Bird, GW & J Chen "Below-Ground Potato Plant Architecture in Early-Die Soil: With Special Reference to Pratylenchus penetrans (Nematoda)." [Vol. 78, 443]

Under both field and greenhouse conditions, the below-ground architecture of potato plants differed significantly (P=0.05) during the first 45 days after planting in the present and absence of early-die soil. Plants were destructively sampled every five days from 10 to 45 days after seed piece planting. Plant resources were partitioned into basal roots, nodal roots, stolon roots, tuber roots, stolons, tubers, below-ground stems and above-ground tissue. All seven of the below-ground parameters had significantly (P=0.05) less dry weight (grams/plant) associated with one or more of the sampling dates when grown in early-die, compared with non-early-die soil. Significant differences (P=0.05) in basal and nodal roots were noted as early as 30 days after planting. Pratylenchus penetrans (Nematoda) was recovered from both stolon and root tissue as early as 30 days after planting. P. penetrans was present in stolon tissue at all subsequent sampling dates when the plants were grown in early-die. A graphic model of the patterns of plant development associated with early-die and non-early-die soil indicated that normal early-season development of basal roots is very important, if not essential for development of a healthy potato plant.

Bird, GW, M Otto, N Hoff, R Brook & R Gore. "Potentials of Precision Agriculture Technology in Potato Early-Die Management." [Vol. 78, 443]

A potato research project was initiated in 1999 to evaluate the potential of precision agriculture technology on potato early-die (PED) management decision-making. A 62.1 acre Michigan commercial potato field in Montcalm County was geo-positioned on a one-acre grid basis and sampled for Pratylenchus penetrans (Nematoda) and Verticillium dahliae (Mycota). In 2000, a PED risk map (1-3) was constructed from the resulting data. The map was used to locate five replicates (16 row by 200 ft) of each of three spring applied soil fumigation treatments (0, 37.5 and 75 gpa, metham) randomly selected throughout the site in each of the three PED risk categories (n = 45). The pathogens were monitored and tuber yields and quality recorded at harvest. The technology allowed for excellent prediction of tuber yield from the PED risk map, and assessment of the economics and environmental impact potentials of variable rate soil fumigation. In 2000, in a commercial potato field in St. Joseph County, geo-positioned PED risk maps allowed a linear regression model to account for a high degree of the variance within tuber yield.

Bisognin, Dilson, Lynn Buszka & David Douches "Mapping Late Blight Resistance and other Agronomic Traits in a S. microdontum Population."  [Vol. 78, 444]

We developed a diploid population with the objectives to map quantitative trait loci conferring late blight (LB) resistance using isozymes and SSR marker and to examine associations between LB resistance and other agronomic traits. The mapping population was a cross between S. microdontum(PI 595511) and a susceptible clone. The progeny of 110 clones and the parents were evaluated at the Muck Soil Research Farm, Bath, MI in 1999 and 2000 for foliar late blight reaction using complex races of US8/A2 mating type of P. infestans. Disease severity was quantified as the relative area under the disease progress curve based upon the percentage of foliar infection over time. This population was also evaluated at Montcalm Research Farm, Entrican, MI for maturity, tuber number and size, yield, tuber appearance, specific gravity, and chip color. High phenotypic correlation (r = 0.89, P < 0.0001) was found for LB reaction between years. No correlation was found between LB and maturity. One allozyme and 14 SSR markers were linked with LB resistance in at least one environment. From these markers, 3 mapped to chromosome I, 1 to chromosome VII, 3 to chromosome VIII, and 2 to chromosome XII. One marker was linked with LB resistance in both environments and with maturity, but four other markers were linked with both maturity and LB resistance in one environment. A total of 13 markers were linked with all tuber traits. The use of this information in a marker assisted selection program will be discussed.

Blenkinsop, Robert W, Leslie J Copp, Alejandro G Marangoni & Rickey Y Yada. "A Potentially Important Role for Anaerobic Carbohydrate Metabolism in Determining Chip Quality of Cold-Stored Potato Tubers." [Vol. 78, 444]

The storage of potato tubers at low temperatures (ie., <10 EC) initiates a process known as low temperature sweetening (LTS), which results in the conversion of starch to sugars. High levels of reducing sugars lead to undesirable nonenzymatic browning during potato chip frying operations. This is an update of an ongoing study elucidating the biochemical differences in carbohydrate metabolism between a cold-tolerant selection (ND 860-2) and a cold-sensitive cultivar (Novachip) during 4 EC storage. Carbohydrate metabolism was evaluated by measuring respiration rate, enzymatic activity (PFK, G6PDH, 6PGDH, ADH), chip color, solids content, weight loss, as well as levels of reducing sugars, NADH, NADPH, ATP, lactate and ethanol. Following three years of study (1997-1999), concentrations of ethanol and lactate consistently showed good correlation with chip color quality. Higher levels of these metabolites in the cold-tolerant selection may be indicative of an overflow pathway of glycolysis; observed trends support the existence of a greater glycolytic flux in the cold-tolerant selection. These trends were further supported by results from the 2000 growing season involving an additional cold-sensitive cultivar (Monona) and two cold-tolerant selections (Wis 1355-1 and V 0056-1).

Bohl, William H & Stephen L Love. "Effect of Planting Depth and Hilling Practices on Yield and Quality of Russet Burbank and Gem Russet Potatoes."  [Vol. 78, 444]

Previous work has shown that planting Russet Burbank seed pieces 15 cm deep decreased total yield when compared with planting 8 cm deep. In the study reported here, depth of post-planting hilling was investigated. Russet Burbank and Gem Russet potatoes (Solanum tuberosum) were planted in 1998, 1999, and 2000. Treatments included a 15-inch non-hilled control, planting at 8 or 15 cm and later hilling to either 15 or 23 cm at emergence or hilling post emergence (PE) after plants formed a rosette approximately 3 to 6 cm in diameter. Compared with the control, all PE hilling treatments significantly decreased Russet Burbank total and U.S. No. 1 yields. Effect of planting and hilling practices on Gem Russet yield were not as clear. All treatments except plant 8 - hill 15 cm and plant 15 -hill 23 cm PE decreased total yield of Gem Russet. Hilling Gem Russet from 8 to 23 cm, 8 to 15 cm PE, or 8 to 23 cm PE resulted in significantly lower U.S. No. 1 yield when compared with the control. Hilling treatment had some impact on yield of green tubers for Russet Burbank and the plant 8 - hill 23 at emergence, plant 8 - hill 23 PE, and plant 15 - hill 23 PE treatments reduced green yield. However, planting depth and hilling practices did not significantly affect the green yield of Gem Russet. Hilling treatments had a distinct impact on vertical tuber distribution in the hill.

Bradeen, James M, S Kristine Naess, Susan M Wielgus, Jeffrey A Davis, Geraldine T Haberlach & John P Helgeson. "Cloning Late Blight Resistance from Solanum bulbocastanum. Bradeen" [Vol. 77, 445]

Late blight remains one of the most important potato diseases worldwide. The wild diploid Mexican species Solanum bulbocastanum is highly resistant to all known races of late blight but cannot be crossed to cultivated potato. We generated somatic hybrids between potato and S. bulbocastanum. The somatic hybrids are fully resistant and resistance segregates in each of three subsequent backcross generations to potato. Late blight resistance maps to S. bulbocastanum chromosome 8. Map location, durability, and lack of race-specificity suggest S. bulbocastanum resistance differs from previously employed R genes. Using markers linked to resistance, we screened an S. bulbocastanum BAC library, recovering multiple BAC clones for each marker. End sequencing allowed the generation of walking probes for contig extension. Nearing completion, the contig is expected to encompass more than 1MB of DNA. Additional mapping efforts, including the identification of individuals recombinant in  the late blight resistance region, will allow us to localize the gene or genes responsible to 4 overlapping BAC clones. These clones will be entirely sequenced by our colleagues at The Institute for Genomic Research (TIGR), allowing detailed sequence analysis. Once late blight resistance genes have been identified and confirmed, they will be incorporated into important potato cultivars.

