Malheur Experiment Station Information for Sustainable Agriculture

POTATO VARIETY TRIALS 2009

Clinton C. Shock, Erik B. G. Feibert, and Lamont D. Saunders
Malheur Experiment Station
Oregon State University
Ontario, OR

Introduction

New potato varieties were evaluated for their productivity and suitability for processing. Potatoes in Malheur County are grown under contract for processors to make frozen potato products for the food service industry and grocery chain stores. There is very little production for fresh pack or open market, and very few growers store potatoes on their farms. There is also no production of varieties for making potato chips.

The varieties grown for processing in Malheur County, Oregon, are mainly ‘Ranger Russet’, ‘Shepody’, and ‘Russet Burbank’. Harvest begins in July and potatoes arrive at processing plants directly from the field. Yield of harvests later than mid-August may be limited by the “early die” syndrome, which causes early senescence of the vines of susceptible varieties, especially Shepody and Russet Burbank. Early die is caused by a complex of soil pathogens, including bacteria, nematodes, and fungi, particularly Verticillium wilt. Early die is worse when the rotation between potato crops is shorter.

Small acreages of new varieties or advanced selections are sometimes grown under contract to study the feasibility of expanding their use. To displace an existing processing variety, a new potato variety must have several outstanding characteristics. The yield should be at least as high as the yield of the currently contracted varieties. The tubers need to have low reducing sugars for light fry color, and high specific gravity. A new variety should be resistant to tuber defects or deformities caused by disease, water stress, or heat.  It should begin tuber bulking early and grow rapidly for early harvest. Late-harvest varieties should be resistant to early die to continue bulking tubers until harvest.

Potato variety development trials at the Malheur Experiment Station in 2009 included the Tri-state Russet Trial with 15 entries, the Oregon Statewide Russet Trial with 20 entries, the Preliminary Russet Yield Trial with 58 entries, the Oregon Statewide Specialty Trial of 13 colored skin and/or flesh potato varieties, and the Preliminary Yield Specialty Trial of 20 colored skin and/or flesh potato varieties. Through these trials and active cooperation with other scientists in Idaho, Oregon, and Washington, promising new lines are bred and evaluated. Eventually, the best of them may be released as new varieties.

Materials and Methods

The potato variety trials were grown using sprinkler irrigation on Owyhee silt loam, where winter wheat was the previous crop.  Based on a soil test, 100 lb./acre sulfur (S)/acre, 5 lb. manganese (Mn)/acre, and 1 lb. boron (B)/acre were applied in the fall of 2008.  Following fertilization, the soil was fumigated with Telone^® II at 25 gal/acre and was bedded on 36-inch row spacing.

Seed of all varieties was hand cut into 2-oz seed pieces and treated with Tops-MZ^® plus Gaucho^® dust and placed in storage to suberize. Potato seed pieces were planted in single row plots using a 2-row assist-feed planter with 9-inch seed spacing in 36-inch rows. Red potatoes were planted at the end of each plot as markers to separate the potato plots at harvest, except in the specialty trials where russet was used as the marker.

The following trials were planted on April 22: Tri-state Russet and Oregon Statewide Russet.  The following trials were planted on April 23: Oregon Specialty, Russet Preliminary Yield, and Specialty Preliminary Yield.  All trials, except the Preliminary Yield trials, had plots that were 30 seed pieces long with 4 replicates.  The Preliminary Yield trials had plots that were 20 seed pieces long and 2 replicates.

After planting, hills were re-formed over the rows with a Lilliston rolling cultivator. Prowl^® H₂O at 0.95 lb. ai/acre, Dual Magnum^® at 1.3 lb. ai/acre, and Buccaneer^® at 2.0 lb. ai/acre were applied as a tank mix for weed control on May 14. The herbicides were incorporated with sprinkler irrigation applying 0.56 inch of water. Matrix^® at 0.38 oz. ai/acre was applied on May 29 through the sprinkler system.  Poast^® at 2.5 pt./acre was broadcast on June 4 for weed control.  QuadrisOpti^® at 0.1lb/acre of azoxystrobin and 1.0 lb. ai/acre of chlorothalonil was applied for preventive control of fungal diseases on June 11.  Dithane^® at 2.0 lb./acre was applied through the sprinkler system for preventive control of fungal diseases on June 22.

