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Suurhasko, Kai. "Det vördade köttet och potatisen : En studie om svenskarnas syn på mat och ätande." Thesis, Linköping University, Department of Religion and Culture, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8212.
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<p>Uppsatsen handlar om hur de som intervjuats ser på mat och ätande. Viktiga avsnitt är, vad som är mat och inte mat. Här tar jag bland annat upp vad som är mat enligt informanterna men också vad som inte är mat. Jag skriver om måltider och deras betydelse. Tid och tidsaspekter som rör mat avhandlas också. Kött och potatis och hur husmanskosten är normerande bearbetas i uppsatsen. Andra ämnen jag tar upp är god mat och mat som ogillas. Till sist beskriver jag det sociala runt mat och idealbilder av mat.</p><br><p>This paper is about five Swedish informants and their views on food. Important parts are what food is and what is not. The meaning of meals and their importance. Time and aspects of time surrounding food is also studied. I write about meat and potatoes and the normative values of the Swedish “husmanskost”. Other subjects are good food, disliked food, social aspects of food and ideal images of food.</p>
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Yasir, Muhamad Samudi Bin. "Detection of irradiated potatoes." Thesis, University of Salford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315359.
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Bjerkendahl, Christel. "Tångodlad potatis- nyttigt eller skadligt?" Thesis, Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-20875.
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The nutrition bound in macroalgae, also known as seaweed, contains high amounts of all the nutrients, micronutrients, vitamins and plant hormones, necessary for plants, animals and humans. Totally for free it is floating in the oceans around the world and has been harvested and used by people for thousands of years. A problem that has arisen in the wake of Industrialism during the past 200 years is that human beings spread non-desirable substancesto air, water and soil, for example heavy metals. Macroalgae accumulate the heavy metals, which may become a problem if we want to eat seaweed or use it to grow plants in. In a growth trial using macroalgal compost made from Fucus radicans collected from the Baltic Sea, the uptake heavy metals in the edible tubers of potatoes of the cultivar ‘Cherie’ was investigated. The following heavy metals were analyzed: lead(Pb), cadmium (Cd), mercury (Hg), arsenic (As) and copper (Cu). There were no differences in the uptake of heavy metal between potatoes grown in macroalgal compost and soil, but the potato tubers from both cultivations contained concentrations of Cd and As higher than those normally found in Swedish potatoes. The concentrations are, however, much lower than the limits set by EFSA. The macroalgal compost and the soil used in the experiment were also analyzed for heavy metal content. The Cd concentration in the compost exceeded the limit for Swedish compost. However, the high levels of Cd in the compost were not reflected in the Cd content of the potato tubers. Soil conductivity and pH values were also investigated. The high conductivityof the macroalgal compost was probably due to insufficient rinsing of the macroalgae, and thus it was not ideal for use in crop cultivation. In spite of this, the crop yield was good. In conclusion, macroalgal compost can be recommended as a cultivation substrate for potatoes.<br>Den näring som finns bunden i makroalger, även kallad tång, innehåller rikliga mängder av alla näringsämnen, spårämnen, vitaminer och växthormoner som växter, djur och människor behöver. Alldeles gratis flyter den omkring i världshaven och har skördats och använts av människan under tusentals år. Problemet som uppstått i industrialismens spår de senaste 200 åren är att människan sprider icke önskvärda ämnen till luft, vatten och jord, t.ex. tungmetaller. Makroalger ackumulerar dessa, vilket kan bli ett problem om vi vill äta eller odla i tång. Vid ett odlingsförsök med potatis i tångkompost av Fucus radicans från Östersjön undersöktes metallupptaget i de ätbara knölarna i potatis av sorten ’Cherie’. De tungmetaller som analyserades var bly (Pb), kadmium (Cd), kvicksilver (Hg), arsenik (As) och koppar (Cu). Analysrapporten visade ingen skillnad i upptag av tungmetaller mellan potatis som odlats i tångkompost eller i jord; däremot innehöll knölarna från båda odlingarna högre halter av kadmium och arsenik än normalvärdena i svensk potatis. Halterna är dock långt under EFSA:s gränsvärden. Även odlingssubstraten, dvs. tångkomposten och jorden undersöktes för tungmetallförekomst. Kadmiumhalterna i tångkomposten översteg gränsvärdet för svenska kompostjordar, men de höga kadmiumhalterna reflekterades inte i potatisknölarnas kadmiuminnehåll. Odlingssubstratens ledningstal och pH-värden undersöktes också. Tångkompostens höga ledningstal (10,8 mS/cm) berodde antagligen på otillräcklig sköljning och gjorde den inte idealisk för odling. Trots detta blev skördeutfallet gott. Således kan tångkompost rekommenderas som odlingssubstrat för potatis.
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Gaspalou, Audrey. "L'arsenic dans les eaux potables." Paris 5, 1998. http://www.theses.fr/1998PA05P234.
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Rioux, Amanda. "Strategies for the Prevention of Potato Spoilage During Storage and the Discovery of the Antimicrobial Activity of Potatoes." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/RiouxA2007.pdf.
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Taylor, Thomas E. "Inheritance of competencies for leaf disc regeneration, anther culture, and protoplast culture in Solanum phureja and correlations among them." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10242009-020252/.
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De, Villiers André Jaco. "The influence of different calcium levels, irrigation methods and storage temperatures on the yield, quality and growth potential of G0 mini-tubers /." Link to the online version, 2007. http://hdl.handle.net/10019.1/2952.
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Ali, Hakoomat. "Studies on phosphorous nutrition of potatoes." Thesis, Aberystwyth University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297898.
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Button, Kimberly. "Processing sweet potatoes into french fries." Kansas State University, 2015. http://hdl.handle.net/2097/20496.