Brown C. R, R Wrolstad, & B Clevidence. "Genetic Variation in Potato with High Levels of Red and Blue Anthocyanins." [Vol. 78, 446]

It is customary to think of potato flesh as either white or various degrees of yellow, reflecting qualitative and quantitative variation of xanthophylls in the flesh. Red and blue colors in the tuber flesh are due to another class of compounds, the anthocyanins. The total anthocyanin content of red and blue fleshed potato ranged from 5 to 35 mg/100g fresh weight. As a dried preparation anthocyanin content falls between strawberries and raspberries. Red pigmented potatoes contained predominantly acylated pelargonidin glycosides comprising about 80% of the total, while blue-fleshed potatoes contained these compounds, and, in addition, acylated petunidin glycosides in a 2 to 1 ratio of the former to the latter. Segregation ratios confirmed the single gene control of presence and absence of either blue or red pigmentation in the skin, and the flesh. The extent of pigmentation in the flesh appeared to be under polygenic control. Solidly pigmented potatoes displayed two to three times higher antioxidant potential than white-fleshed potato, placing high-anthocyanin potato in the range of other vegetables of reputed high antioxidant potentials such as kale and broccoli. Antioxidant food supplements have been implicated in benefiting cardiovascular health, preventing certain types of cancers, and retarding macular degeneration of the retina. Potato offers a vehicle to substantially increase consumption of antioxidants especially in snack foods. These potatoes provide a new health-promoting marketing identity for potato.

Carrera, Lidia M, Ronald Morse, Aref A Abdul-Baki, Kathleen Haynes & John R Teasdale. "Production of Creamer Potatoes in No-Tillage Cover Cropping System. "[Vol. 78, 446]

Conservation tillage conserves soil and together with cover crops improves soil fertility and controls weeds. We evaluated an alternative production system using raised beds, cover crops, and no tillage in creamer potato  (Solanum tuberosum L.) production. The experiments were conducted in two locations, Beltsville, MD, and Blacksburg, VA. The experimental design was a split plot with nine cover crops as main plots, and three potatoes clones (B1145-2, B1491-5, B1492-12) as subplots. The cover crops were rye (R), crimson clover (CC), brassica (BR), Austrian winter peas (AWP), R + CC, BR + CC, CC in flat beds, and bare soil both in flat and raised beds. Yields, weed biomass and disease resistance were recorded. Yields at both locations were significantly influenced by the cover crops. Highest yields at both locations were obtained with R + CC mixture reaching 22 and 15.3 t.ha-1 in MD and VA, respectively. B1145-2 was the highest yielding clone at both locations. The performance of the remaining eight cover crops varied greatly between locations. There were significant clone x cover crop interactions at both locations. These results suggest that use of cover crops and no-tillage appear to be a viable and economic system. However, optimum performance of cultivars depends on selecting the appropriate cover crop for the location.

Chang, Dong Chil, Sung Y, Kim, & Young Il Hahm. "Influence Iron and Manganese Concentration in Nutrient Solution on Growth and Mineral Content of the Potato Plants."" [Vol. 78, 447]

Potatoes (Solanum tuberosum L.) cvs. ’Atlantic’ and ’Superior’ were grown in glasshouse to study the influence of Mn and Fe on plant growth and mineral nutrition. Potato solution containing 0, 0.5, 10, 50, 100 mg·L -1 of Mn, and 0, 3, 10, 50, 100 mg·L -1 of Fe were supplied to potato plants growing in solution cultures. Visual symptoms by Fe and Mn levels in the nutrient solution were observed in the color of plant tops. During the 45-days of growth, Mn-induced yellowing with green veins of young Atlantic leaves was associated with concentrations of 50 mg·L -1 Mn and higher in nutrient solution. With increased toxicity, young leaves of Superior showed blackspotting along the midrib and veins as well as yellowing. In particular, plant growth such as stem height, top fresh weights and stolon dry weights were reduced in 100 mg·L -1 Mn levels. Potato plants grown at 0 mg·L -1 Fe had increased top fresh weights and root dry weights, but showed a delayed tuberization. On the other hand, the middle and lower leaves of potato grown at 100 mg·L -1 Fe showed yellow-green interveinal and marginal necrosis and eventually dried. These toxicity symptoms of Mn and Fe were more increased in severity with Superior than with Atlantic and were associated with mineral contents of potato leaves as follows: As the supply of Mn or Fe increased, T-N content of leaves decreased only at 100 mg·L -1 Mn or 0 mg·L -1 Fe, K increased, but Ca and Mg decreased, whereas P was unaffected.

Coombs, Joseph, David Douches, Edward Grafius, Walter Pett & Dale Moyer.  "Field Evaluation of Natural and Engineered Potato (Solanum tuberosum L.) Resistance Mechanisms for Control of Colorado Potato Beetle (Leptinotarsa decemlineata Say)."  [Vol. 78, 448]

The Colorado potato beetle (CPB), is the leading insect pest of potato in northern latitudes. Host plant resistance is an important tool in an integrated pest management program. Field studies were conducted to compare natural (glandular trichomes and high total glycoalkaloids), engineered (Bt-cry3A), and combined (glandular trichomes+Btcry3A and glycoalkaloids+ Bt-cry3A transgenic potato lines) host plant resistance mechanisms of potato for control of CPB. Twelve different potato lines representing five different host plant resistance mechanisms were evaluated in a choice situation under CPB pressure in Entrican, Michigan and in Riverhead, New York. Treatment plots were planted in the field between alternating rows of a susceptible guard in a randomized complete block design consisting of four replications of ten plants each. Observations were recorded weekly for a visual estimation of percent defoliation by CPB, and the number of egg masses, larvae, and adults. The high glycoalkaloid line, the Bt-cry3A transgenic, and the combined resistance lines were effective in controlling feeding by CPB adults and larvae. Effectively no feeding was observed in the high glycoalkaloid+Btcry3A transgenic line, which was significantly less than one of the Bt-cry3A transgenic lines at the New York location. The glandular trichome line suffered less feeding than the susceptible control. Based on these results, the Bt-cry3A transgenic, glandular trichome, and high glycoalkaloid lines are effective tools that could be incorporated in a resistance management program for control of CPB.

Copp, Leslie J, Robert W Blenkinsop, Rickey Y Yada & Alejandro G Marangoni. "Effect of Chlorpropham (CIPC) upon Carbohydrate Metabolism During Storage of Chipping Potatoes." [Vol. 78, 449]

Two chipping cultivars, Snowden and Monona, with or without Chlorpropham (CIPC) application, were stored in darkness at 12 C and approximately 95% humidity. Chip color, dry matter and protein contents were evaluated over 30 weeks of storage. Tuber concentrations of sucrose, reducing sugars, and major metabolites and enzymes of the pathways of glycolysis, pentose phosphate shunt, anaerobic and oxidative respiration were also monitored during storage. Initially, chip color quality was lower for CIPC-treated tubers, but recovered to exceed that of untreated tubers after approximately 10 weeks of storage. Respiration, as measured by CO2 production, was significantly (P < 0.05) suppressed in CIPC-treated tubers. CIPC treatment had no significant (P > 0.05) effect on tuber concentrations of protein, dry matter, sucrose, reducing sugars, the assayed enzymes and metabolites of glycolysis (phosphofructokinases, NADH, ATP) or the enzymes of the pentose phosphate shunt (glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase). NADPH, a product of the pentose phosphate shunt, was elevated in untreated tubers, consistent with its role in biosynthetic pathways involved in sprout production. Concentrations of ethanol and lactate, products of anaerobic respiration, were significantly (P < 0.05) higher in the CIPC-treated Snowden tubers, relative to the untreated tubers.

