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1.
Summary After three weeks curing at 10°C, potato tubers cv. Record were stored at 4°C under different controlled atmospheres (CA) for six months to study the effect on crisp fry colour, sprout growth and rotting. Combinations of low levels of CO2 (0.7–1.8%) and low levels of O2 (2.1–3.9%) gave a significantly lighter crisp colour, low sprout growth and fewer rotted tubers compared with 0.9% CO2 and 21.0% O2. Tubers stored in these conditions. showed a significantly higher weight loss and shrinkage after reconditioning. High CO2: low O2 combinations during storage completely inhibited sprout growth and caused the darkest crisp colour, but after reconditioning tubers gave the same level of sprouting and crisps as light as the other CA combinations. Furthermore these combinations, especially CO2 at 10 or 15%, increased the onset of rotting. Also our results showed that at low concentrations of CO2 (0.7–1.6%), and low O2 (2–2.4%) there was an increase in tuber rotting.  相似文献   

2.
Marketplace preference for lower pesticide residues in foods has led to research to reduce the residue of chlorpropham (isopropyl N-3-chlorophenyl carbamate; CIPC), a postharvest-applied sprout inhibitor which is widely used around the globe to prevent sprouting of stored potatoes (Solanum tuberosum L.). Ethylene gas, an effective, safe and non-toxic sprout inhibitor used in several countries, sometimes has negative effects on the colour of processed potato products when used alone. Trials were conducted over 3 years using cv. Shepody (French fry) and cv. NorValley (potato chips/crisps) to determine whether a combination of these two sprout inhibitors, at reduced dosages, could inhibit sprouting while maintaining good processing colour. CIPC applied at 0, 0.1, 0.25 and 1.0 times the recommended dosage was combined with 4 μll−1 of ethylene gas applied or no ethylene at all (0 ethylene), for 1 day in 4 days, for 1 day in 2 days or continuously, in a factorial design. Sprout inhibition in both cultivars was excellent at all levels of CIPC application except the 0 rate. In both cultivars, sprouting was inhibited by the continuous ethylene treatment. However, all levels of ethylene exposure except the 0 rate negatively affected processing colour in both cultivars. The darkening was dose dependent, whereby the colour was darkest in continuous ethylene and was less affected by the intermittent exposures. In continuous ethylene, the colour was progressively lighter during storage after initial darkening. Shepody tubers appeared to be more sensitive to ethylene than the NorValley tubers. In Shepody only, colour in the ethylene of 1 day in 4 days treatments was progressively darker with increasing time in storage.  相似文献   

