The rate of respiration of potato tubers during storage. 3. Relationships between rate of respiration,weight loss and other variables

Summary In 1973 the rate of respiration of stored potato tubers was highest in those cultivars which had the greatest weight loss, but this was not found in 1972. The rate of respiration could almost completely be explained by the factors storage temperature, degree of sprouting and storage duration, and the interactions between these factors. The main effects often had a strong curvilinear component. The increase in rate of respiration found after one and a half years of storage at low temperatures was cuased by physiological deterioration of the tubers. Paper No 690, Department of Vegetable Crops, Cornell University, Ithaca, N.Y. 14853, USA     

Development during storage of spraing symptoms in potato tubers infected with tobacco rattle virus

Summary In trials with potato tubers infected with tobacco rattle virus (TRV), symptoms of spraing in cvs Bellona, King Edward, Maris Bard, Matilda, Sv 82146 and Sv 82149 increased during storage when the tubers were cut. Storage of intact tubers at a constant temperature of 9°C or at fluctuating temperatures (2 weeks at 18°C, 2 weeks at 9°C and 2 weeks at 18°C) did not increase the frequency of symptoms.     

Detection of potato virus X in tubers with the enzymelinked immunosorbent assay (ELISA)

Summary Tubers of field-grown plants of ten Dutch potato cultivars, secondarily infected with potato virus X (PVX) or free from this virus were submitted to ELISA after storage at 4°C. About 40 weeks after lifting PVX could be detected reliably. Extinction values with the apical parts of the tubers were slightly higher than those with the basal parts.     

Dormancy and sprout development of some South African potato cultivars during cold storage

Summary Observations were made on dormancy and sprout growth of nine potato cultivars stored at 3–4°C, 7–8°C and 11–12°C, respectively. Tubers of the cultivar Vanderplank had a very long dormant period (232 days at 3–4°C) and showed little sprout growth at 180 days. The cultivar Koos Smit had a very short dormant period (92 days at 3–4°C) and developed considerable sprout growth at the higher temperatures. The reaction of tubers of Up-to-date and BP₁ were approximately the same, and intermediate between those of Vanderplank and Koos Smit.     

In vitro and in silico analysis of two genes (A2-1 and G1-1) differentially regulated during dormancy and sprouting in potato tubers

Summary Two cDNAs, corresponding to genes differentially regulated during dormancy and sprouting in potato tubers, cultivar Désirée, were isolated: i) G1-1 corresponded to a gene that was turned off during dormancy and turned on during early phases of sprouting; ii) A2-1 corresponded to a gene activated during dormancy and strongly repressed during the transition from dormancy to sprouting. When induced, both genes were expressed at low level. Full-length cDNAs and genomic clones were isolated and characterized. G1-1 was a short gene, 452 bp long, containing an intronless open reading frame, coding for a putative protein of 64 aminoacids. Sequence analysis showed that G1-1 was homologous to an expressed sequence tag (EST) ofArabidopsis thaliana. A2-1 full-length cDNA was 1577 bp long and contained an open reading frame coding for a putative protein of 383 aminoacids, which contained a Walker box binding domain, common to a multifunctional family of intracellular ATPases.     

Effect and interaction of crop management factors on the glycoalkaloid concentration of potato tubers

Summary Potato tuber glycoalkaloid content was measured in response to nitrogen fertilizer rate, storage temperature, length of storage period and cultivar. Cvs Gemchip, Norchip and Russet Burbank were grown with applied nitrogen fertilizer rates of 0, 168 or 336 kg/ha and then stored at either 4.4 or 10°C. Total glycoalkaloid content was determined one month before harvest, at harvest, after three months of storage and after nine months of storage. Higher rates of nitrogen, higher storage temperature and a period of storage all resulted in significantly (P<0.05) higher concentration of glycoalkaloids. The cv Norchip had higher glycoalkaloids than cvs Gemchip or Russet Burbank. Only the storage period had more influence than the environment (difference between years). Significant (P<0.05) two-way interactions were detected for year x cultivar, year x nitrogen, storage period x cultivar and nitrogen x cultivar. Most interactions were due to the unique responses of cultivars.     

