Arsenault, Walter J, Debby A LeBlanc,
George CC Tai and Peter Boswall. "Effects of Nitrogen Application and Seedpiece Spacing on Yield
and Tuber Size Distribution in Eight Potato Cultivars." [Vol. 78, 301-309]
The responses of eight cultivars to nitrogen fertilizer and spacing treatments were examined from 1992
to 1996. Experiments were carried out at the Agriculture and Agri-Food Canada Research Farm in Harrington,
Prince Edward Island. Four nitrogen rates and three seedpiece spacings were compared. Total and Canada #1
yields were investigated for patterns of responses of the individual cultivars to both treatments, and
possible interactions between the treatments. Response surfaces were presented for all cultivars. Nitrogen
application increased both total and Canada #1 yields for all cultivars. Increasing rates of nitrogen showed
linear and/or quadratic trends for both total and Canada #1 yields in all cultivars, whereas responses to
spacing treatments showed linear patterns for total yield, but little change for Canada #1 yields in seven
of the eight cultivars. No interactions were detected between fertilizer and spacing treatments for total
of Canada #1 yields. Generalized regression equations representing the responses of the cultivars to
fertilizer and spacing treatments for both total and Canada #1 yields were also derived. These equations
should be useful as a guideline for determining appropriate nitrogen rates and seedpiece spacing for the
eight cultivars tested. Ratios of Canada #1 to total yield were higher after initial application of
nitrogen (0 to low rate) in all but one cultivar. However, only two cultivars showed higher ratios as
nitrogen rate was further increased. Wider seedpiece spacing yielded higher ratios of Canada #1 in five
of the eight cultivars tested.
Baer, Debra, Emily Mitzel, Julie Pasche, and Neil C Gudmestad. "PCR Detection of Clavibacter
michiganensis Subsp. sepedonicus-infected Tuber Samples in a Plate Capture Assay."
E-mail: neil.gudmestad@ndsu.nodak.edu [Vol. 78, 269-277]
The speed and sensitivity of PCR-based assays allow shorter turnaround times for the detection of pathogens for which culture and
serological methods are difficult or unavailable. PCR was performed with primer sets Cms50 and Cms72, designed previously by Mills
et al. (1997) through subtractive hybridization to detect Clavibacter michiganensis subspecies sepedonicus (Cms). In bacterial
suspensions, few than three cells/10 ul reaction were detected after PCR amplicons were hybridized with specific DIG-labeled DNA probes
in an enzyme-linked oligonucleosorbent assay (ELOSA). In naturally infected tuber samples representing three cultivars of potato, the
diagnostic sensitivity of PCR/ELOSA was 96%, while the specificity exceeded 99%. PCR/ELOSA detected Cms in infected tuber
samples with equal sensitivity regardless of colony morphology, potato cultivar, or primer sets.
Bamberg, JB*, SD Kiru, and AH del Rio. "Comparison of Reputed Duplicate Populations
in the Russian and US Potato Genebanks using RAPD Markers."
E-mail: mwmarti1@facstaff.wisc.edu
[Vol. 78, 365-369]
The Association of Potato Intergenebank Collaborators (APIC) produced a global inventory of wild potato genetic resources that is
available on the Internet (www.potgenebank.org/ipd). This database shows that, in many
cases, several genebanks have samples of the progeny from a single original germplasm collection. The assumption has been that these
samples are genetically equivalent, so all the characterization and evaluation data gathered on a seedlot from one genebank can be applied
to all the other "duplicate" seedlots in other genebanks. This assumption was tested by comparing 25 pairs of reputed duplicates
in the VIR (St. Petersburg, Russia) and US (Sturgeon Bay, USA) potato genebanks using RAPDs. In 23 of 25 populations, reputed duplicates
among genebanks had significantly less similarity than replicate samples taken from a single population. The average genetic similarity of
reputed duplicates was 93%, and the lowest was 81%. Thus, users of germplasm should be aware that reputed duplicate populations from
these genebanks may not be genetically identical.
Belanger, G, JR Walsh, JE Richards, PH Milburn, and N Ziadi. "Critical Nitrogen Curve
and Nitrogen Nutrition Index for Potato in Eastern Canada." E-mail John Walsh:
jrwalsh@mccain.ca [Vol. 78, 355-364]
Plant diagnostic methods of N deficiency should be based on the definition of a critical N concentration, that is the minimal N
concentration required to achieve maximum growth. The critical N concentration (Nc)
of potato was determined from six on-farm field trials in which two cultivars (Russet Burbank and Shepody) were grown under three or
four N rates with and without irrigation. Dry matter yield and N concentration of shoots and tubers were determined approximately weekly
during the growing season. The Ncwas determined by selecting data points for which the
highest total biomass comprised of shoots and tubers was obtained, and by expressing N concentration (N) as a function of total
biomass (W). The N nutrition index (NNI), calculated as the ratio between measured N concentration and predicted N
c during the growing season, was then related to the relative yield measured at harvest.
Under non-limiting water conditions, the allometric relationship between Nc and total
biomass for Russet Burbank (Nc - 4.57W) was different from that of Shepody
(Nc = 5.04W), indicating that Shepody had a greater N concentration than Russet Burbank.
The N concentration of Shepody was also greater than that of Russet Burbank under limiting water conditions. These results suggest that
there is intra-specific variability in potato for the relationship between N concentration and biomass. The NNI ranged from 0.050 to 1.4.
The relationship between relative yield and NNI expressed by a quadratic function accounted for a greater proportion of the variability with
irrigation (71% for Russet Burbank and 82% for Shepody) than without irrigation (65% for Russet Burbank and 32% for Shepody). Our
results suggest that the NNI could be a reliable indicator of the level of N street during the growing season, particularly under non-deficient
water conditions.
Belanger, G, JR. Walsh, JE Richards, PH Milburn, and N Ziadi. "Tuber Growth and
Biomass Partitioning of Two Potato Cultivars Grown under Different N Fertilization Rates With and Without Irrigation."
E-mail: jrwalsh@mccain.ca [Vol. 78, 109-117]
Nitrogen and water deficiencies are known to affect potato yield, but much less is known of their effect on tuber growth and biomass
partitioning. The objective of this on-farm study conducted at two sites in each of three years, 1995 to 1997, was to determine the effects of
supplemental irrigation and N fertilization rates on tuber growth and biomass partitioning of the cultivars Shepody and Russet Burbank.
The N fertilization rates were 0, 100, and 250 kg N ha in 1995, and 0, 50, 100, and 250 kg N ha in 1996 and 1997. The highest bulking rate
observed in our study (7.3 g fresh tubers m20C
4) can be considered near the potential bulking rate in New Brunswick. The water deficit
in the absence of supplemental irrigation reduced this potential bulking rate by as much as 40%, but this reduction was much less at five
of six sites and negligible at two of six sites. Nitrogen deficiency reduced the bulking rate at two of six sites. This negative effect of N
deficiency on bulking rate was greater with irrigation than without irrigation at two of six sites; the tuber bulking rate with irrigation was
reduced by as much as 50% with no N applied at one site. Shepody had a greater bulking rate than Russet Burbank. The tuber bulking of
Russet Burbank, however, started earlier and lasted longer than that of Shepody. Water and N deficiencies increased biomass partitioning
to tubers and large roots. Shepody partitioned a greater proportion of its biomass to large roots and had a greater root biomass than
Russet Burbank. Our results demonstrate the ability of potatoes to modify biomass partitioning when grown under water and/or N stresses.
As a result of this compensation, the reduction in tuber yield due to limited N and water stresses is minimized.