3.
Résumé Fusarium culmorum et, dans une moindre mesure,F. avenaceum, F. sambucinum, Colletotrichum coccodes etCylindrocarpon sp. ont été isolés de tubercules entreposés en atmosphère contr?lée (AC) et atteints de pourriture grave. Des expériences d'inoculation de tubercules avec 10 espèces ou variétés fongiques et conservation en AC à 8 et 10°C ont montré que: 1) les champignons non pathogènes en atmosphère normale (ex.:Cylindrocarpon sp.) le devenaient en AC, 2) ceux qui étaient faiblement pathogènes en atmosphère normale étaient nettement plus virulents en AC (ex.:F. culmorum), 3) les espèces ou variétés virulentes en conditions d'air normales (Fusarium sulphureum etPhoma exigua var.foveata) ne provoquaient pas de pourriture plus grave en AC et leur activité pouvait même être légérement freinée.
Summary The extensive rotting of tubers which occurred during storage trials in controlled atmospheres has led to a mycological and pathological study of the rots. The most frequently isolated species wasFusarium culmorum althoughF. avenaceum, F. Sambucinum, Coletotrichum coccodes and aCylindrocarpon sp. were also present. Tubers of cvs Bintje and Ulla were inoculated with 19 isolates of 10 fungal species or varieties associated with rotting of stored tubers (Table 1). The tubers were incubated at 8 or 10°C in normal or controlled (2% O2:1% CO2, 2% O2:6% CO2, 2% O2:12% CO2, 6% O2:6% CO2) atmospheres and the extent of rotting was determined a month later (Tables 2 and 3 and Fig. 2). Species which were weakly virulent in a normal atmosphere (variousFusarium spp. andPhoma exigua var.exigua) were clearly more aggressive in the controlled atmosphere and this was especially evident in the case ofF. culmorum. Species ot pathogenic in a normal atmosphere under experimental conditions (Colletotrichum coccodes, Cylindrocarpon sp.,Phoma eupyrena) caused rotting in the controlled atmosphere. The two species which were virulent in a normal atmosphere (F. sulphureum andP. exigua var.foveata) were also virulent in the controlled atmosphere and in some cases the extent of rotting was even less. As a general rule, rotting caused by weakly virulent fungi was greater in both cultivars in the controlled than in a normal atmosphere.
Zusammenfassung Eine starke F?ulnis von in Kontrotrollierter Atmosph?re gelagerten Kartoffelknollen veranlasste eine mykologische und pathologische Untersuchung. Der am h?ufigsten isolierte Pilz warFusarium culmorum. F. avenaceum, F. sambucinum, Colletotrichum coccodes undCylindrocarpon sp. wurden ebenfalls bestimmt. Neunzehn St?mme von 10 Pilzsorten oder-Arten welche bei Lagerf?ulnis vorkommen (Tab. 1) wurden auf Knollen der Sorten Bintje und Ulla inokuliert. Die Lagerung wurde bei 8 oder 10°C under Normalbedingungen oder kontrollierter Atmosph?re durchgeführt (2% O2:1% CO2, 2% O2:6% CO2, 2% O2:12% CO2, 6% O2:6% CO2). Der F?ulnisgrad (Abb. 1) wurde nach einem Monat bonitiert. Die Ergebnisse sind in den Tabellen 2 und 3 dargestellt und in der Abb. 2 illustriert. Unter in Normalbedingungen nur schwach virulente Arten (verschiedeneFusarien undPhoma exigua var. exigua) waren deutlich aktiver in kontrollierter Atmosph?re. Dies was besonders der Fall fürF. culmorum. Pilze, die im Versuch unter Normalbedingungen nicht pathogen waren (Colletotrichum coccodes, Cylindrocarpon sp., Phoma eupyrena), haben unter kontrollierter Atmosph?re Sch?den verursacht. Hingegen werden die beiden unter Normalbedingungen sehr pathogenen Arten (F. sulphureum undP., exigua var.foveata), durch kontrollierte Atmosph?re wenig beeinflusst. Es wurde sogar in einigen F?llen eine gewisse Verringerung des F?ulnisbefalls beobachtet. Ganz allgemein haben die getesteten kontrollierten Bedingungen die Entwicklung der Pilzf?ulnis an beiden Kartoffelsorten gef?rdert, speziell durch Pilzarten, welche unter Normal-bedingungen wenig Sch?den verursachen.
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4.
The possibility that sugar accumulation of potatoes stored at low temperatures may be linked to activation of cyanide-resistant respiration (CRR) was investigated. After a lag period of several days, continuous HCN treatment stimulated CO2 production of tubers stored in 20% O2. At 1°C in 20% O2, HCN treatment increased respiration over that effected by low temperature treatment. After several weeks of treatment, cyanide-stimulated CO2 production was greater at 1°C than at 10°C. Sucrose and malate levels of HCN treated tubers were sometimes higher than those of the 10°C control tubers, but they were always lower than those of the 1°C control tubers. This indicated that CRR alone could not account for the sugar increases at 1°C. Storage in 2% O2 blocked the increase in CO2 production and changes in constituents associated with HCN treatments in 20% O2. HCN treatment had no significant effect on chip color. The level of CRR was measured in freshly cut slices from Monona, Norchip, and Kennebec tubers previously stored at 10°, 5°, or 1°C for several months. Slices from tubers previously stored at 1°C had increased CRR, but there was no difference in CRR between the 5°C and 10°C treatments. Sugars accumulated at 5°C, again indicating that sugar accumulation in potatoes stored at low temperatures was at least partially independent of the activation of CRR.  相似文献   