Corsini, Dennis, Richard Novy, Annie Marshall & Joseph Pavek. "Protein Levels in Potato Breeding Selections and Cultivars." [Vol. 78, 449]

The protein levels of 379 second field generation potato breeding selections were measured by the Comassie Blue procedure in 1995 to determine the range of protein present in cultivated potato grown under irrigated conditions in the northwest. One objective was to select low protein clones suitable for use in protein restricted diets. These selections were derived from a broad range of potato germplasm including cultivated diploids, S. andigena, and hybrids with wild species. The mean percent protein on a fresh weight basis (FWB) was 0.95%, and the median was 0.94%. Only 12 selections were below the standard deviation from the mean of replicated Russet Burbank control plots (0.70% ± 0.08%). The three highest selections had over 1.4% protein. In 1996 the clones with highest and lowest protein levels were retested, and 90 cultivars in the USDA/ARS (Aberdeen, ID) collection were also screened for protein levels. The mean % protein for the cultivars was 0.82% and median was 0.79% FWB. Atlantic, Lenape, Pilica, Russet Nugget, and Suncrisp were among the highest with over 1.1% protein FWB. Crestone Russet, Granola, Agria, Centennial Russet, and Ptarmigan were the lowest at less than 0.6% protein FWB. In subsequent years of testing, Crestone Russet and Granola continued to show protein levels as low as those of the 3 lowest protein breeding selections.

Davis, James R & Ann T Schneider. "Effects of Azoxystrobin (Quadris) Rates on Colletotrichum coccodes and Verticillium dahliae Colonization in the Russet Burbank Potato." [Vol. 78, 452]

Greenhouse studies showed control of the black dot disease caused by Colletotrichum coccodes when azoxystrobin (Quadris by Zeneca) was applied to foliage of the Russet Burbank potato at 9.5 ppm. With this treatment, C. coccodes lesions were reduced by 80 to 94%, and the colonization of C. coccodes in stem tissue was reduced by >99%. Following three additional greenhouse studies, the threshold rate needed to suppress C. coccodes was found to range from 1.25 to 2.50 ppm. These results were obtained by either spraying Quadris at six different rates (0.0, 0.7, 1.25, 2.50, 5.00, and 10.00 ppm) to run off, followed by foliar inoculations with C. coccodes at 105 cells ml-1, or by applying 0.1 ml of each respective treatment to 15 cm pots of naturally infested field soils to which 5.0 ml of 105 C. coccodes inoculum had also been added. In contrast to the effect on C. coccodes, Quadris had no effect on Verticillium dahliae, but as C. coccodes populations were reduced in Russet Burbank, V. dahliae populations increased. When Russet Burbank was grown in pots containing naturally infested field soil, Quadris reduced (P<0.05) the populations of C. coccodes in underground stem tissue while V. dahliae significantly increased (P<0.05). These results suggest that under these conditions C. coccodes is competing with V. dahliae.

De Jong, H, LM Kawchuk, WK Coleman, CA Verhaeghe, L Russell, VJ Burns & E Tremblay-Deveau. "Development and Characterization of an Adapted Form of Droopy, a Diploid Potato Mutant Deficient in Abscisic Acid." [Vol. 78, 451]

A cultivated diploid potato breeding population has been selected for adaptation to growing, tuberizing and storing (including long dormancy) under New Brunswick conditions. In this population a mutant was discovered which 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 was studied and compared in detail with the description of droopy. A major difference between the mutant described here and droopy is that our mutant has a relatively long tuber dormancy although similar endogenous abscisic acid levels were observed during storage when compared with the normal genotype. A test for allelism indicated that our mutant is allelic to droopy. Classical linkage analyses confirmed previously reported close linkage between the Dr 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 Souza-Dias, JAC; CM de Meo, A Greve, & LJ Paes. "High Quality Minituber Production by Planting Sprouts Detached from Imported Basic Seed Tubers under Aphid-Proof Screenhouse in a Brazilian Citrus Region." [Vol. 78, 450]

Last year, three orange producers in the citrus region of Limeira, SP, produced seed-potato minitubers from sprouts (Bryan et al., 1981, CIP: 20p.) detached from imported high-grade potato seed (Souza-Dias et al., 1998. Summa Phytopat. 24(1):73.). About 20 thousand sprouts of different varieties, sizing 2-3cm high per 0.3-0.7 cm large, were individually planted in U-shape plastic pots (10 cm x 10 cm), containing 2:1 (v:v) soil:Plantmax (Eucatex, Paulinia, SP), under aphid-free screenhouses, surrounded by over 50 km of orange orchards, free of any potato crop. At planting, 20 g/pot of fertilizer 4-14-8 was added. Regular preventive nutritional and disease treatments were applied biweekly. About 80 days after planting the number of minitubers from 2 to 5 cm in diameter per plant, was: Atlantic: 1 to 2; Agata, Mondial and Monalisa: 2-3 and Bintje: 2-4. Except for Atlantic, foliage and tuber DAS-ELISA in 0.5% of the plants revealed < 1 % of PLRV and PVY. Atlantic showed 2-3 % of PVY even after discarding near 4% of symptomatic plants (PVY+/ELISA). The production cost ranged US$ 0.05 to 0.10/minituber; but, 50 percent cost reductions are expected. Potato seed growers are initiating contracts with citrus growers and supplying them with sprouts and technical assistance. Minituber production from sprouts has proved to be an economic alternative, for citrus growers to earn income in during the current financial crisis.

del Rio, Alfonso H & John B Bamberg." Genetic Heterogeneity among Breeding Systems of Potato Species and its Ramifications in Germplasm Conservation."  [Vol. 78, 452]

Most germplasm in the US Potato Genebank is in the form of botanical seed populations. So, depending on the breeding system, plants within these populations may be highly heterozygous and heterogeneous. Or, if they are facultative selfers, they may be homozygous and perhaps also homogeneous. The population structure in this sense has a great impact on germplasm conservation and use. Specifically, the more heterogeneous plants within a populations are, the more care needs to be taken to avoid losing genes when that population is sampled for original collection, genebank multiplication, or evaluation for economic traits. This study used RAPD markers to investigate genetic heterogeneity (GH) among 18-24 plants in each of 21 potato populations from 3 species. These represented three different breeding systems observed in Solanum species: S. jamesii (diploid outcrosser), S. fendleri (disomic tetraploid selfer) and S. verrucosum (diploid selfer). Plants within all populations of selfing S.verrucosum and S. fendleri were very homogeneous (GH = 0.036 and 0.082, respectively). In contrast, outcrossing S. jamesii populations were all much more heterogeneous (GH= 0.295). This pilot study demonstrates the usefulness of RAPD markers to gain insights into population structure and thereby optimize the efficiency of germplasm preservation and use. A more comprehensive study is in progress.

Geary, Brad, DA Johnson & PB Hamm. "Influence of Seed-Borne Helminthosporium solani on Progeny-Tuber Disease Levels." [Vol. 78, 454]

Silver scurf of potato, caused by Helminthosporium solani, is a disfiguring disease of the tuber periderm that reduces marketability, particularly in fresh-marketed potatoes. Results of studies to determine if a relationship occurs between infected seed- and infected progeny-tubers suggest a relationship exists, however, not all studies agree. Results from this study further substantiate the importance of the disease level on seed tubers. In 1997 and 1998 (Washington), and in 1999 (Oregon), the level of H. solani was determined on both seed tubers in numerous seed lots, and then from the progeny (harvested) tubers from each seed lot. In 1999, disease levels were determined on  successive generations of certified seed (generation 1, 2, and 3) as well as the subsequent progeny tubers from each generation. There was a positive significant correlation between the severity of silver scurf on the seed and on the corresponding progeny tubers in all three years. As the severity of seed tuber infections increased, the amount of silver scurf on the progeny tubers also increased. Therefore, the use of silver scurf free seed is an important step when growing potatoes for the fresh market. However, disease severity of seed tubers did not account for the entire amount of disease increase on progeny tubers, indicating other factors also contribute to disease levels.

