AN ABSTRACT OF THE THESIS OF
Robert L. Brunick for the degree of Master of Science in Crop Science presented on
March 15, 2002. Title: Clonal Variation in Russet Norkotah and Umatilla
Russet Potato Varieties.
Redacted for privacy
Abstract Approved:
iii R. Mosley
These studies compared giant hill strains of Russet Norkotah and Umatilla
Russet to the parent varieties. Selections were initially based on late maturity and
increased vine vigor. Subsequent evaluations emphasized yield and quality
parameters in comparison to the parent varieties.
Giant hills were collected from the Columbia Basin and Central Oregon in
1999. Seed was tested and increased in a greenhouse during the winter of 1999 and
in the field in 2000. Clones were inspected for viruses and other diseases in both
years.
Replicated performance trials were conducted at the Hermiston Agricultural
Research and Extension Center in the Columbia Basin and at the Central Oregon
Agricultural Research Center, near Madras, in 2001. Trials were grown using
commercial management practices common to the areas. Tubers from the Madras
trial were retained for use in future plantings.
Relative yields of Russet Norkotah strains differed drastically between sites
even though the growing seasons were similar in length. Several Russet Norkotah
strains preformed better than the parent variety at Madras when the strains achieved
good vine growth and the parent variety did not. Vine growth was subnormal at
Madras in 2001 primarily due to delayed emergence and the subsequent short
growing season. Few performance differences and no advantages were evident when
Russet Norkotah strains were grown in the Columbia Basin under conditions with
less environmental stress than usual.
All strains of Umatilla Russet grown under a long season in the Columbia
Basin out-yielded the parent variety; however, many strains also produced a high
percentage of malformed tubers. In general, Umatilla Russet strains failed to
produce adequate yields and tubers of acceptable size when delayed emergence
shortened the growing season at Madras. At Madras, strains of Umatilla Russet with
high biomass tended to have lower yields while strains of Russet Norkotah with high
biomass tended to have high yields.
Some strains performed better than the parent varieties at the two trial sites.
Superior strains have been submitted to the Oregon Potato Variety Development
Program and Oregon Foundation Potato Seed Project for further evaluation.
CLONAL VARIATION IN RUSSET NORKOTAH AND
UMATILLA RUSSET POTATO VARIETIES
by
Robert L. Brunick
A THESIS
submitted to
Oregon State University
in partial fulfillment of
the requirements for the
degree of
Master of Science
Presented March 15, 2002
Commencement June 2002
Master of Science thesis of Robert L. Brunick presented on March 15. 2002.
Approved:
Redacted for privacy
Major professor, representing
Redacted for privacy
Head of Department of Crop and Soil Science
Redacted for privacy
Dean of (dflte School
I understand that my thesis will become part of the permanent collection of Oregon
State University libraries. My signature below authorizes release of my thesis to any
reader upon request.
Redacted for privacy
Robert L. Brunick, Author
ACKNOWLEDGEMENTS
Working with my own research has been fun and challenging. Along the
way I have made new friends and strengthened bonds with old friends. It is with
sincere gratitude that I say thanks to those who have helped and supported me over
this period of time.
My family encouraged me the entire way. They showed interest in both my
research and classes by asking challenging questions which helped me understand
what I was doing better. I owe a special thanks to my wife who not only supported
me but also, on numerous occasions, took time to travel with me and assisted with
data collection. For the time she spent assisting with errorless data collection I am
grateful and for the companionship she provided during the days we traveled
together and I am even more grateful.
Committee members Alvin Mosley, Dan Hane, Ken Rykbost and Jack Stang
provided direction and helped establish goals, but also gave me a great deal of room
to work, for which I am thankful. In addition, I thank Alvin for the opportunities he
provided me.
Dr. Dan Hane and Steve James were instrumental in planting, producing,
collecting field data, harvesting and grading the trials in their respective regions. To
say the least, it would have been nearly impossible to produce and evaluate the crops
in their areas without their selfless support. Thanks for your toil and guidance, Dan
and Steve.
Solomon Yilma provided a great deal of direction and assistance with the
organization of the studies. He was often the first person I would go to when I had
questions and he was always willing to help and guide me. Solomon also assisted
with the interpretation of data. He allowed me to occupy much of his time even
when he was at his busiest. With the utmost respect Solomon, I more than
appreciate your willingness to help.
Again, thanks to everyone who helped me complete this task.
TABLE OF CONTENTS
Page
INTRODUCTION ......................................................................
1
LITERATURE REVIEW ............................................................
4
Characteristics of Giant Hills ...............................................
4
Clonal Variation ..............................................................
5
Giant Hill Selection ..........................................................
6
Fertility Requirments .........................................................
7
SpecificGravity ...............................................................
7
FryQuality .....................................................................
8
Disease Resistance ............................................................ 10
MATERIALS AND METHODS....................................................
11
Clonal Selection ..............................................................
11
SeedIncrease ..................................................................
11
2001 Hermiston Russet Norkotah Yield Trial ............................
13
2001 Hermiston Umatilla Russet Yield Trial .............................
13
2001 Madras Russet Norkotah and Umatilla Russet Yield Trials ......
15
Madras Seed Increase........................................................
15
BiomassSamples .............................................................
16
Umatilla Russet Fry Tests ..................................................... 16
Determination of Specific Gravity ...........................................
17
TABLE OF CONTENTS (Continued)
Page
RESULTS AND DISCUSSION.....................................................
18
Russet Norkotah Yield Trials ...............................................
18
Umatilla Russet Yield Trials ................................................ 30
Umatilla Russet Fry Quality................................................. 43
Biomass Samples At Madras ................................................. 43
CONCLUSIONS
......................................................................
BIBLIOGRAPHY ......................................................................
46
49
LIST OF TABLES
Table
1.
Internal and External Tuber Characteristics, Plant Emergence,
Final Stand and Number of Tubers per Plant for 9 Strains and
3 Seed Lots of Russet Norkotah at Hermiston, OR, 2001 ............... 19
2.
Yield, Grade, Size Distribution and Specific Gravity for
9 Strains and 3 Seed Lots of Russet Norkotah at
Hermiston, OR, 2001 ........................................................
20
Above Ground Plant Biomass, Plant Emergence, Final Stand
and Number of Tubers per Plant for 16 Strains and 3 Seed
Lots of Russet Norkotah at Madras, OR, 2001 ..........................
22
Yield, Grade, Size Distribution and Specific Gravity for
16 Strains and 3 Seed Lots of Russet Norkotah at
Madras, OR, 2001 ...........................................................
24
3.
4.
5.
Tuber Size and Grade Characteristics for 9 Strains and 3
Seed Lots of Russet Norkotah at Hermiston, OR, 2001 ................. 25
6.
Tuber Size and Grade Characteristics for 16 Strains and 3
Seed Lots of Russet Norkotah at Madras, OR, 2001 ....................
27
7.
Internal and External Tuber Characteristics for 16 Strains
and 3 Seed Lots of Russet Norkotah at Madras, OR, 2001 ............. 29
8.
Internal and External Tuber Characteristics, Plant Emergence,
Final Stand and Number of Tubers per Plant for 11 Strains
and 3 Seed Lots of Umatilla Russet at Hermiston, OR, 2001 .......... 32
9.
Yield, Grade, Size Distribution and Specific Gravity for
11 Strains and 3 Seed Lots of Umatilla Russet at
Hermiston, OR, 2001 ......................................................... 33
10.
Above Ground Plant Biomass, Plant Emergence, Final Stand
and Number of Tubers per Plant for 13 Strains and 3 Seed
Lots of Umatilla Russet at Madras, OR, 2001 ............................ 35
LIST OF TABLES (Continued)
Table
11.
Page
Yield, Grade, Size Distribution and Specific Gravity for
13 Strains and 3 Seed Lots of Umatilla Russet at
Madras, OR, 2001 .............................................................
36
12.
Tuber Size and Grade Characteristics for 11 Strains and
3 Seed Lots of Umatilla Russet at Hermiston, OR, 2001 ................ 38
13.
Tuber Size and Grade Characteristics for 13 Strains and
3 Seed Lots of Umatilla Russet at Madras, OR, 2001 ...................
39
Internal and External Tuber Characteristics for 13 Strains
and 3 Seed Lots of Umatilla Russet at Madras, OR, 2001 ...............
41
Photovolt Reading, USDA Fry Color and % Sugar Ends
for 13 Umatilla Russet Strains and 3 Seed Lots at Hermiston
and Madras, OR, 2001 .......................................................
44
14.
15.
CLONAL VARIATION IN RUSSET NORKOTAH
AND UMATILLA RUSSET POTATO VARIETIES
INTRODUCTION
Giant hills, large vigorous plants sometimes known as "bolters", were first
described in 1924 (Hill, 1934). The giant hill syndrome is thought to result from a
spontaneous, persistent mutation which intensifies tuberization response to short
days (Howard, 1970). In general, giant hills are morphologically distinct from the
parent variety. They are typically larger, later maturing, profusely flowering plants
which often produce high yields with a high percentage of large, poorly shaped
tubers. Giant hill plants appear to be resistant to a number of common diseases. The
giant hill mutation is thought to occur in all varieties but is most often commercially
exploited in early maturing types.
Because of potential cropping advantages, giant hill selections are frequently
compared to parent varieties in an attempt to improve performance through increased
yield, quality, pest resistance or vigor. Giant hill selection can be a useful addition to
standard breeding programs. It provides an efficient method for improving yields,
especially for early maturing types with smooth tuber shape such as Russet
Norkotah. Giant hill selection is typically based on vine type (size, vigor, maturity)
the first year and tuber characteristics affecting yield and quality in subsequent years.
Giant hills usually mature later than the parent cultivar. Consequently, yield
advantages may not occur in short season areas, especially with late maturing
varieties. However, differences between giant hill and normal clones are usually
noticeable during seasons with abnormally high environmental stress (Mills, 1999).