Bohl, William H, Stephen L Love, and Asunta L Thompson. "Effect of Seed Piece Removal on
Yield and Agronomic Characteristics of Russet Burbank Potatoes." E-mail:
wbohl@uidaho.edu
[Vol. 78, 397-402]
There is adequate information available to ascertain the length of time seed pieces contribute to the yield and agronomic characteristics
of potatoes (Solanum tuberosum L.) under field conditions. Previous studies have not accounted for root system disturbance during
seed piece removal. In 1994, 1995, and 1997 a field study was conducted using Russet Burbank to determine whether seed piece removal
at each of three growth stages affects yield and agronomic characteristics. A trowel was used to tunnel into the side of potato hills to remove
seed pieces by hand either at emergence, at 20-cm plant height, or at first bloom. Control plots consisted of plants with root systems
disturbed on the same date as seed removal (disturbed control) or not treated (non-disturbed control). Seed pieces were analyzed for
solids, sucrose, and reducing sugars before planting and after removal at each growth stage in 1997. Removing seed pieces or disturbing
roots at all growth stages significantly decreased total and U.S. No. 1 yields compared with non-disturbed control. Total yield from plots disturbed
at emergence was 37.8 Mg ha compared to 22.1 Mg ha when the seed pieces were removed. Disturbing seed pieces at emergence resulted in
U.S. No. 1 yield of 21.2 Mg ha compared with a 10.6 Mg ha when seed pieces were removed at the same growth stage. For U.S. No. 1 yield, a
difference between removing the seed pieces and disturbing the root systems was still evident at the 20 cm plant height growth stage (15.4 Mg
ha vs 20.3 Mg ha, respectively). Disturbing plants at emergence or at 20-cm plant height growth stage reduced the number of tubers per
plant to 8.8 for both treatments compared to 9.7 for the non-disturbed control. Removing seed pieces at these same growth stages further
reduced tubers per plant to 6.9 and 7.6, respectively. Vines of plants with seed pieces removed at emergence were shorter and remained green
later into the season compared with disturbed and non-disturbed control treatments. Percent solids in seed pieces decreased from 20.68
at planting to 5.03 at first bloom. Seed piece percent sucrose remained constant from planting through the 20-cm plant height growth stage
and then fell to nearly zero at first bloom. Reducing sugar in the seed pieces at planting and emergence was 0.67%, rose to 1.08% at the
20-cm plant height growth stage, and then decreased to 0.89% at first bloom.
Boylston, Terri D, Joseph R Powers, Karen M Weller, and Jian Yang. "Comparison of Sensory
Differences of Stored Russet Burbank Potatoes Treated with CIPC and Alternative Sprout Inhibitors."
E-mail: powersjr@wsu.edu [Vol. 78, 99-107]
The sensory properties of Russet Burbank potatoes treated with three naturally occurring volatile compounds, as alternatives to CIPC for
sprout inhibition, were evaluated. Potatoes from the 1995 and 1996 crop years were treated with salicylaldehyde, 1,8-cineole,
1,4-dimethlnaphthalene, or CIPC prior to dormancy break during storage and stored for up to 16 wk. Sensory differences between potatoes
treated with alternative sprout inhibitors and CIPC-treated or untreated potatoes and inhibitor concentration were determined at 2-wk intervals.
Potatoes treated with 1,8-cineole or salicylaldehyde, but not 1,4-dimethylnaphthalene, were significantly different from the untreated
potatoes or potatoes treated with CIPC. Sensory detection threshold levels for the alternative inhibitors were measured in a model potato
system. The residual levels of the sprout inhibitors were within the detection threshold range for 1,8-cineloe (0.02-=0.04 ppm), but not for
salicylaldehyde (0.09 - 0.10 ppm) or 1,4-dimethylnaphthalene (0.80-1.40 ppm). The presence of the residual sprout inhibitors and/or the
influence of sprout inhibitors on potato metabolism during storage contributed to observed differences in sensory quality of stored potatoes.
Caldiz, DO, LV Fernandez, and MH Inchausti. "Maleic Hydrazide Effects on Tuber Yield,
Sprouting Characteristics, and French Fry Processing Quality in Various Potato (Solanum tuberosum L.) Cultivars Grown under Argentinian
Conditions.". E-mail: dcaldiz@mccain.com.ar
[Vol. 78, 119-128]
Field trials were carried out during 1995-1998 in commercial crops of five potato cultivars grown at several locations in Argentina to test
maleic hydrazide (MH potassium salt, 36%) effects on tuber yield, sprouting characteristics, and processing quality. MH was applied at grown
stage IV, when developing tubers were 40-70 mm, at 9, 10, 12, and 14 I ha in single or split treatments. MH treatments did not produce
phytotoxicity symptoms in the foliage and did not decrease tuber yield. MH increased tuber yield in Kennebec, Russet Burbank and Shepody
in several experiments, while not in Atlantic and Ranger Russet. MH treatments delayed initial sprouting date and inhibited sprout growth
during storage periods up to 8 months, which resulted in lower weight losses due to sprouting. Tuber dry matter content and fry color
were similar or in some cases improved due to MH treatments, while no consistent results were found regarding reducing sugar content.
Cheng, Hsiang-Tai, Stephanie Peavey, and Alan S Kezis. "Regional Differences in Consumer
Potato-purchasing Decision in the Eastern United States." [Vol. 78,1-7]
This study investigates and compares factors that influence the potato-purchasing decision among consumers in two different regions
of the eastern United States. Previous studies have focused on identifying only the physical attributes and culinary characteristics of potatoes
that consumers prefer. This study was done to gain a detailed understanding of consumers' potato-purchasing decision based on visual
presentation of the type of potato along with the message attributes presented on the bag label. These attributes include product origin,
brand labeling, product guarantee, and price.
In-person surveys were conducted in two eastern U.S. market areas separately in 1997 and 1998. The results indicate that potato
choices and the factors that affect those choices differ significantly between consumers in different regions. In particular, potato origin
plays a key role in consumer purchase decisions and varies from one region to another. Differences in the effect of price on potato purchase
also vary between regions.
Coleman, Warren K, Danielle J Donnelly and Shirlyn E Coleman. "Potato microtubers as
Research Tools: A Review." E-mail: colemanw@agr.gc.ca
[Vol. 78, 47-55]
Although in vitro production of potato tubers or microtuberization was achieved more than 40 years ago, the application of
microtubers in reliable model research systems has been slow to develop. Several factors such as the use of growth regulators in
microtuber induction and growth media, the mixotropic nature of the in vitro system, and cultivar-specific responses have led to
interpretive difficulties. A cautionary note is also necessary in view of apparent growth and development differences, metabolic alterations,
and somaclonal variation encountered in microtubers that may not be found in field-grown tubers. Evidence for strong and consistent
analogies between microtubers and field-grown tubers for their induction, growth and development, and metabolism often is lacking.
However, several components such as the rapid and near-synchronous induction and growth, which can be modified by a range of
exogenous compounds or conditions, make the microtuber a valuable model system. Complex problems such as dormancy also appear
to be particularly amenable to examination by the microtuber system. In addition, the use of microtubers as experimental research tools has
potential in the areas of plant metabolism, germplasm selection and evaluation, genetic transformation, somatic hybridization, and molecular
farming.
Coleman, Warren K, Greg Lonergan, and Peter Silk. "Potato Sprout Growth Suppression by
Menthone and Neomenthol, Volatile Oil Components of Minthostachys, Satureja, Bystropogon, and Mentha Species."
E-mail: colemanw@agr.gc.ca [Vol. 78, 345-354]
The replacement of synthetic pesticides such as chlorpropham (CIPC) with effective potato sprout suppressants that have negligible
environmental impact is needed due to increased concern for consumer health and safety. To date, however, only S-(+)-carvone, a
monoterpene produced from caraway seeds, has been developed commercially as a competitive product to CIPC. Consequently, the effects
of menthone and neomenthol vapor were compared to S-(+)-carvone for sprout suppressant efficacy as well as for effects on soluble sugar
levels, respiration, and processing quality during high and low temperature storage. In the majority of treatments, tubers were enclosed in
3.8 1 glass jars at 25 C. Liquid test compounds were applied to a 10-cm-long x 2-cm-wide filter paper strip (Whatman No. 1) enclosed in
each jar. Treatment with either menthone or S-(+)-carvone at 5 ul liquid/l of treatment volume gave complete sprout suppression in
non-dormant Russet Burbank tubers. An examination of changes in CO2 output, glucose, or sucrose
levels over 4 wk at 10 C indicated that the effects of menthone and S-(+)-carvone were similar. In addition, menthone significantly inhibited sprouting
without adversely affecting the percentage glucose content or sucrose content when this compound was applied at 4 ul/l to five-month-old,
non-dormant tubers of AC Novachip, Russet Burbank, Shepody, and Snowden for two months at 10 C. Menthone and neomenthol
were five to ten times more effective in suppressing tuber sprouting than S-(+)-carvone when applied together at 0.5 ul/l each.
Conley, Shawn P, Larry K Binning, and Timothy R Connell. "Effect of Cultivar, Row Spacing,
and Weed Management on Weed Biomass, Potato Yield, and Net Crop Value."
