Russet Burbank Potatoes Research Articles

Polymer Coated Urea in ‘Russet Burbank’ Potato: Yield and Tuber Quality

Nitrogen (N) fertilizer applied as polymer coated urea (PCU) may have the potential to improve potato (Solanum tuberosum L.) production. The objectives of this study were to determine the effects of PCU on potato yield and quality. ‘Russet Burbank’ potato was grown at three Idaho, USA locations. Five rates of N (0, 33, 67, 100, and 133% of the recommended rate) were applied in all combinations of: PCU applied at emergence, urea applied at emergence, or urea split-applied. The PCU-fertilized treatments produced 11%, 11%, and 10% higher US No. 1, marketable and total tuber yields, respectively, than urea-split applied. PCU trended toward increased tuber size. At equivalent rates, PCU was more efficient than urea N in providing N to potato. These results confirm findings from other researchers that a single application of PCU fertilizer, just prior to emergence, can efficiently meet seasonal N requirements for Russet Burbank potato.

Apoptotic-like PCD inducing HRC gene when silenced enhances multiple disease resistance in plants

Programmed cell death (PCD) plays an important role in plant environmental stress and has the potential to be manipulated to enhance disease resistance. Plants have innate immunity and, following pathogen perception, the host induces a Hypersensitive Response PCD (HR-PCD), leading to pattern (PTI) or effector triggered immunity (ETI). Here we report a non-HR type or Apoptotic-Like PCD (AL-PCD) in pathogen infected wheat and potato based on apoptotic-like DNA fragmentation. A deletion mutation in the gene encoding histidine rich calcium binding protein (TaHRC) in FHB-resistant wheat (R-NIL) failed to induce AL-PCD. Similarly, the CRISPR-Cas9 based silencing of StHRC gene in Russet Burbank potato failed to induce apoptotic-like DNA fragmentation, proved based on DNA laddering and TUNEL assays. The absence of AL-PCD in wheat R-NIL reduced pathogen biomass and mycotoxins, increasing the accumulation of resistance metabolites and FHB-resistance, and in potato it enhanced resistance to multiple pathogens. In addition, the reduced expressions of metacaspase (StMC7) and Ca2+ dependent endonuclease 2 (StCaN2) genes in potato with Sthrc indicated an involvement of a hierarchy of genes in the induction of AL-PCD. The HRC in commercial varieties of different crops, if functional, can be silenced by genome editing possibly to enhance resistance to multiple pathogens.

Field asymmetric ion mobility spectrometry for pre-symptomatic rot detection in stored Ranger Russet and Russet Burbank potatoes

This study was aimed at early detection and rot progression monitoring in stored potatoes using a portable field asymmetric ion mobility spectrometry (FAIMS) system. Tuber samples of Ranger Russet (RR) and Russet Burbank (RB) cultivars were inoculated with Pectobacterium carotovorumsubsp.carotovorum (causes soft rot) and sterile water (control). The samples were stored in jars either at room temperature (25 °C with 30 % relative humidity [RH]) or reduced temperature (4 °C with 95 % RH). Volatile headspace from samples was scanned with FAIMS at regular intervals up to 14 days for room temperature and 31 days for reduced temperature storages. Infection symptoms were detected for higher ion current pertinent to headspace of inoculated samples compared to the controls of both the cultivars. Such discrimination was evident at FAIMS compensation voltage (CV)-dispersion field (DF) ranges of −1.70–1.31 V and 38–90 % for room temperature and −1.58–1.31 V and 36–92 % for reduced temperature storages. The rot was detected as early as one day after inoculation (DAI) under room temperature and five DAI under reduced temperature storages. The ion currents were affected by the storage temperature and humidity, and associated interaction with the DAI and cultivar (F7,712 = 21.6–31.4, p < 0.001). The FAIMS responses of control and inoculated tubers were also classified by the Naïve Bayes and Random Forest algorithms at accuracies in the ranges of 70–90 % and 75–100 %, respectively. Overall, a portable and tunable FAIMS system was found suitable for high throughput early detection of soft rot in potato tubers. Future studies need to revalidate the FAIMS system in commercial storage facilities for timely rot detection and initiation of potential remedial measures.

The caffeoyl-CoA O-methyltransferase gene SNP replacement in Russet Burbank potato variety enhances late blight resistance through cell wall reinforcement.