Giant hill types often show advantages over the parent variety under stressful
conditions (Mills, 1999). Giant hills often have vigorous vines with improved
resistance to environmental stresses such as wind, heat, drought or hail (Miller, C.J.
Jr. et al., 1999). Miller et al. (1999) demonstrated that Texas Russet Norkotah giant
hill selections out yielded the standard by 20-30% over a three year period. Giant
hill types have also been shown to have increased resistance to early blight and
rhizoctonia (Yarwood, 1946) and Verticillium wilt (Easton and Nagel, 1981) and
may have lower fertility requirements (Thompson and Davidson, 2000).
In studies described herein, giant hill clones of Russet Norkotah and Umatilla
Russet were selected from fields in Central Oregon and the Columbia Basin in late
July and August of 1999. Seed pieces were planted in greenhouse pots in December
1999 and daughter plants were inspected for viruses and other diseases by
representatives of the Oregon State University Seed Certification Service. Diseased
selections were discarded. Plants of healthy selections were grown to maturity.
Only disease free and virus free seed was advanced in order to eliminate yield losses
caused by diseases and to decrease contamination in future generations. Tubers were
harvested in April 2000, treated with gibberellic acid, to break dormancy, and field
planted at Powell Butte in June for further increase.
Seed tubers produced at Powell Butte in 2000 were used to plant yield trials
at the Hermiston Agricultural Research Center, Hermiston and the Central Oregon
3
Agricultural Research Center, Madras in 2001. Crops were grown using cultural
practices common to commercial operations in the two areas. Data were collected to
characterize clonal suitability for the fresh and frozen-processing markets for Russet
Norkotah and Umatilla Russet selections, respectively.
Identifying and releasing superior clones of named varieties typically
requires less time than developing new varieties through traditional breeding
methods which may require 12 to 14 years between the initial cross and release to the
industry. Clonal selection has been used with considerable success by some
programs. Breeders at Texas A&M University and Colorado State University
selected numerous Russet Norkotah strains in 1989 and the early 1990's. Texas
strains TXNSI 12, TXNS223 and TXNS278 and Colorado strains CORN-3 and
CORN-8 have performed better than the parent variety in selected producing regions.
Because giant hill clones remain relatively stable from generation to
generation, and are morphologically distinct from the parent, they are considered
eligible for protection under the Plant Variety Protection (PVP) Act. Consequently,
Texas and Colorado have applied for PVP for their respective strains. Plant variety
protection is of interest to breeding programs, because it improves breeder
opportunities for control and profit from the variety. Seed growers typically pay the
owner(s) licensing fees and royalties for permission to grow the variety.
4
LITERATURE REVIEW
CHARACTERISTICS OF GIANT HILLS
Giant hill plants are large, robust plants which flower relatively late and
profusely. They often produce higher yields of larger, rougher shaped, less desirable
tubers than the parent variety (Easton and Nagle, 1987). Giant hills tend to have
longer tuber dormancy, emerge later and initially grow slower than standard
varieties. Yarwood (1946) demonstrated that green weights of giant hills and
standard types are approximately equal at 50 days after planting. Standards reached
maximum green weight at 65 days while giant hills peaked at 98 days. Hill (1934)
reported that giant hills often survive frosts that kill standard types. This trait has
allowed seed growers to easily identify the giant hills after killing frosts and rogue
them prior to harvest. Seed lot purity is important; therefore, seed certification
standards typically require genetic and/or morphological uniformity within lots.
Leever et al. (1994) demonstrated that early maturing giant hill mutants
frequently show reduced tuber set and smaller tubers than the parent variety, while
late maturing mutants tend to have heavier vines and increased tuber set compared to
the parent. He also noted that early maturing mutants showed less obvious
differences in vine type and growth pattern than late maturing mutants in comparison
to the parent variety.
Giant hills with abnormally large vines are associated with increased yields.
Yield increases are most obvious under high stress growing conditions and potential
5
yield advantages from giant hills may not be realized unless plants are moderately to
severely stressed; however, vigorous strains offer advantages and stability when
averaged over several seasons (Miller, C.J. Jr., et aL, 1995). Greater differences in
yield occur when suboptimal environmental conditions persist throughout the
growing season. Much of the giant hill yield increase results from larger tuber size
rather than increased tuber numbers.
CLONAL VARIATION
Clonally propagated crops such as potatoes do not require sexual
reproduction for commercial production and therefore show little genetic variation
(Coleman et al.,
1991);
however variation does occur. Clonal mutation is known to
alter russeting (Burbank
Russet Burbank), skin color (Lasoda -* Red Lasoda),
tuber quality and size, vine vigor (Norgold Russet
Norgold Russet M), yield
(Miller, C.J. Jr., et al., 1999) and disease resistance (Yarwood,
Yarwood
(1946)
1946).
reported that giant hills in the field show no unusual growth
patterns during the first 60 days. However, between 90 and 100 days, the vigorous
dark green giant hill plants began to clearly stand out as their neighbors senesced.
Variation within a commercial seed lot typically increases with time from the
prenuclear or greenhouse generation onward because meristems used to produce
prenuclear stocks are often derived from a single plant with, presumably, zero
variation.
The giant hill syndrome apparently involves a mutation requiring short rather
than normal long days for tuberization (Howard, 1970). Stanton (1952) identified
degrees (semi-bolters, bolters and super bolters) of giant hill. Sussex (1955) found
that the degree of mutation is based on the number and types of cellular layers of the
growing point (Li, L2 and L3) that are affected. Hawkes (1947) demonstrated that
normal plants and giant hills were indistinguishable when grown under short days.
GIANT HILL SELECTION
Cional selection has long been used to develop improved strains of
commercial varieties. Strains are sometimes referred to as "lines" or sub-clonal or
intraclonal selections (Miller, C.J. Jr., et al., 1999). Leever et al. (1994) defined
"strain" as an advantageous deviation in plant maturity that can be selected and
propagated to improve yield, vigor or appearance. Clonal selection was first
practiced in Nebraska in the 1920's in an attempt to improve yields (Leever et al.,
1994). Clonal selection can be used in conjunction with traditional breeding to
improve characteristics of commercial varieties. Miller (1954) stated that it is easier
to improve a variety than create a new one.
Selections, especially giant hill types, are typically later maturing than the
standard (sometimes referred to as the "parent" variety). Later developing strains,
often classed as giant hills, are morphologically distinct (Hill, 1934). Clonal
selection is initially based on vine type and later on tuber characteristics related to
yield and quality (Miller, C.J. Jr., personal correspondence).
7
FERTILITY REQUIREMENTS
Advanced giant hill strains of Russet Norkotah from Colorado and Texas
reportedly require less nitrogen (N) than the standard while still producing higher
yields and quality during most growing seasons. Under standard rates of N, Russet
Norkotah strains show delayed tuber set, tuber bulking and inadequate skin set;
further, tubers may be rougher shaped and prolonged vine vigor (delayed
senescence) may complicate harvest (Thompson-Johns, et al., 1999). Reduced N
fertilization is routinely recommended for commercial production of Texas and
Colorado Russet Norkotah strains. Thompson (2001) demonstrated standard Russet
Norkotah yields of 3 50-500 cwt/A (hundred weight per acre) with 2 10-230 lbs N/A
(nitrogen per acre) in the San Luis Valley of Colorado. In comparison, Russet
Norkotah strain CORN-8 peaked at only 160-180 lbs N/A. Thompson (2001) also
demonstrated that standard Russet Norkotah grew best when fertilized with 110-140
lbs N/A applied pre-plant while CORN-8 and CORN-3 grew best with 80-100 lbs
N/A. Differences in N requirement observed between the standard and strains may
also exist among strains.
SPECIFIC GRAVITY
Specific gravity is the ratio of dry matter (primarily starch) to water in tubers.
Dry matter is heavier than water (specific gravity of 1.00); therefore, the higher the
tuber dry matter, the higher the specific gravity will be (Dean, 1995). Schark et al.
(1956) demonstrated that high dry matter potatoes produce mealy processed
products, typically preferred by consumers. Tubers with higher specific gravity do
not absorb as much oil as tubers with low specific gravity when fried and are
therefore more desirable.
Love and Pavek (1991) stated that "both mean specific gravity and the
uniformity of specific gravity are important characteristics for the potato industry"
and that they are not strongly associated in certain genetic populations. They found
that the uniformity of specific gravity among tubers within a lot is almost random
when compared to the corresponding mean. When the standard deviation of specific
gravity was plotted against the mean specific gravity, it showed a highly significant
positive relationship between mean specific gravity and variability within the lot.
They concluded that breeders' selections can be based on either or both mean
specific gravity or uniformity within the lot. Furthermore, Sayre et al., (1975)
concluded that the specific gravity or solids content of an entire tuber is not
representative of its processing capabilities since the solids content may vary
throughout the tuber.
Yarwood (1946) reported that longer growing seasons favor high specific
gravity. Giant hill tubers have lower specific gravity than the parent variety early in
the growing season, but sometimes higher gravities at full maturity. When selecting
for high specific gravity, later maturing giant hill strains may be preferable.
FRY QUALITY
Fry quality is greatly influenced by tuber sugar levels. It is well known that
higher levels of reducing (six carbon) sugars decrease the marketability of a cultivar
for processing. When tubers are stored below 500 F, starches are more rapidly
converted to sugars (reducing sugars) than at higher temperatures. The sugars cause
a nonenzymatic darkening of fries and a burnt taste (Terman et al., 1950). Reducing
sugar levels can be affected by tuber respiration rate, which is largely determined by
storage temperature. In general, levels of reducing sugars increase with increasing
time in cold storage. A balance must be maintained between tuber dormancy and
acceptable levels of reducing sugars. This is difficult because tubers remain dormant
longer when stored at cooler temperatures; which tend to elevate reducing sugars.
Barichello et al., (1990) reported that sugar accumulation in stored tubers is
significantly affected not only by storage temperature but also by cultivar. They also
found that at 16 weeks of storage, sugar content was most similar to sugar levels at
the time of initial storage. This was most likely due to the remobilization of sugars
as the tubers broke dormancy and began to sprout.