The relationship between respiration and chip color during long-term storage of potato tubers

Processing potatoes, both sprout inhibited and untreated, were evaluated for respiration rate and chip color during storage under commercial conditions (12 C, approximately 95% relative humidity, in darkness) following three growing seasons. While absolute respiration rates varied depending upon growing season and treatment, all cultivars and treatments studied during the 1995, 1996, and 1997 storage seasons showed similar respiration profiles. The initial stage following curing and sprout inhibition treatment (if applied) showed essentially constant respiration rates for a period of time varying from two to 15 weeks, depending upon growing season, treatment and cultivar. This was followed by a stage that showed a linear increase in respiration rates. In some cases the respiration rates eventually stabilized, or decreased. There was an apparent correlation between respiration trends and chip color changes in most cases, though the statistical significance varied between cultivars and seasons. Qualitative analysis of the data showed that the point at which respiration rates began to increase coincided with the onset of the decline in chip color quality. These trends suggest that measurement of tuber respiration may provide a non-destructive andin situ method to predict changes in processing quality of stored potato tubers.     

The distributions of tuber sizes in droughted and irrigated crops of potato. II. Relation between size and weight of tubers and the variability of tuber-size distributions

Summary Tubers from six cultivars of potato grown in irrigated and droughted conditions were examined to show whether observed differences in grade distributions were simple consequences of differences in yield or were the results of changes in tuber shape or in the relative variability (Rv=σ/μ) of the distributions. Differences in tuber shape, indicated by the relations between tuber size (mm) and weight, were statistically significant but were insufficient to cause measurable changes in the grade distributions. There was a range of values of Rv but drought had no statistically significant effect on Rv and may only affect it by influencing the numbers of tubers set. The main effect of drought on the distribution of tuber sizes was through its effect on total yield and hence on mean tuber size. Yield and number of tubers define a unique tuber-size distribution regardless of the soil moisture stress experienced by the crop.     

The free amino acids of tubers of potato varieties grown in England and Ireland

Summary The results of 91 analyses of the free amino acids of potato tubers, comprising a total of 31 varieties grown in England and Ireland between the years 1968–1973, are reported. Whilst a discriminant-analysis test on part of these results strongly indicated quantitative differences of amino acids between varieties, there was also evidence of differences due to location and year of growth.

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Zusammenfassung Die freien Aminos?uren von 91 Proben von Kartoffelknollen, die insgesamt 31 Sorten vertreten, wurden mit 70% w?ssrigem ?thanol extrahiert (ausgenommen die 4 Proben des Jahres 1973) und durch Ionenaustauschchromatographie bestimmt. Der hohe Gehalt an Asparagin und Glutamin in diesen Extrakten verursachte grosse Schwierigkeiten und die Ergebnisse für diese Amide sollten mit Vorsicht betrachtet werden. Die Ergebnisse sind bezogen auf die Sorte (Tabelle 1), die Standorte (Tabelle 2), das Jahr (Tabelle 3) und auf die Zeit der Lagerung (Tabelle 4). Eine bis ins Einzelne gehende statistische Analyse der gesamten Ergebnisse wurde nicht durchgeführt, aber die Aminos?ureanalysen der 4 Sorten (gewachsen 1968) wurden der Diskriminanzanalyse unterworfen. Sie deuten auf sortenabh?ngige Unterschiedein der Zusammensetzung der Aminos?uren hin. Tabelle 2 vergleicht die Durchschnittsergebnisse der in England und Irland gepflanzten selben Sorten. Einige Aminos?uren scheinen durch den Standort st?rker beeinflusst zu sein und von diesen k?nen die Ver?nderungen bei Prolin und Tyrosin durch bekannte klimatische Einflüsse erkl?rt werden. Die j?hrlichen Durchschnittsergebnisse (Tabelle 3) zeigten, dass Ver?nderungen im Gehalt an Aminos?uren auftraten, aber dass das Gesamtbild der Aminos?urezusammensetzung im allgemeinen stabil blieb. Die Zusammensetzung der Aminos?uren in den Kartoffeln wurde durch eine kurze Lagerungsperiode nicht stark beeinflusst (Tabelle 4), obwohl Arginin eine best?ndige Zunahme zeigte. Das mag eher auf einer ?nderung der Bindung oder Anlagerung beruhen als auf einer Synthese von Arginin.