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Master of Science<br>Food Science Institute - Animal Sciences & Industry<br>Fadi M. Aramouni<br>Sweet potatoes are a significant crop and are popular among consumers, particularly as french fries. Because the processing steps of making white potato french fries may be detrimental to the quality of a sweet potato fry, it is important to understand the impact of processing on quality and consumer acceptability. The variety of sweet potatoes can affect the texture, appearance, and consumer preference. Peeling processes have evolved from harsh lye treatments to more quick and efficient methods such as steam peeling. Blanching is one of the most important steps because it deactivates enzymes, including polyphenol oxidase and amylases, that affect texture and appearance. While hot water blanching is used by majority of french fry manufacturers, novel techniques like microwave blanching may be similarly effective and less detrimental to the texture and nutritional composition. Time and temperature of the blanching method can affect the texture and flavor by weakening cell walls and leaching sugars. Drying of sweet potato fries prepares the product prior to frying. Drying drives moisture off and allows the starch on the surface of the fries to gelatinize. Many types of dryers, including vacuum, hot air, and fluidized bed, have been evaluated for the rate of moisture loss and final product texture. Drying should not be done too quickly because case hardening will occur and make the product have a tough and chewy bite. Frying uses oil at elevated temperatures to develop color, flavor, and a crispy external texture. The type of oil, oil temperature, and time of frying will affect the finished product attributes. Low oil temperature may lead to higher oil uptake into the sweet potato fries. Vacuum frying compared to deep fat frying can create sweet potato fries with less darkening and less oil uptake, but this method would be difficult in large scale manufacturing. Opportunities in creating high quality sweet potato french fries are directly related to consumer acceptability and manufacturing capability.
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Suharjo, Usman Kris Joko. "Use of Polyethylene Glycol (PEG) 8000 for Rapid Screening of Potato (Solanum tuberosum L) Genotypes for Water Stress Tolerance." Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/SuharjoUKJ2004.pdf.
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Gouws, Reinette. "Etiology and integrated control of common scab on seed potatoes in South Africa." Diss., Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-08212007-102435.
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Ajuoga, Okeyo James. "Evaluation of yield and quality of five potato cultivars grown in Southwest Virginia." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-12042009-020021/.
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Hiles, Christopher D. "Defining in-season nitrogen needs for maximum economic yields and quality for Alturas and Premier Russet." Pullman, Wash. : Washington State University, 2010. http://www.dissertations.wsu.edu/Thesis/Spring2010/C_Hiles_042110.pdf.
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Thesis (M.S. in horticulture)--Washington State University, May 2010.<br>Title from PDF title page (viewed on May 11, 2010). "Department of Horticulture and Landscape Architecture." Includes bibliographical references.
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ARSLAN, AHMET. "PHYSIOLOGICAL STUDIES OF POTATOES, SOLANUM TUBEROSUM L., GROWN IN ARIZONA (WATER STRESS, SUGARS AND STARCH, CARBOHYDRATE, BARLEY, POLLEN)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183878.
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The physiological development of potato plants and tubers grown in Arizona desert regions were examined and spectrophotometric methods were developed for the analysis of carbohydrates in potato tubers, pollen, and leaf tissues from various plants. Seed pieces were planted (March 1979, 1980) and harvested (June, July) in 2 locations. Emergence, tuber initiation, and maximum tuber numbers occurred 3, 5, and 10 weeks, respectively, after planting. In 1979, tuber yields in Mesa were low because of a shortened growing season; in Tucson, yields were drastically reduced because of soil water-logging. In 1980, tubers were planted in Mesa (March 5) and yield of the cultivar 'Kennebec' was higher, 'Denali' was nearly equal to whereas 'Norgold Russet' was lower than the national average for the respective cultivars. 'Kennebec' had the highest leaf area index (LAI) and plant height. Plantings in Marana (March 21) had lower LAI and plant height than in Mesa and yielded less, but rankings of cultivars for yield were the same. During rapid tuber growth, air temperatures often exceeded 40°C, but lower canopy temperatures were 30°C or lower, and water potentials (ψ) were -9 bars or higher. Chemical analysis showed tubers increased starch percentages during development, and levels at maturity were similar to those found in other regions of the country. Extracts for carbohydrate analysis were obtained by overnight immersion in 80% ethanol and total soluble sugars (TSS) were analyzed by an improved anthrone assay and also with para-hydroxybenzoic acid hydrazide (p-HBAH) following methylation and permanganate oxidation. Methods were also developed for estimating total keto sugars with phenol in acetic/sulfuric acid (PASA) and also with thiobarbituric acid (TBA). Aldohexoses were determined with o-toluidine and o-ethylaniline; total reducing sugars were analyzed with p-HBAH, and sucrose was estimated with anthrone or PASA or TBA following alkaline enolization or borohydride reduction of monosaccharides. Starch was determined quantitatively after enzymatic hydrolysis to glucose and analyzing with anthrone, o-toluidine, or p-HBAH. Potential errors involved in the methods are discussed and the techniques were applied to carbohydrate analysis in plant tissues and pollen.
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Leighton, Christina Stephanie. "Nutrient and sensory quality of orange-fleshed sweet potato." Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-09222008-114748.
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Laza, Miruna. "Mechanical properties affecting slicing performance of potatoes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ45080.pdf.
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Rutherford, Michael Andrew. "Biological control of Rhizoctonia solani on potatoes." Thesis, Queen's University Belfast, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336000.
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Van, Hest Petrus A. A. M. "Production of potatoes through true botanic seed." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295248.
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Dunford, Robin. "Pyruvate kinase and glycolytic control in potatoes." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259704.
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Greiner, Blake William. "Inoculation and Spread of Dickeya in Potatoes." Thesis, North Dakota State University, 2019. https://hdl.handle.net/10365/29461.
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Field experiments were conducted in two different growing environments to evaluate the spread and movement of Dickeya dadantii. A procedure to inoculate seed potatoes with Dickeya dadantii was developed to use during this study. Spread of Dickeya dadantii from inoculated potato seed to healthy potato seed during the handling, cutting and planting procedures was not detected at either location. Spread of Dickeya dadantii from inoculated seed to surrounding progeny tubers in the field was documented in both locations. In Florida, 33% of progeny tubers tested positive for Dickeya using PCR, and in North Dakota, 13% of the progeny tubers tested positive. Stunting was observed in plants grown from Dickeya dadantii inoculated seed tubers in North Dakota, but not in Florida. These results indicate that Dickeya dadantii may spread during the seed handling and cutting processes and can spread in the field from infected seed tubers to progeny tubers.
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Lanas, M. (Maija). "Smashing potatoes – challenging student agency as utterances." Doctoral thesis, Oulun yliopisto, 2011. http://urn.fi/urn:isbn:9789514295874.