Ehlenfeldt and Boe (1989) and Barichello et a1., (1990) found that higher
respiration rates in cold-chippers is not the single most important reason for low
sugar accumulation. Studies of tubers stored at 39.2° F (cold) revealed that tubers
with intermediate respiration rates had high levels of sugars while tubers with the
lowest respiration rates had accumulated moderate levels of sugars.
One goal of selecting giant hill strains of processing varieties is to find
superior strains that fry better than the parent variety from cold storage.
IDI
DISEASE RESISTANCE
Giant hill advantages go beyond increased yield. Many giant hill clones
show increased disease resistance, notably to Verticillium wilt (also known as early
die), but also to early blight and rhizoctonia (Yarwood, 1946) and late blight
(Howard, 1970).
11
MATERIALS AND METHODS
CLONAL SELECTION
Giant hill plants of Russet Norkotah and Umatilla Russet were identified in
Eastern and Central Oregon fields during July and August, 1999. Selection was
based primarily on late maturity as evidenced by delayed vine senescence and
prolonged flowering. Initially, 17 Russet Norkotah plants were selected at
Hermiston and 13 Russet Norkotah and 13 Umatilla Russet plants were collected at
Madras. Tubers were harvested and stored at
4Ø0
F.
SEED INCREASE
To provide for seed increase and virus screening, five seed pieces
(originating from one to five tubers) from each selection were planted individually
into one gallon pots and grown in the greenhouse during December 1999 thru March
of 2000. Since field harvest occurred in July and August 1999, tubers were still
dormant in late October. Dormancy break was hastened by dipping tubers in 70
ppm giberalic acid (GA) for one minute on November 1, 1999 followed by storage at
80° F and 75% relative humidity for 29 days. Seed pieces were cut on November 29,
held at room temperature and planted in the greenhouse on December 1, 1999.
Oregon State University Seed Certification Service Personnel inspected all plants for
viruses and other diseases. Twelve of the original 30 Russet Norkotah selections
were discarded due to virus contamination. None of the Umatilla Russet selections
were diseased and all were retained. Selections of Russet Norkotah collected at
12
Hermiston were numbered 101-108; selections of Russet Norkotah collected at
Madras were numbered 201-210 and selections of Umatilla Russet collected at
Madras were numbered 301-3 13. Vines were removed on March 30, 2000 and
tubers were harvested on April 12. Tubers were immersed for one minute in 7.0 ppm
GA on April 17 and again on May 8, 2000 to break dormancy. Because of lack of
bud growth, tubers were dipped into 14.0 ppm GA for five minutes on May 22. Seed
pieces were cut on June 7 and field planted at Powell Butte on June 12.
The Russet Norkotah and Umatilla Russet parental clones for the Madras
selections were increased and inspected for viruses and other diseases along with the
strains. Seed for standard lots 99-9 (Russet Norkotah) and 99-11 (Umatilla Russet)
were collected from Seed Certification winter grow out trials; produced with the
same management practices as the selections (to reduce experimental error), and
used as parental controls. Disease-free selections and the controls were advanced
and increased at Powell Butte, a seed production site in Central Oregon, in 2000.
Two Russet Norkotah selections failed to tuberize and were discarded. Seed tubers
were harvested in October 2000 and stored at 40° F.
Seed of entries one and two (commercial controls) for both Russet Norkotah
and Umatilla Russet were obtained from the Central Oregon Agricultural Research
Center (COARC) and a private seed grower in Madras, in 2001 and are referred to as
commercial controls.
13
2001 HERMISTON RUSSET NORKOTAH YIELD TRIAL
Seed pieces averaging 1.5-2.0 oz. were hand cut on March 20, treated with
Tops MZ, and machine planted in an Adkins fine sandy loam on March 30.
Treatments were arranged in a complete randomized block design with four
replications. Individual plots were 20 hills (15.4 feet of row), with seed pieces
spaced at 9.25 inches within rows and 34 inches between rows. Plot rows were
separated by single rows of standard Russet Norkotah in order to equalize
competition for all plots. Selections 102, 104, 105, 107, 201, 202 and 206 were not
grown at Hermiston because there was not enough seed. The crop was fertilized
with 250 lbs K20 and 2 lbs B per acre broadcast pre-plant, 75 lbs N, 100 lbs P (as
P205) and 50 lbs S per acre side dressed at planting. An additional 225 lbs N/A was
applied through sprinkler irrigation between June 4 and July 2. Vapam was applied
on 9/06/00 to control Verticillium wilt, MoCap was applied on March 7 to control
wireworms and Admire was banded at planting for insect control. Gramoxone was
applied pre-emergent on April 26 to control weeds followed by Eptam and Matrix
applied through the irrigation system on May 4. Late Blight was controlled by Bravo
and Dithane alternated weekly starting May 23 and ending July 5. Vines were killed
on July 26 with Enquik. All pesticides were applied as labeled. Tubers were
harvested and graded on August 9.
2001 HERMISTON UMATILLA RUSSET YIELD TRIAL
Seed pieces averaging 1.5-2.0 oz. were prepared on April 10, treated with
Tops MZ, and machine planted in an Adkins fme sandy loam on April 20.
14
Treatments were arranged in a complete randomized block design with four
replications. Individual plots were 30 hills (23.13 feet of row), with seed pieces
spaced at 9.25 inches within rows and 34 inches between rows. Plot rows were
separated by single rows of standard Umatilla Russet in order to equalize
competition and reduce experimental error. Selections 304 and 310 were not grown
at Hermiston because there was not enough seed. The planting was fertilized with
250 lbs K20 and 2 lbs B per acre broadcast pre-plant, 60 lbs N, 80 lbs P (as P205)
and 50 lbs S per acre side dressed at planting. An additional 270 lbs N/A was
applied through the irrigation system between June 18 and July 30. Vapam was
applied the preceding fall on September 6 to control Verticillium wilt. MoCap was
applied on March 7 for wireworms and Admire was banded at planting to control
insects. Gramoxone was applied pre-emergent on April 27 to control weeds
followed by Eptam and Matrix applied through the irrigation system on May 4. Late
Blight was controlled by alternating Bravo and Dithane weekly beginning May 23
and ending September 7. Monitor was applied on July 3 and August 16 to control
aphids. Comite was applied for mites on August 2. Vines were killed on September
24 with Enquik. All pesticides were applied as labeled. Plots were harvested and
tubers were stored in burlap bags on October 15 and graded on October 18. Samples
were saved from each plot and stored at 45°F.
15
2001 MADRAS RUSSET NORKOTAH AND UMATILLA RUSSET YIELD
TRIALS
Both the Russet Norkotah and Umatilla Russet Madras trials were planted in
Madras loam on May 22. Seed pieces averaging 1.5-2.0 oz. were cut on May 12 and
treated with Tops MZ according to the label. Both trials used complete randomized
block designs with four replications. Russet Norkotah plots were 20 hills
(15 feet of row), with seed pieces spaced at 9.0 inches within rows and 36 inches
between rows. Umatilla Russet plots were 30 hills (22.5 feet of row) with identical
spacing. Plot rows were alternated with commercial seed of the parent clones in
order to equalize competition and reduce experimental error. Fertilizer was banded at
planting as 230 lbs N, 138 lbs P (as P205), 135 lbs K and 66 lbs S per acre. Eptam
was applied pre-plant on May 10 to control weeds followed by Sencor on June 12.
On May 23, 0.66 inches of rain fell within a matter of minutes causing the soil
surface to crust and delaying plant emergence. A Lilliston Cultivator was used to
break up the soil crust on June 16. Vines were desiccated with Reglone on
September 19. All pesticides were applied as labeled. Tubers were harvested and
graded on October 11.
MADRAS SEED INCREASE
Trials at Madras provided not only yield and quality information but also
seed for subsequent trials. Therefore, diseased plants were rogued as soon as
symptoms appeared. The Umatilla Russet trial was rogued on July 10 and 17
reducing final plant stands by as much as 22%. All entries in the Umatilla Russet
16
trial except 99-11 and 304 had some percentage of plants rogued. No disease
symptoms appeared in the Russet Norkotah trial. Yields were adjusted according to
the number of plants per plot after roguing.
BIOMASS SAMPLES
Above ground plant biomass samples were collected from both Madras trials
on September 18. Entries differed in the degree of senescence at the time of
collection. The first five plants in each plot were cut at ground level and all above
ground biomass was collected and fresh weights were determined within 30 minutes.
Plants were dried in paper bags at 102° F, for two weeks, and dry weights were
obtained.
UMATILLA RUSSET FRY TESTS
Samples of Umatilla Russet entries grown at Madras were fried on October
12, one day after harvest. Samples grown at Hermiston were fried after 32 and 64
days of storage, at 45° F, on November 19 and December 20. Ten tubers from each
plot were sliced from bud to stem end using a steak fry cutter. Samples consisting of
the center fry from each often tubers were fried at 375° F for four minutes at Madras
while samples were fried for three and one half minutes at Hermiston. Fries were
then drained and a photovolt meter was used to read the light reflectance of both the
stem and bud ends of each of the ten fries.
The following formula was used to convert photovolt readings to USDA
color: USDA color
5.017114 (photovolt x 0.11148); R squared for the
17
regression is 0.848. The USDA colors range from 000 to 4.0, with 000 being light
and 4.0, dark. No distinction of colors will be made for 000 or 00. All colors less
than zero are expressed as zero.
DETERMINATION OF SPECIFIC GRAVITY
Specific gravities were determined using the air/water method. Random
samples consisting often tubers were weighed dry and then in water.
18
RESULTS AND DISCUSSION
Marketable yield (primarily U.S. number one grade) is more important to
growers than total yield, especially for fresh market uses. Total yield indicates the
maximum tuber production of a variety while U.S. No. 1 serves as an index of
economic performance. The leading U.S. variety, Russet Burbank, typically
produces high total yields but low U.S. No. 1 yields because of external tuber defects
and undersized tubers. Although U.S.