5.
Ethylene is an effective potato (Solanum tuberosum L.) sprout inhibitor, but it often darkens fry colour. Trials were conducted over nine consecutive storage seasons to identify ethylene application methods which would mitigate darkening while retaining adequate sprout inhibition, using cv. Russet Burbank plus cvs Shepody, Asterix and Santana in some years. Tubers were stored for up to 35 weeks in closed chambers with ethylene gas delivered via the ventilation airstream. Exposure to continuous 4 μl l−1 ethylene after suberization and cooling were completed was designated the ethylene check. Alternative ethylene treatments included commencing exposure either before or after suberization was completed; gradually introducing the ethylene either by a concentration gradient of eight steps over 4 or 8 weeks or by increasing the duration of exposure from 6 to 24 h per day in four weekly steps; repeatedly interrupting exposure for several hours per day or for durations of 1 or more days; and warm storage. Selected ethylene treatment combinations were applied in each year, plus untreated controls, chlorpropham-treated (CIPC) checks and ethylene checks. Sprout growth, fry colour, loss of mass and disease incidence were evaluated at regular intervals. In all cultivars and all years, the ethylene check darkened fry colour more than the other treatments. Commencing before suberization ended, gradually introducing the ethylene by either concentration or time gradient and interrupting the exposure all reduced the negative effect of ethylene sprout inhibitor on fry colour. Continuous ethylene treatments inhibited sprout growth as effectively as CIPC, except at 13 °C storage. Interruptions of 18 h and 2 or more days reduced sprout inhibition. Regardless of cultivar variations, an early start using either a concentration or time-increment gradient had the least effect on fry colour while maintaining good sprout inhibition.  相似文献   

6.
Previous short-term trials (9-week duration) have shown that the fry colour of stored potatoes (Solanum tuberosum L.) can be negatively affected by simultaneous exposure to elevated CO2 plus a trace concentration of ethylene gas. In the present study, trials were conducted during each of two storage seasons (2008–2009 and 2009–2010), to examine the effects of long-term exposure to these two gases during the entire November to June storage season. In each year, 0 or 2 kPa CO2 and 0 or 0.5 μl l−1 ethylene were applied in a factorial design to tubers of four processing cultivars (Russet Burbank, Shepody, Innovator and Dakota Pearl). Processing colour of the tubers was evaluated at the start of each trial and at intervals of 4 weeks thereafter. In the three French fry cultivars (i.e. Russet Burbank, Shepody and Innovator), the fry colour of tubers exposed to CO2 + ethylene together was darker than the controls. In the chipping cultivar Dakota Pearl, the gas treatments had only a small effect on chip colour. Fry colour darkening due to an interaction of CO2 × ethylene × time was significant only in Innovator. Processing colour of all cultivars was darkened by these gases, but the magnitude and timing of the responses varied widely between gases, among cultivars and from the start to the end of the season.  相似文献   

7.
Recently, it has been shown that the darkening of potato processing colour attributable to a trace concentration of ethylene gas is more severe when CO2 is also elevated. In view of the increasing use of ethylene gas for sprout suppression in potato storage facilities, it was considered important to determine whether this effect also occurs at the much higher ethylene concentration used in commercial practice. Sprouting and processing colour of the French fry cultivars Russet Burbank, Shepody and Innovator and the potato crisp cultivar Dakota Pearl were tested during the November to June storage season of two consecutive years. Treatments were 0 or 2 kPa CO2 and 0 or 10 μL?L?1 ethylene in a factorial design, plus a chlorpropham check. The 0 CO2?+?0 ethylene treatment constituted an untreated control. The ethylene exposure was commenced abruptly to maximize its effect on colour. The main effect of ethylene resulted in darker processing colour in all cultivars, whereas darkening attributable to the main effect of CO2 was observed only in Innovator and Dakota Pearl. The statistical interaction of the CO2 and ethylene was not significant except in Dakota Pearl Hunter a (redness) scores, although a tendency to darker colour when both gases were present was seen in Russet Burbank and Innovator at all evaluation dates. The results indicate that both gases can affect processing colour when ethylene is used to control sprouting, although considerable variability in the response exists among cultivars. This variability in combination with management of storage conditions such as temperature and CO2 can be utilized to minimize the impact of these gases on the processing colour of stored potatoes.  相似文献   