Groza, Horia, Timothy Connell, Bryan Bowen & Jiming Jiang. "Cultural Practice, A Tool in Promoting New Advanced Selections." [Vol. 78, 454]

Two advanced selections from the Wisconsin breeding program have been promoted for processing market, in demonstration trials: W 1355-1 (a cold sweetening  resistant chipping line) and W 1348 rus (a dual purpose russet line with good frying characteristics). The industry tuber size requirements are: 88% tubers over 170.1 g (TO1) and 10% tubers over 283.5 g (TO2) for chipping varieties, and 95% tubers over 170.1 g (TO1) and 30% tubers over 283.5 g (TO2) for frying varieties. In order to increase the proportion of larger tubers of these two W-lines cultural practice field trials, including hill spacing on a row and Nitrogen fertilization, have been conducted. Although good correlations were obtained between the hill spacing increase and the proportion of TO1, no significant improvements were recorded among spacing variants of 30.4, 38.1 and 45.7 cm. However the percentage of culls has increased at higher spacing distance for W 1355-1. Among the Nitrogen rates (201.6, 246.6 and 291.4 kg A.I./ha), used in two post emergent applications, the 246.6 kg/ha rate increased significantly the yield of TO2 in W 1348 rus.

Gunter, Christopher C & Jiwan P Palta. "Supplemental Calcium Application During Seed Tuber Production: Impact on Plant Quality and Yield the Following Year." [Vol. 78, 455]

Production of high quality seed tubers is of paramount concern to potato growers. High quality seed tubers are required to have freedom from defects and diseases, minimal sprouting and the capability for vigorous growth after planting. Little work has been done to examine the impact of the calcium concentration of seed tubers on the quality of the plant produced by that tuber the following season. Plots were established at a commercial seed production farm, on silt loam soil, in northern Wisconsin using the following cultivars, Superior, Dark Red Norland, Atlantic, Snowden, and Russet Burbank. Calcium was applied, in a split application, using calcium nitrate (9N-0P-0K-11Ca) at a rate of 168 kg/ha -1. Control plots received nitrogen only, from ammonium nitrate (34N-0P-0K), delivered at the same rate and timing as the calcium plots. It was found that the mean calcium content of the seed tuber can be raised following supplemental calcium application, resulting in an increased proportion of high calcium tubers in calcium treated plots. Supplemental calcium can increase mean tuber yield and may influence the growth of above ground stems and foliage produced early in the season. Results of these studies indicate that the odds of obtaining high yield are better if the seed piece contains high calcium and may indicate a positive relationship between calcium and yield when plotted across seasons.

Hale, Anna L, Luis Cisneros-Zevallos, John B Bamberg & J Creighton Miller, Jr. "Identification of Named Varieties, Advanced Selections, and Accessions with High Antioxidant Activity for use in Breeding Potatoes for Enhanced Human Health Benefits."  [Vol. 78, 455]

Potatoes are recognized by many consumers as an important source of carbohydrate, but little is known about their antioxidant content. Other crops, for example blueberries, are reported to be very high in antioxidants and have been promoted for this reason. However, the average per capita consumption of blueberries in the U.S. is only about 13.9 oz, compared to 145 pounds for potato. Thus, even moderate levels of antioxidants in potato could benefit human health and provide a basis for promotion of the crop. Therefore, the objective of this investigation was to assess the variability in potato for antioxidant activity. Some 25 varieties, 69 advanced selections, and 30 accessions were screened for total antioxidant activity. Antioxidants were extracted and allowed to react with the stable radical, 2,2,-Dipheny l-1-picrylhydrazyl (DPPH). This provided an easy and rapid evaluation of the antiradical activities of the potato extracts based on absorbance. Purple Peruvian, TXNS112, All Blue, ATX9312-1Ru, CORN8, ATX96007-1P/Y, Russet Norkotah, and TXNS296 were identified as significantly higher in total antioxidant activity. Significant differences were found between Russet Norkotah and its strains. In the subsequent screen, several wild relatives of potato were determined to be high in total antioxidant activity. The highest of these was a bulked sample of S. pinnatisectum. Of the varieties and advanced selections, NDC4069 and All Blue ranked highest. This variability is evidence for genetic control of antioxidant capacity and provides the opportunity to breed new potato varieties with increased human health benefits.

Halseth, DE "Survey of Environmental Conditions and Cultural Practices Associated with Embedded Stone Problems in Chip Potatoes." [Vol. 78, 456]

Chip processors frequently have had problems with embedded stones in early harvested potatoes. These small stones, often no larger than 3 mm in diameter, can break slicing knives and cause a loss in raw product because of improper slicing. There are many suggested reasons for this problem, including soil-type, soil compaction, rainfall events, and harvesting practices. Field samples of 100 tubers were collected at various locations in grower fields (from wheel tracks, wet spots, field headlands, non-compacted beds) and at several stages of the harvesting operation (off windrower, harvester, bulk body trucks, conveyors). Most samples were collected off of equipment, with a small number hand-dug for compaction comparisons. All samples were inspected for embedded stones before and after washing and again after an abrasive peeling. Results from samples collected during the 1998 - 2000 harvest seasons indicate no significant trends for embedded stones due to variety, nitrogen rates, vine-kill date nor harvester make. While a trend does exist for higher stone numbers in samples from later stages of the harvesting operation, no one harvest operation appears to contribute much more than another, so stone counts often are a function of additive effects of a series of harvesting operations. There does appear to be good correlation with soil type, soil compaction and also to rainfall within two days of digging on specific soil types.

Hamernik, AJ, M Ramon & RE Hanneman, Jr. "Modified Conventional Breeding Methods to Efficiently Transfer Unique Late Blight Resistance from 2x(1EBN) Mexican Species to 2x(2EBN) and 4x(4EBN) Breeding Lines." [Vol. 78, 456]

Several 2x(1EBN) Mexican species exhibit extreme late blight resistance, but have not been used in breeding because they do not readily cross with haploids or common cultivars due to EBN differences. Two methods have been developed using sexual hybridization to transfer germplasm from 2x(1EBN) species to the 2x(2EBN) and 4x(4EBN) levels. One uses double pollination techniques coupled with embryo rescue and has resulted in the formation of a S. pinnatisectum-Tuberosum haploid hybrid. This hybrid, though male sterile, has been successfully crossed as a female to 2x(2EBN) S. chacoense, S. phureja, S. sparispilum, and a 4x(4EBN) cultivar. A second method uses the Mexican species, 2x(2EBN) S. verrucosum, as a bridge species with 2x(1EBN) species. The 2x(1 1/2EBN) hybrids should segregate for EBN and therefore be crossable to 2x(1EBN) and 2x(2EBN) lines as well as to 4x(4EBN) parental material, if 2n gametes function. The 2x(1 1/2EBN) hybrids have been successfully crossed with 2x(2EBN) S. chacoense, S. phureja and Tuberosum haploids; with 2x(1EBN) S. commersonii, S. pinnatisectum and S. trifidum, and with a 4x(4EBN) cultivar. The derived hybrids have been crossed extensively with haploids and cultivars. We have demonstrated two modified conventional breeding methods to successfully transfer this resistance to the 2x(2EBN) or 4x(4EBN) level.