Metabolic pathway gene editing in tetraploid potato enhanced resistance to late blight. Multiallelic mutation correction of a caffeoyl-CoA O-methyltransferase gene increased accumulation of resistance metabolites in Russet Burbank potato. Late blight of potato is a devastating disease worldwide and requires weekly applications of fungicides to manage. Genetic improvement is the best option, but the self-incompatibility and inter-specific incompatibility makes potato breeding very challenging. Immune receptor gene stacking has increased resistance, but its durability is limited. Quantitative resistance is durable, and it mainly involves secondary cell wall thickening due to several metabolites and their conjugates. Deleterious mutations in biosynthetic genes can hinder resistance metabolite biosynthesis. Here a probable resistance role of the StCCoAOMT gene was first confirmed by an in-planta transient overexpression of the functional StCCoAOMT allele in late blight susceptible Russet Burbank (RB) genotype. Following this, a precise single nucleotide polymorphism (SNP) mutation correction of the StCCoAOMT gene in RB potato was carried out using CRISPR-Cas9 mediated homology directed repair (HDR). The StCCoAOMT gene editing increased the transcript abundance of downstream biosynthetic resistance genes. Following pathogen inoculation, several phenylpropanoid pathway genes were highly expressed in the edited RB plants, as compared to the non-edited. The disease severity (fold change = 3.76) and pathogen biomass in inoculated stems of gene-edited RB significantly reduced (FC = 21.14), relative to non-edited control. The metabolic profiling revealed a significant increase in the accumulation of resistance-related metabolites in StCCoAOMT edited RB plants. Most of these metabolites are involved in suberization and lignification. The StCCoAOMT gene, if mutated, can be edited in other potato cultivars to enhance resistance to late blight, provided it is associated with other functional genes in the metabolic pathway network.

Low-dose foliar treatments of the auxin analog 2,4-D reduce potato common scab and powdery scab for multiple potato cultivars and enhance root development

Common scab and powdery scab are major soilborne diseases of potato (Solanum tuberosum). The agricultural cost of both diseases is due to discounting or rejection of infected seed tubers or the formation of lesions on the surface of the tubers that make them unmarketable or, for powdery scab, yield loss. There are no widely accessible and efficacious disease management options for either common scab or powdery scab. In prior work, low-dose foliar treatment with the auxin analog herbicide 2,4-D has been shown to reduce common scab severity of select S. tuberosum cultivars in field and greenhouse settings. In the present study, we address the broad applicability of 2,4-D in disease management by testing the efficacy of 2,4-D treatment across diverse potato cultivars and in suppressing multiple scab diseases of potato. Specifically, we tested whether low-dose 2,4-D treatment is broadly efficacious on multiple white potato cultivars used in Eastern United States potato production. Additionally, we sought to determine whether 2,4-D is efficacious for mitigating powdery scab for Russet Burbank potatoes in a commercial field setting. In two years of field trials, low-dose foliar 2,4-D treatment significantly reduced common scab of all tested potato cultivars with no impact on total tuber yield. In two years of field trials in Tasmania, Australia, low-dose foliar 2,4-D treatment also reduced powdery scab of Russet Burbank potato with no impact on total tuber yield while stimulating potato plant root growth. The ability of 2,4-D to suppress two major tuber diseases and stimulate potato root growth warrants further investigation and optimization for integration into commercial growing systems.

Elimination of Tobacco rattle virus from viruliferous Paratrichodorus allius in greenhouse pot experiments through cultivation of castle russet.

Corky ringspot (CRS) is a widespread potato tuber necrotic disease caused by Tobacco rattle virus (TRV) infection. In the Pacific Northwest, this virus is transmitted by the stubby root nematode (SRN) within the genus Paratrichodorus. Remediating CRS affected fields is a major challenge that can be mitigated by growing plant varieties that are resistant to TRV infection. Growing alfalfa has been shown to reduce TRV levels in CRS infested fields over time but the development of a potato cultivar with these same capabilities would be of great economic benefit to potato growers. Castle Russet is a new potato clone that does not develop symptoms of CRS disease. To assess its ability to reduce soil virus load, Castle Russet, tobacco var. “Samsun NN”, alfalfa var. “Vernema”, and Russet Burbank potato were grown for a period of 1 to 3 months in soils containing viruliferous SRN populations at two different inoculation pressures (60 nematodes/pot and 1060 nematodes/pot) in greenhouse pot experiments. SRN population size and the presence of TRV were assessed over several months post inoculation. Results indicate that plant host and length of exposure significantly influence SRN population dynamics, whereas the TRV infection status of bait plants was significantly affected by both of these factors as well as inoculation pressure. These results suggest that both alfalfa var. “Vernema” and Castle Russet are resistant to TRV infection and may potentially be used to eliminate the virus from fields affected by CRS.