2
yields are not commonly sold on the fresh
market, they are usable for processing.
RUSSET NORKOTAH YIELD TRIALS
Emergence and Stand Establishment at Hermiston
At 40 days after planting commercial controls one and two were over 60%
emerged compared to six percent for the parental control (Table 1). This likely
reflects differences in growing and storage conditions. All selections were similar to
the parental control in emergence. Final stands were similar for all entries.
Yields at Hermiston
Overall yields for this trial were high compared to Russet Norkotah yields
averaged over six years at the Hermiston Agricultural Research and Extension
Center (HAREC) (Table
2),
where total and U.S. No. 1 yields averaged 443 and 346
cwt/A, respectively. The highest yield in six years of trials was 542 cwt/A. In these
trials, the three parental clones averaged 706 and 651 cwt/A for total and U.S. No. 1,
Table 1. Internal and External Tuber Characteristics, Plant Emergence,
Final Stand and Number of Tubers per Plant for 9 Strains and 3 Seed Lots
of Russet Norkotah at Hermiston, OR, 2001.
Emergence
Stand
% Vt)'
L!W2
W/D3
% 40 DAP4
%
2.0
2.0
5.0
8.0
7.0
4.0
8.0
6.0
6.0
9.0
1.77
1.79
1.80
1.80
1.75
1.83
1.84
1.79
1.78
1.75
63.0
62.0
6.0
10.0
1.81
4.0
1.77
1.20
1.22
1.15
1.23
1.27
1.24
1.19
1.22
1.20
1.20
1.20
1.22
100.0
100.0
95.0
93.8
97.5
97.5
93.8
97.5
97.5
97.5
93.8
100.0
Mean
5.9
1.79
1.21
CV%
113
5
4
Entry
1*
2*
99..9**
101
103
106
108
204
205
207
208
210
12.0
6.0
16.0
13.0
8.0
10.0
10.0
6.0
11.0
NS
0.07
LSD (0.05)
NS
* Commercial seed lots
** Control; parental seed lot for all selections, grown and stored
with selections
'Vt) vascular disorder
2
L/W = length/width ratio of average tuber
W/t) = width/depth ratio of average tuber
"DAP = days after planting
Tubers!
Plant
7.1
6.8
7.1
7.6
6.3
7.5
7.9
6.3
6.9
7.3
6.7
6.8
7.0
15
1.6
Table 2. Yield, Grade, Size Distribution and Specific Gravity for 9 Strains and 3 Seed Lots of Russet Norkotah at
Hermiston, OR, 2001.
cwtlA'
U.S. No.1 ct/A
cwt/A
%
% of
Total
735
659
724
725
730
747
722
612
710
677
605
657
No.1
687
592
675
685
695
694
680
559
665
632
550
608
No.1
93
90
93
95
95
93
94
92
94
94
Control2
4-8 Oz.
8-10 Oz.
> 10 Oz.
<4 Oz.
102
88
100
181
190
197
190
201
124
177
121
91
93
40
48
33
34
22
47
36
34
34
39
43
40
Mean
692
644
CV%
9
10
Entry
1*
2*
99..9**
101
103
106
108
204
205
207
208
210
Oz./
Spec.
Culls
Tuber3
Gray.4
4
4
8.3
5
13
10
6
7.9
8.9
8.4
9.7
1.065
1.064
1.066
1.067
1.066
1.065
1.068
1.065
1.064
1.068
1.064
1.067
U.S.
No. 2
171
163
145
164
138
146
153
129
166
250
161
81
166
121
90
210
150
315
274
340
320
434
371
302
260
336
221
264
248
93
188
149
307
38
5
6
8.3
3
37
NS
28
35
156
41
174
147
14
23
NS
NS
1.6
101
103
103
101
83
99
94
225
94
91
NS
61
LSD (0.05)
* Commercial seed lots
** Control; parental seed lot for all selections, grown and stored with selections
'To convert cwtlA to kg/ha, divide by 20
2
No.1 yield of strain/No. 1 yield of 99-9
To convert oz. to grams, multiply by 28.35
4Air/water method
5
1
8
5
1
5
2
4
8.3
8.0
7
2
12
8.1
8
3
2
4
8
2
7
8.6
7.8
8.0
7.7
1.066
0.4
NS
21
respectively, while selections averaged 687 and 641 cwt/A for total and U.S. No. 1
yields, respectively. Environmental stresses were lower than normal for the
Columbia Basin through most of the 2001 production season (personal
correspondence, Dan Hane). Total and U.S. No. 1 yields were similar for all entries
except for selections 204 and 208 which yielded significantly less than the parental
control (Table 2). The relative lack of yield differences may be attributed to the
fairly short growing season (66 days from stand establishment to vine kill) and low
seasonal environmental stress. Russet Norkotah is often planted early and harvested
early to take advantage of higher prices often associated with early season markets.
Results are similar to those reported by Miller, C.J. Jr. et al., (1995) who found that
in years when good vine growth was achieved, yield differences were less
noticeable.
Greater differences in yield would probably have occurred in a longer season
because tuber initiation and bulking are typically delayed for giant hills compared to
the parent variety. Giant hills usually have a yield advantage under long growing
seasons or when environmental stress is high.
Emergence and Stand Establishment at Madras
Though emergence was somewhat delayed because of weather induced soil
crusting, all entries were at 95% or higher at 51 days after planting at Madras
(Table 3). The crusted soil created a barrier at the soil surface through which no
entries were able to penetrate prior to cultivation on June 16. The delayed uniform
22
Table 3. Above Ground Plant Biomass, Plant Emergence, Final Stand and
Number of Tubers per Plant for 16 Strains and 3 Seed Lots of Russet
Norkotah at Madras, OR, 2001.
Fresh Weight
Entry
1*
g'/plant
140
127
Dry Weight
g'!plant
23
2*
99..9**
217
20
27
101
231
33
950
24
62
27
62
44
26
32
27
24
28
27
28
29
42
38
102
103
104
105
106
107
108
201
202
204
205
206
207
208
210
Mean
CV%
471
137
484
291
158
246
253
158
200
158
217
230
349
305
277
29
Emergence
%
Stand
51 DAP2
%
85.0
92.5
91.3
91.3
93.8
86.3
85.0
95.0
90.0
91.3
93.8
90.0
95.0
96.3
90.0
88.8
90.0
95.0
92.5
98.8
96.3
95.0
96.3
97.5
92.5
96.3
98.8
91.3
92.5
96.3
93.8
97.5
98.8
95.0
97.5
95.0
98.8
95.0
Tubers!
Plant
4.3
3.7
3.9
4.2
3.7
4.4
3.5
4.3
4.0
3.9
4.0
3.6
3.1
3.8
3.9
4.1
3.5
4.5
4.5
37
4.0
17
18
LSD (0.05)
113
9
* Commercial seed lots
** Control; parental seed lot for all selections, grown and stored with selections
'To convert grams to oz. divide by 28.35
2
DAP = days after planting
1
23
emergence makes it appear that all entries were equally dormant when in fact they
were probably not. Final stands were similar for all entries.
Yields at Madras
In 11 years of trials at Powell Butte (20 miles south of Madras) Russet
Norkotah averaged 346 and 282 cwtfA for total and U.S. No. I yields, respectively,
with a high total yield of 447 cwt/A. Overall total yield for this trial was nearly 20%
lower than the 11 year average (Table 4). Delayed emergence caused by soil
crusting may have been a contributing factor to reduced yields. All selections
produced yields equivalent to the parental control, although selections 103 and 210
yielded significantly more than commercial controls one and two. Selections 101,
103, 105, 206 and 208 produced higher, though not significantly higher, U.S. No. I
yields than the parental control. Selection 210 had significantly greater U.S. No. I
yield than the parental control. Six selections produced 7-40% higher No. 1 yields
than the parental control. Miller, J.C., Jr. et al., (1999) and Thompson and Davidson
(2000) describe similar yield responses for Russet Norkotah strains when optimal
plant growth is not obtained.
Grade-out
There were few differences in grade-out between selections and the parental
control at Hermiston (Tables 2, 5). Selection 208 produced a significantly greater
percentage of undersized tubers (<4 oz.) based on tuber number than that of the
parental control. The most apparent differences among Russet Norkotah entries
Table 4. Yield, Grade, Size Distribution and Specific Gravity for 16 Strains and 3 Seed Lots of Russet Norkotah at Madras,
OR, 2001.
cwt/A
Entry
1*
2*
99..9**
101
102
103
104
105
106
107
108
201
202
204
205
206
207
208
210
Total
245
239
276
327
268
360
215
342
266
227
278
287
219
259
286
318
232
338
373
No.1
173
179
231
246
215
285
170
271
200
165
228
232
U.S. No.1 cwtlA
%
% of
No.1
70
75
84
Control'
4-8 Oz.
75
88
82
99
77
79
79
79
80
74
72
82
185
80
80
74
80
80
79
264
322
78
87
173
192
231
254
Mean
77
100
107
101
93
123
95
96
74
117
87
72
98
98
99
100
75
83
100
110
80
114
140
101
109
132
84
8-10 Oz.
32
34
43
46
40
45
25
57
23
27
39
39
36
'No.1 yield of strainfNo.l yield of 99-9
2Ajr/water method
<4 Oz.
53
63
89
46
37
99
80
37
34
25
29
34
39
46
144
48
116
76
30
57
31
0
Culls
26
6
18
1
13
8
36
Oz./
Tuber
5.5
1
14
3
35
3
24
6.0
6.5
6.8
6.5
7.7
5.9
6.8
6.3
1
14
5.3
15
21
5.9
1
17
20
30
31
3
7
Spec.
