Processing Potato Trial Nesson Valley, North Dakota 2015 Asunta (Susie) Thompson, Jerald Bergman, Tyler Tjelde North Dakota State University Areas of North Dakota and Minnesota, both part of the northern plains potato production region, produce potatoes for all markets, including tablestock, seed, and processing. Approximately 60 of production in ND and MN is for processing (frozen including French fries, and chips). Russet Burbank accounts for about 35 and Prospect Russet about 15 of the acreage in North Dakota. Russet Burbank, the industry standard for frozen processing and russet fresh marketing, has several shortcomings. It is a long-season cultivar, requiring high amounts of inputs including fertilizer and water, and Russet Burbank is susceptible to many pests (pathogens, insects, nematodes), but more importantly to many stresses including temperature and moisture. Producers, processors, and consumers are interested in cultivars that are more environmentally and economically sustainable, and that possess excellent processing qualities including low sugar accumulation and high specific gravity. In order to identify these outstanding genotypes, the North Dakota State University (NDSU) potato breeding program as part of the potato improvement team conducts crossing, selection, evaluation, and cultivar development activities across North Dakota and western Minnesota. Field research trials were grown at eight sites in 2015; five sites were irrigated (Larimore, Oakes, Inkster, Williston, and Park Rapids), while three were non-irrigated (Hoople, Crystal and Grand Forks) sites. These trials aid in identifying selections with high yield potential, disease and pest resistance, stress tolerance, adaptability, and consumer quality attributes for tablestock and processing genotypes. This report summarizes the results from the Nesson Valley Processing Trial. Many of the entries are russet selections considered to be dual-purpose, in that they produce acceptable frozen processed products including French fries, and are also suitable for tablestock. Eighteen advancing dual-purpose russet selections and commercially acceptable cultivars were included in the trial planted on May 4, 2015. The field plot design was a randomized complete block with four replicates; cultural practices typical of the growing area were used during the growing season, including sprinkler irrigation. Rows were 36 inches apart, with a 12-inch within-row spacing. The trial was harvested on September 30; days to harvest totaled 149. Agronomic and quality evaluations, yield and grade, and French fry quality are summarized in Tables 1, 2 and 3, respectively. Percentage stand ranged from 81 to 100 (Table 1). Ranger Russet and Shepody had the lowest percentage stand and were the only two statistically significant from the other entries. There was not a clear reason for low stand in these two processing industry standards. Total yields were significantly different, ranging from 248 cwt./acre for ND113099-2Russ to 424 cwt./acre for Umatilla Russet (Table 2). Russet Burbank and Umatilla Russet total yields were significantly higher than for all other clones. ND8068-5Russ is an exceptionally early clone,
with maturity 7 to 10 days earlier than a standard Russet Norkotah. Total yields for this selection will not compete with those of later maturity in a full season trial such as the trial at Nesson Valley. Total yields and yield of US No. 1 tubers was less than in 2014. Yield of US No. 1s ranged from 152 for AND97279-5Russ and ND102647-3Russ, to 307 for Umatilla Russet. Similarly, percentage US No. 1s ranged from 52 for AND97279-5Russ and ND102647-3Russ, to 91 for Dakota Trailblazer. The tuber size profile was smaller than for entries in 2014. The percentage of 6 to 12 ounce size tubers for most clones was in the 40 to mid-50 percentage range. Several entries had more than 40 undersized tubers (tubers 0-4 ounces), an undesirable trait for processing genotypes. Similarly, many of these same entries, including AND97279-5Russ, ND8068-5Russ, ND102647-3RussND113099-2Russand ND113526CB-1Russ, produced 30 or more of tubers om the 4-6 ounce category. Tubers in the 6-12 ounce range, tend to be the most desirable for French fry processing. Industry standards led the way in terms of percentage of yield for this grade category, along with new selections ND113065CB-1Russ and ND113065CB-2Russ. ND7882b-7Russ, Bannock Russet and Dakota Trailblazer had the most propensity to produced oversized tubers (>12 ounces). All entries had few US No. 2 tubers and Culls, with the exception of Russet Burbank. Russet Burbank, the industry standard for French fry production and russet tablestock, is very sensitive to environmental conditions, particularly moisture stress. Uneven watering results in misshapen tubers. Tubers per plant ranged from 5.0 to 10.5 for Dakota Trailblazer and Ranger Russet, respectively; mean tuber number per plant was 7.7 (Table 1). Several quality attributes are presented in Table 1. Mean specific gravity was 1.0910, with a range of 1.0825 for Russet Norkotah to 1.1196 for Dakota Trailblazer (Table 1). Hollow heart and brown center were not a significant problem for any entries, thought ND113526CB-1Russ should be monitored in future trials. Blackspot bruise potential is assessed using the abrasive peel method of Pavek and Corsini. Blackspot bruises result when polyphenol oxidase and tyrosine combine within damaged cells due to tubers bumping around during harvest and handling. Usually the skin is not broken and bruises are difficult to detect without peeling. Based on a scale of 1 (none) to 5 (severe), clones ranged from 1.8 for Bannock Russet to 4.6 for Ranger Russet (the susceptible check in this assessment). Our results indicate producers should use management practices to maximize the marketing of bruise-free tubers, including a preharvest irrigation if appropriate, maintain belts and conveyors full of tubers and soil as the potatoes move through the harvester, limit drops, and utilize padding on harvesters, in trucks, and on conveyors going into storage. Shatter bruise potential was assessed using a bruising chamber with digger chain link baffles. As for blackspot, tubers are shattered after pulp temperatures in storage reach 45F. Entries are rated on a scale of 1 (none) to 5 (many and severe). Clones ranged from 1.5 to 2.6 for ND11526CB-1Russ and Alpine Russet, respectively. Keeping tubers properly hydrated, using bruise-free management techniques, and minimizing damage limit shatters. Shatter bruises may serve as an entrance point for pathogens such as Fusarium graminearum, Fusarium sambucinum and Fusarium coeruleum. as well as Alternaria solani, the causal agent of foliar and tuber early blight. The general rating score is based on tuber appearance, tuber yield and size distribution, and external defects; it is similar to a breeder s merit score. Entries ranged from 2.0 for MonDak Gold (pointed tubers and dry rot due to early blight tuber decay), to 4.4 for Dakota Trailblazer and Russet Norkotah (attractive, long and blocky tubers).