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Abstract The research investigates how student agency is inscribed as challenging or as misbehaviour in schools. The purpose is to open up and enable alternative ways of interpreting student agency. The empirical part of the research is based on reflexive ethnography and narrative methodology. The data is comprised of narrative and thematic interviews conducted during a period of 3 years (2006–2009), and 4 months of ethnographic fieldwork conducted in the autumn of 2008. The context for analyzing the meanings inscribed in student agency is a northern Finnish village school. In the villagers’ narrations, the research villages were presented as centres of the people’s lives, dynamic even in their quietude, and life in the villages was presented as an active choice. These stories challenge the national representations that tend to derive from the discourse of social exclusion. These societal discourses ‘other’ the life in northern villages and direct children, through education, concretely, socio-culturally, and emotionally away from their villages towards southern cities. Based on the fieldwork and applying Mihail Bakhtin’s dialogism and interactionist approach to emotions, I find that the meanings inscribed in student agency are determined dialogically. The meanings and emotions with which student agency is inscribed in a particular situation is, thereby, not determined by the students but come from the broader social, cultural, and political contexts, and the histories of those involved in the dialogue. Thereby, for instance “bad behaviour” cannot be improved simply by targeting the student or by changing student behaviour. This derives from the fact that any action, for example smashing potatoes, can end up carrying historical, political, social, and cultural meanings, and thus, any action can become inscribed as contesting behaviour. I conclude that contesting behaviour of a student does not cause as much as it performs challenging emotions that derive from broader societal, sociocultural, and political contexts. Thereby the problem is not that challenging emotions take place in school but the illusion that they should not. If challenging emotions in school are imagined to indicate failure, it is assumed that they must be excluded rather than endured and managed<br>Tiivistelmä Tarkastelen tutkimuksessa, miten oppilaan toiminta saa merkityksen haastavana tai huonona käytöksenä koulussa. Tavoitteenani on avata ja mahdollistaa vaihtoehtoisten merkitysten näkeminen oppilaan toiminnalle. Tutkimuksen empiirinen osa nojautuu refleksiiviseen etnografiseen ja narratiiviseen metodologiaan, ja aineistona on käytetty haastatteluaineistoa 3 vuoden ajalta (2006–2009) sekä hieman yli neljän kuukauden mittaista kouluetnografiaa syksyllä 2008. Oppilaan toimijuuden tarkastelun kontekstina on pohjoinen pienkylän koulu. Kyläläisten omissa kertomuksissa kylät näyttäytyvät hiljetessäänkin dynaamisina elämän keskuksina, ja eläminen kylissä aktiivisena valintana. Nämä kertomukset haastavat valtakunnalliset representaatiot, jotka rakentuvat usein syrjäytymispuheelle. Syrjäytymispuhe toiseuttaa elämää pohjoisissa pienkylissä ja ohjaa koulutuksen kautta lapsia konkreettisesti, kulttuurisesti ja kokemuksellisesti pois kylästään, kohti etelää ja kaupunkeja. Mihail Bakhtinin dialogismia soveltaen ja kenttätyöhön pohjautuen totean, että oppilaan toiminnan saamat merkitykset ja siihen liittyvät tunteet määrittyvät dialogisesti. Toiminnan saamat merkitykset ja siihen liitetyt tunteet eivät siis ole oppilaan omassa hallinnassa vaan tulevat laajemmasta sosiaalisesta, poliittisesta, kulttuurisesta ja yhteiskunnallisesta kehyksestä sekä dialogin osapuolten erillisistä ja yhteisestä historiasta. Näin ollen, esimerkiksi ”huonoa käytöstä” ei voida parantaa yksinkertaisesti kohdistamalla toimenpiteitä oppilaaseen tai tämän käytökseen. Tämä johtuu siitä, että lähes mikä hyvänsä toiminta, tutkimuksessa muun muassa perunan soseuttaminen, voi päätyä kantamaan historiallisia, poliittisia, sosiaalisia ja kulttuurisia merkityksiä ja tulla siten merkityksi haastavaksi käytökseksi. Tutkimuksessa totean, että oppilaan haastava toiminta ei niinkään aiheuta vaan pikemminkin performoi haastavia tunteita, jotka juontuvat laajemmista yhteiskunnallisista, sosiokulttuurisista ja poliittisista konteksteista. Tällöin ongelma ei ole haastavien tunteiden esiintyminen koulussa vaan luulo, että niitä ei pitäisi esiintyä koulussa. Jos haastavat tunteet erehdytään koulussa kuvittelemaan jonkin tai jonkun epäonnistumiseksi, ne yritetään sulkea pois sen sijana että ne kestettäisiin ja käsiteltäisiin
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Abdulnour, Jihad. "Nutrient manipulation in potato plantlets and microtubers." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35671.
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In vitro culture techniques are widely used in potato for rapid production of specific pathogen tested plantlets and microtubers, which are essential for seed certification programs. The limited calcium (Ca) uptake in vitro promotes physiological disorders in many micropropagated species including potato. Factors that may affect Ca uptake by potato plantlets, including cations, osmotic potential, and boron (B) were examined. The possibility of improving microtuber yield by low pH shock or successive harvests, which stimulated greenhouse potato production, were also investigated. Ca uptake by cvs. Norland and Bintje potato plantlets grown on modified Murashige and Skoog (MS, 1962) media was enhanced by diluting the total macroelements in the nutrient medium, except Ca. Increasing Ca:specific cation ratios, by lowering either NH 4, Mg or K, had little effect on Ca uptake by Norland plantlets. At equivalent Ca:total cation, Ca uptake was promoted further when the total macroelement concentration was reduced by half than when the Ca level was doubled (from 3 to 6 mM). This suggested that the increase in the osmotic potential of the medium had a great impact on Ca uptake, probably by affecting the root pressure. B contamination from impurities in the nutrient chemical components always occurred. The addition of the recommended H3BO 3 level of 0.1 mM (1.08 ppm) or more (0.3 mM) to the medium decreased Ca content of leaves and shoots in Norland but not Bintje, while addition of only 25% of this level was sufficient to provide plantlets with adequate B tissue concentration without compromising normal growth. Macroelement dilution along with Ca addition, and lower B levels than commonly used in MS (0.1 mM) are recommended for optimal Ca uptake in potato and possibly other plant species. Microtuber yield was not improved by a low pH shock. Adjusting microtuberization medium pH to less than 5.7 (3.5, 4.3 or 5.2), prior to autoclaving, reduced microtuber number and/or weight
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Lowe, Robert 1961. "In vitro hardening, improved greenhouse minituber production and field performance of potato (Solanum tuberosum L.) cv. Norland." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21598.