Gray.2
1.090
1.090
1.091
1.094
1.093
1.089
1.095
1.096
1.101
1.095
1.095
1.089
1.090
1.092
1.096
1.091
1.094
1.088
1.088
100
118
33
36
57
60
77
96
90
47
111
27
24
39
29
24
34
61
31
3
13
102
44
67
119
156
37
8
29
35
3
13
5.9
6.7
7.2
6.2
6.6
7.4
84
58
33
4
22
6.4
34
148
81
18
1.092
0.54
69
16
8
NS
1.6
0.008
81
99
282
222
78
98
39
25
28
9
24
59
100
88
10
LSD (0.05)
34
33
* Commercial seed lots
** Control; parental seed lot for all selections, grown and stored with selections
CV%
> 10 Oz.
cwtlA
U.S.
No.2
109
3
1
2
3
19
27
24
37
7.3
6.1
Table 5. Tuber Size and Grade Characteristics for 9 Strains and 3 Seed Lots of Russet Norkotah at Hermiston, OR, 2001.
Entry
1*
2*
999**
101
103
106
108
204
205
207
208
210
Mean
CV%
4-8 Oz.
%'
Oz./Tuber
6.0
34.3
6.4
36.7
6.1
37.4
6.1
37.6
6.2
26.2
6.2
31.3
6.0
40.9
6.2
36.3
6.1
31.9
6.4
44.7
6.2
35.0
6.1
40.2
6.1
6
U.s. No.1
8-10 Oz.
Oz./Tuber
%l
9.7
22.2
9.3
9.3
9.4
9.1
9.0
9.3
9.1
15.6
18.6
19.8
19.9
17.7
17.9
18.8
9.0
9.5
9.4
9.4
22.0
35.5
9.3
23
12
7
NS
18.8
23
19.3
16.6
18.7
> 10 Oz.
Oz./Tuber
13.5
13.2
14.0
13.7
14.3
13.5
13.1
13.2
13.6
12.7
14.8
12.6
%'
26.4
24.6
29.1
26.5
39.8
30.2
25.2
26.0
29.5
19.9
23.1
22.8
U.S. No.2
Oz./Tuber %'
14.4
0.4
7.8
0.7
21.6
0.6
15.6
0.4
<4 Oz.
Oz./Tuber
2.7
2.7
2.8
7.5
1.4
2.5
2.4
2.8
0.3
0.2
0.6
0.4
0.5
1.0
0.5
2.6
2.6
2.6
2.6
2.9
2.4
2.8
13.6
14.9
7.6
6.9
5.1
5.1
%'
16.4
21.1
14.0
15.3
11.9
19.8
15.3
17.5
15.5
15.4
22.9
16.7
13.4
27.8
4.0
0.6
2.7
II
39
141
123
11
16.5
32
8
NS
NS
8
NS
LSD (0.05)
6
2
NS
* Commercial seed lots
** Control; parental seed lot for all selections, grown and stored with selections
Percent is based on tuber number
Culls
Oz.ITuber %'
13.2
0.4
11.9
18.8
2.1
8.0
8.0
7.7
18.8
13.4
12.8
7.8
7.2
1.3
0.4
0.5
0.8
0.7
0.5
0.8
0.7
0.2
1.4
1.1
5.4
0.8
110
9
134
NS
26
involved average tuber weight for both U.S. No. 2's and culls. Defective tubers of
the clonal selections tended to weigh less than those of the parental control and all
but one selection produced a higher percentage of culls (Table 5). Higher
percentages of culls and undersized tubers from giant hill types are not unexpected
since giant hills often have rougher shaped tubers and produce more tubers per hill
according to Yarwood (1946).
At Madras, where plant growth was curtailed by delayed emergence caused
by soil crusting, seven of nine selections (101, 103, 105, 201, 206, 208 and 210)
which produced higher total yields than the parental control also produced more
large tubers (> 10 oz.) (Table 4). Though there is little difference in average tuber
size between the parental control and the selections, the selections that out-yielded
the parental control had greater total weights of large tubers (Table 4). Selections
103, 206 and 210 which produced higher US. No. I yields than the parental control
tended to have higher percentages of large tubers (Tables 4, 6). This may indicate
that though giant hills grow slower early in the season as indicated by Yarwood
(1946), they may bulk faster than normal later in the season Except for selections
207 and 210, all selections had higher yields of culls than the parental control
(Table 4) and the selections generally produced higher percentages of culls (Table 6).
Selections 101 and 105 produced significantly greater yields of culls than the
parental control; although this occurred, the percent of U.S. No. l's produced by
selections 101 and 105 were higher than for the parental control.
Table 6. Tuber Size and Grade Characteristics for 16 Strains and 3 Seed Lots of Russet Norkotah at Madras, OR, 2001.
Entry
1*
4-8 Oz.
Oz./Tuber %'
5.8
34.7
2*
6.1
999**
5.7
101
6.1
102
103
104
105
106
107
108
201
6.2
6.1
202
204
205
206
207
208
210
5.8
5.6
5.9
5.7
5.9
6.3
5.9
5.8
6.2
6.0
5.7
5.5
6.0
Mean
5.9
CV%
5
33.3
40.9
35.3
37.0
34.1
46.6
35.0
40.0
44.6
48.5
34.4
39.2
38.6
44.9
36.9
41.3
35.9
32.8
38.7
22
U.s. No.1
8-10 Oz.
Oz./Tuber
%'
9.1
7.9
9.0
9.5
9.2
9.0
8.8
9.0
9.0
9.0
8.7
11.0
11.0
11.0
10.8
7.6
12.8
6.0
7.1
9.2
11.3
11.2
8.5
9.1
9.2
9.2
9.4
9.0
9.1
8.9
9.3
9.0
9.1
> 10 Oz.
Oz./Tuber
%'
12.6
12.3
13.3
13.6
13.5
14.4
12.2
9.6
15.1
13.9
14.2
12.2
13.8
13.4
12.9
15.7
15.5
14.3
21.6
10.9
15.5
12.6
5.0
10.2
20.3
12.1
13.1
10.2
9.1
13.8
13.0
12.9
13.8
13.7
13.1
11.8
9.5
9.3
14.6
8.9
9.8
12.8
16
58
20
NS
19.5
12.3
16.6
U.s. No.2
Oz./Tuber %'
0.0
0.0
12.3
1.1
5.4
8.9
8.3
9.3
5.8
0.4
8.3
7.5
6.1
9.9
11.3
10.2
6.4
8.2
9.8
1.9
0.4
4.6
0.4
0.6
1.1
0.4
0.7
1.6
0.9
0.3
0.7
0.7
22.4
7.1
10.0
8.5
0.6
13.7
52
4.3
109
1.0
127
7
NS
NS
12
NS
8
10
LSD (0.05)
* Commercial seed lots
** Control; parental seed lot for all selections, grown and stored with selections
'Percent is based on tuber number
1.2
1.5
<4 Oz.
Oz./Tuber
2.6
2.4
2.5
2.6
2.5
2.3
2.6
%'
40.5
38.6
28.8
29.8
33.3
23.6
30.7
29.8
34.0
39.6
28.9
27.7
30.2
36.9
25.4
22.6
Culls
Oz./Tuber %'
26.6
9.8
8.6
8.7
7.2
4.5
3.2
6.5
4.0
5.2
3.8
6.4
6.3
3.2
2.6
4.7
6.5
5.5
6.7
8.4
3.6
6.4
3.0
2.5
31.7
9.0
5.0
13
31
43
74
N5
14
NS
NS
2.3
2.6
2.7
2.3
2.5
2.3
2.4
2.6
2.4
2.5
2.4
2.6
32.1
30.3
8.3
9.7
9.6
11.9
10.4
12.4
10.6
10.9
8.8
10.6
12.8
11.5
8.3
11.2
8.4
10.1
-1
28
Tubers of selections
103, 104
parental control and selection
104
and 201 are somewhat short compared to the
is fairly flat. In addition, selections 205 and 206
are somewhat longer than the parental control. Tuber shape of fresh market varieties
is important because often tuber shape alone can determine the marketability of a
variety. Commonly, when superior strains of giant hill types and standard Russet
Norkotah are produced side by side under other than favorable environmental
conditions, giant hills show advantages in tuber shape and development, which is the
case here for selections 101, 103, 105, 206, 208 and 210. Delayed emergence may
have affected performance of the parental control to a greater degree than that of the
selections because the selections, which produced more vine later in the season, had
more time for tuber bulking to occur while the parental control senesced, an
advantage of strains reported by Yarwood (1946), Miller, J.C., Jr. et al., (1999) and
Thompson-Johns, et al. (1999).
Internal Defects
Vascular discoloration (VD) was the only notable internal tuber defect at
Hermiston (Table 1) and differences were not significant. Internal defects are
minimal in Russet Norkotah and this data would indicate a similar response for the
giant hill selections.
Internal purpling was evident in Russet Norkotah selection 103 at Madras
(Table 7). Internal purpling under stressful growing conditions has been reported
for Texas and Colorado Russet Norkotah selections and standard Russet Norkotah by
29
Table 7. Internal and External Tuber Characteristics for 16 Strains and 3
Seed Lots of Russet Norkotah at Madras, OR, 2001.
Entry
1*
2*
99_9**
101
102
103
104
105
106
107
108
201
202
204
205
206
207
208
210
Mean
CV%
LSD(0.05)
% BS'
% VD2
10.0
15.0
25.0
30.0
% IPS3
0.0
0.0
0.0
22.5
27.5
25.0
0.0
0.0
0.0
0.0
0.0
20.0
0.0
2.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
4.1
168
21.7
1.2
53
10
16
10.0
5.0
5.0
0.0
2.5
2.5
5.0
2.5
10.0
5.0
2.5
5.0
2.5
5.0
10.0
7.5
20.0
35.0
22.5
30.0
22.5
17.5
20.0
15.0
25.0
20.0
12.5
17.5
% IF'
L/W5
0.0
1.81
10.0
5.0
0.0
2.5
2.5
0.0
0.0
1.78
1.69
1.94
1.92
1.55
1.56
1.74
1.82
1.83
1.77
1.56
0.0
0.0
0.0
2.5
7.5
5.0
5.0
0.0
0.0
5.0
2.5
1.71
1.80
2.05
2.06
1.87
1.87
1.67
'BS = blackspot
VD = vascular disorder
IPS = internal purple syndrome
'TE = translucent ends
L/W = length/width ratio of average tuber
6
W/D = width/depth ratio of average tuber
1.21
1.17
1.22
1.23
1.16
1.49
1.22
1.16
1.20
1.17
1.16
1.14
1.17
1.21
1.19
1.18
1.23
1.17
1.79
556
2.5
224
12
11
9
8
0.31
0.19
* Commercial seed lots
** Control; parental seed lot for all selections, grown and stored with selections
2
W/D6
1.20
1.20
30
Thompson and Davidson (2000). Internal purpling was not detected in any clonal
selections, the parental control or the commercial controls at Hermiston.