8.
Summary A comparative study of nine Indian potato varieties showed a good correlation between their total carotenoid content and the tuber flesh colour. Regardless of varietal differences, carotenoid level showed an increase during storage at ambient temperature (25–30°C) and to a lesser extent at 2–4°C and 15°C. Tubers exposed to an irradiation dose of 10 krad for sprout inhibition showed decreased levels of carotenoids during storage, particularly at 15°C where 50% loss was observed after 6 months of storage. Irradiated tubers stored for seven months at 15°C, on reconditioning at 34–35°C for 6 to 12 days showed a 2- to 6-fold increase in their carotenoid content.  相似文献   

9.
Summary Potato seed tubers may suffer from premature sprouting during storage, thus limiting their suitability for cultivation. Commonly used sprout suppressant treatments negatively affect but viability and therefore a reliable method to inhibit bud development must still be found for seed tubers. The monoterpene carvone ((S)-(+)-carvone) was tested in small scale experiments. The vapour of this compound fully inhibited bud growth of tubers cv. Monalisa stored at 23°C without affecting bud viability throughout 6 months of treatment. The most effective range of carvone vapour concentrations was between 0.34 and 1.06 μmol mol−1. With these qualities we can expect carvone to become a suitable sprout suppressant for seed tubers.  相似文献   

10.
Indigenous non-refrigerated methods like heaps and pits are used in India for short-term storage of potatoes (Solanum tuberosum L.) to avoid distress sale. Storing untreated potatoes generally results in high losses from sprouting, moisture loss and rotting. To reduce storage losses by inhibition of sprouting and to determine the suitability of stored potatoes for processing into crisps, a single spray application of a commercial formulation of 3-chlorophenyl carbamate (CIPC or chlorpropham) 50% a.i., (Oorja, United Phosphorus Limited, Mumbai, India) of CIPC (or chlorpropham) was tested on potatoes during storage from March to June under two traditional storage methods [heap (17–33 °C, 58–92% relative humidity (RH)) and pit (17–27 °C, 72–95% RH)] in 2 years [2005 up to 90 days of storage (DOS) and 2006 up to 105 DOS], using four cultivars and two rates of CIPC application (20 and 30 mg a.i. kg−1 tubers). The two rates of application were comparably effective in reducing weight losses, sprouting and sprout growth in stored tubers, and the effect was more pronounced in pit storage than in heap storage. By contrast to untreated tubers, CIPC-treated potatoes remained turgid under the two storage methods and fetched market prices comparable to those for cold-stored (2–4 °C) potatoes after 105 days of storage. Reducing sugar concentrations in treated potatoes decreased during storage especially in 2006 when the initial reducing sugar concentration was higher than in 2005. Crisp colour improved only in 2005 after 90 DOS, but it deteriorated in 2006 during storage up to 105 DOS. Sucrose concentration increased tremendously during storage in 2 years. Only one cultivar (Kufri Chipsona-1) with low initial reducing sugar concentration and less sucrose accumulation during storage could produce acceptable colour crisps after storage in both years. The remaining three cultivars—with high initial reducing sugar concentration—were suitable for processing after storage in heap and pit in 2005, but not in 2006. Stored potatoes were safe for human consumption as the CIPC residue concentrations were far below the permissible level of 10 mg kg−1 as prescribed by the European Union. Single spray application of CIPC (20 mg kg−1 treatment) can effectively reduce storage losses in potatoes stored in traditional non-refrigerated methods of heap and pit and extend the storage life by 90 to 105 days.  相似文献   