E-mail Larry Binning: lbinning@wisc.edu
[Vol. 78, 31-37]
Research was conducted to quantify the effects of potato cultivar, row spacing, and weed control treatments on weed biomass, crop
yield, and net crop value. Cultivars evaluated included Russet Burbank, Russet Norkotah, Goldrush, Dark Red Norland, Snowden, and
Atlantic. Inter-row spacings of 76 and 91 cm with an intra-row spacing of 30 cm were evaluated in 1996 and 1997. Weed control
treatments included a herbicide tank-mix of metribuzin and metolachlor, cultivation, and a hilling-only control. Common lambs quarters
and total weed biomass were greater in the 76-cm row spacing than in the 91-cm row spacing across all cultivars in 1996 and 1997. In
1997, chemical control resulted in less weed biomass than both the hilling-only and cultivation treatments. Total marketable yield was
greater in the 91-cm row spacing than in the 76-cm row spacing in 1996. Reduced weed biomass in 1996 and 1997, coupled with greater
total marketable yield and net return in 1996, indicated that the 91-cm row spacing was the optimal row spacing for Russet Burbank,
Goldrush, Russet Norkotah, Snowden, and Atlantic cultivars in 1996 and 1997. Similar yields and net crop value among weed control
treatments in 1996 and 1997 indicated that cultivation and possibly even hilling-only areas within fields can be viable alternatives to
herbicide use.
Davenport, JR and EM Bentley. "Does Potassium, Fertilizer Form, Source, and Time of
Application Influence Potato Yield and Quality in the Columbia Basin?"
E-mail: jdavenp@wsu.edu [Vol. 78, 311-318]
Potassium (K) fertilizer form (liquid or granular), source (chloride or sulfate), and time of application (pre-plant or in-season) were
evaluated for effects on potato tuber yield and quality in Washington's Columbia Basin. Potato yield and quality did not respond positively to
potassium fertilizer although pre-plant soil-test K values were in the range where adding K fertilizer is recommended in the current (1999)
Washington guidelines. In one of three years, total tuber yield was reduced with in-season fertilization with potassium chloride and with
75% in-season liquid K application. While the results were inconsistent over growing seasons, a few of the in-season, liquid K fertilizer
treatments resulted in a significant reduction in percent marketable yield. Thus, the study results uphold the current practice of using
granular K fertilizers pre-plant. In addition, the results of this study strongly indicate that K source does not affect tuber specific gravity.
The limited response of yield and quality factors to K fertilizer on sites that Washington's current soil-test and K fertilizer guidelines indicate
should be K responsive suggest that further research is needed to fine tune the guidelines.
Daayf, F., HW (Bud) Platt, G Mahuku, and RD Peters. "Relationships Between Pathotypes and
RAPDs, Gpi-Allozyme Patterns, Mating Types, and Resistance to Metalaxyl of Phytophthora infestans in Canada in 1997."
E-mail: platth@agr.gc.ca
[Vol. 78, 129-139]
Relationships between pathotypes and other markers such as mating types, metalaxyl resistance, Gpi-allozyme and random amplified
polymorphic DNA (RAPD) patterns, were investigated among 33 isolates of Phytophthora infestans obtained from both potato and
tomato across Canada in 1997. Pathogenicity testings, based on virulence against potato differentials carrying single-resistance genes
and the size of lesions on leaves, revealed higher pathogenic diversity in 1997 than in the few past years, with more pathotypes and more
race-complex isolates. A higher pathogenic diversity was observed within A2 (US-8) than within A1 (US-11) isolates. There was no correlation
between the level of resistance to metalaxyl of an isolate and its pathogenicity. Nevertheless, when grouped into metalaxyl-sensitive (MS),
-intermediate (MI), and -resistant (MR) classes, both average pathotype complexity and average lesion size were lowest for MS group. RAPD
data revealed a good distinction between A1 (US-11) and A2 (US-8) mating type groups, and between isolates from British Columbia and
those from other provinces. The detection in the last few years of both A1 and A2 mating types in Canada and the occurrence in 1997 of
some isolates sharing different characteristics of both of these two groups suggest that sexual reproduction may have occurred locally.
Davis, JR, OC Huisman, DO Everson and AT Schneider. "Verticillium Wilt of Potato: A Model
of Key Factors Related to Disease Severity and Tuber Yield in Southeastern Idaho." E-mail:
jrd2@micron.net [Vol. 78, 291-300]
In three years (1994, 1995, and 1996), a total of 100 commercial potato fields in southeastern Idaho were surveyed for soil variables
of Verticillium dahliae and Colletotrichum coccodes, colonization of stems, root, and tubers by V. dahliae and C.
coccodes, and tuber yield, size, and quality. As a generalization, factors related to soil integrity (organic matter, organic nitrogen, and
increased nutrient availability) were most closely related to wilt suppression and higher tuber yields, whereas factors related to loss of
soil integrity (sodium and reduced nutrient availability) were related to increased wilt and lower tuber yields. In a multiple regression
analysis, three independent variables, feed-root infections by V. dahliae, sodium content in soil, and soil organic content, were
significant predictors of tuber yield. With these three factors, this model accounted for 49%, 53%, and 62% of the field variability related to
total yield in 1994, 1995, and 1996, respectively. Throughout this investigation, V. dahliae root infections had the most direct effect on
tuber yield, which emphasizes the importance of quantifying root infections in epidemiological studies of Verticillium wilt. Based on these
results, organic matter may be one factor that can be manipulated for suppression of Verticillium wilt without reducing soil populations of the
pathogen.
De Jong, H, LM Kawchuk, WK Coleman, CA Verhaeghe, L Russell, VJ Burns, and E
Tremblay-Deveau. "Development and Characterization of an Adapted Form of Droopy, a Diploid Potato Mutant Deficient in
Abscisic Acid." E-mail: hdejong@nbnet.nb.ca
[Vol. 78, 279-290]
A cultivated diploid potato breeding population has been selected for adaptation to growing, tuberizing (under relatively long days), and
storing (including long dormancy) under New Brunswick conditions. In this population, a mutant was discovered that appeared similar to the
earlier described droopy mutant, which is deficient in abscisic acid and is unable to regulate water loss from its leaves. The
physiology and genetics of the newly discovered mutant were studied and compared in detail with the description of droopy. This
mutant has a longer tuber dormancy than the original droopy. In families segregating for droopy and normal, similar dormancies
and endogenous abscisic acid levels in tubers were observed between droopy and normal genotypes. The effect of the mutant gene
appears to be tissue specific, affecting aboveground plant parts only. A test for allelism indicated that this mutant is allelic to droopy.
Classical linkage analyses confirmed previously reported close linkage between the Dr (droopy) and the S (incompatibility) loci.
The Dr locus has been mapped in this study to the top of chromosome I. Several test crosses indicated reciprocal differences in the
segregation ratios between droopy and normal. In keeping with the droopy (drdr) genotype, drought-stressed leaves of the
mutant were incapable of increasing abscisic acid production compared to the normal. This mutant, with its apparent developmentally
restricted expression, may be useful in elucidating the genetic and physiological processes associated with such major events as
tuberization, response to drought stress and tuber dormancy.
De Jong, H, KG Proudfoot and AM Murphy. "The Germplasm Release of F87084, A Fertile,
Adapted Clone With Multiple Disease Resistances." E-mail:
hdejong@nbnet.nb.ca
[Vol. 78, 141-149]
F87-84 is a germplasm release that has been developed by conventional breeding methods and can be traced back to very diverse
germplasm sources. This clone has excellent female fertility, round-oval tubers and is well adapted to Eastern Canada. The vine maturity
is slightly later than that of Kennebec, and the mean marketable yield is 78% of Kennebec. The specific gravity, boil, bake and chip scores
are somewhat lower than Kennebec. F87084 is resistant to late blight, Verticillium dahliae, early blight, and the pathotypes of wart
occurring in Newfoundland. F87084 has extreme resistance to PVYo and PVX. It is also
resistant to the potato cyst nematode pathotype Ro1. Progeny analyses indicate that F87084 is duplex for the genes controlling extreme
resistance to PVX as well as resistance to the potato cyst nematode (Ro1).
Delgado, Efren, Jaroslaw Poberezny, Elke Pawelzik and Ilona Rogozinska. "Comparison of
Two Methods for Determining the Discoloration Potential of Potato Tubers Based on Their Chemical and Biochemical Properties."