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Micropropagated potato (Solanum tuberosum L.) plantlets are routinely used for producing specific pathogen tested minitubers in the Canadian seed tuber certification industry. In vitro hardening methods for micropropagated 'Norland' were investigated, involving full and half strength Murashige and Skoog (1962) based propagation medium supplemented with NaCl, KCl, CaCl2, polyethyleneglycol, or paclobutrazol. Ten different media treatments were compared for their effect on stomatal function and early transplant performance using porometry, microscopy, and direct ex vitro transplanting. PEG, NaCl and 1/2 MS + 3 mM Ca treatments did lead to decreased leaf water losses. However, these treatments did not improve ex vitro transplant performance compared to controls. Minituber production was investigated using ex vitro plantlets in a rockwool-based hydroponic system. Productivity was evaluated for treatments involving photoperiod pretreatment, planting orientation, planting density, and hilling. No difference in total yield was detected when plantlets were exposed to 12 compared with 16 hour photoperiod pretreatments. However, short photoperiod pretreatment increased the number of minitubers in the most desirable size range. Increased planting density reduced yield per plant. However, small increases in yield per m2 occurred with increased planting density. Hilling, pinching, and planting orientation had no effect upon minituber size, number, or overall fresh weight yield. Significant differences in minituber yield occurred in field experiments. Larger minitubers (10--40 g) had larger yields compared with smaller minitubers (1--5 g). These results will contribute to improved minituber production technology for the Canadian certified potato seed tuber industry.
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Leclerc, Yves. "The production and utilization of potato microtubers." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41512.
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A protocol is presented for the rapid (28 days) induction of microtubers on micropropagated layered potato plantlets of 'Kennebec', 'Russet Burbank' and 'Superior' in medium devoid of growth regulators. With this method the addition of coumarin, 6-(2-chloroethyl)-trimethylammonium chloride and 6-benzylamino-purine to the microtuberization medium either had no effect or significantly reduced microtuber weight per plantlet. Increasing the incubation period from 28 to 56 days significantly increased the weight of microtubers per plantlet and the proportion of microtubers heavier than 1 gram. Increasing the volume of microtuberization medium from 50 to 100 ml significantly increased the number of microtubers per plantlet. Microtuber dormancy periods were cultivar-specific and microtubers $ le$250 mg had longer dormancy periods as compared to microtubers $>$250 mg. A positive correlation was established between endogenous abscisic acid levels and microtuber dormancy periods. Microtubers $ le$250 mg had lower specific gravity, fewer eyes and produce fewer sprouts than microtubers $>$250 mg. Microtuber-derived plants were generally single-stemmed. Severe physiological ageing treatment ($>$2500 degree-days) had no effect on microtuber sprout development, stem number, tuber number and only minimally influenced tuber weight of microtuber-derived plants. Decreasing field in-row planting density from 30 to 10 cm reduced tuber weights and numbers per plant but increased them on a per hectare basis. Economic analysis indicated that optimum planting density varied depending on plantlet cost. The optimum planting density was 10 cm if the cost of the plantlet was $0.10 or less, 20 if plantlet cost were from $0.10 and $0.20 and 30 cm for plantlet cost greater than $0.20. A potato seed tuber certification program adapted to the needs and constraints of Egypt is presented.
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Habib, Ahsan. "Studies on the improvement of calcium uptake into micropropagated potato." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84255.
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Various aspects of Ca2+ uptake into greenhouse-grown potato plants and micropropagated potato plantlets were examined, including the movement of Ca2+ into potato plants and tubers, identification of Ca-packing genotypes and assessment of the effect of improved medium Ca2+ level on different parameters such as plantlet growth, microtuber induction, yield and tissue Ca concentration. The effect of exogenous vitamin Ds and UV-elicited endogenous vitamin D synthesis on regulation of 45Ca 2+ uptake into plantlet shoots was also examined. Safranin dye was not as suitable as the tracer 45Ca2+ for monitoring translocation of Ca2+ into tubers. Uptake of Ca2+ into tubers occurred indirectly through the main basal roots and stolon roots and directly through tuber periderm. Liquid scintillation counting and flame atomic absorption spectrophotometry were used to screen six potato cultivars and two wild species for ability to take up Ca2+ from treatment solutions containing high or low Ca2+ levels. In vitro potato micropropagation, microtuberization, and tissue calcium concentration were compared for six cultivars when Murashige-Skoog basal medium Ca2+ level was increased from 3, to 5 or 15 mM. All aspects of growth including shoot dry weight, early microtuber induction, microtuber yield and tissue Ca concentration were improved when medium Ca2+ level was 15 mM. Cultivar Bintje was the most efficient genotype at accumulating Ca 2+ from treatment solutions or growth media containing high or low Ca2+ levels. Vitamin Ds improved 45Ca 2+ uptake into shoots of micropropagated potato plantlets and D 3 was more efficient in this regard than D2 or a combination of D3 and D2. Plantlets had increased 45Ca 2+ uptake when exposed to UV irradiation compared with the untreated control plantlets. Plantlets given a 24 hour interval in the dark after UV exposure had even greater 45Ca2+ uptake, suggesting that vitamin D, metabolites, specifically calcitriol (1, 25(OH)2-v
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Guthrie, Kelly. "Vitamin C and Glycoalkaloids in Organically Grown Potatoes of Novel Varieties." Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/GuthrieKX2006.pdf.
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Pak, Paul Kote-Tak. "Glucose and sucrose levels in potato tubers by cultivars and farms stored under different regimes and their influence on potato chip color /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487263399026372.
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Nourian, Farideh. "Quality changes in raw and processed potatoes as influenced by storage conditions and bacterial soft rot disease." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=83083.
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Potato ranks fourth after wheat, rice and corn as a major food crop. It is an excellent source of nutrients and at the same time relatively inexpensive, therefore it is the mainstay in the diets of people in both developed and developing countries. Potato losses and quality degradation due to the effect of storage variables or processing conditions must be reduced to increase the world food supply. To accomplish these objectives, studies have been conducted to evaluate: (a) quality changes in potatoes during cooking and frying, (b) quality changes in raw potatoes as influenced by storage conditions, (c) changes in cooking quality of potatoes as influence by storage conditions, (d) changes in frying quality of potatoes as influenced by storage conditions, and finally (e) quality changes in potatoes as influenced by Erwinia carotovora ssp. carotovora infection (Ecc, casual agent of soft rot disease in potato).<br>Kinetics of quality changes during cooking and frying of potatoes were evaluated. Potatoes were cooked at 80--100°C or fried at 160--190°C for selected times and their texture and color were evaluated. Results showed that texture values of cooked potatoes decreased with the progress of cooking, and the rate of texture changes at each temperature was found to be consistent with two pseudo first-order kinetic mechanisms. Textural values of fried potatoes increased with frying time and followed a first order kinetic model. Cooked potatoes were less bright, more red and less yellow in color as compared to raw samples. A modified first order model was used to characterize the color changes kinetics of both cooked and fried potatoes based on the changes occurring between the initial and a maximum or minimum value. 10 min cooking at 100°C and 10 min frying at 180°C were considered to give the designed cooked and fried products, respectively.<br>The changes in quality characteristics of potatoes as a function of storage variables (temperature and time) were evaluated. Potatoes were stored at five temperatures (4, 8, 12, 16 and 20°C) for selected duration (at least 5 time intervals) and different physico-chemical quality parameters were evaluated. Potatoes remained healthier when they stored at lower temperatures due to absence of sprouts and visible spoilage. They became softer and darker by passage of time.