Hayes, Ryan J & CA Thill. "Identification of 4ºC Chipping in 12 Late Blight Resistant Solanum Species." [Vol. 78, 457]

Wild Solanum species contain variation for many traits having economic importance. Therefore, species and accessions combining desirable characteristics are useful in breeding new cultivars. Two breeding objectives in cultivar development are late blight (LB) resistance and cold (4 C) chipping. Using wild germplasm with reported LB resistance, the objectives of this research were to determine: 1) if variation for cold (4 C) chipping exists among Solanum species, accessions, and genotypes within accessions, and 2) if genotypes having LB resistance and 4 C chipping could be identified for use in co-current introgression. Chip color was evaluated on 665 genotypes from 43 accessions of 12 species having 1, 2 or 4 EBN, and 59 genotypes previously selected for having LB resistance. One chip per genotype was made after 6 mo. storage at 4 C, then scored 1-10 for color; scores < 4 are acceptable. Species differed for mean chip color and percentage of acceptable chipping genotypes and ranged from S. verrucosum (4.33-mean / 67%) to S. bulbocastanum (9.05 / 0). Accessions within species did not differ significantly for mean chip color. Accessions within S. berthaultii, S. cardiophyllum, and S. microdontum differed significantly for the frequency of genotypes chipping < 4. The best accessions tested were S. verrucosum PI 161173 (4.33-mean / 67%-acceptable), S. stoloniferum PI 250510 (4.36 / 64%), S. pinnatisectum PI 347766 (4.65 / 35%) and PI 275233 (4.73 / 44%), and S. megistacrolobum PI 195210 (5.14 / 29%). Co-current introgression is possible since 4 C chipping was detected within the 59 selected LB resistant genotypes. Sixteen genotypes were identified, 9 from S. pinnatisectum, 2 each from S. verrucosum, and S. trifidum, and 1 each from S. fendleri, S. stoloniferum, and S. microdontum.

Hayes, Ryan J "Early Generation Selection for Cold (4ºC) Chipping Potato Progenies" [Vol. 78, 457]

Chip color is a market-limiting trait for potato chipping cultivars; without light colored chips other traits have reduced importance. Storage at 4 C reduces storage losses, but dark chips typically result. Genetic variation for chip color from 4 C storage exists and acceptable genotypes can be selected. Combining this with early generation selection may promote rapid development of 4 C chipping cultivars. The research objectives were: 1) to identify early generations from which to select 4 C chipping genotypes, and 2) to compare differences among early generation groups. Progeny from 4x-4x crosses were field planted as single hills (SH) from greenhouse grown tubers (GT-173 families) and from seedling transplants (TR-97 families). Two populations were created at harvest, a group comprised of 20 random clones per family (3256-GT, 1940-TR) and selected clones lacking obvious tuber defects (189-GT, 204-TR). Progeny were chipped after 6 mo. storage at 4 C. The random group was additionally chipped after 3 mo. One chip per genotype was scored 1-10 for color, < 4 is acceptable. Acceptable chipping progeny were found across both storage durations and propagation methods (32-GT/14-TR, 3mo.) and (32-GT/12-TR, 6 mo.). Six GT progeny chipped < 4 after both 3 and 6 mo., but none in TR. Moreover, chip color means were significantly different (7.94-GT/8.49-TR, 3 mo.) and (8.00-GT/8.18-TR, 6 mo.). Selection is possible after 3 and/or 6 mo. storage in GT or in TR, but with higher false rejection in TR. Progeny chipping < 4 were identified within the selected group (5-GT/3-TR). Co-current selection is possible, but clones combining good tuber characteristics and 4 C chipping were rare. Future goals are to evaluate 4x-2x populations for frequency of desirable progeny and selection efficiency relative to 4x-4x.

Hornbacher, Andy, Nora Olsen, Phil Nolte & Lynn Woodell. "The Influence of Seed Growing and Storage Temperatures on the Performance of Five Seed Potato Cultivars. " [Vol. 78, 458]

Seed potato performance is important for obtaining uniform emergence, desired stem numbers and tuber size profile, and optimum yields. Individually evaluating potato cultivars should provide information to determine if environmental conditions during the seed-growing season influence subsequent seed performance, and to determine the optimum seed storage temperatures to create an ideal seed physiological age for the needs of the end user. During the 1999 and 2000 growing seasons, air and soil temperatures were measured in ‘Russet Burbank’, ‘Ranger Russet’, ‘Umatilla Russet’, ‘Shepody’, and ‘Russet Norkotah’ seed potato fields. Harvested seed tubers were stored at 1) 3.°C until planting, 2) 3.3 °C and 30 days at 7.2 °C prior to planting, 3) 3.3 °C and 15 days at 15.5 °C prior to planting to create three levels of heat unit accumulation. Seed tubers were planted in field trials (RCBD) and evaluated for performance. In 2000, ‘Russet Burbank’, ‘Shepody’, and ‘Russet Norkotah’ responded to elevated temperature storage treatments with earlier emergence and increased stem numbers. For ‘Russet Burbank’ stem numbers increased from 2.8 to 3.1, ‘Shepody’ 1.8 to 2.2, and ‘Russet Norkotah’ 2.5 to 2.7 with the highest level of heat unit accumulation in storage. Emergence and stem numbers for ‘Ranger Russet’ and ‘Umatilla Russet’ were not significantly impacted by storage treatments. No significant alteration in tuber size profile and yield were evident for the cultivars, however, trends were apparent among storage treatments. Seed performance data collected this season (2001) will be compared to 2000 data to evaluate seed-growing environmental influences.

Hughes, Becky R & Candy NF Keith. "The Effects of the Addition of Slow Release Fertilizer on the Yield and Size Distribution of Greenhouse-Grown Minitubers."  [Vol. 78, 458]

Three potato cultivars were grown to produce minitubers in the greenhouse in 1999 and 2000. Two slow release fertilizers, 14-14-14 and 20-7-10, were added to the regular liquid fertility program and a modified liquid fertility program. The effect on yield (number and weight of tubers) and tuber-size varied with cultivar and year. The addition of slow release fertilizer increased the weight produced and the average tuber size of Yukon Gold, whether or not the liquid fertilizer program was continued after the start of the short-day period. The number of tubers produced was significantly increased by the addition of 14-14-14, but not by 20-7-10. The addition of 14-14-14 increased the weight of Shepody produced in 1999, but not in 2000. Over the two years, the addition of 14-14-14 increased the average tuber size as well as the number and weight of large tubers produced in Shepody. The addition of 20-7-10 reduced the number of tubers formed in both Shepody and Kennebec. However, in Kennebec, the addition of either slow release fertilizer significantly reduced the weight produced and the average tuber size in 1999. Given these results, the treatments for Kennebec were modified in 2000. Slow release 14-14-14 with only two applications of liquid fertilizer gave the same yields as the control in 2000, while all other treatments continued to produce less yield.