[Vol. 78, 389-394]
The aim of this study was to compare the homogenization and visual methods that are used to determine the discoloration potential
of potato tubers. Two German cultivars, Agria and Satina, and two Polish cultivars, Lena and Mors, were planted during 1998 and 1999 in
Goettingen, Germany, and in Bydgoszcz, Poland. The discoloration potential of the tubers was measured after harvesting and after 6 months
of storage at 4 C and 8 C. Both methods correlated significantly at harvest (0.709, P < 0.001). After storage the correlation was significant
but low (r = 0.403, P < 0.001) probably because of physical changes in the tuber during storage. The visual method can be used as a
fast method, especially at harvest. However, the homogenization and visual methods determine, to a certain degree, different tuber
properties leading to the discoloration potential. Therefore, a complete comparison is not possible. The methods studied in this paper can
complement but not substitute each other. Reliable comparisons between institutes require use of the same method to determine the
discoloration potential of the tuber.
Dorrance, AE, DA Inglis, JP Helgeson, and CR Brown. "Partial Resistance to Phytophthora
infestans in Four Solanum Crosses." E-mail:
cbrown@pars.ars.usda.gov [Vol. 78, 9-17]
Thirty progeny from each of four Solanum crosses were evaluated in the field at Mount Vernon, WA, in 1996 and 1997 for partial
resistance to Phytophthora infestans. Of the four parents, three have high levels of partial resistance to P. infestans; one
derived from somatic hybridization of S. Bulbocastanum, the other two from traditional breeding efforts for multiple disease
resistance. Data were collected from each cross to estimate area under the disease progress curve (AUDPC), days to 5% disease
severity threshold (DT5) and sporangia production (SP). All of these variables differed
significantly among the progeny within each cross in each year. Correlation analysis indicated that DT5
was highly correlated with AUDPC for all four populations for both years. Log-transformed SP was significantly (P <0.001) correlated
to AUDPC values for one population in both years, but the significance of the correlation was variable between years for the remaining three
crosses. The variable DT5, which is composed of three components (infection efficiency, latent
period, and lesion growth rate), was the most important in identifying progeny with partial resistance to late blight in all four crosses in this
study.
Douches, DS, JB Bamberg, W Kirk, K Jastrzebski, BA Niemira, J Coombs, DA Bisognin, and KJ
Felcher. "Evaluating of Wild Solanum Species for Resistance to the US-8 Genotype of Phytophthora infestans Utilizing a
Fine-Screening Technique." E-mail:
douchesd@pilot.msu.edu [Vol. 78, 159-165]
Greenhouse assays were carried out to characterize Solanum accessions previously reported to be late blight resistant and to
identify individuals within the accessions with high levels of resistance to late blight. Foliage of wild Solanum species accessions
or hybrid cultivated potato x wild species (diploid or tetraploid) from Mexico, Russia, or South America was inoculated with Phytophthora
infestans (US-8) and was scored for severity of foliar symptoms at 7 and 14 days after inoculation (DAI). Mexican accessions
(S. brachycarpum, S. pinnatisectum, S. guerreroense, and S. fendleri) were significantly more resistant (1.1% infection at 14
DAI) than either Russian (59.1% infection at 14 DAI) or South American (53.4% infection at 14 DAI) accessions. Moreover, the genotypes
within the Mexican accessions tended to be more uniformly resistant whereas genotypes within the Russian and South American
accessions tended to segregate for resistance. The more resistance genotypes of Russian and South American accessions (176/546) were
retested, and 56 genotypes were identified as having potential for use in potato breeding programs for resistance to late blight. Fifty percent
of the selected genotypes were from S. microdontum accessions P1498124, P1595510, and P1595511. The potential of these
species for incorporation into breeding programs for late blight resistance is discussed.
Douches, DS*, KJ Felcher, J Coombs, C Long, R Hammerschmidt and WW Kirk.
"Michigan Purple: A Purple Skinned Tablestock Variety."
E-mail: douchesd@pilot.msu.edu
{Vol. 78, 421-424]
Michigan Purple is a purple-skinned tablestock variety. The tubers have an attractive round-ovoid shape and a strong iridescent purple
skin. It has a medium set of bright purple-skinned tubers similar in shape to Norland. The tuber flesh is white; it has a few internal defects
and does not darken after cooking. Under irrigated conditions the yield is high and specific gravity intermediate. Michigan Purple has
mid-early vine maturity.
Douches, DS*, K. Jastrzebski, J Coombs, RW Chase, R Hammerschmidt, and WW Kirk.
"Liberator: A Round White Chip-processing Variety with Resistance to Scab."
E-mail: douchesd@pilot.msu.edu [Vol. 78, 425-431]
Liberator is a round white chip-processing selection with medium-high specific gravity and resistance to scab (Streptomyces
scabies Thaxter). The tubers will chip process out of the field and from 100 C storage. The tuber appearance is similar to Norchip.
Post-harvest tuber tests indicate a tolerance to fusarium dry rot. Liberator was tested in the North Central Regional Trials and the
National Snack Food Association Trials. Under irrigated conditions, the yield and specific gravity are similar to Snowden and Atlantic.
Liberator has a full-season vine maturity that is similar to Snowden and tuber dormancy equal to Atlantic.
Douches, DS, K Jastrzebski, J Coombs, WW Kirk, KJ Felcher, R Hammerschmidt and RW
Chase. "Jacqueline Lee: A Late Blight-Resistant Tablestock Variety."
E-mail: douchesd@pilot.msu.edu [Vol. 78, 413-419]
Jacqueline Lee has a bright golden skin, yellow flesh, attractive oval shape, and excellent cooking qualities that make it suitable for
tablestock use. In addition, it has been determined to have a high level of foliar resistance to the US-8 genotype of Phytophthora
infestans (Mont.) de Bary under Michigan field and greenhouse conditions. It is a full-season variety with vine maturity similar to
Snowden. Jacqueline Lee has high yield potential. It has a high set (14-16 tubers/hill) of medium sized tubers that leads to 65%-80%
marketable yield. Tubers are low in internal and external defects. It has a scab reaction similar to Atlantic, and the tubers have been
observed to have a long dormancy.
Haynes, KG, GA Porter, BJ Christ, RW Goth, KO DeLong, DE Halseth, JB Sieczka, MR Henninger, SB
Sterrett, GC Yencho and RE Webb. "Amey: A Multipurpose, Russet-Skinned Potato Cultivar for the Eastern United
States." E-mail: haynesk@ba.ars.usda.gov
[Vol. 78, 175-181]
Amey is a late-maturing, russet-skinned, white-fleshed potato cultivar that yields more than Russet Burbank in most eastern United
States potato production areas. Tubers of Amey are mostly oblong, occasionally long, with an evenly russeted skin. Tubers of Amey are
smoother, more attractive, and have a much lower incidence of external defects than Russet Burbank. The specific gravity of Amey is
equal to or greater than the specific gravity of Russet Burbank. French fries produced from Amey are lighter than or equal in color to those
produced from Russet Burbank; however, tubers are frequently not long enough to satisfy the french fry industry. Baking and taste quality
of Amey are excellent, and it has potential as a fresh market potato. Amey is resistant to race Ro1 of the golden nematode, powdery scab,
and common scab. It is moderately susceptible to Verticillium wilt. It is susceptible to potato leafroll virus, late blight, and early blight.