Bazı Patates (Solanum tuberosum L.) Çeşitlerinin Depolama Davranışları ile Depoda Kalite Değişimlerinin Belirlenmesi

Bu çalışma, farklı olgunlaşma sürelerine sahip bazı patates çeşitlerinin Isparta koşullarında verim performansları ile hasat sonrası depo davranışları ve depoda kalite değişimlerinin belirlenmesi amacıyla 2018 yılında yürütülmüştür. Çalışmada ülkemizde yaygın olarak tarımı yapılan Agria, Agata, Alegria, Desiree, Granola, Hermes, LadyAnna, Marabel, Morfona ve Russet Burbank patates çeşitleri kullanılmıştır. Araştırmada çeşitlerin arazi koşullarında verim performansları belirlendikten sonra her çeşitten alınan yumru örnekleri 6-8°C sıcaklıkta 6 ay süreyle depolanmıştır. Çeşitlerin yumru verimleri 2.860-5.331 kg/da, vejetasyon süreleri ise 97,7-146,6 gün arasında değişmiştir. Depolama sürecinde yumruların %50‘sinde dormansinin kırılması için geçen süreler 23,3-111,6 gün arasında değişmiş, erkenci çeşitlerde dormansi daha erken kırılmıştır. Çalışmada 6 aylık depolama devresi sonunda çeşitlerin %4,13 ile %6,48 oranında ağırlık kaybettikleri saptanmıştır. Çeşitlerin depolama süresine bağlı olarak nişasta oranları, indirgen şeker içerikleri ve parmak patates verimleri değişkenlik göstermekle birlikte depolama süresi boyunca genellikle azalma göstermiştir. Araştırmada kullanılan patates çeşitlerinin depolama sürecinde parmak patates ve sofralık kalitelerinde önemli değişimlerin olduğu, cips sanayisine uygun olmayan, düşük kuru madde oranına sahip çeşitler ile erkenci özellikteki çeşitlerin depoda ağırlık ve kalite kayıplarının daha fazla olduğu belirlenmiştir. Çalışmada patates çeşitlerinin dormansi süreleri ile olgunlaşma özelliklerinin depo kalitesine önemli derecede etki gösterdiği ve bu nedenle patates depolamasında çeşit özelliklerinin dikkate alınarak depo süresinin belirlenmesi gerektiği sonucuna varılmıştır.

Nitrogen Fertilization Effects on the Composition of Foliar Amino Acids of Russet Burbank Potato

Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), is an important pest of potato crops. Potato foliar amino acids play essential roles in CPB growth. In this study, amino acids were classified into four groups according to their different roles in promoting CPB growth. Then, nitrogen (N) rate effects on the concentrations of amino acid groups were investigated under field conditions. Experiments were carried out with five N rates of 0, 60, 120, 180, and 240 kg N ha−1 in a randomized complete block design. Twenty leaves were collected at 40, 54, 68, and 82 days after planting (DAP) for amino acids analysis. Results showed that N rate had no significant effect on concentrations of each amino acid group at 40 DAP. However, their concentrations linearly increased as N rate increased at 54, 68, and 82 DAP, suggesting that higher N rates could potentially favor CPB growth after potato enters tuber initiation stage.