All advancing selections and industry standards had acceptable French fry color when fried at harvest (Table 3). Many demonstrate sugar end resistance, and while most clones considered resistant to sugar ends had some, they were light enough to be manageable during processing. ND8068-5Russ, ND113526CB-1Russ, Alpine Russet, Bannock Russet, Dakota Trailblazer and MonDak Gold would be considered resistant based on fry scores after harvest. A better assessment would be following 8 weeks storage at 45F. ND113174B-2 Russ, Russet Norkotah, and Russet Burbank had the most severe and the most sugar ends as defined by the industry. Our program assesses a sugar end as any color deviation from the main fry. This is more stringent than the processing industry that requires a score of a 3 or 4 on the color chart to be called a sugar end. Clones with stem end colors 2 or less from storage can usually be managed during processing. Our research efforts are designed to identify processing (both chip and frozen) germplasm that will reliably and consistently process from long-term cold 38F and 42F (3.3C and/or 5.5C) storage. As we grade, a field (zero time) sample is collected for immediate French fry processing. French fry/frozen processing selections are also evaluated from 45F (7.2C) storage after eight weeks, and again the following May or June for fry color, stem end fry color, sugar ends, and other defects. All clones with processing potential (chip and frozen) are chipped from 38F after 8 weeks of storage as we seek genotypes that will reliable process from that temperature. Entries from this trial were not French fried from long-term storage in June/July 2016. Promising advancing dual-purpose (frozen processing and tablestock) russet selections included ND8068-5Russ, ND113065CB-1Russ and ND113065CB-2Russ. The most advanced is ND8068-5Russ. ND8068-5Russ has very early maturity, thus will not compete with late season cultivars for yield. However, ND8068-5Russ sizes early and has potential as an early russet for packing or may be used in place of Shepody or Ranger Russet as a clone for opening processing plants in mid-july. It will be considered for release in late 2016 or early 2017. We wish to express our gratitude to Richard Nilles (research specialist potato breeding) and the staff at the Nesson Research Extension Center for assisting with planting, plot maintenance, and harvesting this trial. We are appreciative and grateful to our many grower, industry, and research cooperators in North Dakota, the North Dakota Specialty Crops Block Grant Program (NDDA), and to RD Offutt Company and Enander Seed for certified seed potatoes in support of this processing research.