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Pehu, Eija. "Analysis of anther-derived plants of Solanum phureja: variation in ploidy, photosynthetic efficiency and structure of the nuclear genome." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/71169.
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The ultimate goal of the· breeding scheme, of which the present study is a part, is to introduce exotic germplasm into existing cultivars of Solanum tuberosum through· 4x X 2x crosses using the South American diploid potato species Solanum phureja as the pollen parent. The first phase of this program includes the 'reconstruction' of a highly heterozygous diploid, pollen parent by .first : reducing the chromosome number of the S. phureja clones to the monoploid level and subsequently fusing genomes of two unrelated monoploid plants either by somatic hybridization or by cross-pollination between fertile doubled monoploids.
Within this framework, the objectives of this research were to analyze variation among anther-derived plants of Solanum phureja regarding their: 1) ploidy level and morphology, 2) net photosynthesis and its biochemical components, and 3) nuclear genomic structure, particularly with regard ·to the amplification of rRNA genes as influenced by the anther-culture process.
Based on the analysis of several morphological characters of the anther-derived plants by canonical discriminant function, four characters (anther length, number of chloroplasts/pair of guard cells, leaf width, corolla width) were selected for most effective assignment of plants to their ploidy groups by clustering procedures. Clustering of the anther-derived plants proved to be an efficient means of separating monoploids from higher ploidy levels.
To assess the impact of the process of anther-culture on the physiology of the resulting plants and to evaluate the possibility of selecting anther-derived genotypes for further breeding efforts, monoploid, diploid and tetraploid anther-derived plants were studied regarding their net photosynthesis and its component characteristics. Leaf area, net photosynthesis and chlorophyll content increased with increasing ploidy' Among .the. monoploids I. Rubisco activity and concentration displayed a. significant genotypic effect; whereas in the diploid group variation among genotypes was significant for total protein content and maximum specific activity of ribulose bisphosphate carboxylase. Among the tetraploid genotypes, significant differenc.es were found with respect to net photosynthesis and specific leaf weight. Two exceptional genotypes were identified: a monoploid with an increase of 28% fcfr maximum activity of ribulose bisphosphate carboxylase and a tetraploid with an increase of 30% for net photosynthesis over the anther-donor plant.
To evaluate DNA variation among the anther-derived plants, the nuclear genomes of anther-derived monoploid and diploid plant were studied by DNA reassociation kinetics. It was found that the nuclear genome of the monoploid has undergone differential replication resulting in an increase of sequences consisting of highly· repetitive DNA. Free solution RNA-DNA hybridization showed that the monoploid DNA contained 30% more rDNA sequences than the diploid. Southern blot analysis using rRNA as the probe revealed variation for copy number of certain restriction fragments and for restriction enzyme cleavage sites.<br>Ph. D.
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Singh, Baljinder. "Visible and near-infrared spectroscopic analysis of potatoes." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84074.
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The potential of different spectroscopic techniques for evaluating potato (Solanum tuberosum L.) quality was investigated. Spectral data in the wavelength range of 400-1750 nm were used to develop quality prediction models. The Partial Least Squares (PLS) regression was used for predicting the water content in potato samples. Water content was predicted with R2 ≥ 0.938.<br>A further study was conducted to find the best wavelengths for predicting water content using two methods, PLS and multiple linear regression. Wavelength ranges of 910-1020, 1129-1211, 1363-1403 nm were selected for samples without skin, while 700-900, 930-1050, 1100-1300, 1400-1550 nm were selected for samples with-skin. Weight prediction models were established using the predicted water content.<br>Visible spectroscopy was used for classifying shriveled and non-shriveled potatoes. The wavelength ranges best suited to such a classification were those of 442-452, 456-466, 641-651, and 684-694 nm, with accuracies as high as 94.28% and as low as 80%.
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Teider, Irina, and Yuliya Tomilenko. "Historia om grönsakslandet eller Vems potatis är störst?" Thesis, Stockholm University, The Stockholm Institute of Education, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7710.
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<p>Vi fick bekanta oss med en miljö som ger barnen nya möjligheter att upptäcka, forska och experimentera. Vi kunde se att den delen av utemiljön som den lilla kolonilotten är bidrar till barnens utveckling och lärande. Dessutom utvecklas barnens ”förståelse för sin egen delaktighet i naturens kretslopp” (Lpfö 98, s. 37). Vi blev inspirerade att undersöka saker ytterligare. Först och främst ville vi ta reda på hur man planerar och arbetar i en sådan miljö. Som exempel tog vi kolonilottens projekt på A-förskolan som vi fick inspiration av. Att utforska vilken betydelse kolonilotten har för barnens utveckling och lärande och vilka utforskande möjligheter finns där var det viktigt för oss. De frågorna ligger till grund för vårt examensarbete. Vi gjorde en djup kvalitativ undersökning. De intervjuer och samtal med pedagogerna på avdelning B, deltagande observationer och bearbetning av förskolans dokumentation gav ett bra resultat så att vi kunde uppnå målet. Vi fick fram att kolonilotten skulle fungera som en pedagogisk resurs krävs det mycket arbete och genomtänkt planering. Man planerar och utför arbetet på kolonilotten utifrån barnsperspektiv. Vi kunde se att arbetet på kolonilotten är intressant, roligt och meningsfullt för barnen. Genom att sköta sitt grönsaksland får barnen mängder av nya begrepp. Undersökningen visar att när barnen tar hand om växter upplever de naturen på ett speciellt sätt. Vi fick fram att arbetet utförs på ett utforskande sätt som engagerar barnen till aktivt deltagande, utmanar dem, väcker lust och stimulerar deras tankar. Genom det kreativa arbetet på kolonilotten skaffar barnen möjlighet att göra sina egna uppfinningar och får nya insikter. De skapande och utforskande aktiviteterna bidrar till barnens utveckling och lärande.</p>
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Renwick, Randall R. "Evaluation of a crop simulation model for potatoes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ41762.pdf.