Impact of Plow Timing on Simultaneous Nitrogen Losses in Potato Production Systems Using Conventional Tillage Practices

Improving plowing management of high nitrogen (N) containing crops is essential in reducing both environmental and economic losses. The timing of plowing may be an important soil and nutrient conservation practice. A field study on a 3 yr potato rotation was conducted in Prince Edward Island, Canada to examine the effects of plow time on corresponding N losses of nitrate-N (NO3--N) and nitrous oxide (N2O). The study site consisted of nine tile drained plots (12 m spacing) with three treatments of plow time; early fall (EF), late fall (LF) temperature based, and the following spring (S) plow. The cropping rotations consisted of barley under-seeded with red clover in yr 1, red clover in yr 2, and Russet Burbank potatoes in yr 3. Each tile drained plot fed into a sample collection station where 50 mL water samples were obtained during flow events and analyzed for NO3--N. Nitrous oxide samples were also simultaneously obtained from the soil surface throughout the monitoring period using a static chamber methodology. Cumulative NO3--N loads over the 3 yrs were found to be reduced at 14.3 and 19.9 kg ha-1 for LF and S respectively, when compared to the EF plow at 24.4 kg ha-1. Nitrous oxide losses were variable and low in magnitude throughout the study (0.04-1.2% of the N applied). Overall, findings from this research suggest that the timing of plowing could be considered when trying to minimize N losses via tile drainage effluent. When considering NO3--N total loads during the rotation period, LF had reduced losses compared to EF in all years of the study. Late fall reduced N2O losses in 1 year by 38.2% compared to S, likely due the incorporation of red clover legume crop. Yields were found to be similar throughout treatments and cropping years, although LF was found to have 2 and 3-fold significant increases in yield of 10 oz potatoes vs. EF and S, respectively. Findings generated from this study will provide nutrient management and environmental farm planners, as well as producers with useful information for improving current management strategies within agricultural drainage systems.

Nitrate Leaching and Potato Yield under Varying Plow Timing and Nitrogen Rate

Core Ideas Fall plowing created more post–fall‐plowing nitrate leaching than spring plowing. Fall or spring plowing did not influence post–potato‐harvest nitrate leaching and potato yield. Increasing fertilizer N input to potato crops increased post–potato‐harvest nitrate leaching. Increasing fertilizer N input to potato crops suppressed potato yield. Excessive nitrate leaching from potato (Solanum tuberosum L.) production has been linked to groundwater nitrate contamination and eutrophication in receiving surface water. This study was conducted to assess the effects on nitrate leaching and potato yield of delaying red clover (Trifolium pratense L.) plowing from late fall to spring in a barley (Hordeum vulgare L.)–red clover–potato rotation and varying additions of fertilizer N to potato crops in Prince Edward Island, Canada, between 2014 and 2017. The experiment used a split‐plot arrangement in a completely randomized design with three replications. A stainless steel lysimeter was installed in each plot to collect soil water to test nitrate concentrations in leachate. Nitrate leaching occurred primarily between late fall, after the potato harvest, and in spring. Delaying forage plowing from late fall to spring reduced post–fall‐plowing nitrate leaching but had no influence on either post–potato‐harvest nitrate leaching or potato yield. Increasing fertilizer N input to the potato crops was shown to not only increase the risk of excessive nitrate leaching but also to suppress potato yield. Higher levels of soil N supplies from the mineralization of the plowed‐down red clover and soil organic matter to the potato crops in combination with a shorter than ideal growth period for the long‐season Russet Burbank potato appear to create overfertilizing situations, resulting in excessive post–potato‐harvest nitrate leaching and suppressed yields. Adequately accounting for soil N supplies is critical for enhancing potato productivity while minimizing nitrate leaching.

Nitrogen fertilization effects on the leaf chemical concentrations in Russet Burbank potato

The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), is a destructive pest of potato (Solanum tuberosum L.) crops. Leaf sugars are regarded as energy sources for the growth of the CPB, while glycoalkaloids are used to suppress the feeding behaviors of the CPB. The metabolic pathway of these leaf compounds is closely related to nitrogen (N) nutrition. Additionally, N plays an important role in determining tuber yield. The objective of this study was to investigate the effects of N fertilization on the concentrations of sugars and glycoalkaloids in potato leaves and on marketable tuber yield under field conditions in eastern Canada. Experiments were conducted at three sites and five N rates (0, 60, 120, 180, and 240 kg N ha−1) provided in a randomized complete block design. The potato cultivar “Russet Burbank” was used throughout the experiments. Twenty potato plants were randomly selected in each plot and the fourth leaf from the top of each plant was collected at 40, 54, 68, and 82 days after planting (DAP) for analyzing the concentrations of sugars (sucrose, glucose, and fructose) and glycoalkaloids (α-solanine and α-chaconine). Marketable tuber yield was determined along with the whole plant (vine + tuber) N accumulation. A significant decline of the averaged total sugar, including sucrose and glucose, was observed with increasing N rates. The average concentration of total glycoalkaloid, including α-chaconine, increased significantly in response to the increasing N rates. Based on our results, a rate of 205 kg N ha-1 was identified to obtain a maximum marketable tuber yield along with high concentrations of glycoalkaloid and low sugar concentrations which may influence the CPB feeding.