Haynes, Kathleen G "Variance Components for Yield and Specific Gravity in a Diploid
Potato Population after Two Cycles of Recurrent Selection." E-mail:
haynesk@ba.ars.usda.gov
[Vol. 78, 69-75]
The potato (Solanum tuberosum L.) processing industry needs cultivars with high tuber specific gravity and acceptable color of
processed product. All of the cultivars with high specific gravity currently grown in the U.S. are very closely related, which increases their
genetic vulnerability and results in inbreeding as efforts are made to improve these traits. The use of diploid Solanum sp. in breeding
may resolve these problems. The purposes of this study were (1) to estimate narrow-sense heritability for yield and specific gravity in
random-mating diploid hybrid potato populations of S. phureja - S. stenotomum (PHU-STN) following two cycles of recurrent
selection, (2) to examine phenotypic variances for yield and specific gravity following two cycles of recurrent selection within PHU-STN, (3)
to compare the yield and specific gravity of individual PHU-STN clones with Atlantic, and (4) to screen these PHU-STN clones for the
presence of 2n pollen. Four clones from each of 72 maternal half-sib families were evaluated for yield and specific gravity in replicated field
tests in 1990 and 1991. A second selection cycle, using a randomly mated population obtained from the highest specific gravity clone in
each maternal half-sib family, was similarly evaluated for yield and specific gravity in replicated field tests in 1995 and 1996. Narrow-sense
heritability for specific gravity was estimated as 0.37 ± 0.25 and 0.43 ± 0.27, in the first and
second selection cycles, respectively, with a 27% decrease in phenotypic variance. Narrow-sense heritability for yield was estimated as
0.60 ± 0.26 and 0.06 ± 0.24, in the first and second selection cycles, respectively, with a 73%
decrease in phenotypic variance. There were significant correlations between yield and specific gravity in 1990 (r=0.32) and 1996 (r=0.37),
but not 1991 (r=0.08) and 1995 (r=0.05). These results indicate that additional breeding efforts in this PHU-STN population could result in
improvements in specific gravity. However, the amount of variation for yield in this population is decreasing and may indicate that the yield
potential of this population is rapidly approaching its limit. In the second selection cycle, many of the 288 clones were significantly higher in
specific gravity than the high-specific-gravity cultivar Atlantic, but none were higher yielding. Fifty-eight clones from the second selection
cycle produced at least 5% 2n pollen. When used in tetraploid x diploid hybridizations, this diploid population could furnish new genetic
material to the tetraploid potato germplasm base for simultaneously increasing specific gravity and yield.
Hijmans, Robert J "Global Distribution of the Potato Crop."
E-mail: rhijmans@uclink.berkeley.edu
[Vol. 78, 403-412]
The global distribution of potato area is described using country-level statistics and a new geo-referenced database. There are two
main peaks in global potato distribution by latitude. The major peak is between 450 N and 57
0 N and represents potato production zones in the temperate climates where potato is a summer crop.
The other peak is between 230 N and 340 N, and
mainly represents production zones in the subtropical lowlands, where potato is a winter crop. Between 1950 and 1998 potato production
area, increased at low latitudes and decreased at high latitudes, particularly around 530
N (this zone includes parts of Belarus, Germany, Poland, Russia, and Ukraine). The northern limit of potato production coincides with the
boundaries of agriculture and the presence of human population. The peak between 230 N and 34
0 N coincides with the area of highest populations density) per area of land and per area
of arable land). About 25% of the global potato area is in the highlands (above 1000 m).
Hosaka, Kazuyowhi, Yuko Hosaka, Motoyuki Mori, Tsutomu Maida, and Hiroshi Matsunaga.
"Detection of a Simplex RAPD Marker Linked to Resistance to Potato Virus Y in a Tetraploid Potato."
E-mail: hosaka@kobe-u.ac.jp [Vol. 78, 191-196]
Extreme resistance to potato virus Y, derived from a wild diploid species Solanum chacoense, was found in Japanese cultivar
Konafubuki. The segregation ratio of resistant vs susceptible in the tetraploid population from Kita-akari (susceptible) x Konafubuki
(resistant) indicated that the resistance gene followed a monogenic dominant fashion. Bulked DNA samples of resistant and of susceptible
clones were screened with 306 decamer primers by PCR to find RAPD markers linked to the resistance. The RAPD marker 38-530 was
reproducibly detected in the resistant clones with a recombination frequency of 16.3%. Except for Konafubuki the marker band was found only
in a few limited parental lines and cultivars where the resistance is not involved. Thus, using Konafubuki as a resistance gene source, the
RAPD marker 38-530 would be practically and widely useful in tetraploid breeding programs.
Johnson, Alexander AT, Suzanne M Piovano, Vidya Ravichandran and Richard E Veilleux.
"Selection of Monoploids for Protoplast Fusion and Generation of Intermonoploid Somatic Hybrids of Potato."
E-mail: potato@vt.edu [Vol. 78, 19-29]
The union of potato monoploid genotypes (2n=1x=12) through protoplast fusion may result in vigorous somatic hybrids due to a
reduction of the "genetic load" normally present in this highly heterozygous tetraploid (2n=4x=48) crop. More than 100
androgenic monoploids derived from diploid (2n=2x=24) Solanum phureja Juz. & Buk. and S. chacoense Bitt. x S.
phureja clones were evaluated in field trials during 1996 and 1997 to identify the most promising genotypes for protoplast fusion
experiments. Compared to the total population, the 1996 selected genotypes had higher means for tuber number (30.1 vs 11.2 tubers/plant),
average tuber weight (3.0 vs 1.8 g/tuber) and total yield (66.1 vs 20.4 g/plant). Similarly, the 1997 selected genotypes had higher means for
tuber number (42.8 vs 25.4 tubers/plant), average tuber weight (3.6 vs 2.5 g/tuber) and total yield (114.0 vs 63.4 g/plant) compared to the
total population. The 31 selected monoploid genotypes from 1996-97 varied in their response to protoplast isolation and culture from no
growth (9), cell enlargement (5), limited cellular divisions (8), callus formation (5) to plant regeneration from callus (4). Chemical fusion and
electrofusion produced three groups of intermonoploid somatic hybrids. Polymorphic simple sequence repeat (SSR) loci enabled distinction
of somatic hybrids from parental somaclones. Rapid DNA extraction with SSR analysis enabled screening of calluses to identify somatic
hybrid tissue prior to plant regeneration. The somatic hybrids were highly polyploid, mostly hexaploid (2n=6x=72), possibly due to fusion
of endopolyploid protoplasts and/or chromosomal doubling during plant regeneration.
Kirk, William W, Kimberly J Felcher, David S Douches, Brendan A Niemira and Raymond Hammerschmidt.
"Susceptibility of Potato (Solanum tuberosum L.) Foliage and Tubers to the US8 Genotype of Phytophthora
infestans." E-mail: kirkw@msu.edu
[Vol. 78, 319-322]
Late Blight is an important disease of potato (Solanum tuberosum L.) worldwide, and therefore, many potato-breeding programs
have prioritized the development of late blight-resistant potato cultivars. Although the emphasis has been to enhance foliar resistance, it
is also necessary to evaluate tuber late blight resistance in new breeding lines and new sources of late blight resistance. We report here
on the assessment of foliar and tuber resistance and the correlation between these aspects of resistance in a sample of Michigan State
University potato breeding lines. Two MSU breeding lines had significantly less infected foliage than the susceptible check cultivars. Tuber
susceptibility was significantly different (P < 0.05) only between the most susceptible and the least susceptible breeding lines/cultivars.
Foliar and tuber susceptibility to potato late blight were not correlated as low tuber susceptibility was associated both with extremely low
(e.g., MSG274-3) and high (e.g. MSE202-3Rus) foliar susceptibility.
Levy, D, Y Itzhak, E Fogelman, E Margalit and RE Veilleux. "Ori, Idit, Zohar and Zahov: Tablestock and
Chipstock Cultivars Bred for Adaptation to Israel." E-mail:
potato@vt.edu
[Vol. 78, 167-173]
The cultivars Ori, Idit, Zohar, and Zahov have been bred specifically for adaption to the Mediterranean climate: Ori and Idit are early
tablestock cultivars, Idit is suited for "mini potatoes" (20 to 35 mm in diameter); Zohar is a midseason tablestock cultivar, and
Zahov is used as an early chipstock cultivar. The cultivars can be grown in either of the two main seasons in the Mediterranean region: the
spring season (January through July) and the winter season (September through March). The cultivars have rapid emergence and early
tuber set, they are tolerant to high temperatures and drought, and are not susceptible to external or internal defects. In field experiments, Idit
yields were lower than the cultivar checks (Alpha, Nicola or Desiree) in six of seven trials. However, the attractive appearance of the small
oval tubers (20 to 35 mm in diameter) and the good aroma of the baked tubers are advantages. Yield of Ori and Zohar occasionally exceeded
those of cultivar checks, and their yellowish skin, especially in sandy soils, is an advantage. Yields and tuber dry matter content of the
early-maturing cultivar Zahov were similar to Hermes, a standard chipstock cultivar commonly used in Israel. The early maturation of
Zahov is desirable to extend the harvest season.
Lynch, DR, LM Kawchuk, CA Schaupmeyer, J Holley, DK Fujimoto, D Driedger, TR Tarn, D Waterer, J Wahab
and MS Goettel. "AC Maple Gold: A High-yielding Yellow-fleshed French Fry Cultivar."