11.
Abscisic acid (ABA), sucrose, reducing sugars and proline contents were monitored over an eleven-month period in tubers of three potato cultivars that varied in tuber dormancy. ABA and proline levels increased after top pulling the haulms and were not affected by harvest date. Proline did not change in either a storage temperature or cultivar-specific manner. The highest concentrations of ABA were found in tubers stored at 2°C while the lowest concentrations occurred in tubers stored at 20°C. At 10°C, the end of tuber dormancy in the cultivars Kennebec and Nooksack (but not Sebago) coincided with the decline in ABA content. There was no evidence of a threshold concentration of ABA below which sprouting would occur. Tuber samples of 10 different cultivars were removed from 10°C and placed in 20°C storage (in darkness). Initial ABA concentrations (i.e., at the time of removal from 10°C storage) were positively correlated with duration of dormancy and negatively correlated with subsequent rates of sprout elongation at 20°C. Sucrose content was negatively correlated with duration of dormancy. Reducing sugars responded primarily to storage temperature and did not appear to be related to dormancy or sprouting.  相似文献   

12.
Zusammenfassung Nach Inokulation mit abgestuften Bakteriendichten wurde über eine Vitalf?rbung von Knollengewebe der Schwellenwert zur F?uleausl?sung bestimmt. Seine Erh?hung nach 24 h Wundheilung charakterisiert die Effizienz der biochemischen F?uleabwehr. Die Abwehrreaktionen des Knollengewebes und der Prozess der F?uleausl?sung sind in unterschiedlichem Masse von der Temperatur, der Feuchtigkeit und dem O2- sowie dem CO2-Gehalt der Atmosph?re abh?ngig.
Summary The inoculum densities (effective dose) ofErwinia carotovora sub sp.atroseptica (Eca) needed to initiate infection of tuber tissue before and after a 24 h wound-healing period, was determined using a vital stain. The effects of various treatments on the efficiency of the defence reaction associated with wound healing, and on rot initiation were manifested as changes in the effective dose. The defence reaction was inhibited by temperatures <10°C, reduced O2 levels ≤5%, and CO2 proportions ≥20% (Fig. 3a and 4a). Moisture loss in stored tubers increased their defence reaction compared to that of freshly harvested ones (Table 1). The effect of these factors on Eca development was identical to that which occurs in potato production where tuber wounds are generally contaminated with Eca. Rot initiation was best prevented by removal of water (Table 1), storage at 15°C, avoidance of reduced O2 levels <10% and CO2 accumulation (Fig. 3b and 4b).
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13.
Summary Routine fry tests of material from the potato breeding programme at the Scottish Crop Research Institute (SCRI) detected clones which gave superior (paler coloured) crisps than the control cultivar Record, after storage at low temperatures (4°C). Thirteen of these clones and nine cultivars were fry tested at intervals after storage at 4°C and 10°C. The ability of these clones to produce an acceptable fry product direct from storage at low temperature and their superiority in this respect over existing cultivars was confirmed. Some clones examined produced an acceptable fry colour even after 30 weeks' storage at 4°C.  相似文献   

14.
Ethylene effectively inhibits sprouting of potatoes (Solanum tuberosum L.) during storage, but it often darkens fry color. The objective of the work described here was to determine if altering the concentration of ethylene applied would reduce the darkening while retaining adequate sprout inhibition. Trials were conducted over three consecutive years (1991–1992, 1992–1993, and 1993–1994). Tubers of cv Russet Burbank (ca 150–300 g) were stored at 9 C for 25 wk in closed chambers in a refrigerated room under continuous exposure to 0.4, 4, 40, or 400 µL L?1 ethylene gas delivered with the ventilation airstream (ca 0.5 air exchanges per h, for 6 h each day). Untreated control and chlorpropham-treated (CIPC) check tubers were stored under the same conditions but without ethylene supplementation. Sprout number, length, and biomass, fry color, loss of tuber mass, disease, and dry matter content were evaluated at 5-wk intervals. Dose-dependent effects (400>40>4>0.4 µL L?1) of ethylene on sprout growth and fry color were observed. The 400, 40, and 4 µL L?1 ethylene treatments inhibited sprout growth as effectively as CIPC, whereas in 0.4 µL L?1 ethylene sprouting was midway between CIPC and the untreated control. Sprout mass and maximum sprout length in all ethylene treatments were significantly lower (P<0.05) than in the untreated control. Compared with the initial value (57.3 Agtron reflectance units [ARu]), after 5 wk of storage fry color was up to 5 ARu darker in the ethylene treatments, but recovered steadily at the subsequent evaluation dates. At 25 wk of storage the fry color of tubers from the 40 and 4 µL L?1 ethylene treatments were, however, still darker than tubers stored with CIPC. Inhibition of sprout growth was slightly more effective in the 400 and 40 µL L?1 ethylene treatments than in 4 µL L?1, although there were no significant differences (P<0.01) in fry color between these treatments. In comparison with the other ethylene treatments, fry color in 0.4 µL L?1 ethylene was lighter, but inhibition of sprout growth was significantly (P<0.05) poorer. There were no differences in tuber disease incidence or dry matter content between the treatments. At 25 wk, the untreated tubers had ca 50% greater loss of tuber mass than any other treatment, attributable to their heavy sprouting. Loss of tuber mass in the ethylene treatments was not significantly different (P<0.001) from that in the CIPC treatment.  相似文献   