Intumescence Injury in the Leaves of Russet Burbank Potato Plants is Mitigated by Calcium Nutrition

Many plants including potato, tobacco, tomato, and geraniums often develop intumescence (oedema) injury, which is observed exclusively on plants grown in controlled environments. Early studies have suggested a link between light quality and intumescence by showing UV and/or far-red light mitigation of injury. Here, we report that intumescence can be mitigated by calcium nutrition. Commercial cultivars of Solanum tuberosum L. cvs ‘Russet Burbank’ and ‘Atlantic’ were grown from in vitro shoot cultures in 20.4 L pots within a climate-controlled greenhouse. Plants were irrigated daily to excess with Peter’s Professional Peat Lite Special 20–10-20 fertilizer (0.52 g·L−1 tap water) supplemented with either 1 mM or 10 mM CaCl2·2H2O. We evaluated 13 replications from both potato cultivars and Ca2+ treatments. Intumescences were observed at about 32 days after calcium treatments began, exclusively on the upper and lower leaf surfaces of Russet Burbank. Upper canopy leaves of Russet Burbank showed approximately 65 and 5% intumescence injury for the 1 mM and 10 mM Ca2+ treatments, respectively. Average leaf calcium concentration was nearly double in the plants supplemented with 10 mM compared with 1 mM Ca2+. Tuber yield and foliage weight were higher in the plants supplemented with 10 mM Ca2+ as compared with 1 mM Ca2+ and suggests that intumescence injury reduced growth and partitioning. These data provide evidence that supplemental calcium can mitigate intumescence injury on susceptible cultivars of potato in controlled environments.

Glycoalkaloids and phenolic compounds in three commercial potato cultivars grown in Hebei, China

In order to investigate the food nutrition and safety of potato, the objective of the present study is to quantify glycoalkaloids (α-chaconine and α-solanine) and phenolic compounds in three potato cultivars, namely, Russet Burbank, Atlantic, and Shepody, grown in Hebei, China, and these two classes of biologically active compounds in commercial dehydrated potato flakes were also investigated. The total glycoalkaloid levels in whole potatoes ranged from 4.72mg/kg for Shepody potatoes to 34.45mg/kg for Russet Burbank potatoes. The ratio of α-chaconine to α-solanine in whole potatoes ranged from 0.41 for Russet Burbank potatoes to 3.61 for Atlantic potatoes. The removal rate of total glycoalkaloids in Russet Burbank potatoes during dehydrated potato flake processing is 90.0%. Chlorogenic acid is the dominant phenolic compound in Russet Burbank potatoes. By contrast, Atlantic and Shepody potatoes contain considerable caffeic acid. The loss rate of phenolic compounds in Russet Burbank during dehydrated potato flake processing is 50.47%.

The Impact of Retail Light Source on Greening of Russet Burbank Potato Tubers

The use of accent lighting in retail stores has focused illumination on potatoes for greater consumer awareness. Unfortunately, this directed light on displayed potatoes may impact the rate or level of tuber greening. The objective of this study was to evaluate the influence of various retail accent light sources on greening and quality of illuminated tubers. Two separate experiments exposed ‘Russet Burbank’ potato tubers to fiber optic, ceramic metal halide, fluorescent, fluorescent with filter lighting (experiment 1) and fiber optic, halogen, and fluorescent lighting (experiment 2). In each experiment, tubers were exposed to a consistent light intensity (1390 lx in experiment 1 and 1300 lx in experiment 2) in addition to a dark control. Tubers were illuminated for 22 h per day at an ambient room temperature of 22 C. Six randomly selected tubers were evaluated for level of greening, chlorophyll concentration, and weight loss at day 0, 2, 4, 7, and 9. Total glycoalkaloid content was analyzed at days 0 and 9. In experiment 1, the fiber optic and fluorescent illuminated tubers showed significantly lower chlorophyll content compared to the ceramic metal halide light source. There was no significant difference in chlorophyll level or greening rating between the fluorescent light source and fluorescent with filter. In experiment 2, the fiber optic illuminated tubers had lower chlorophyll content and less visual greening compared to the halogen illuminated tubers. Total glycoalkaloids were not significantly impacted by light source. The use of fiber optic lighting or a combination of fiber optic lighting with standard fluorescent lighting would retard the progression of greening in the retail store yet potentially highlight the commodity for consumer eye-appeal.