Emergence started on May 22.  Irrigation was applied 13 times, from June 10 to September 1, with scheduling based on a soil water tension criterion of 60 cb.  Soil water tension was measured at seed piece depth using 12 Watermark soil moisture sensors Model 200SS connected to two dataloggers.  Irrigations were managed to maintain soil moisture below 60 cb.  Irrigation decisions were based on the average of all 12 sensors. Crop evapotranspiration (ET_c) was estimated by the U.S. Bureau of Reclamation using data from an AgriMet weather station on the Malheur Experiment Station.

Fertilizer was applied based on petiole tests taken on June 26 and July 13. Fertilizer was injected into the sprinkler system during irrigation.  During the season, 140 lb. N/acre, 5 lb. magnesium (Mg)/acre, and 0.25 lb. Zn/acre were applied.

The vines were flailed on September 22.  The potatoes in each plot were lifted with a two-row digger that laid the tubers back onto the soil in each row from September 28 through October 2. 

At harvest, visual evaluations were made that included observations of desirable traits (i.e., high yield of large, smooth, uniformly shaped and sized, oblong to long, attractively russeted tubers, with shallow eyes evenly distributed over the tuber length).

Observations were also taken of tuber defects such as growth cracks, knobs, curved or irregularly shaped tubers, pointed ends, stem-end decay, attached stolons, heat sprouts and chain tubers, folded bud ends, rough skin due to excessive russeting, pigmented eyes, or any other defect. A note was made for each plot to keep or discard the clone based on the overall appearance of the tubers.

Tubers were placed into burlap sacks and hauled to a barn where they were kept under tarps until grading. Tubers were graded by market class (U.S. No. 1 and U.S. No. 2) and weight (<4 oz., 4-6 oz., 6-12 oz., and >12 oz.). Tubers were graded as U.S. No. 2 if any of the following conditions occurred: growth cracks, bottleneck shape, abnormally curved shape, or two or more knobs. A 20-tuber sample from each plot was placed into storage. The storage temperature was gradually reduced to 45°F. After 6 weeks, a 20-tuber sample from each plot (except the Specialty Trials) was evaluated for tuber quality traits for processing. Specific gravity was measured using the weight-in-air, weight-in-water method. Ten tubers per plot were cut lengthwise and the 10 center slices were fried for 3.5 min. in 375°F soybean oil. Percent light reflectance was measured on the stem and bud ends of each slice using a Photovolt Reflectance Meter model 577 (Seradyn, Inc., Indianapolis, IN), with a green tristimulus filter, calibrated to read 0 percent light reflectance on the black standard cup and 73.6 percent light reflectance on the white porcelain standard plate.

Data from all trials were analyzed with the General Linear Models analysis of variance procedure in NCSS (Number Cruncher Statistical Systems, Kaysville, UT) using Fisher's protected LSD (least significant difference) for means separation at the 95 percent confidence level.

Results and Discussion

From June 10 to September 1, 12.6 inches of irrigation water were applied.  Precipitation from emergence to vine kill totaled 3.8 inches.  Evapotranspiration from emergence to vine kill totaled 27.5 inches. 

Tri-state Russet Trial

The clones with the highest total yields in the Western Regional Late Harvest Trial were ‘A98345-1’ with 634 cwt/acre, ‘AO02183-2’ with 572 cwt/acre, and ‘PA99N2-1’ with 558 cwt/acre (Table 1).  The clones A98345-1, PA99N2-1, and ‘A00324-1’ were among the clones with the highest U.S. No. 1 yields.  Clones ‘A97066-42LB’, ‘A96814-65LB’, and ‘Ranger Russet’ were among the clones with the highest specific gravity.  Clones AO00057-2, ‘AO96305-3’, and ‘AO02183-2’ were among the clones with the lightest frying tubers. ‘Russet Burbank’ produced significantly more U.S. No. 2 tubers than the other clones in this trial.  Most of the clones including ‘Russet Norkotah’ and Ranger Russet had better visual appearance at harvest than Russet Burbank (Table 2).

Oregon Statewide Trial

‘OR05078-1’, ‘AO02183-2’, and ‘AO96365-2’ were among the clones with the highest total yields and U.S. No. 1 yields.  The clones ‘POR06V12-3’, Ranger Russet, and ‘AO99152-1’ had among the highest specific gravity, a measure of tuber solids.  The clones 'AO96305-3', ‘AO00057-2’, and POR06V12-3 were among the clones with the lightest fry color for processing (Table 3).  Most of the clones had better visual appearance at harvest than Russet Burbank (Table 4).