E-mail: drlynch@telus.net. [Vol. 78, 339-343]
AC Maple Gold is a high-yielding oval/oblong, yellow-fleshed potato with an attractive appearance for the fresh market coupled with
excellent french fry quality. The cultivar can be harvested early for french fry processing, but also maintains excellent fry quality during
long-term storage. AC Maple Gold produces french fries with a uniform deep yellow color.
Lynch, DR, GC Kozub and LM Kawchuk. "The Relationship Between Yield, Mainstem Number,
and Tuber Number in Five Maincrop and Two Early-maturing Cultivars." E-mail:
drlynch@telus.net [Vol. 78, 83-90]
Using data from an 11-year period, total and marketable yield were related, using regression analysis, to mainstem and tuber number
for five maincrop varieties (Russet Burbank, Shepody, Atlantic, Norchip, and Norland) and two early-maturing varieties (Conestoga and
Carlton), at irrigated and dryland sites in western Canada. Mainstem number by itself was a poor predictor or total and marketable yield.
Highly significant regressions of yield on the derived variable tuber number per mainstem were evident for all cultivars grown at the dryland
sites. In general, the proportion of the total variation in yield accounted for by the regression models was much higher at the dryland than
at the irrigated sites, indicating that the relationship between yield and its predictor variables was more complex for irrigated sites. While
the study suggests that the use of tuber number per mainstem may be useful as an early-season predictor of tuber yield for cultivars,
particularly under dryland conditions, a model using the predictor variables mainstem and tuber number will generally be superior due
to the additional information it provides when competitive effects are present for light energy within the canopy or for assimilates among
developing tubers. Contour plots provide a useful way to study the yield response to changes in tuber number at specific stem density levels.
Lynch, DR, SJ Peloquin, LM Kawchuk, CA Schaupmeyer, J Holley, DK Fukimoto, D Driedger, D
Waterer, J Wahab and MS Goettel. "AC Glacier Chip: A High-yielding Chip Cultivar for Long-term Storage."
E-mail: drlynch@telus.net [Vol. 78, 327-332]
AC Glacier Chip has a maincrop maturity, higher yields than Snowden and excellent quality (color and dry matter) for the chip industry.
The tubers are oval and very uniform in size with white flesh. It performs best under irrigated conditions. AC Glacier Chip provides the
industry with a high-yielding chip cultivar that produces excellent quality friend product out of the field and for long-term storage.
Lynch, D.R., G Secor, LM Kawchuk, D Waterer, CA Schaupmeyer, J Holley, DK Fujimoto, D Driedger,
J Wahab and MS Goettel. "AC Peregrine Red: A High-yielding Red-skinned Fresh Market Cultivar."
E-mail: drlynch@telus.net [Vol. 78, 333-337]
AC Peregrine Red is a maincrop cultivar that produces very uniform attractive tubers with a deep red skin color. Marketable yields and
skin color retention in storage are superior to Norland in Canadian and some U.S.A. locations. The cultivar provides the fresh market
industry with a high-yielding, red-skinned potato, with good storage capacity and resistance to fusarium dry rot.
Maki-Valkama, Tuula, Jari PT Valkonen, Ari Lehtinen and Eija Pehu. "Protection Against Potato
Virus (PVY) in the Field in Potatoes Transformed with the PVY P1 Gene."
E-mail: jari.valkonen@helsinki.fi [Vol. 78, 209-214]
Lines of potato cv. Pito transformed with P1 gene of Potato virus Y (PVY) in sense or antisense orientation were evaluated for
resistance to PVY in the field in 1997 and 1998. The transgenic resistance fully protected the crop from infection with PVY transmitted
by aphids in both years. These plants were not resistant to the field isolates of the PVY strain group, which is in agreement with our
greenhouse experiments. Consequently, several transgenic lines produced higher yields than the non-transgenic cv. Pito plants. These
results showed that the P1 gene-mediated resistance provides significant benefits under conditions were the incidence of infections and
damage by PVY are considerable.
Mojtahedi, H, JM Crosslin, GS Santo, CR Brown and PE Thomas. "Pathogenicity of Washington
and Oregon Isolates of Tobacco Rattle Virus on Potato."
E-mail Charles Brown: cbrown@pars.ars.usda.gov
{Vol. 78, 183-190]
Soil samples from corky ringspot (CRS) problem fields of potato in the states of Washington and Oregon were collected and planted
with Nicotiana tabacum 'Samsun NN' tobacco to bait tobacco rattle virus (TRV) and to increase Paratrichodorus allius
populations; the vector of TRV. Pathogenicity of three isolates of TRV was assessed on Russet Burbank and Russet Norkotah plants
using P. Allius as the vector. The most severe CRS tuber symptoms were with TRV from Pasco, WA, followed by Umatilla, OR, and
Mattawa, WA, indicating a distinct variation in virulence among virus isolates. The lowest number of P. allius that transmitted
TRV resulting in CRS symptoms on Russet Norkotah was three nematodes per 250 cm3 soil. When
potato plants were exposed to P. allius at different times in their growth, tubers on older plants were more resistant than younger
tubers to CRS. Severity of CRS tuber symptoms was correlated with age of potato plants in pot culture. Reproduction of P. allius on
potato roots did not influence the incidence and severity of tubers symptoms. Under similar conditions, Bintje, a variety known to be
resistant to CRS, served as a host for P. allius, yet remained asymptomatic. The protocol employed in these studies is appropriate
for testing potato germplasm for resistance to CRS.
Mosley, AR, KA Rykbost, SR James, DC Hane, CC Shock, BA Charlton, JJ Pavek, SL Love, DL Corsini and
RE Thornton. "Klamath Russet: A Full Season, Fresh Market, Long Russet."
E-mail: alvin.r.mosley@oregonstate.edu [Vol. 78, 377-381]
Klamath Russet, a late-maturing cultivar for fresh market use, was jointly released by the Agricultural Experiment Stations of Oregon,
Idaho, and Washington and the U.S. Department of Agriculture in 2000. Klamath Russet was tested in irrigated trials in Oregon from 1990 to
1999 and in Western Regional Trials from 1994 to 1996. Klamath Russet yields of U.S. #1s have exceeded those for Russet Burbank and
Russet Norkotah by more than 30%, averaged across all trials. Klamath Russet is moderately resistant to Verticillium wilt and highly
resistant to common scab. Specific gravity for Klamath Russet has averaged 1.076 across all trials compared with 1.070 and 1.081 for
Russet Norkotah and Russet Burbank, respectively. Klamath Russet is not considered suitable for french fry production because of high
sugar and low starch contents.
Pavek, JJ* and DL Corsini. "Utilization of Potato Genetic Resources in Variety
Development." E-mail: sjpavek@gemstate.net
[Vol. 78, 433-441]
Potato varieties of Europe, widely grown prior to the late blight epidemic of the 1840s, were apparently derived mainly from Chilean
Solanum tuberosum Group (Gp) Tuberosum and with contributions from Gp Andigena. A small number of these old varieties had
field resistance and consequently survived the late blight. These survivors, along with a limited number of 19th and early 20th century
introductions, provided the very narrow genetic base for our modern potato variety development. Beginning in the first half of the 20th
century, resistance to diseases and pests from exotic species and primitive relatives was backcrossed into the existing parental
stocks, with little improvement in broadening of the genebase. By the 1980s, 77% of European and somewhat fewer North American
varieties had genes, derived by backcrossing, from S. demissum (late blight resistance) and Andigena (resistance to cyst nematode).
Broadening of the Tuberosum genebase was undertaken in 1959 by creating long-day adapted Neo-Tuberosum (N-T) from large
populations of Andigena. This took six or more cycles of recurrent mass selection. Simmonds, in England, was the first to begin this work,
followed shortly after by Plaisted, in the U.S., and Tarn, in Canada. Varieties with N-T in their pedigrees include the New York releases
"Rosa", which is 50% N-T, and "Eva", 25% N-T. The Tuberosum genebase has also been broadened with diploid
Gp Phureja resulting in the releases of "Yukon Gold," with yellow flesh and high internal quality, and "NorValley,"
a chipper with resistance to cold sweetening. Over 5000 accessions of about 150 wild species are available to breeders from the U.S.