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Edgell, Teresa. "Ultrastructural and physiological aspects of bruising in potatoes." Thesis, Nottingham Trent University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341224.
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Xiang, Mingyan. "Enzymes associated with oxidative stress in sweet potatoes." Thesis, University of Greenwich, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401561.
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Thomas, Mark Nathan. "The control of tuber size in maincrop potatoes." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293832.
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McPartlan, Helen Clare. "Transgenic potatoes (Solanum tuberosum) : gene dispersal and stability." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241045.
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Sobieska, Aleksandra Cecylia. "An Exploration in Group Testing: Finding Radioactive Potatoes." Kent State University Honors College / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1400245519.
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Meyer, Danielle Susan. "Influence of Potato Type on Satiety and Related Responses." Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/MeyerDS2008.pdf.
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Sarries, Juan Miguel. "Effects of physiological age of potato seed on plant development and yield in dual cropping systems in Uruguay." Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=185659.
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In N. Uruguay two potato (Solanum tuberosum L.) crops are grown per year, one in the fall and the other in spring. In each season physiologically young seed tubers are planted, resulting in relatively slow crop emergence and low yields. The aim of the current research was to determine the effects of physiological ageing of seed tubers on the dynamics of canopy growth, radiation interception and radiation use efficiency (RUE) of crops in the short seasons of Uruguay and to identify opportunities for increasing yield. Experiments were conducted on cv Chieftain over three years from 2000 to 2002. Prior to planting seed was stored at different controlled temperatures to generate physiological ages (measured in thermal time) ranging from 0 (the youngest) to 1200 oC days (the oldest). Ageing led to earlier crop emergence (3-9 days depending on the year), but its potential benefits on radiation interception, dry matter production and yield were negated by an earlier canopy senescence and often smaller canopy size. There was no consistent effect of ageing on RUE although the harvest index was increased. Leaf tagging showed that leaf appearance and senescence was advanced by ageing and the lifespan of individual leaves was reduced. Leaf lifespan did not appear to be related to the sink demand by tubers for assimilate, because removal of tubers at the start of bulking had no effect on lifespan. Maintaining canopy structure during senescence led to a small increase in yield. Although physiological ageing did not result in a consistent increase in yield in either season, use of older seed may provide an insurance against the risk of adverse weather conditions late in the season terminating tuber bulking prematurely.
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Monday, Tyler Anthony Foshee Wheeler G. "Industrial sweetpotato a viable biofuel crop for Alabama /." Auburn, Ala, 2009. http://hdl.handle.net/10415/1763.
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Leclerc, Yves. "Acclimatization, field performance and microtuberization of tissue cultured potato (Solanum tubererosum L.) cv. Russet Burbank." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61861.
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Ortiz-Medina, Estela. "Potato tuber protein and its manipulation by chimeral disassembly using specific tissue explantation for somatic embryogenesis." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103001.
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Potato is a major part of the human diet in many countries of the world, providing substantial levels of carbohydrate, protein, and vitamins. This study examined the tuber protein content. In the first part of the research, total soluble protein (TSP) and patatin concentration were determined in periderm, cortex, and pith, in tubers of 20 important potato cultivars. TSP concentration was greater in periderm and lesser in cortex and pith tissues. Patatin was present in all tuber tissues but with the opposite pattern, less in periderm and greater in cortex and pith tissues. For intercultivar comparisons, a means of converting the specific tissue-based TSP and patatin data (dry weight) into a uniform weight whole tuber basis was developed. This relied on conversion factor values that were generated from percent weight tissue proportion and percent dry matter for each tissue layer. Cultivars with relatively more or less TSP and patatin in each tissue layer, and on a whole tuber basis, were identified. In the second part of the study, disassembly of chimeral (Russet Burbank) and putatively chimeral (Alpha, Bintje, Red Gold) tubers into their component genotypes was evaluated as a strategy for the production of intraclones with altered protein content. Explants were selected from tissue with greater or lesser protein levels and somatic embryogenesis was used to produce regenerants from each tissue source. Russeting was used as a phenotypic marker and TSP as a biochemical marker. Russet Burbank was confirmed as a periclinal chimera, although chimeral instability was evident, since some non-chimeral regenerants showed displacement of LI tunic cells with the russeting mutation into the pith. Red Gold was "uncovered" as an LII periclinal chimera (Red-Gold-Red). The value of chimeral disassembly in explaining an important component of somatic variation was clearly seen with this cultivar. The inconsistent TSP distribution in Russet Burbank intraclones proved that TSP was not distributed in a periclinal chimeral manner, as initially hypothesized. However, there was clear variation in protein content in the tubers of non-chimeral regenerants. Periclinal chimeral disassembly and somatic embryogenesis are potentially useful technologies for the production of improved intraclones of potato.
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Boukes, Gerhardt Johannes. "The in vitro biological activities of three Hypoxis species and their active compounds." Thesis, Nelson Mandela Metropolitan University, 2010. http://hdl.handle.net/10948/1228.
