford, 1980 season Tuber yield, T/A Tuber specific gravity Spacing variables (inches) Tops Tops Tops Tops Between rows Within rows removed mature removed mature 20 12 16.1 35.1 1.046 1.066 20 18 16.2 33.9 1.039 1.059 20 24 15.9 32.6 1.042 1.050 40 12 17.4 35.7 1.052 1.056 40 18 16.6 30.9 1.032 1.045 40' 24 14.2 29.2 1.028 1.040 Mean 16.1 32.9 1.037 1.053 LSD, 5% N.S.