Department of Agriculture. National Research Support Project 6 (NRSP-6) genebank. Many of these accessions have been evaluated for
resistance to diseases and pests as well as other important traits. Six genebanks in other countries also have many accessions for
breeders. These seven collections are a great source of valuable traits for breeding, but remain under-utilized, mainly because of the time
and additional resources required in eliminating the "wildness" characters associated with the desired traits.
"Pre-breeding" is needed to help breeders utilize the many needed genes and alleles in the wild species. There now are two
projects with pre-breeding as an objective in the U.S., one at Madison, WI, and the other at Prosser, WA. Resistance to cold sweetening (low
sugar build up in cold storage) has been backcrossed from several wild species into the Tuberosum background, as has resistance to
late blight, the Columbia rootknot nematode, and the potato leafroll virus (PLRV). Resistance to potato virus Y (PVY) and PLRV obtained
from N-T has been incorporated into Tuberosum parental stocks. Durable resistance to late blight in Polish breeding stocks, with
S. demissum and S. stoloniferum background, and in improved Bolivian and Peruvian Andigena has also been utilized by
North American programs.
Peters, RD, H Forster, HS (Bud) Platt, R Hall and MD Coffey. "Novel Genotypes of Phytophthora
infestans in Canada during 1994 and 1995." E-mail:
petersr@agr.gc.ca [Vol. 78, 39-45]
Populations of Phytophthora infestans, causing late blight of potato, changed significantly in Canada in the mid-1990s.
The US-1 genotype (A1, metalarxyl-sensitive [MS]) was displaced by novel genotypes (mainly US-8) in much of the country in 1994 and
1995. Many of the new genotypes were insensitive to metalaxyl and were of the A2 mating type, although metalaxyl-insensitive (MI) A1
isolates of the g11 (or US-11) genotype were found in British Columbia. A total of 14 unique multilocus genotypes were described over
the two years of the study based on mating type (A1 or A2), metalaxyl sensitivity (MS or MI), allozyme banding patterns (Gpi and Pep), and
random amplified polymorphic DNA (RAPD) markers. Six of these genotypes could be distinguished by allozyme banding patterns of the
Gpi locus alone; RAPD analysis revealed additional variation within allozyme groupings and defined additional genotypes. Among 82
isolates collected from various Canadian provinces in 1994, US-1 and US-8 constituted 30% and 49% of isolates, respectively; other
genotypes occurred in minor frequency. Among 50 isolates collected in 1995, US-1 and US-8 constituted 10% and 49%, respectively.
Isolates of g11 (US-11) were found in British Columbia in 1995. Diversity of genotypes was greater in 1994 (11 genotypes) than in 1995
(six genotypes). We hypothesize that sexual reproduction may have been responsible for generating some of the genetic variability in
P. infestans populations, during a time period in which A2 isolates first migrated into many provinces in Canada.
Plaisted, RL, DE Halseth, BB Brodie, SA Slack, JB Sieczka, BJ Christ, KM Paddock and MW Peck.
"Eva: A Midseason Golden Nematode- and Virus-resistant Variety for Use as Tablestock or Chipstock."
E-mail: rlp3@cornell.edu [Vol. 78, 65-68]
Eva is a new potato variety being released by the New York and Pennsylvania Experiment Stations. Eva is notable for its bright clear
skin and attractive round to oval shape. It produces a chip color comparable to Monona from 9 C storage and has specific gravity .014 less
than that of Atlantic. It has exceptionally long tuber dormancy and has extreme resistance to PVX, PVY, and race R01 of the golden nematode.
Scab resistance is like that of Monona. It is expected that Eva will find primary acceptance as a tablestock variety.
Platt, HW (Bud) and WJ Arsenault. "Management of Nitrogen and Phosphorus Rates Does
Not Suppress Verticillium Wilt in Yukon Gold." E-mail:
platth@agr.gc.ca [Vol. 78, 215-219]
Effect of nitrogen and phosphorus fertilization rates on the incidence of Verticillium wilt caused by Verticillium albo-atrum
or V. dahliae and tuber yield in potato cv Yukon Gold was evaluated in field plots. In three years of study, V. albo-atrum
caused a higher incidence of wilt symptoms (74%-100%) than V. dahliae (5%-81%) resulting in lower marketable tuber yield. In
plots infested with V. albo-atrum, tuber yield ranged from 12.3-22.8 T ha compared to 18.1 - 31.5 T ha in plots infested with
V. dahliae. Application of nitrogen above (280 kg ha) or below (70 kg ha) the recommended rate of 140 kg ha at planting did
not suppress foliar symptoms or protect against yield loss caused by either V. albo-atrum or V. dahliae. Similarly,
phosphorus rate adjustments did not consistently affect disease incidence regardless of the pathogen. Management of nitrogen or
phosphorus fertility rates at planting does not appear to be a viable approach for suppressing Verticillium wilt in the determinant,
wild-susceptible, cultivar Yukon Gold.
Rykbost, KA, R Voss, SR James, AR Mosley, BA Charlton, DC Hane, RH Johansen, SL Love, and
RE Thornton. "Mazama: An Early Maturing, Bright Red-Skinned Cultivar for Fresh Market."
E-mail: kenneth.rykbost@oregonstate.edu [Vol. 78, 383-387]
Mazama, an early maturing red-skinned cultivar for fresh market use, was jointly released in 2000 by the Agricultural Experiment Stations
of Oregon, North Dakota, California, Idaho, and Washington. Mazama was tested in irrigated trials in Oregon from 1999 to 2000 and in the
Western Regional Trial in 1994, 1995, and 1997. Mazama produces lower total yields than Dark Red Norland and Red LaSoda, but similar
marketable yields with a high percentage of small, high-value tubers and significantly fewer culls. In 22 location-years of replicated Oregon
and California trials, Mazama produced 40% and 26% higher marketable yields of U.S. #1s under 280 g than Red LaSoda and Dark Red
Norland, respectively. In three years of replicated trials in six western states, Mazama produced 115% and 102% of marketable yields of
U.S. #1s under 280 g compared with Red LaSoda and Dark Red Norland, respectively. Mazama tubers are smooth skinned and shallow
eyed. Mazama's bright red color does not fade in storage. Mazama is less susceptible to potato virus Y than Dark Red Norland or Red
LaSoda.
Rykbost, KA, R Voss, SR James, AR Mosley, BA Charlton, DC Hane, RH Johansen, SL Love and RE
Thornton. "Winema: An Early Maturing, Red-Skinned Cultivar for Fresh Market."
E-mail: kenneth.rykbost@oregonstate.edu [Vol. 78, 371-375]
Winema, an early maturing, red-skinned cultivar for fresh market use, was jointly released in 2000 by the Agricultural Experiment
Stations of Oregon, North Dakota, California, Idaho, and Washington. Winema was evaluated in irrigated trials in Oregon and California
from 1990 to 2000 and in the Western Regional Trial in 1995, 1997, and 1998. Winema has produced lower total yields than Dark Red
Norland and Red LaSoda at most locations, but similar or higher marketable yields and significantly fewer culls. In 20 location-years of
replicated Oregon and California trials, Winema produced 108% and 99% of marketable yields of tubers under 280 g compared with
Red LaSoda and Dark Red Norland, respectively. Similarly, in 23 location-years of The Western Regional Trial in 6 western states,
Winema produced 109% and 92% of marketable yields of tubers under 280 g compared with Red LaSoda and Dark Red Norland,
respectively. Winema tubers are smooth-skinned with shallow eyes. Winema's bright red color does not fade appreciably in storage.
Winema is susceptible to potato virus Y (PVY). Foliar symptoms of PVY are difficult to detect visually.