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Résumé Les acides aminés libres de 91 échantillons de pommes de terre comprenant au total 31 variétés ont été extraits par de l'alcool à 70% (excepté pour les quatre échanitillons provenant des cultures de l'année 1973) et déterminés par chromatographie sur colonne. Les grandes quantités d'asparagine et de glutamine présentes dans les extraints sont la cause de difficultés considérables et les résultats obtenus avec ces amides seront à considérer avec prudence. Les résultats sont donnés par variétés (tableau 1), par lieu de culture (tableau 2), par année (tableau 3), et par durée de conservation (tableau 4). L'analyse statistique détaillée de l'ensemble de ces résultats n'a pas été effectuée mais les quatre variétés cultivées en 1968 ont été classées par une analyse discriminante indiquant l'interdépendance des variétés sur la base de leur composition en acides aminés. Le tableau 2 permet de comparer la moyenne des résultats obtenus pour une même variété cultivée en Angleterre et en Irlande. Un petit nombre d'acides aminés appara?t être grandement influencé par le lieu de culture et la variation des teneurs en proline et en tyrosine pourrait s'expliquer par l'effet bien connu des conditions climatiques. Les résultats moyens annuels (tableau 3) indiquent qu'il y a des variations dans les teneurs en acides aminés mais que globalement leur proportion oar rapport à l'ensemble est généralement stable. Les tests de conservation (tableau 4) indiquent que la composition en acides aminés des pommes de terre n'est pas fortement affectée par le stockage pendant une courte période bien que la teneur en arginine montre une augmentation importante. Ceci pourrait être attribué à une modification de son mode de fixation ou à sa localisation plut?t qu'à sa formation dans less tubercules.

     

Nematicides induced changes in the chemical constituents of potato tubers

Changes in the chemical constituents of potato tubers grown under different concentrations of 3 synthetic organic nematicides (carbofuran, aldicarb and phorate) and a natural plant product (sawdust) were investigated. There were no significant differences in the specific gravity, dry matter and starch content of tubers from different treatments. A significant increase in the content of non-reducing and total sugars was observed in all the treatments. Nematicidal treatments had significant effects on reducing sugars, true protein, free amino acids, orthodihydroxy phenols, beta-carotene and ascorbic acid. Application of nematicides reduced the content of total phenolic compounds which is a desirable change from a processing viewpoint. Potatoes grown under different nematicidal treatments can be processed into chips and French fries as they contain permissible levels of reducing sugars required for these forms of processing.     

Free amino acids of potato tubers: a survey of published results set out according to potato variety

Summary Ranges of contents of free amino acids (mg/100 g tuber dry matter) are tabulated for 13 varieties grown in 7 different countries. Publications reporting less-complete analyses are cited, and relate to approximately 45 further varieties.

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Zusammenfassung Tabelle 1 zeigt den Gehalt an freien Aminos?uren (mg/100 g Trockengewicht) von 13 Kartoffelsorten, die in 7 verschiedenen L?ndern gewachsen sind. Ver?ffentlichungen mit unvollst?ndigen Analysenergebnissen sind in Tabelle 2 aufgeführt und verweisen auf ungef?hr 45 weitere Kartoffelsorten.

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Résumé Les écarts dans la teneur en acides aminés libres des tubercules (mg/100 g de matiére sèche) sont répertoriés pour 13 variétés cultivées dans 7 régions différentes (tableau 1). Les publications mentionnant les analyses sont citées et il est donné une liste des publications moins complètes concernant environ 45 autres variétés (tableau 2).