Specific Gravity
Specific gravity did not vary significantly among entries grown at Hermiston
(Table 2). Yarwood (1976) reports that giant hills commonly have higher specific
gravity than the parental standard. However with this variety, specific gravity is low
at Hermiston compared to other varieties and the results measured here, though not
higher than the parental control, are typical for Russet Norkotah.
At Madras, specific gravities were uniformly high for the 2001 production
season compared to historic values (personal correspondence, Steve James). In 11
years of trials at Powell Butte, specific gravity of Russet Norkotah averaged 1.075.
Russet Norkotah selection 106 had significantly higher tuber specific gravity (1.101)
than the parental control at Madras (Table 4). This indicates extremely high dry
matter for Russet Norkotah. Russet Norkotah is a popular fresh market variety
which is often baked. High dry matter potatoes tend to bake well compared to
potatoes with low dry matter (Mosley and Chase 1993; Dean 1990). All other entries
had relatively similar specific gravities.
UMATILLA RUSSET YIELD TRIALS
Emergence and Stand Establishment at Hermiston
Emergence at 40 days after planting was 93% or higher for the two
commercial controls and ranged from 53 to 84% for the selections and parental
31
control (Table 8). Final stands were above 95% for all entries. As noted for Russet
Norkotah, early emergence by the two commercial lots may be attributed to different
production and storage conditions.
Yields at Hermiston
Overall yields for this trial were very high compared to a six year average for
Umatilla Russet at the HAREC. Umatilla Russet yields have averaged 685 and 527
cwt/A, total and U.S. No. 1 yields, respectively, with a high total yield of 837 cwt/A.
Comparatively, in this work total yields averaged 921 cwt/A for the parental clones
and 1039 cwt/A for the 11 clonal selections. The highest total yield was 1323 cwt/A
for selection 307.
The long Columbia Basin growing season allowed many of the selections to
maximize growth and out-yield the earlier maturing parental control (Table 9). All
selections produced higher yields than the parental control and nine of the eleven
clonal selections produced significantly higher yields than the parental control. The
highest yielding selection produced 44% more than the parental control. However,
the total yield advantage for clonal selections did not translate into higher U.S. No. 1
yields primarily due to lower percentages of U.S. No. 1 tubers (Table 9). Results are
consistent with those of Howard (1970) who reported that giant hill strains often
show a range in the degree of mutation. Frequently, strains with the greatest degree
of mutation also produce highest yields, but tend to show a greater percentage of
misshapen tubers. Commercial control two had significantly higher total and U.S.
No. 1 yields than commercial control one. In addition, the parental control yielded
32
Table 8. Internal and External Tuber Characteristics, Plant Emergence, Final Stand
and Number of Tubers per Plant for 11 Strains and 3 Seed Lots of Umatilla Russet
at Hermiston, OR, 2001.
Emergence
Entry
1*
2*
991l**
301
302
303
305
306
307
308
309
% BS'
20.0
21.0
22.0
40.0
25.0
24.0
24.0
19.0
20.0
312
313
19.0
31.0
53.0
29.0
36.0
Mean
27.4
CV%
41
311
% lBS2
L!W3
W/D4
% 40 DAP5
1.0
1.67
1.72
1.21
1.23
1.71
1.19
1.79
1.60
1.78
1.97
1.76
1.85
1.79
1.83
1.76
1.70
1.82
1.21
93.0
95.0
67.0
71.0
70.0
84.0
76.0
78.0
80.0
68.0
53.0
70.0
73.0
69.0
1.77
1.22
10
11
5.0
10.0
1.0
1.0
2.0
4.0
4.0
0.0
0.0
0.0
0.0
3.0
1.0
2.3
149
1.44
1.20
1.20
1.22
1.17
1.20
1.22
1.22
1.22
1.22
LSD (0.05)
16
5
0.24
NS
* Commercial seed lots
** Control; parental seed lot for all selections, grown and stored with selections
'BS = blackspot
2
lBS = internal brown spot
L/W = length/width ratio of average tuber
W/D = width/depth ratio of average tuber
DAP = days after planting
Stand %
98.3
100.0
96.7
99.2
100.0
98.3
99.2
98.3
99.2
95.8
100.0
98.3
100.0
98.3
Tubers!
Plant
10.9
11.2
9.4
8.5
8.6
8.4
9.3
9.6
10.0
9.0
7.8
9.0
9.2
9.2
9.3
12
1.6
Table 9. Yield, Grade, Size Distribution and Specific Gravity for 11 Strains and 3 Seed Lots of Umatilla Russet at
Hermiston, OR, 2001.
c/A
Total
No.!
1*
851
2*
998
916
504
624
648
725
649
Entry
9911**
301
302
303
305
306
307
308
309
1153
1072
1036
1158
997
312
313
1323
1107
1133
1166
1086
1200
Mean
311
CV%
LSD(0.05)
c/A
U.S. No.1 c/A
573
680
521
725
684
739
%
% of
No.1
59
63
Control1
71
63
61
56
59
52
55
62
731
718
723
65
63
66
60
1085
660
61
9
13
10
145
119
9
78
96
100
4-12 Oz.
416
481
456
112
100
305
301
89
267
346
105
80
112
106
114
113
111
112
321
287
324
242
326
316
324
336
20
97
> 12 Oz.
<4 Oz.
88
144
192
112
78
58
41
420
348
306
334
200
438
360
497
405
403
399
324
25
117
* Commercial seed lots
** Control; parental seed lot for all selections, grown and stored with selections
'No.1 yield of strain/No. I yield of 99-11
2
Air/water method
51
47
45
78
50
45
34
51
68
48
58
30
25
U.S.
No.2
197
231
179
290
268
311
332
306
447
292
252
321
205
347
284
28
114
65
32
Oz.I
Tuber
6.4
7.2
8.2
96
11.0
103
105
102
10.1
10.1
10.1
92
8.7
10.7
10.3
11.8
10.6
9.5
10.7
Culls
39
100
86
109
62
95
82
84
38
45
9.7
Spec.
Gray.2
1.076
1.077
1.079
1.086
1.088
1.079
1.083
1.078
1.083
1.081
1.085
1.086
1.081
1.085
1.082
8
1
1.1
0.007
34
significantly more U.S. No. l's than that of commercial control one. The differences
observed among the parental control and the two commercial controls may have
resulted from dissimilarities in previous production and storage conditions.
Emergence and Stand Establishment at Madras
Emergence at 51 days after planting ranged from about 92% to over 99% at
Madras (Table 10). This uniformity in emergence would indicate similar affects
from soil crusting for all entries. Delayed emergence did not affect final stands;
however, fmal stands were reduced by field roguing to remove diseased plants.
Diseased plants were rogued to eliminate contamination of seed lots.
Yields at Madras
In these tests, the three parental clones averaged 392 and 292 cwt/A for total
and U.S. No. 1 yields, respectively (Table 11) while selections averaged 324 and
219. This compares to an eight year average of Umatilla Russet at Powell Butte of
433 and 329 cwt/A for total and U.S. No. 1, respectively with a high total yield of
509 cwt/A. Yields were adjusted based on numbers of plants after roguing. The
parental control produced significantly higher total yield than selections 304, 305,
308, 309 and 310 and all but selection 311 produced numerically lower total yields.
All selections had lower U.S. No. 1 yields than the parental control. Yield
advantages of the selections grown at Hermiston did not repeat at Madras
(Tables 9, 11). This suggests the need for a long growing season (at Madras vs. at
Hermiston) to maximize yield advantages of giant hill selections. The differing
Table 10. Above Ground Plant Biomass, Plant Emergence, Final Stand and
Number of Tubers per Plant for 13 Strains and 3 Seed Lots of Umatilla Russet
at Madras, OR, 2001.
Entry
1*
2*
9911**
301
302
303
304
305
306
307
308
309
310
311
312
313
Mean
CV%
Fresh Weight
g/plant
668
Dry Weight
g/plant
67
1012
763
1406
1425
1428
1218
1351
680
1076
1379
1069
822
1329
1101
1282
85
1126
29
77
151
165
121
126
157
80
117
149
130
83
147
126
155
Emergence
Stand
% 51 DAP'
%2
93.3
97.5
94.2
94.2
95.0
91.7
95.0
96.7
99.2
96.7
93.3
93.3
92.5
95.8
94.2
96.7
80.8
94.2
94.2
88.3
85.0
88.3
95.0
87.5
90.0
88.3
88.3
72.5
76.7
84.2
90.0
92.5
121
19
32
456
LSD (0.05)
* Commercial seed lots
** Control; parental seed lot for all selections, grown and stored with selections
'DAP days after planting
25tand % may be lower than emergence % because diseased
plants were rogued
Tubers!
Plant
5.2
4.9
5.3
5.4
5.2
4.1
5.0
4.8
5.2
5.5
4.6
5.6
5.7
5.4
5.0
5.3
5.1
24
NS
Table 11. Yield, Grade, Size Distribution and Specific Gravity for 13 Strains and 3 Seed Lots of Umatilla Russet at Madras,
OR, 2001.
cwt/A
Entry
1*
2*
9911**
301
302
303
304
305
306
307
308
309
310
311
312
313
Mean
CV%
Total
337
412
427
392
338
308
258
300
308
368
277
274
258
444
330
356
No.1
231
317
329
337
26
233
28
93
123
LSD (0.05)
*
Commercial seed lots
266
220
200
149
204
223
275
177
197
178
301
218
244
U.S. No.1 cwt/A
%
% of
No.1
70
77
76
68
66
65
57
67
72
74
Control'
70
96
63
72
68
69
66
68
4-8 Oz.