Salas, Alberto R, David M Spooner, Zosimo Huaman, Rafael Vinci Torres Maita, Roel Hoekstra,
Konrad Schuler, and Robert J Hijmans. "Taxonomy and New Collections of Wild Potato Species in Central and Southern Peru
in 1999." E-mail: a.salas@cgiar.org
[Vol. 78, 197-207]
Peru contains about half of the described wild potato taxa, and many of these are not yet preserved in genebanks. This paper reports
results of the second of a series of five planned collecting expeditions to Peru. Collections were made in the central Peruvian departments of
Ancash, Huancavelica, La Libertad, and Lima, from March 8 to April 25, 1999. They follow collections in 1998 in the southern Peruvian
departments of Apurimac, Arequipa, Cusco, Moquegua, Puno, and Tacna. We collected 101 germplasm accessions, including first
germplasm collections of the following 22 Solanum taxa: Solanum amayanum, S. anamatophilum, S. arahuayum (lost in
germplasm increase), S. augustil, S. bill-hookeri, S. cantense, S. chavinense, S. chomatophilum var. subnivale, S. chrysoflorum,
S. gracilifrons, S. hapalosum, S. huarochiriense, S. hypacrarthrum, S. jalcae, S. moniliforme, S. multiinterruptum, f. longipilosum, S.
taulisense (lost in germplasm increase), and S. wittmackii. In addition, new collections were made of the under-collected species
S. hastiforme (three collections). The above taxonomy is that used in planning our expedition, that we compare to a new treatment
of Peruvian wild potatoes published by C. Ochoa in 1999. This paper reports the collection and new species identifications of the 1999
collections, and germplasm conservation and survival of the 1998 and 1999 collections. In addition, chromosome counts are provided for
134 accessions from the 1998 and 1999 expeditions, including first reports for S. chomatophilum var. subnivale (2n = 2x = 24),
S. megistacrolobum subsp. purpureum (2n = 2x = 24), and S. multiinterruptum var. multiinterruptum f. albiflorum
(2n-= 2x = 24); we also report the first triploid count of an accession of S. immite.
Sowokinos, Joseph R "Allele and Isozyme Patterns of UDP-glucose Pyrophosphorylase as a
Marker for Cold-Sweetening Resistance in Potatoes." E-mail:
sowok001@umn.edu [Vol. 78, 57-64]
Uridine-5-'diphosphoglucose pyrophosphorylase (UTP a-d-glucose-1-phosphate uridylyltransferase, E.C. 2.7.7.9) (UGPase) was
cloned from 16 potato cultivars (Solanum tuberosum L.) that differed in their ability to accumulate reducing sugars in cold
storage (3 C) using RT-PCR. Two UGPase-alleles designated as UgpA (minus a BamH1 site) and UgpB (containing one BamH1 site),
were present in most cultivars. Cultivars that were cold-resistant (CR) to sweetening demonstrated an UgpA:UgpB ratio favoring the
UgpA allele (4:0 or 3:1) while cultivars that were cold-sensitive (CS) exhibited a predominance for the UgpB allele (1:3 or 0:4). Following
cold-storage at 3C for two months, the CR and CS clones accumulated 10.3 ±2.1 and 31.2 ±
2.2 umol glucose/g FW, respectively. The glucose content and chip color between the CR and CS clones were significantly different at
the 99% level of confidence. Staining for UGPase activity in nondenaturing polyacrylamide gels of proteins extracted from CS potatoes
revealed up to three acidic isozymes of UGPase (i.e. UGP1, UGP2, UGP3) with UGP3 being the most abundant. Activity staining using CR
cultivars demonstrated two additional isozymes of UGPase with greater electrophoretic mobility (more basic in charge) which were
designated UGP4 and UGP5. The potential for using UGPase allelic ratios and/or UGPase isozymic patterns as a selective tool to screen
segregating progeny in a potato breeding program for cold-sweetening-resistant germplasm is discussed.
Sowokinos, Joseph R "Biochemical and Molecular Control of Cold-Induced Sweetening
in Potatoes." (Invited Review) E-mail:
sowok001@umn.edu [Vol. 78, 221-236]
The benefits of being able to process potatoes directly into chips or fries from cold storage (2 to 4 C) include less shrinkage, retention of
dry matter, decreased disease loss, extended marketability, and the elimination of the need for dormancy-prolonging chemicals. Unfortunately
at low temperature, potato tubers undergo a phenomenon known as cold-induced sweetening where the rate of conversion of starch to
reducing sugars (i.e. glucose and fructose) is accelerated. As raw potatoes are sliced and cooked in oil at high temperature, the
accumulated reducing sugars react with free amino acids in the potato cell forming unacceptably brown to black-pigmented chips or fries
via a non-enzymatic, Maillard-type reaction. Potatoes yielding these unacceptably colored products are generally rejected for purchase by the
processing plant. All commercial potato cultivars presently used for the production of potato chips and fries accumulate excess free reducing
sugars when exposed to cold stress. If a "cold-processing potato" was available, energy savings would be realized in
potato-growing regions where outside storage temperatures are cool. In regions where outside temperatures are moderately high,
increased refrigeration costs may occur. This expense would be offset, however, by removal of the need to purchase dormancy-prolonging
chemicals, by a decreased need for disease control and by improvement of long-term tuber quality. The primary goal of this review is to
describe recent research of a biochemical and molecular nature that relates to the underlaying mechanisms regulating post harvest,
cold-induced sweetening in potato tubers. No attempt was made to outline the extensive research conducted on the genetic manipulation
of carbon metabolism between starch and free sugars during photosynthesis and/or during potato development in relation to source/sink
interactions.
Spooner, David M and Robert J Hijmans. "Potato Systematics and Germplasm Collecting,
1989-2000." [Vol. 78, 237-268]
This paper reviews the systematics of wild potatoes over the past 11 years, in reference to the latest comprehensive taxonomic treatment
by Hawkes (1990. The potato: evolution, biodiversity and genetic resources. Belhaven Press, Washington, D.C.). Included here is
information on monographs and floras, new germplasm collections made since 1988 compared to total potato distributional data, new
taxonomic changes (including synonymy and new species descriptions), ingroup and outgroup relationships, intraspecific studies,
diversity studies, and fingerprinting. In addition, data supporting taxonomic changes and phylogeny from ploidy levels, Endosperm
Balance Numbers, and morphological studies of taxonomically important characters are reviewed. A revised list of 206 species is
presented (from 232 in Hawkes) that incorporates recent synonymy of names, recognition of new names, and new species descriptions.
New germplasm collections of 58 potato taxa were collected that did not occur in genebanks before 1988.
Spooner, David M, Roel Hoekstra and Braulio Vilchez. "Solanum Section Petota in
Costa Rica: Taxonomy and Genetic Resources." E-mail:
dspooner@wisc.edu [Vol. 78, 91-98]
Prior to 1996, worldwide holdings of germplasm of wild potatoes from Costa Rica amounted to just two collections; this country
therefore formed a priority for collecting. We mapped all localities of wild potatoes from herbarium specimen data from Costa Rica
and collected throughout the country. We made 13 collections, 10 of these with botanical seeds. These collections considerably
extend the numbers of accessions and geographic range of the germplasm available from Costa Rica. The taxonomic identity of the
species of wild potatoes (Solanum sect. Petota) in Costa Rica was previously unresolved. Our fieldwork supports the
concept that Costa Rican wild potatoes belong to a single species, S. longiconicum.
Yee, Shirley, Birt Stevens, Shirlyn Coleman, Jane EA Seabrook and Xiu-Qing, Li. "High-Efficiency
Regeneration in vitro from Potato Petioles with Intact Leaflets."
E-mail Shirlyn Coleman: shirlyn.coleman@gnb.ca
[Vol. 78, 151-157]
The shoot/plantlet regeneration in vitro of seven potato (Solanum tuberosum L.) cultivars from petioles with intact
leaflets was assessed using six treatment combinations - a basal medium with or without silver thiosulphate (STS) or thidiazuron (TDZ)
at two concentrations of 2 or 0.5 mg/l) of the indoleacetic acid (IAA). The basal medium consisted of Murashige and Skoog (MS) salts and
vitamins supplemented with 3 mg/l 6-benzylaminopurine, and 1 mg/l gibberellic acid, 30 g/l sucrose, and 7.0 g/l phytoagar. Two full sets
repeats and one partial set repeat of independent experiments were conducted and all produced similar results. Silver thiosulphate
decreased the regeneration rates of (100%) with up to 20 shoots/plantlets per callus were achieved at 2 mg/l IAA with cultivars Desiree,
Kennebec, Niska, and Lenape. These cultivars still showed high regeneration rates (87% - 98%) on media with 0.5 mg//l IAA, and good
regeneration rates were also achieved by the other three cultivars (48%, 94%, and 50% for Chieftain, Russet Burbank, and Shepody,
respectively). Even with the single medium protocol (0.5% IAA without thiosulphate or thidiazuron), Desiree, Lenape, and Niska exhibited a
regeneration rate of 98%. The use of petiole-with-leaflet explants could be ideal for the regeneration step of potato genetic transformation
protocol because of their high regeneration efficiency and their small cut surface area for Agrobacterium elimination after
co-incubation.