Hutchinson, Pamela JS, Dennis J Tonks, Corey V Ransom, Rick A Boydston & Claude G Ross. "Pacific Northwest Potato Tolerance and Varietal Response to Sulfentrazone." [Vol. 78, 459]

Field studies were conducted in the PNW, in 1999 and 2000 to evaluate potato tolerance to sulfentrazone in weed-free trials. Herbicides were applied after hilling and prior to potato and weed emergence. Sulfentrazone was applied alone or in mixtures with metribuzin, EPTC, s-metolachor, dimethenamid-p, or pendimethalin, depending on location. Initial injury from sulfentrazone applied alone ranged from 0 to 8% in Malheur, OR, and 4 to 18% in Aberdeen, ID, depending on rate. Initial injury for mixtures ranged from 0 to 3% and 3 to 15% in Oregon and Idaho, respectively. In Oregon, U.S. No. 1 tuber yield was significantly reduced by 0.42 kg/ha sulfentrazone, while total tuber yield was not significantly affected by sulfentrazone treatments regardless of rate or mixture. Tuber yield was not affected in Idaho regardless of rate or mixture, similar to Prosser, WA trials where sulfentrazone tank-mixed with metribuzin or pendimethalin resulted in early, transient visual potato injury and did not affect tuber yield . In a separate 2000 Idaho trial, potato cultivar tolerance was evaluated by applying sulfentrazone preemergence at 0, 0.11, and 0.21 kg/ha to ’Russet Burbank’, ’Ranger Russet’, ’Russet Norkotah’, and ’Shepody’ potatoes. Initial injury ranged from 5 to 25% depending on rate. ’Russet Burbank’ exhibited greatest visual injury during the season, regardless of rate, compared to the other cultivars. Both U.S. No. 1 and total tuber yields were reduced in sulfentrazone-treated ’Russet Burbank’ relative to the untreated "Russet Burbank’ control. Tuber yield was not affected in the other potato cultivars.

Jin-Cheol, Jeong, Robert K Prange & Barbara J Daniels-Lake. "Long-term Exposure to Ethylene Affects Polyamine Levels and Sprout Development in ‘Russet Burbank’ and ‘Shepody’ Potatoes." [Vol. 78, 460]

Potato (Solanum tuberosum L. cvs. Russet Burbank and Shepody) tubers were exposed to continuous 4 µL×L -1 66¡¡ PRO . m) ethylene, commencing after 8 storage weeks, during long-term storage at 9°C over one (‘Russet Burbank’) and two (‘Shepody’) storage seasons. Thereafter, tubers were sampled at 3 week (‘Shepody’) or 5 week (‘Russet Burbank’) intervals for polyamine content [putrescine, (PUT); spermidine, (SPD); and spermine, (SPM)] and sprout number and weight. During the storage period, ‘Shepody’ had higher concentrations of all three polyamines and a higher PUT/(SPD + SPM) ratio, compared with ‘Russet Burbank’. During storage, all three polyamines in both cultivars increased, with the increase being more rapid in ‘Shepody’ than in ‘Russet Burbank’. Regardless of cultivar and year, exposure to ethylene induced higher spermidine (SPD) content and a lower PUT/(SPD + SPM) ratio, compared with the air treatment. Sprouts appeared later and were smaller on ethylene-treated tubers and were more numerous in ‘Russet Burbank’. Our results suggest that these long-term ethylene effects may be due, in part, to enhanced transformation of PUT to SPD.

Johnson, AA TBA Nault & RE Veilleux. "Transgenic Resistance to Colorado Potato Beetle (Leptinotarsa decemlineata) Transmitted to Tetraploid Potato through 4x-2x Hybridization." [Vol. 78, 461]

A highly heterozygous, interspecific diploid potato hybrid (APM-2) that produces 2n pollen by FDR was transformed with a codon-modified Bacillus thuringiensis cryIIIA transgene via Agrobacterium tumefaciens leaf-disc inoculation. Diploid transformants determined to have either single or multiple copy inserts were regenerated and established in the greenhouse and field. In a no-choice assay, Colorado potato beetle (CPB) adults consumed significantly less leaf area from all APM-2 transformants compared to untransformed APM-2 and cv. Atlantic. Four transformed clones were as resistant to CPB as the commercial cv. NewLeaf â Atlantic (also engineered with a cryIIIA transgene). A DAS-ELISA test using antibodies for the CryIIIA protein showed a high negative correlation between leaf area consumed and the amount of CryIIIA protein detected (r= -0.90; p<0.01). Tetraploid progeny were generated by 4x-2x hybridization between cv. Atlantic and both single- and multiple- copy APM-2 transformants. In a replicated greenhouse experiment, no significant differences were found for CryIIIA expression estimated by ELISA between the single-insert transformant and 25 of its progeny. However, 17 of 25 progeny derived from the multiple-insert transformant showed significantly lower ELISA readings than the parent, with 8 progeny exhibiting virtually no CryIIIA protein production. The results verify sexual transmission of a transgene through 2n pollen in potato and suggest the possibility of combining transgenic breeding with sexual polyploidization for true potato seed (TPS) cultivar development.

Karlsson, Björn, Jiwan Palta & Senay Özgen. "Reduction of Potato Tuber Bruising and Internal Defects by Supplemental Calcium Field Applications."  [Vol. 78, 462]

Supplemental calcium application has been shown in our previous work to improve tuber quality and reduce internal defects. However, the influence of calcium on bruising is not well known. In both 1999 and 2000 we evaluated under field conditions five commercially relevant cultivars (Russet Burbank, Atlantic, Snowden, Superior, Dark Red Norland) for bruising, yield and internal defects. Experimental field plots were supplied with 168 kg.ha -1 supplemental calcium while control plots were given no additional calcium. Applications were made at hilling and at two additional times during the tuber bulking period other than grower control (nonsplit) which received all applications at hilling. All plots received equal nitrogen. Bruise reduction was seen in both years for most of the cultivars and tuber grades. In 2000, for example, Russet Burbank treated with the combined calcium nitrate, calcium chloride and urea reduced bruising by 25% as compared to control. In 1999, treatments containing calcium nitrate+calcium chloride+urea resulted in half the incidence of bruise for Atlantic as compared to grower control. Furthermore, there were dramatic cultivar differences for the incidence of bruising. Supplemental calcium applications thus present the opportunity of reducing tuber bruising and other internal defects which profoundly affect all levels of the potato industry.

Kirk, William WR Scott Shaw, Brendan A Niemira, Jeffrey M Stein & Robert L Schafer. "Thermal Properties of Potato Cull Piles and Different Genotypes of Phytophthora infestans in Relation to Overwintering of Potato Late Blight."  [Vol. 78, 463]

The late blight inoculum that initiates crop infection in succeeding years may be started by infected potato tuber(s) surviving winter as seed tubers, volunteer tubers in fields or within culls. The objectives of this study were to evaluate the influence of temperature on survival of different genotypes of P. infestans in vitro and to profile thermal characteristics of potato cull piles. P. infestans genotypes (US1, US6, US8 and US14) growing on rye agar plates were exposed to temperatures -10 to 50 C for different periods and survival estimated by digital image analysis. Temperature was monitored in potato cull piles (sizes ca. 1, 5, 10, 15 t) at the base, interior and surface of the piles (November - April in Michigan, 1996 and 1997). Base temperature for survival of all genotypes of P. infestans in vitro was < -5 C and upper temperature for survival varied with exposure time but was about 45 C. The number of hours of exposure of tubers in cull piles above and below the estimated lethal thresholds was calculated. Tubers within cull piles were occasionally exposed to temperatures below -5 C but rarely to temperatures above 45 C.  Tubers in culls in both years failed to produce sprouts the following year suggesting that tuber death had occurred as a result of temperature exposure. Ambient temperature information gathered during winter months in potato growing regions would enable risk of a late blight epidemic initiated from cull piles to be estimated based on survival of host and pathogen.

Kiru, Stepan, Svetlana Makovskaya & John Bamberg. "Resistance of Solanum andigenum Accessions Maintained at VIR and US Potato Genebanks to Golden Nematode. " [Vol. 78, 463]

The best method for combating golden nematode, Heterodera rostochiensis is the creation of varieties resistant to this pest. The cultivated potato species Solanum andigenum Juz. et Buk. has a great diversity of forms. Many forms are resistant to golden nematode. In 1998-2000 a joint evaluation of resistance to this pest was done on 115 accessions maintained both at N. Vavilov Institute and the US Potato Genebank, NRSP-6. Evaluation was made by growing clones in a greenhouse in pots with soil infested with golden nematode cysts (RO2 and RO4) by the test method of the Plant Protection Institute. Fourteen accessions were found to be free of nematode cysts. Eight of these confirm resistance earlier noted by cooperators who screened the same materials from US Potato Genebank. The inheritance of resistance of the selected accessions was tested by evaluating the progeny from crosses with non-resistant cultivars. Resistance of 28 F1 combinations varied from 35 to 78. The most frequent ratio of resistant to infected seedlings was 3:1, suggesting that resistance to nematode is dominant and monogenic. The majority of the selected resistant accessions were originally collected in Argentina.