     

Effect ofErwinia carotovora subsp.atroseptica on yield of potatoes from cut and uncut seed tubers in Valencia

Summary The effect on the development of blackleg symptoms and on yield of inoculating seed tubers of 15 cultivars withErwinia carotovora subsp.atroseptica (Eca) was investigated. Tubers were planted either whole or as pieces. Eca inoculation reduced the mean yield per plant by 8% for whole tubers and by 12% for cut tubers. There was no correlation between blackleg symptoms and yield loss.     

The quality of seed tubers multiplied in the Golan Heights for the spring season in Israel

Summary Seed tubers grown in the northern mountain region — the Golan Heights — were as productive as imported seed tubers. In cvs. Blanka and Désirée, both the locally grown and the imported seed tubers were similar when yield components and tuber fresh weight are considered. In Up-to-Date, the locally grown seeds produced higher yields of marketable tubers (over 60 g/tuber) than those imported. Désirée seed tubers grown for two generations in the Golan Heights did not differ significantly in their productivity as compared with common Golan seeds and with imported ones. Seed tubers harvested from plots which were protected by means of white coarse nets and weekly sprays with insecticides, were virtually virus-free and were used for growing commercial seeds in the Golan. The use of this method for seed multiplication is suggested. Contribution from the Agricultural Research Organization. The Volcani Center, Bet Dagan, Israel. No 137-E, 1981 Series.     

The effect of storage conditions on subsequent field performance of potato seed tubers in Tunisia

Summary Seed tubers of four cultivars were grown under similar conditions and harvested simulataneously. They were stored in traditional dark storage, diffused-light storage, or cold storage, and with combinations of these three methods for 150 or 230 days beginning in the hot, dry summer period. The effect of storage conditions on emergence, stem and tuber number, tuber size distribution and yield is discussed. Results suggest an optimal combination of storage method, cultivar choice, and sprout management practices may be achieved to obviate the need for cold storage in warm climates. Emergence and yield were consistently good for the 150-day storage period when traditional storage was followed by diffused-light storage. The sam technology gave promising results for the 230-day period with cultivars Claustar or Désirée when seed was desprouted prior to planting.     

Amylolytic activity in stored potato tubers. 2. The effect of low-temperature storage on the activities of α-and β-amylase and α-glucosidase in potato tubers

Summary Tubers of the potato cultivars Record, Wilja, Pentland Dell and Brodick (formerly clone 137371) were sampled before and after storage at either 4°C or 10°C. Reducing sugar content stayed constant during storage at 10°C in all four cultivars but rose greatly during the first 6–12 weeks of storage at 4°C in Record, Wilja and Pentland Dell but not in Brodick. Amylolytic activity was determined after 5 weeks storage using blockedp-nitrophenyl maltoheptaoside as substrate for α-amylase,p-nitrophenyl maltopentaoside as substrate for β-amylase, andp-nitrophenylglucopyranoside as substrate for α-glucosidase. The values obtained from tubers stored at 4°C were higher than those from tubers stored at 10°C, the differences being much less in Brodick than in the other three cultivars.     

Some aspects of total losses during storage and reconditioning of potato tubers

Summary Total losses during storage and reconditioning of several Polish varieties and strains in comparison with the American varietyKennebec are discussed. Several varieties or strains show such high losses that they are not acceptable for processing after storage. Susceptibility to loss is an attribute which must be taken into account when assessing varieties.     

Alpha-amylase inhibitor changes during processing of sweet potato and taro tubers

Alpha-amylase inhibitor changes during processing ofsweet potatoes (Ipomoea batatas) and taro (Colocasia esculenta)indicated that varietal differences profoundly influence the thermalinactivation profile. The -amylase inhibitors of taro were almosttotally inactivated during oven drying of the chips at 90 ^°C and100 ^°C for 24h, while 0.8–10% activity was retained in sweetpotato chips under the same conditions. Relatively better thermal stabilitywas exhibited by the sweet potato amylase inhibitors at lower temperatures(70 and 80 ^deg;C) as well. Cooking by boiling the tuber pieces inwater resulted in retention of 29–59% amylase inhibitor in sweet potatoand 11–16% in taro. Microwave baking was a better method forinactivation of amylase inhibitors in these tubers. Flour prepared from thetubers retained only trivial amounts of the inhibitor.