79
91
88
106
88
92
70
54
87
120
99
82
80
88
76
66
74
79
94
100
81
67
61
45
62
68
83
54
60
54
69
86
11
31
11
38
8-10
Oz.
37
51
79
37
37
46
25
30
32
50
36
40
30
57
39
51
42
36
22
** Control; parental seed lot for all selections, grown and stored with selections
No.1 yield of strain/No. 1 yield of 99-11
2
Air/water method
cwt/A
U.S.
No.2
4
> 10 Oz.
<4 Oz.
115
178
144
48
44
45
141
53
13
91
47
34
1
71
9
65
75
53
55
15
19
7
54
52
48
60
37
6
6
5
36
27
33
42
24
6
14
7
51
11
99
50
52
7
48
50
29
71
21
9
84
70
87
71
125
59
77
60
168
100
100
104
7
3
3
Culls
54
45
50
50
Oz./
Tuber
6.9
7.6
7.0
6.7
6.3
7.4
4.5
6.0
5.6
6.3
5.6
5.8
4.9
Spec.
Gray.2
1.098
1.096
1.093
1.084
1.090
1.091
1.092
1.091
1.091
53
6.2
5.8
1.098
1.089
1.105
1.099
1.086
1.094
1.096
7
46
6.3
1.093
91
73
17
1
49
1.5
0.018
8.3
37
results between locations are consistent with published reports for giant hill
selections (Yarwood, 1946; Leever et al., 1994).
Grade-out
Six selections (303, 305, 306, 307, 311 and 313) produced significantly
greater U.S. No. 2 yields than the parental control at Hermiston and ten selections
(301, 302, 303, 305, 306, 307, 308, 309, 312 and 313) had significantly greater
yields of culls. Selection 311 produced the lowest yield of culls among the
selections (Table 9). Selection 306 produced small tubers compared to the other
selections, and was closest in size to that of the parental control. Subsequently,
selection 306 also produced the lowest U.S. No. 1 yield. Selections 301, 302, 305,
307, 308, 309, 311, 312 and 313 produced the highest total yields and consequently,
those same selections produced the highest yields of tubers in the 12 oz. or greater
size class (Tables 9, 12). Results are consistent with those reported by Hill (1934),
Yarwood (1946) and Easton and Nagle (1987). Plants averaged 9.3 tubers at
Hermiston and 5.1 at Madras (Tables 8, 10). Later maturing types like Umatilla
Russet would be expected to set fewer tubers per plant in a short season.
The parental control significantly out-yielded all but selection 311 in the 8-10
oz. size class at Madras and significantly out-yielded selections 304, 306, 308 and
310 in the greater than 10 oz. size class. Selections 304, 305, 308, 309 and 310
produced significantly greater percentages of undersized (<4 oz.) tubers based on
tuber number than the parental control. The parental control generally produced
higher percentages of medium and large sized tubers (Tables 11, 13). The parental
Table 12. Tuber Size and Grade Characteristics for 11 Strains and 3 Seed Lots of Umatilla Russet at
Hermiston, OR, 2001.
Entry
1*
2*
9911**
301
302
303
305
306
307
308
309
311
312
313
U.s. No.1
> 12 Oz.
4-12 Oz.
Oz./Tuber %'
Oz./Tuber
%1
7.6
41.2
14.8
4.4
7.7
44.9
15.2
6.8
8.2
49.4
15.4
11.0
8.6
34.0
17.4
23.1
9.1
30.9
16.8
19.4
8.6
30.3
18.4
16.2
8.2
36.6
16.9
17.1
8.1
34.0
18.8
9.1
8.1
28.6
18.0
19.7
8.7
34.8
17.6
19.0
8.6
29.2
19.0
26.9
8.7
33.7
17.9
20.5
7.9
35.1
19.0
18.5
8.8
32.8
18.0
19.7
U.S. No.2
Oz./Tuber
%'
7.3
20.4
7.2
23.1
9.1
13.5
11.3
11.9
11.7
10.0
12.9
11.8
13.0
12.2
17.4
20.4
22.2
25.4
24.5
26.4
28.0
23.1
19.9
23.8
9.8
18.1
13.3
23.3
Mean
8.4
35.1
17.4
16.7
11.0
23.0
CV%
7
15
6
26
12
19
8
LSD (0.05)
2
6
2
6
* Commercial seed lots
** Control; parental seed lot for all selections, grown and stored with selections
'Percent is based on tuber number
1
<4 Oz.
Oz./Tuber
2.8
2.8
2.8
2.8
2.9
2.6
2.7
2.9
2.7
2.8
2.6
2.9
2.9
2.7
2.7
9
NS
%'
30.4
20.3
18.3
14.2
16.5
17.6
14.5
23.1
14.9
14.9
12.9
16.2
Culls
Oz./Tuber
8.1
9.4
7.2
11.0
8.9
9.8
12.4
10.7
9.2
9.7
10.2
9.7
%'
3.6
4.9
3.9
8.3
10.9
10.4
7.1
7.4
8.8
8.2
11.0
20.4
10.5
15.7
8.7
5.8
7.9
8.4
17.9
9.7
7.7
23
15
33
6
2
4
00
Table 13. Tuber Size and Grade Characteristics for 13 Strains and 3 Seed Lots of Umatilla Russet at Madras, OR, 2001.
Entry
1*
2*
9911**
301
302
303
304
305
306
307
308
309
310
4-8 Oz.
Oz./Tuber
5.9
6.0
5.8
5.8
5.7
6.4
%l
27.5
26.7
30.5
26.2
9.1
30.1
8.9
9.0
8.7
26.2
9.1
17.1
29.9
30.5
30.8
24.2
25.9
28.9
8.8
8.8
8.8
9.2
8.6
8.5
8.8
8.9
9.0
8.8
312
313
5.5
5.8
5.5
5.7
5.7
5.5
5.6
5.9
5.7
5.5
Mean
5.7
28.3
CV%
6
25
311
U.s. No.1
8-10 Oz.
Oz./Tuber
%'
8.8
8.8
29.9
39.1
30.1
10.3
14.8
7.1
7.9
12.0
4.9
6.8
6.6
9.4
8.8
9.7
6.7
11.9
>10 Oz.
Oz./Tuber %'
15.0
14.6
14.5
15.0
14.8
14.6
12.2
13.3
13.9
14.3
13.9
14.5
13.6
16.1
9.8
13.7
14.5
8.9
8.9
13.9
4
33
18
8.1
15.8
22.2
16.7
U.S. No.2
Oz./Tuber %'
7.4
1.0
13.4
0.9
8.5
0.7
1.7
2.1
1.0
1.0
2.5
2.5
2.5
2.4
2.3
2.3
2.5
2.4
2.2
1.3
2.4
102
8
39.0
20
NS
11
2.1
13.0
9.3
15.2
8.8
11.2
8.6
19.7
13.5
11.6
8.6
9.0
12.7
13.0
12.0
10.6
8.4
10.9
0.7
13.3
38
7.9
70
8
NS
11.5
13.7
10.1
NS
10
NS
4
NS
7
LSD (0.05)
* Commercial seed lots
** Control; parental seed lot for all selections, grown and stored with selections
'Percent is based on tuber number
%'
2.7
10.5
6.1
13.0
10.0
14.3
16.1
<4 Oz.
Oz./Tuber
2.6
2.5
2.5
2.4
2.4
2.4
0.2
1.2
1.0
0.8
1.0
1.3
2.4
Culls
Oz./Tuber %'
38.3
31.9
29.8
38.9
37.4
33.4
61.7
42.7
39.2
37.4
44.7
42.6
50.4
27.2
39.7
39.9
13.1
10.0
11.1
10.8
10.4
12.0
9.4
10.8
9.5
8.6
12.5
8.5
8.0
7.5
9.5
12.9
13.0
3.5
6.6
5.1
6.6
6.9
10.1
10.5
5.1
11.8
9.1
10.4
15.7
10.3
8.8
9.9
28
4
8.1
2.5
62
7
40
control produced significantly greater U.S. No. 1 yields than selections 303, 304 and
308. Selection 311 had significantly greater yields of culls than the parental control
at Madras (Table 11). All but selection 311 produced a higher percentage of
undersized tubers than the parental control at Madras and selections 304, 305, 308
309 and 310 produced significantly greater percentages of undersized tubers
(Table 13). Selections 301 and 304 yielded significantly greater U.S. 2's than the
parental control. Selections which produced significantly greater U.S. No. 2 yields,
than the parental control at Hermiston did not do so at Madras. Lower numbers of
2's and culls are often an advantage of giant bill strains grown under less than
favorable conditions. Tubers of the selections generally fell into the small to
medium size ranges (Table 13). Late emergence coupled with the short growing
season apparently delayed both tuber set and bulking. Smaller tubers like those
produced by selections 304, 306, 308, 309 and 310 are less favorable for processing.
Internal Defects
Blackspot bruise was present at high rates in all Umatilla Russet selections at
Hermiston, but only at low levels at Madras (Tables 8, 14). Blackspot bruising could
be a serious defect in commercial production for selections 301 and 311 at
Hermiston considering the levels measured there. Differences in blackspot rates
between the sites may be due to differences in grading and harvesting for the two
sites. Blackspot can be caused by excessive or rough handling of tubers. These
observations coincide with those of Pavek et al., (1993) who reported that blackspot
can be related to the variety and the environmental conditions in which it is
41
Table 14. Internal and External Tuber Characteristics for 13
Strains and 3 Seed Lots of Umatilla Russet at Madras, OR, 2001.