Kleinhenz, Matthew DEC Wittmeyer, Mark A Bennett, & Richard L Hassell. "Variety Selection for Resistance to Abiotic Stresses, A Summary of Ohio’s Involvement in the North-Central and Northeast Regional Genetics and Breeding Projects."  [Vol. 78, 463]

The North-central 84 (NCR84) and Northeast 184 (NE184) regional genetics and breeding projects began over thirty years ago under different names. They established networks of potato researchers and others partly to increase the availability of varieties adapted to a wide range of production conditions. Ohio began official participation in the projects in 1976 (NCR84) and 1980 (NE184). Since then, thousands of experimental genotypes developed in breeding programs at the USDA and from Maine to Alberta, Canada have been evaluated at OSU research stations and on the farms of grower-cooperators. In 2000, for example, we evaluated 157 genotypes from ten breeding programs associated with the USDA, two Canadian provinces and seven U.S. states. More than twenty-five varieties grown commercially in Ohio first entered the state as experimental selections. And, on average, nearly one-hundred percent of Ohio’s annual crop (fresh, chip-stock) is planted to varieties developed and evaluated in the projects. The majority of Ohio’s crop is dryland; high nighttime temperatures, low soil moisture availability, and fine to coarse-textured soils are significant production challenges. Genotypes are evaluated using breeder- and market-selected criteria, including those related to chipping and cooking quality. Data on more than one-thousand entries evaluated at the OARDC in Wooster suggest that average annual total and marketable yield have remained relatively similar since 1987, being primarily affected by climatic conditions. Maturity, estimated on more than five-hundred genotypes from the NE184 project since 1990, has been mostly medium-late with a recent trend toward medium to medium-early.

Kuhl, JC, MJ Havey & RE Hanneman, Jr.   "Genetic Studies of Unilateral Incompatibility between Diploid (1EBN) Mexican Species Solanum pinnatisectum and S. cardiophyllumsubsp. cardiophyllum" [Vol. 78, 464]

Many angiosperms have developed mechanisms to prevent self pollination and inbreeding. The most wide spread system self incompatibility (SI) is gametophytic, where pollen tube growth is inhibited in the style by the action of a single locus (S-locus). Similar inhibition of pollen tube growth can also be observed in interspecific crosses, where successful pollinations occur in only one direction, termed unilateral incompatibility. Unilateral incompatibility was observed in crosses between S. pinnatisectum and S. cardiophyllum progenies only when S. pinnatisectum was used as the pistillate parent. Segregations in the BC₁ family backcrossed to S. cardiophyllum revealed two independent putative loci controlling unilateral incompatibility, with both putative loci inherited independent of the S-locus. However, segregation ratios in the second backcross family did not agree with those observed in the first family. Segregation disparity between the two families may be due to distorted transfer of specific alleles or the presence of different mechanisms controlling pistil and pollen recognition systems in the two species.

Lara-Cabrera, Sabina I & David M Spooner. "Taxonomy of Mexican Diploid Wild Potato (Solanum sect. Petot a) Species: Morphological and Microsatellite Data. " [Vol. 78, 465]

Solanum section Petota, the potato and its wild relatives, contains over 200 wild species. Most grow in the Andes, but the United States, Mexico, and Central America contain about 30 taxa of diploids, tetraploids, and hexaploids. Chloroplast DNA restriction site data showed 13 of these 30 taxa to form a clade containing only diploid species, but there was low resolution within the clade. Some of these 13 taxa are similar morphologically and we questioned whether they were valid species. We analyzed these taxa, and others in South America that may be related to them, with morphological and microsatellite data. Morphological data showed extensive overlap of putative species-specific characters, but most species could be supported by multivariate techniques, except S. brachistotrichum, and perhaps S. stenophyllidium, that were harder to define. Mapped nuclear microsatellite markers, developed in S. tuberosum, also were used to help define species but provided no support for them. To explore possible causes of discordance of morphological and microsatellite results we sequenced three microsatellite fragments from three species, and compared these to sequences of S. tuberosum. Divergence among priming sites explained some cases of non-amplification. There also was divergence of microsatellite flanking sequences, showing non-homology of fragment sizes, explaining morphological and microsatellite disconcordance. These results show that microsatellites have reduced phylogenetic utility to analyze the United States, Mexican, and Central American diploid wild potato species.

Lightbourn, Gordon & Richard E Veilleux. "Ploidy Reduction of a Fertile Tetraploid Intermonoploid Somatic Hybrid for Studying Somaclonal Variation."  [Vol. 78, 466]

The disappointing performance of intermonoploid somatic hybrids of potato, expected to be both heterozygous and free of lethal and deleterious alleles, may derive from increased methylation status of DNA or activation of retrotransposons. Both processes are known to be activated by the tissue culture technique. Our objective was to develop unique potato germplasm that will allow us to examine these processes and address their involvement in somaclonal variation that may result from either protoplast fusion (and subsequent plant regeneration) or anther culture. A tetraploid intermonoploid somatic hybrid (SH18C) has been developed by electrofusion of independently derived monoploids. Microsatellite polymorphism was used to distinguish SH18C from somaclones derived from unfused protoplasts. Its tetraploidy was confirmed by flow cytometry. SH18C was male and female fertile in crosses with tetraploid potato cvs. Atlantic and Katahdin. Seedling progeny (SH18C x Katahdin and Atlantic x SH18C) were transplanted to the field in May 2000 in a RCB design with three replications of two families represented by 20-plant plots. Mean yield of hybrid seedlings (720 g/plant) exceeded that of SH18C (453 g/plant) and approached that of Atlantic (800 g/plant). Anther culture of SH18C yielded more than 200 androgenic haploids (2n=2x=24). For DNA methylation and retrotransposon studies, we have the original anther-derived monoploids, their tetraploid somatic hybrid and haploids derived by anther culture of the somatic hybrid. For testing the effects of anther culture without confounding with protoplast regeneration, we have available androgenic and gynogenic monoploids derived from a selection of adapted S. phureja

Liu, Q. & R Yada. "Physicochemical Properties of Starches during Potato Growth." [Vol. 78, 466]

The characterization of physicochemical properties of starch during potato growth is critical to the development of new starch products. Desired functional properties may be achieved by controlling the growth period, without further physical or chemical modification of the starch. In this study, starch was extracted from three potato cultivars (Shepody, Snowden and Superior) during growth. The physicochemical properties of starches were characterized by different analytical techniques. Gelatinization and retrogradation of starches were measured using differential scanning calorimetry. Granule size and size distribution were determined by optical microscopy. High performance size-exclusion chromatography was employed to analyze molecular chain size and size distribution of starches. Starch crystalline structure was evaluated by x-ray diffraction. Rapid viscosity analysis was also employed to measure starch paste viscosity and changes during heating. Results indicate that physicochemical properties of starches varied among the potato cultivars as well as during growth. Different granular size, starch molecular size and size distribution, and chemical composition in starch could be major factors influencing starch functional properties. The mechanism of starch biosynthesis during potato growth is also explored in this study.