Colored Flesh Potato Trials

Potato tubers with red to yellow carotinoid or red, blue, and purple anthocyanin pigments are of interest because of the anti-oxidant properties of these pigments in human nutrition.  Two trials tested specialty potato varieties in 2009: Oregon Specialty and Preliminary Yield Specialty.

Oregon Specialty Potato Trial

The clone 'OR05045-1', ‘POR06PG57-2’, and ‘POR05PG26-11’ were among the clones with the highest total yield (Table 5).  ‘Yukon Gold’ had more than 100 cwt/acre of tubers over 10 oz.  Most of the clones and ‘All Blue’ had better visual appearance at harvest than Yukon Gold (Table 6).

Preliminary Russet Yield Trial

Of the 58 clones tested, a few were selected for further testing (Table 7).  Some of the varieties had significantly higher yield and grade and better processing quality than the three commercial varieties in the trial.  Some of the clones and Russet Norkotah had better visual appearance at harvest than Ranger Russet or Russet Burbank (Table 8).

Preliminary Specialty Yield Trial

Of the 20 clones tested, many were retained for further testing (Table 9).  Some of the varieties had significantly higher yield and grade and better processing quality than Yukon Gold.  Some of the clones and All Blue had better visual appearance at harvest than Yukon Gold (Table 10).

Table 1. Tri-state  Russet Trial potato yield, grade, and processing quality, Malheur Experiment Station, Oregon State University, Ontario, OR, 2009.

Table 2. Tri-state Russet Trial tuber visual observations at harvest. Tuber defect observations are from a total of four plots for each clone. K = clone should be saved, D = clone should be discarded. Capital letters denote a higher intensity of an observation compared to lower case letters.  Since there were four replicates, a clone could be scored for the same attribute up to four times.

Table 3. Oregon Statewide Russet Trial potato yield, grade, and processing quality, Malheur Experiment Station, Oregon State University, Ontario, OR, 2009.

Table 4. Oregon Statewide Russet Trial tuber visual observations at harvest. Tuber defect observations are from a total of four plots for each clone. K = clone should be saved, D = clone should be discarded. Capital letters denote a higher intensity of an observation compared to lower case letters.  Since there were four replicates, a clone could be scored for the same attribute up to four times.

Table 5. Oregon Statewide Specialty Potato Trial yield and grade of colored flesh clones. Malheur Experiment Station, Oregon State University, Ontario, OR, 2009.

Table 6. Oregon Specialty Trial tuber visual observations at harvest. Tuber defect observations are from a total of four plots for each clone. K = clone should be saved, D = clone should be discarded. Capital letters denote a higher intensity of an observation compared to lower case letters.  Since there were four replicates, a clone could be scored for the same attribute up to four times.

Table 7. Preliminary Russet Yield Trial yield, grade, and processing quality. Malheur Experiment Station, Oregon State University, Ontario, OR, 2009.

Table 8. Preliminary Russet Yield Trial tuber visual observations at harvest. Tuber defect observations are from a total of two plots for each clone. K = clone should be saved, D = clone should be discarded. Capital letters denote a higher intensity of an observation compared to lower case letters.  Since there were two replicates, a clone could be scored for the same attribute up to two times.

Table 9. Preliminary Specialty Potato Yield Trial yield, grade, and processing quality. Malheur Experiment Station, Oregon State University, Ontario, OR, 2009.

Table 10. Preliminary Specialty Potato Yield Trial tuber visual observations at harvest. Tuber defect observations are from a total of two plots for each clone except the checks. K = clone should be saved, D = clone should be discarded. Capital letters denote a higher intensity of an observation compared to lower case letters.  Since there were two replicates, a clone could be scored for the same attribute up to two times.

Shock, C.C., Feibert, E.B.G. and Saunders, L.D.  2009. Potato Variety Trials 2009. p 129-144. In Shock C.C. (Ed.) Oregon State University Agricultural Experiment Station, Malheur Experiment Station Annual Report 2009, Department of Crop and Soil Science Ext/CrS 131.

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Last updated  Tuesday July 19, 2011.