Interactive Effects of Fumigation and Fungicides on Potato Response to Nitrogen Rate or Timing

The availability and use of crop protectants including azoxystrobin in combination with fumigation has extended the Central Wisconsin effective growing season by 2 to 4 weeks. This study, evaluating the influence of these crop protection practices on the optimum nitrogen rate and time of application for Russet Burbank potato (Solanum tuberosum L.), was established as two 3-year field trials designed as split-split plot experiments. Both experiments used metam sodium as the main plots and fungicide treatment (chlorothalonil Zn alone or chlorothalonil Zn alternated with azoxystrobin for the first six sprays) as the first split. In-season fertilizer N rate (179, 224, 269, or 313 kg N ha−1) or in-season N timing (N split into two, three, or four applications at 269 kg N ha−1) was the second split. Not fumigating resulted in significantly higher verticillium ratings and severely repressed crop yield and tuber quality responses to both fungicide treatment and N rate. On average, fumigation increased total yield 13.6 Mg ha−1yr−1, U.S. No. 1 tubers by 9 % and U.S. No. 1 tubers >170 g by 5 % over where fumigation was not used. In 2 of the 3 years when azoxystrobin was included in the fungicide program early blight severity was reduced by about 50 %, and on fumigated areas yields were increased 4.8 Mg ha−1, whereas no yield increase was seen from this fungicide treatment on the non-fumigated plots. In these same years, fumigation increased optimum N rate by about 50 kg ha−1; however, there was no apparent interaction with fungicide treatment. Although fumigation, fungicide treatment, and time of N application each influenced tuber yield or tuber quality in some years, in the two more responsive years some interactions between these factors were statistically significant, with benefits generally only seen where plots were fumigated.

A Historical Look at Russet Burbank Potato (Solanum tuberosum L.) Quality Under Different Storage Regimes

Russet Burbank is the predominant potato (Solanum tuberosum L.) cultivar grown and stored for fresh market and frozen processing (French fry) use in North America. Multi-year assessments of potato tuber quality under different storage regimes can provide information about a cultivar’s ability to retain process quality when challenged with seasonal variations across multiple years. The objective of a 15-year study initiated in 1999 was to evaluate the quality of Russet Burbank tubers grown and stored at the Kimberly Research and Extension Center. Potatoes were measured for specific gravity at harvest and stored for eight months under three temperatures (5.6, 7.2 and 8.9 °C) and periodically sampled throughout the storage season to determine dormancy length, sugar content, fry color and mottling severity (a quality issue), and weight loss. The year in which the crop was grown significantly (p < 0.001) affected all quality characteristics except specific gravity (average ranged between 1.071 and 1.081). Tubers held during the 2011–2012 and 2013–2014 storage seasons exhibited generally higher glucose, darker fry color, more severe mottling, and higher weight loss. Average sucrose content at 7.2 °C and 8.9 °C across the 15 years significantly decreased over the eight-month storage while average glucose content remained consistent after first month of storage. Average percent weight loss across the 15 years was 6.1 % after eight months in storage. This 15-year study emphasized that variation of post-harvest storage quality from year to year was likely a result of variable seasonal growing conditions. Storage temperatures between 7.2 and 8.9 °C were the optimum range for storing fry processing Russet Burbank potatoes and the warmer temperature of 8.9 °C appears to ameliorate the seasonal effects on glucose content and fry color to maintain better processing quality throughout storage.