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The African potato is used as an African traditional medicine for its nutritional and medicinal properties. Most research has been carried out on H. hemerocallidea, with very little or nothing on other Hypoxis spp. The main aim of this project was to provide scientific data on the anticancer, anti-inflammatory and antioxidant properties of H. hemerocallidea, H. stellipilis and H. sobolifera chloroform extracts and their active compounds. The hypoxoside and phytosterol contents of the three Hypoxis spp. were determined using TLC, HPLC and GC. H. hemerocallidea and H. sobolifera chloroform extracts contained the highest amounts of hypoxoside and β-sitosterol, respectively. For the anticancer properties, cytotoxicity of the Hypoxis extracts and its purified compounds were determined against the HeLa, HT-29 and MCF-7 cancer cell lines (using MTT), and PBMCs (using CellTiter-Blue®). H. sobolifera had the best cytotoxicity against the three cancer cell lines, whereas H. stellipilis stimulated HeLa and HT-29 cancer cell growth. IC50 values of hypoxoside and rooperol were determined. DNA cell cycle arrest (using PI staining) occurred in the late G1/early S (confirmed by increased p21Waf1/Cip1 expression) and G2/M phases after 15 and 48 hrs, respectively, when treated with Hypoxis extracts and rooperol. H. sobolifera and rooperol activated caspase-3 and -7 (using fluorescently labelled antibodies) in HeLa and HT-29 cancer cells, and caspase-7 in MCF-7 cancer cells after 48 hrs. Annexin V binding to phosphatidylserines in rooperol treated U937 cells confirmed early apoptosis after 15 hrs. The TUNEL assay showed DNA fragmentation in the three cancer cell lines when treated with H. sobolifera and rooperol for 48 hrs. A shift pass the G2/M phase has led to the investigation of endoreduplication, which was confirmed by cell/nucleus size, and anti-apoptotic proteins (Akt, phospho-Akt, phospho-Bcl-2 and p21Waf1/Cip1). U937 cell differentiation to monocyte-macrophages was optimized using PMA and 1,25(OH)2D3, which was confirmed by morphological and biochemical changes. For the anti-inflammatory properties, Hypoxis extracts and rooperol significantly increased NO production in monocyte-macrophages (pre-loaded with DAF-2 DA) and phagocytosis of pHrodoTM E. coli BioParticles®. The treatments had no effect on COX-2 expression in monocyte-macrophages. The phytosterols significantly increased IL-1β and IL-6 secretion xv (using the FlowCytomix Multiplex human Th1/Th2 10plex Kit I) in the PBMCs of one donor. For the antioxidant properties, Hypoxis extracts and rooperol significantly increased ROS production in undifferentiated and differentiated U937 cells, which were pre-loaded with DCFH-DA. Hypoxis extracts and purified compounds had ferric reducing activities, but only rooperol had ferric reducing activities significantly greater than ascorbic acid. β-sitosterol, campesterol and cholesterol significantly increased SOD activity in Chang liver cells, while H. stellipilis, H. sobolifera and rooperol decreased SOD activity. Anticancer, anti-inflammatory and antioxidant properties of the Hypoxis extracts may be attributed to the β-sitosterol content, because Hypoxis chloroform extracts contained very little or no hypoxoside. Unidentified compounds, and synergistic and additive effects of the compounds may have contributed to the biological effects. This study confirms previous reports that rooperol is the active compound. Results provide scientific data on the medicinal properties of one of the most frequently used medicinal plants in South Africa.
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Dresow, Jana Franziska [Verfasser]. "Optimization of organic potato production : influence of agronomical measures on yield and quality of table potatoes and processing potatoes / Jana Franziska Dresow." Kassel : Universitätsbibliothek Kassel, 2013. http://d-nb.info/1046188526/34.
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Collado, Lilia S. "Physical properties and utilization of sweet potato starch and flour." Thesis, Click to view the E-thesis via HKUTO, 1997. http://sunzi.lib.hku.hk/hkuto/record/B42574675.
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Shen, Liu Yin. "Studies of androgenic processes in diploid potato." Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/42094.
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Androgenic processes in diploid potato (2n=2x=24) were studied in three interspecific hybrids. Five incubation temperature treatments were examined. Temperature shock (35°C) during the first 12 h of anther culture and elevated incubation temperature (30°C 16h/20°C 8h) (hereafter 35°C-30°C/20°C) enhanced androgenic embryo production. Variation among experiment dates was highly significant. Temperature treatment (35°C-30°C/20°C) during anther culture did not influence the subsequent conversion rate of androgenic embryos, thus providing a simple and effective way to enhance androgenic embryo yield.
Repeated experiments were conducted to study extended anther culture by replacing anthers into medium following the usual harvest 6 weeks after culture initiation. Embryos continued to be produced after the first harvest. Embryo yield at the first harvest was significantly correlated with that at the second harvest (P <0.01). Significantly more embryos were produced when anthers were put back into the same medium compared to fresh medium in extended anther culture. Although relatively high embryo yield was produced in extended anther culture, high contamination and low regeneration rate eliminate any practical use unless a better regeneration protocol is developed.
Randomly amplified polymorphic DNA (RAPD) techniques were applied to analyze the genetic composition of anther-derived plants, whose ploidy level was predetermined by flow cytometry. The RAPD fragments amplified from various anther derived diploid plants (2n=2x=24) were compared with those from anther donor (2n=2x=24) and anther-derived monoploids (2n=1x=12). Anther donor and anther-derived monoploids were distinguished by scoring segregating bands as well as total number of scorable bands that exhibited polymorphism. Thus RAPD has the potential to separate homozygous from heterozygous diploids, since the frequency of RAPDs present in homozygous diploids is expected to be the same as in a group of known monoploids, whereas heterozygous ones will be similar to the anther donor.<br>Master of Science
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Sadie, Louise. "Characterisation of "glassiness" in commercially processed French fried potatoes /." Link to the online version, 2005. http://hdl.handle.net/10019/1186.
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Hämäläinen, Jaana. "Molecular mapping of potyvirus resistance genes in diploid potatoes /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5703-3.pdf.
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Lewis, Christine Elaine. "Anthocyanins and related compounds in potatoes (Solanum tuberosum L.)." Thesis, University of Canterbury. Plant and Microbial Sciences, 1996. http://hdl.handle.net/10092/6549.
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Coloured potatoes may have economic value as natural food colourants and as food products such as novelty potato crisps and coloured potato salads. This thesis investigated the biochemistry and physiology of anthocyanins and related compounds in Solanum tuberosum L., and the relationship to tuber colour. These factors were discussed in terms of consumer requirements.