Locke, Kerry A "National Ugandan Potato Program Review."  [Vol. 78, 467]

The potato plant provides an abundant, nutritious food source, which is appreciated by Ugandans who have experienced a crop produced with healthy seed. The biggest obstacle to the National Ugandan Potato Program is adequate funding. This is a complex, long-term undertaking that requires a long-term, dependable funding source. The main potato production constraint is an available source of healthy, improved seed. Disease free seed from the International Potato Center, in Peru is being evaluated for productive characteristics at the Kalengyere Research Station, Kabale, Uganda. A multiplication  program to increase improved lines for seed production is being coordinated with progressive growers in the Kabale District. The greatest threat to their success is bacterial wilt, Ralstonia solanacearum. A foundation seed program to produce disease free seed and a system to monitor the increase of healthy seed needs to be implemented. Adequate linkages between research, extension and the university need to be in place and functioning to have a strong, sustainable program. The potential for Ugandan potato production and the needs for an abundant food source are great. This is an exciting and challenging time for the National Ugandan Potato Program!

Ludy, RL, ML Powelson, B Gunderson & D Inglis. "Evaluation of Seed Piece Fungicides and Application Time to Control Tuberborne Late Blight."  [Vol. 78, 468]

Seed piece treatments with activity against Phytophthora infestans (Evolve MZ, Maxim MZ, Seed Treatment for Potatoes or Tops MZ) were evaluated in the field in Corvallis, OR and Mount Vernon, WA. Treatments were applied to cut seed pieces immediately following inoculation with 0, 100, 400 or 800 sporangia/seed piece using US-8 or US-11 in Oregon and Washington, respectively. Across inoculum densities, all fungicides were equally effective in protecting seed pieces from P. infestans as indicated by 99 (OR) and 96% (WA) emergence and 3 (OR) and 6% (WA) seed piece decay. Without seed treatment, an increase in inoculum density resulted in a decrease in emergence and an increase in seed piece decay. Time of treatment (0, 1.5 or 3 days post inoculation) was evaluated with Tops MZ and Tops 5D using the genotypes and pathogen inoculum densities discussed above. A significant 3-way interaction (inoculum density x timing x fungicide) was observed. When seed pieces received no inoculum, application time and fungicide had no impact on emergence (99%) or seed piece decay (1%). With inoculum densities of 100 to 800 sporangia/seed piece, Tops MZ was effective in protecting seed pieces if applied immediately following inoculation (99% emergence) compared to Tops 5D (24% emergence). Emergence was less than 30% for both Tops MZ and Tops 5D when seed treatment was delayed 1.5 or 3 days following inoculation. Results were similar in Washington. Transmission of P. infestans from seed pieces to the foliage was not observed.

Malkawi, AA, BL Jensen & Alan R Langille. "Some Secondary Plant Hormones Isolated from ’Katahdin’ Potato Plant Tissues Whose Levels were Influenced by Induction." [Vol. 78, 471]

'Katahdin’ potato plants were grown under "inducing" and "non-inducing" conditions and sampled at 2 day intervals. High performance liquid chromatography, in combination with gas chromatography and mass spectrometry, revealed the presence of several cytokinins and jasmonates in above- and below-ground tissues of the potato plants. Along with the major cytokinin, cis-zeatin riboside, other cytokinin compounds including, trans-zeatin and its riboside and isopentenyladenine were significantly influenced by induction. Likewise, over time changes were observed in levels of tuberonic acid, methyl tuberonate, methyl cucurbate and dihydromethyl jasmonate as a result of subjecting the plant to inducing conditions. The roles that these natural products may play in the development of the potato tuber will be discussed.

Mikitzel, Loretta J & David Wattie. "Pre-Planting Management to Maximize Short Season Yield Potential." [Vol. 78, 471]

Sprouting seed tubers in light prior to planting (greensprouting or chitting) may increase yield in short growing season areas, such as New Brunswick, Canada. Whole E1 Chieftain, Kennebec and Red Pontiac seed tubers were chitted under natural light for 40 days prior to planting. Half of the tubers were held in the dark for 7 days at 20C before chitting. Control tubers were planted directly from 4C storage. Tubers were hand-cut one week before planting. All chitted tubers emerged faster that control tubers. Warming Chieftain seed at 20C before chitting significantly increased total yields compared with chitting alone and increased total yield by 63 cwt/A over the non-chitted control. After a 73-d growing season, both chitting treatments increased total yields of Kennebec by -100 cwt/A. Both chitting treatments increased Red Pontiac tuber yields by 41% to 260 cwt/A by 73 days after planting. Chitting did not affect total tuber number produced by any cultivar tested. Only Red Pontiac stem numbers per plant were reduced by chitting. Yield increases due to chitting were realized for the three cultivars through higher yields of >51 mm diameter tubers. Significantly fewer oversize tubers (>64 mm dia.) were produced when seed tubers were warmed prior to green sprouting.

Miller, Jeff S & Carl J Rosen. "Effect of Fungicide Programs on Early Blight Control and Nitrogen Fertilizer Response in Potato." [Vol. 78, 471]

The use of azoxystrobin (Quadris) for early blight control often results in vines remaining greener longer in the growing season. This observation has lead to the suggestion that N fertilizer could be applied at lower rates when Quadris is used in a fungicide program since high N rates are often used to compensate for early blight. This study was conducted to determine if the use of Quadris affects N fertilizer requirements for potato. Plots were established in 1999 and 2000 at Becker, MN on a Hubbard loamy sand as a complete factorial, split-plot arrangement using a randomized complete block design with four replications. Fungicide treatments were used as the whole plot factor and included an untreated control, Bravo, and Bravo rotated with Quadris. Fertility treatments were used as the sub-plot factor and included nitrogen applied at three levels (150, 225, and 300 lbs/A N) and two timings (pre-hilling and all season). Early blight was problematic in 1999 and both early and late blight were severe in 2000. Significant interactions were observed between fungicide and fertility treatments for disease control in both study years. Control of diseases with fungicides was generally more effective at higher N rates. In 1999, an interaction was not observed between N rate and fungicide treatment for yield and tuber quality. However, a significant interaction did occur between fungicide and N rate in 2000 for yield where yields increased linearly with N rate using Bravo, but increased quadratically with N rate using Quadris/Bravo. Timing of N application had no effect on yield in 1999, but all season N application tended to depress yield compared to N applied prehill in 2000.

Mills, Dallice, Jessica M Schrunk, Philip B Hamm & DA Johnson. "Telomere- Associated RFLP Variability among Phytophthora infestans Strains Isolated in Oregon." [Vol. 78, 470]

Phytophthora infestans strains isolated in Oregon during 1992-1999 are being subjected to telomere-associated RFLP analysis to evaluate the genetic variability in pathogen populations vis a vis other methods of measurement. Total genomic DNA isolated from each strain was digested with Msp I and Hin dIII, separated by gel electrophoresis and Southern-blotted. A telomere probe constructed from an Arabidopsis telomere DNA sequence was hybridized to the blots to highlight length variation among telomere-associated fragments and create a fingerprint for each strain. The NSYSpc computer program was used to obtain a measure of the relatedness of the fingerprints for within-year and between-year combinations for strains isolated in 1995-1997. Among 18 US8 strains of A2 mating type from the 1995 collection, 17 different genotypes were identified. The most divergent strains had on average 84 percent similarity. Of 35 strains examined from the 1996 collection, there were 18 different genotypes, of which 5 were comprised of 2 or more strains. One genotype had 10 strains and both mating types. The most divergent of the 1996 strains on average were 77 percent similar. Of 23 strains examined from the 1997 collection, 17 different genotypes were detected. There were 9 different genotypes among 10 known US8 strains, and the most divergent strains were 80 percent similar. Although some strains isolated during 1995-1997 have a common genotype, 45 different genotypes were detected, and the most divergent strains on average were 72 percent similar. This method of analysis appears to identify greater genetic variability than has been observed by other methods.