Cold-induced starch degradation in potato leaves - intercultivar differences in the gene expression and activity of key enzymes

Exposure to low temperatures is one of the most important factors that generate abiotic stress in plants, and the rapid accumulation of soluble sugars belongs to significant metabolic responses to cold stress. The accumulation of soluble sugars may be at least partially triggered by an increased rate of starch degradation. The analysis of transcript profiles and starch degrading enzyme activities in leaves of two potato cultivars was performed during a 12-h exposure to 2 °C. An induction of β-amylase expression and activity as well as an accumulation of reducing sugars were observed in cv. Desiree. No accumulation of reducing sugars and no significant changes in the β-amylase activity were initially observed in cv. Russet Burbank. Surprisingly, an increased α-amylase activity was observed in the last hours of the experiment, which was accompanied by an increased amount of reducing sugars. The results indicate that the leaves of Desiree and Russet Burbank potatoes growing under cold stress may degrade starch via different pathways.

Role of co‐infection by Pectobacterium and Verticillium dahliae in the development of early dying and aerial stem rot of Russet Burbank potato

Potato early dying (PED) is a disease complex primarily caused by the fungus Verticillium dahliae. Pectolytic bacteria in the genus Pectobacterium can also cause PED symptoms as well as aerial stem rot (ASR) of potato. Both pathogens can be present in potato production settings, but it is not entirely clear if additive or synergistic interactions occur during co‐infection of potato. The objective of this study was to determine if co‐infection by V. dahliae and Pectobacterium results in greater PED or ASR severity using a greenhouse assay and quantitative real‐time PCR to quantify pathogen levels in planta. PED symptoms caused by Pectobacterium carotovorum subsp. carotovorum isolate Ec101 or V. dahliae isolate 653 alone included wilt, chlorosis and senescence and were nearly indistinguishable. Pectobacterium wasabiae isolate PwO405 caused ASR symptoms including water‐soaked lesions and necrosis. Greater Pectobacterium levels were detected in plants inoculated with PwO405 compared to Ec101, suggesting that ASR can result in high Pectobacterium populations in potato stems. Significant additive or synergistic effects were not observed following co‐inoculation with these strains of V. dahliae and Pectobacterium. However, infection coefficients of V. dahliae and Ec101 were higher and premature senescence was greater in plants co‐inoculated with both pathogens compared to either pathogen alone in both trials, and V. dahliae levels were greater in basal stems of plants co‐inoculated with either Pectobacterium isolate. Overall, these results indicate that although co‐infection by Pectobacterium and V. dahliae does not always result in significant additive or synergistic interactions in potato, co‐infection can increase PED severity.

Modeling Long-Term Trends in Russet Burbank Potato Growth and Development in Wisconsin

Improving understanding and prediction of the potato (Solanum tuberosum) tuber size over the growing season is important due to its effects on crop price and marketing. Several models have been proposed to describe potato growth and development, but are based on short-term data and have little use for predicting yields or in-season management decisions. This analysis uses long-term data collected from 1979 to 1993 in central Wisconsin to describe growth and development of the Russet Burbank potato variety. This paper describes average number of potato tubers per plant and tuber length as influenced by thermal time and stem number per plant over 14 years. For each plant variable, data analysis uses multivariate techniques to fit a hierarchical logistic model with parameters potentially depending on stem number per plant. Analysis finds that the average number of potato tubers and average tuber length were affected by thermal time and stem number per plant. Estimated models are biologically relevant, provide an understanding of seasonal thermal variability and stem number per plant effects on average tuber set and growth, and can be used to describe yearly variation in average potato growth and development. Increased understanding of potato growth in response to thermal time and stem number per plant can improve management recommendations and predictions of crop economic value.

Effect of Phosphorus Fertilizer Rate on Irrigated Russet Burbank Potato

Phosphorus (P) fertilizer is routinely applied to potato (Solanum tuberosum L.) in Manitoba, Canada; however, little information is available regarding P responses in this region. Field studies were conducted from 2003 through 2006 to determine the impact of P rate [0, 15, 29, 43 kg P ha−1 as broadcast incorporated monoammonium phosphate (MAP)] on Russet Burbank potato. Increasing P rate resulted in a linear increase in marketable yield in 2005, a quadratic increase in 2006, and no effect in 2003 and 2004. Phosphorus application had no effect on the yield of tubers <85 g, tuber number, or quality, but petiole P concentration and postharvest soil-test P levels increased with increasing P rate. Results of this and other studies show that P fertilization may improve potato yields, although increases are not completely predictable. Additional research is required to refine soil-test guidelines and petiole P sufficiency levels for this region.