% BS'
% HW
312
313
2.5
12.5
15.0
5.0
2.5
7.5
2.5
0.0
5.0
0.0
7.5
2.5
2.5
5.0
5.0
2.5
0.0
0.0
0.0
2.5
5.0
5.0
2.5
0.0
0.0
2.5
2.5
0.0
0.0
5.0
0.0
Mean
4.8
CV%
179
Entry
1*
2
9911**
301
302
303
304
305
306
307
308
309
310
311
% VD3
L/W4
W/D5
10.0
1.89
20.0
1.91
10.0
1.67
1.82
1.88
1.19
1.24
1.24
1.19
1.22
1.17
1.25
1.22
0.0
17.5
7.5
20.0
20.0
22.5
15.0
17.5
10.0
10.0
15.0
12.5
12.5
12.5
2.5
249
13.6
86
1.81
1.91
1.62
1.70
1.83
1.99
1.67
1.69
1.90
1.73
1.64
'BS = blackspot
hollow heart
I-1I-1
VD = vascular disorder
L/W = length width ratio of average tuber
WD = width depth ratio of average tuber
1.23
1.23
1.19
1.23
1.23
1.23
1.23
1.79
1.21
11
4
0.07
12
9
17
0.27
LSD (0.05)
* Commercial seed lots
** Control; parental seed lot for all selections, grown and stored
with selections
2
1.21
42
harvested. Tubers graded at Hermiston were bandied much more roughly than at
Madras.
The parental control bad a significantly higher level of internal brown spot
(IBS) than all other entries at Hermiston (Table 8), possibly due to earlier vine death.
Vine senescence exposes the soil to direct sunlight resulting in higher soil
temperatures. Higher levels of lBS have been reported for stressful growing
conditions resulting from high soil temperatures or low soil calcium levels (Olsen et
al., 1995). Long growing seasons provide more opportunity for plant stress. At
Hermiston, the control may have been more susceptible to stresses which caused
IBS, than were the selections. Conversely, low lBS in the selections may be an
indicator of relatively low stress for the 2001 HAREC growing season.
Specific Gravity
Specific gravities averaged 1.093 at Madras and 1.082 at Hermiston
(Tables 9, 11). At Hermiston, selections 301, 302 and 311 had significantly higher
specific gravities than the parental control and nine of the eleven selections had
numerically higher gravities. Specific gravities of selection 311 were identical for
the two sites. Stability of specific gravity across sites has been reported as desirable
in processing potatoes by Love and Pavek (1991). Dean (1995, 1999) explains that
starch production in potatoes is most affected by air temperature. Clones that show
little variation in specific gravity are likely affected less by temperature differences
from site to site; so, the production of sugars and the subsequent conversion of
sugars to starch may be maintained at a more constant rate over a greater range of
43
environmental conditions. There were no specific gravity differences among entries
at Madras (Table 11).
UMATILLA RUSSET FRY QUALITY
Nearly all varieties that have been bred or selected for processing will fry
well from the field. As expected, fry color for all selections was equivalent to the
commercial controls and the parental control at both Hermiston and Madras
(Table 15).
Fry quality often decreases with time in cold storage due to increases in
reducing sugars. Starch is converted to reducing sugars during storage; these sugars
cause fries to darken. Fry colors of the selections tended to darken more than the
parental control after 32 days in storage; this is evidenced by the differences between
frying out of the field and later from storage. Fry quality of the parental control after
32 days in storage was significantly lighter than selections 307, 308 and 309.
There were no color differences among the entries after 64 days in storage
and all readings were well within acceptable limits for the processing industry. The
ability to fly well from storage is important because processing potatoes are stored
up to ten months in the Pacific Northwest.
BIOMASS SAMPLES AT MADRAS
Russet Norkotah
Dry weights of above ground biomass collected just prior to vine kill were
higher for selections 103, 105, 106, 208 and 210 than for the parental control
Table 15. Photovolt Reading, USDA Fry Color and % Sugar Ends for 13 Umatilla Russet Strains and 3 Seed Lots at
Hermiston and Madras, OR, 2001.
Photovolt reading'
Entry
USDA fly
% Sugar ends3
color2
Madras4
Hermiston5
Hermiston6
Madras4
Hermiston5
Hermiston6
Hermiston5
Hermiston6
42.10
41.96
42.70
42.09
41.19
0.32
0.34
0.26
0.32
0.43
0.57
0
0
0
0
0.44
0
0
0
0
0
0
0
0
--
--
--
--
--
--
40.87
42.08
38.77
38.86
0.46
0.33
0.70
0.69
0.72
0.33
0.34
0.59
0.60
0.67
0.1
0
38.51
42.08
41.93
39.75
39.65
39.05
--
--
--
40.90
40.92
39.98
40.50
38.73
40.25
-0.22
-0.32
-0.15
-0.32
-0.06
-0.48
-0.31
-0.62
-0.15
-0.10
-0.41
-0.39
-0.49
-0.47
-0.39
-0.35
0.59
0.45
0.45
39.91
39.70
41.00
41.00
41.33
42.90
41.05
312
313
46.99
47.86
46.32
47.87
45.57
49.30
47.76
50.57
46.31
45.89
48.67
48.51
49.44
49.26
48.49
48.19
0.46
0.46
0.56
Mean
47.94
40.77
40.64
CV%
5
5
6
1*
2*
9911**
301
302
303
304
305
306
307
308
309
310
311
0.41
0.24
0
0
0.1
0.1
0
10
--
--
--
0.50
0.70
0.53
0
0
0
10
0
10
4
3
LSD (0.05)
3
* Commercial seed lots
** Control; parental seed lot for all selections, grown and stored with selections
'Photovolt reading; high number indicates lighter fry color
fry color = 5.017114 - (photovolt x 0.11148); USDA value is an indication of snack food value
3% often fries; sugar end is determined as a fry with #3 or darker at one end and #2 or lighter at the other end
one day after harvest
5Fried after 32 days of storage
6
after 64 days of storage
10
0
45
(Table 3). Emergence was delayed at Madras by weather induced soil crusting
which may also have reduced overall biomass accumulation. It has been
demonstrated that giant hill plants are typically larger than average and that
maximum growth of giant hills usually takes longer (Yarwood, 1946). A higher
number of clonal selections may have produced larger amounts of biomass than the
control if emergence had not been delayed.
Umatilla Russet
Seven of the thirteen selections had significantly higher biomass fresh
weights than the parental control and eleven of the thirteen selections had
significantly greater total dry weights (Table 10). These results coincide with those
of Leever et al., (1994) who reported that late maturing strains show greater
differences in vine type and growth and also with those of Miller, J.C. Jr., et al.,
(1999) who noted that many strains show increased vine vigor relative to standards.
46
CONCLUSIONS
Clonal selections of both Russet Norkotah and Umatilla Russet showed
obvious performance differences. Performance of both parent varieties and strains
depended very much on the environment in which they were grown. The two
varieties grown in these trials seemed to respond differently to environment and
length of growing season.
Advantages of giant hill strains of Russet Norkotah were expressed to the
greatest extent at Madras under suboptimal growing conditions. No advantages were
apparent when Russet Norkotah strains were produced under relatively favorable
growing conditions at Hermiston where vine growth was good for all entries. The
similarity of Russet Norkotah strains and controls at Hermiston was likely due to
favorable 2001 growing conditions. Russet Norkotah strain yields differed between
the two sites even though growing seasons were similar in length. Yield differences
at Madras may have resulted from differences in vine growth.
Umatilla Russet strains yielded relatively high when grown under long
season conditions at Hermiston but not under the short, suboptimal season at
Madras. In general, external tuber quality of Umatilla Russet strains was low
compared to the parental standard at Hermiston, but similar at Madras. Several
Umatilla Russet strains produced higher yields of U.S. No. 1 tubers than the parental
standard at Hermiston due to higher overall yields. At Hermiston, tubers were
downgraded to U.S. No. 2 mainly due to bottle necking at the stem end. These types
47
of tubers are not usually marketable, but could be processed, with slightly more
waste than normal. Selection 311 produced exceptionally high yields at both
Hermiston and Madras, the only Umatilla Russet strain to do so at both locations.
As expected, results of biomass collections indicated that giant hills typically
produced larger vines than the parental standard. The range in biomass provided
further evidence for varying degrees of giant hill expression.
Some Umatilla Russet strains produced extremely large vines compared to
the parental standard, but lower tuber yields. Conversely, vines of Russet Norkotah
strains were comparable to or larger than the parental standard. Russet Norkotah
strains which produced larger vines also produced superior yields. It appears that
environmental conditions not conducive to good vine growth of standard Russet
Norkotah still resulted in vigorous vine growth (as evidenced by dry biomass
weights) for some strains. Greater vine growth may have allowed some strains to
better assimilate and partition photoassimilates than the parent variety.
Although total yields of Russet Norkotah selections did not differ
significantly, four of the six selections produced significantly greater biomass (dry
weight) than the parental standard; those six strains subsequently produced the
highest total yields. It may be possible to positively link vine growth and tuber
yields at Madras for both Russet Norkotah and Umatilla Russet.
Significant differences in fry color were few for Umatilla Russet selections.
Even when differences occurred, fry colors would still be very acceptable for the
processing industry.
48
Some clonal selections of both Russet Norkotah and Umatilla Russet showed
potential for increased yield and tuber quality. Selections 101, 103, 105, 206, 208,
210, 307, 311 and 313 are recommended for further evaluation. Selections 101 and
103 are recommended for advancement primarily based on yield performances and
higher percentages of larger tubers at both Hermiston and Madras. Selections 105
and 206 are recommended for advancement based on superior yield and tuber quality
at Madras. Their all around yield advantage and high grade-out, particularly of
larger U.S. No. 1 's, may give them an edge in the market place when larger tubers of
Russet Norkotah are in demand. Selections 208 and 210 are recommended for
advancement based on superior yields and high tuber quality at Madras. Umatilla
Russet selection 307 is recommended for advancement based on high biomass
production at Hermiston. Selection 311 is recommended for advancement due to
high yields at both Hermiston and Madras. Selection 313 is recommended for
advancement based on Hermiston yields.
Though some strains recommended for further evaluation were not
statistically different from that of the parental control, yield differences would be
beneficial to growers.
49
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