Table 1. Agronomic and quality evaluations for advanced processing selections and cultivars, full season, Nesson Valley, ND, 2015. Clone Stand Tubers Per Plant Specific Gravity 1 Hollow Heart 2 Blackspot Bruise 3 Shatter Bruise 4 General Rating 1. AND97279-5Russ 100 9.8 1.1008 0 3.7 2.4 2.9 2. ND7882b-7Russ 88 5.9 1.0874 0 4.2 1.6 3.4 3. ND8068-5Russ 98 7.4 1.0908 0 4.5 2.3 3.0 4. ND102647-3Russ 98 9.2 1.0832 0 2.5 2.0 2.6 5. ND113065CB-1Russ 99 8.4 1.0842 0 4.0 1.8 3.8 6. ND113065CB-2Russ 94 7.2 1.0824 0 3.6 1.8 4.0 7. ND113099-2Russ 96 6.0 1.0786 0 3.1 2.3 3.1 8. ND113174B-1Russ 98 9.8 1.1108 0 2.4 2.0 3.0 9. ND113526CB-1Russ 99 9.5 1.0914 3 3.5 1.5 2.3 10. Alpine Russet 96 6.7 1.0883 0 2.9 2.6 3.5 11. Bannock Russet 99 6.2 1.0934 0 1.8 2.5 3.8 12. Dakota Trailblazer 95 5.0 1.1196 0 2.1 2.4 4.4 13. MonDak Gold 93 7.4 1.0902 0 4.5 2.6 2.0 14. Ranger Russet 81 10.5 1.0940 0 4.6 1.9 3.1 15. Russet Burbank 95 8.5 1.0838 0 3.4 2.3 3.1 16. Russet Norkotah 94 6.1 1.0825 0 4.2 1.6 4.4 17. Shepody 83 6.6 1.0888 0 2.6 1.8 3.4 18. Umatilla Russet 99 9.3 1.0875 1 2.5 2.3 3.4 Mean 95 7.7 1.0910 0 3.6 2.1 3.3 LSD ( =0.05) 10 2.3 0.0049 2 0.8 0.7 0.6 1 Determined using weight-in-air, weight-in-water method. 2 Hollow heart includes brown center. 3 Blackspot bruise determined by the abrasive peel method, scale 1-5, 1=none, 5=severe. 4 Shatter bruise is evaluated using a bruising chamber with digger chain link baffles. Tubers are stored at 45F prior bruising. Shatter bruises are rated on a scale of 1-5, with 1 = none and 5 = many and severe. 5 The general rating is a score given based on appearance, yield, tuber size distribution, external defects, similar to a breeder s merit score.
Table 2. Yield and grade for advanced processing selections and cultivars, full season, Nesson Valley, ND, 2015. Clone Total Yield Cwt./A US No. 1 Cwt./A US No. 1 0-4 4-6 6-12 >12 US No. 2 1. AND97279-5Russ 296 152 52 47 34 17 1 0 1 2. ND7882b-7Russ 282 223 79 15 19 39 22 1 4 3. ND8068-5Russ 255 154 61 35 33 27 1 0 4 4. ND102647-3Russ 291 152 52 47 33 18 1 1 0 5. ND113065CB-1Russ 338 248 73 26 29 42 2 0 0 6. ND113065CB-2Russ 271 196 73 27 27 41 5 0 0 7. ND113099-2Russ 248 183 74 24 34 33 7 1 2 8. ND113174B-1Russ 328 185 55 41 29 25 2 0 3 9. ND113526CB-1Russ 286 160 56 44 33 23 0 1 0 10. Alpine Russet 334 275 82 15 20 48 14 2 0 11. Bannock Russet 356 303 85 13 18 48 20 0 2 12. Dakota Trailblazer 305 279 91 9 18 56 18 0 0 13. MonDak Gold 284 213 75 25 29 43 3 0 0 14. Ranger Russet 374 298 80 18 20 45 14 1 2 15. Russet Burbank 420 294 69 17 20 40 10 2 11 16. Russet Norkotah 271 216 80 19 21 47 13 0 0 17. Shepody 266 207 77 19 24 41 12 1 2 18. Umatilla Russet 424 307 72 23 25 37 11 2 3 Mean 313 225 71 26 26 37 9 1 2 LSD ( =0.05) 57 61 11 11 9 11 12 1 2 Culls
Table 3. French fry evaluations following harvest, full season trial, Nesson Valley, ND, 2015. Clone Fry Color 1 Stem-end Color Sugar End 2 Field Fry 1. AND97279-5Russ 0.6 1.3 42 2. ND7882b-7Russ 0.8 1.4 67 3. ND8068-5Russ 0.5 1.0 17 4. ND102647-3Russ 0.5 1.4 42 5. ND113065CB-1Russ 1.3 1.8 25 6. ND113065CB-2Russ 1.0 1.6 17 7. ND113099-2Russ 1.3 2.0 50 8. ND113174B-1Russ 0.6 2.0 75 9. ND113526CB-1Russ 0.5 1.0 25 10. Alpine Russet 1.0 1.1 8 11. Bannock Russet 0.8 1.1 50 12. Dakota Trailblazer 0.5 0.8 25 13. MonDak Gold 0.6 0.7 8 14. Ranger Russet 0.8 1.5 25 15. Russet Burbank 0.6 2.4 100 16. Russet Norkotah 1.9 2.9 33 17. Shepody 0.6 1.1 50 18. Umatilla Russet 0.8 1.4 50 Mean 0.8 1.5 39 LSD ( =0.05) 0.5 1.1 48 1 Fry color scores: 0.1 corresponds to 000, 0.3 corresponds to 00, 0.5 corresponds to 0, 1.0 equals 1.0; subsequent numbers follow French fry rating scale 000 to 4.0. Scores of 3.0 and above are unacceptable because adequate sugars cannot be leached from the tuber flesh to make an acceptable fry of good texture. 2 Any stem end darker than the main fry is considered a sugar end in these evaluations, thus mirroring the worst case scenario. The processing industry defines a sugar end as a 3.0 or darker.