Phenolic acids, flavonoids and anthocyanins were surveyed and quantified in the tubers (skin and flesh), flowers and leaves of twenty nine cultivars of S. tuberosum and eight other Solanum species (S. acaule, S. berthaultii, S. gourlayi, S. oplocense, S. sanctaerosae, S. spars/pilum, S. speggazzinii, S. stenotomum). The main anthocyanin found in red tubers was pelargonidin-3-(p-coumaroyl-rutinoside)-5-glucoside (200-2000μg/gFW) with lower amounts of peonidin-3-(p-coumaroyl-rutinoside)-5-glucoside (20-400μg/gFW), Light to medium pmple coloured tubers contained mostly petunidin-3- (p-coumaroyl-rutinoside)-5-glucoside (400-2000μg/gFW) pills low concentrations of malvidin-3-(p-coumaroyl- rutinoside)-5-glucoside (20-200μg/gFW), whilst dark purple black coloured tubers contained a similar concentration of petunidin-3-(p-coumaroyl-rutinoside)-5-glucoside (1000-2000μg/gFW) to the light to medium purple tubers, but with high concentrations of malvidin-3-(p-coumaroyl-rutinoside)-5-glucoside (2000- 5000μg/gFW). Red and purple tubers also contained a number of minor anthocyanins, with the same aglycones as above, but mostly as the 3-rutinosides. Tubers contained high concentrations of phenolic acids (2000-5000μg/gFW), with chlorogenic acid making up 60-90%. Apart from the anthocyanins, there were low concentrations of other flavonoids (200-300μg/gFW). The major anthocyanin present in the flowers was petunidin-3-(p-coumaroyl-rutinoside)-5-glucoside. Flowers and leaves contained higher concentrations of flavonoids (1000-3000μg/gFW), the major flavonoids being quercetinglycosides. The flavonoid patterns of flowers and leaves fell into two different categories with some cultivars containing high concentrations of quercetin-glycosides, whilst others contained low concentrations.
Tubers of the other available Solanum species did not show the range of colours shown by S. tuberosum cultivars, and were mostly white or light purple, with petunidin-3-(pcoumaroyl-rutinoside)-5-glucoside being the major anthocyanin (when present) in the skin of tubers of the other Solanum species. The major anthocyanin in flowers of the other Solanum species was petunidin-3-(p-coumaroyl-rutinoside)-5-glucoside, with levels similar to those found in S. tuberosum flowers. Low levels of anthocyanin were found in the leaves of the other Solanum species whereas in S. tuberosum no anthocyanins were found in the leaves. There was considerable variation among plants and species in both phenolic acid and flavonoid concentrations, but generally a similar pattern was found in the other Solanum species as in S. tuberosum cultivars, except that S. tuberosum flowers contained lower concentrations of total phenolic acids and flavonoids on average, and tubers and leaves contained high concentrations of flavonoids.
The expression of different pathways appeared to depend on the species, plant tissue and environmental factors. Diseased tubers contained higher concentrations of phenolic acids, flavanones and flavonols than healthy tubers, and some flavonols which were not present in healthy tubers were produced in diseased tubers. There was differential expression of anthocyanins, flavonoids and phenolic acids in the different parts of the plant (tubers, flowers and leaves). These compounds also responded differently to light, with anthocyanins showing a large increase, flavonoids a smaller increase, and phenolic acids no change in concentration, in minitubers after indirect exposure to light.
The biosynthesis of anthocyanins in tubers was investigated throughout tuber development and during storage. Newly initiated tubers contained no anthocyanin, and subsequent production of colour occurred firstly at the stem end of the developing tuber, and then proceeded to the bud end. Anthocyanin concentrations increased throughout the development of the tuber, reaching a maximum at a tuber size which was dependent on the cultivar (about 150-200g for Desiree). Concentrations were higher at the stem end of the tuber than the bud end for most of tuber development although, as the maximum anthocyanin concentration was reached, the distribution of anthocyanin over the tuber became more uniform. This suggested that the transport of some compound (carbohydrate or "trigger”) was responsible for the initiation of anthocyanin biosynthesis. Concentration of other flavonoids also increased and followed a similar pattern to that of the anthocyanins, with maximum concentrations occurring in Desiree tubers about 150-200g. Phenolic acid concentrations also increased during tuber development, although these reached a maximum concentration in slightly smaller tubers (about 70-100g).
Microscopical studies of anthocyanin-containing cells showed that the difference in colour intensities of the different cultivars was because of differences in the amount of anthocyanin produced in individual cortex cells, in the proportion of cortical cells within a layer producing anthocyanin, and the number of layers of coloured cells. Totally white tubers did not contain any anthocyanin coloured cells, whilst more highly coloured tubers contained a greater number of more highly coloured cells in these layers. Additionally, the strongly coloured tubers had increased amounts of anthocyanin present in the phellem cells and intense1y coloured deposits of anthocyanin around the cell walls of these cells.
Cold storage (4°C) of tubers caused an increased concentration of anthocyanins, especially at the bud end of the tuber, so that the distribution pattern of anthocyanins was reversed from that found in developing tubers. Storage at higher temperatures (10°C and above) caused a decrease in anthocyanin concentration. These changes in anthocyanin concentration were thought to be related to sprouting and also the sugar concentration within the tuber. Cooking (boiling, steaming or crisping) of tubers (until they were ready to eat) did not result in any significant loss in anthocyanin colour, although after two to three times the normal cooking time some loss of anthocyanin colour occurred.
Anthocyanin colour may have been affected by the high concentration of starch or sugars found in tubers. Addition of amylose, amylopectin, α-cyclodextrin and β-cyclodextrin to anthocyanin solutions caused a decrease in anthocyanin colour, whilst the addition of sugars (glucose, sucrose and maltose) resulted in increased anthocyanin colour.
Tissue-cultured minitubers were used to investigate the effects of light on anthocyanin biosynthesis. Although anthocyanins were produced in the dark in field grown tubers, the presence of light on the plant leaves was necessary for anthocyanin production in some cultivars. Anthocyanin concentration increased with increased light intensities in all cultivars studied (to a maximum of about 3.2ng/cm² of surface area in Desirée minitubers), and the activities of enzymes (phenylalanine ammonia-lyase, cinnamic acid 4-hydroxylase, chalcone isomerase, flavanone 3-hydroxylase, flavonoid 3'-hydroxylase, dihydroflavonol reductase and glycosyltransferase) showed related increases. Biosynthesis of anthocyanins was a high irradianceresponse and required at least eight hours of exposure to light for a significant increase in anthocyanin concentration to occur, after which anthocyanin concentration (to a similar maximum concentration) increased linearly with increasing time of exposure. Both phytochrome and cryptochrome light receptors were thought to be involved because light of blue, red and purple wavelengths enhanced anthocyanin production, compared with white light of similar intensity.
The regulation of anthocyanin biosynthesis in potato tubers is different from most other plants and tissues because direct light exposure of the tuber is not necessary for anthocyanin production. However, for maximum anthocyanin synthesis the exposure of the plant leaves to light is required. It is proposed that this synthesis of anthocyanins intubers in the dark requires genetic capability of the tubers, a supply of carbohydrates, and is mediated by a "trigger" compound produced after the exposure of the leaves to light and transported to the tubers.
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Wood, John Richard. "Ice nucleation active bacteria on potatoes in Northern Ireland." Thesis, Queen's University Belfast, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336034.
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