15.
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.  相似文献   

16.
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.  相似文献   

17.
A. Cherif 《Potato Research》1973,16(2):126-147
Résumé Le métabolisme des lipides des tubercules de pomme de terre au cours de leur conservation à différentes températures ou sous des atmosphères de composition variée, a été étudié, et les modifications induites pour un traitement à la ‘rindite’ mélange synergique connu pour lever le repos végétatif, ont été examinées. Une augmentation appréciable de la teneur en acides gras totaux dans la pulpe a été enregistrée à 0,4,10 et 18°C, dans les premiers mois de conservation. Une chute de la teneur en acides gras totaux de la pulpe a été notée au cours de l'entreposage dans les atmosphères enrichies en CO2 (20%) ou en O2 (37%). La ‘rindite’ provoque une synthèse accrue de lipides, surtout dans la période de croissance active des germes.
Summary The potato tuber is low in lipids, which form only 0.1% of the fresh weight of the tissue. Of the tuber lipids, 60–80% are unsaturated fatty acids, linoleic acid predominating (Tables 1 and 2). It has been observed that there is an appreciable increase in the total fatty acid content of the tuber flesh during storage at 10°C and 18°C. This increase occurs mainly during the phase of rapid sprout growth, thus fairly long after the tubers have broken dormancy. The increase continues in the case of tubers stored at 10°C, up to the stage of incubation or tuberisation of the sprouts. The opposite occurs in tubers stored at 18°C; total fatty acids decrease during this period. This is probably due to a physiological imbalance of the cells arising from a heavy loss of water by the tubers (Fig. 3). With regard to tubers stored at low temperature (0°C and 4°C), it has been noted that the total fatty acid content increases (accompanied by an increase in the degree of unsaturation of the lipids). This increase is followed by a marked fall during the final months of storage. This could be accounted for either by a disturbance of cellular function at low temperature or by a progressive degradation of the lipids by lipases (Fig. 3). Study of tuber storage in different atmospheres gave interesting results. The mixture enriched with oxygen (37%) partially inhibits sprout extension and apical dominance; air containing 20% CO2 totally inhibits sprouting and leads to the death of the tuber. On the other hand, air containing 6% CO2 accelerates sprouting, leads to earlier tuberisation of the stolons and increases the number of tubers formed per sprout. Such a result could be of interest in practical agronomy (Fig. 4). It was observed that, with the onset of sprouting, there is an increase in total fatty acids in the flesh of tubers stored in air enriched with CO2 (6%). This is followed by a decrease. In the case of air containing 20% CO2, even if the total fatty acid content remains more or less static for a period, a sharp fall follows. On the other hand, the flesh of tubers stored in air and in an atmosphere low in oxygen shows an appreciable increase in total fatty acid content; whereas in air enriched with oxygen (O2:37%) there is a fall (Fig. 5). ‘Rindite’, a compound which breaks dormancy, has a marked effect on the formation of fatty acids in the tuber parenchyma. It leads to a progressive synthesis of lipids. particularly during the period of active sprout growth. This increase in the total fatty acid content affects particularly the unsaturated fatty acids and also palmitic acid. This increase in lipid synthesis could be due to a general increase in carbon metabolism by the ‘rindite’ (Fig. 7 and 8).
Zusammenfassung Die Kartoffelknolle ist ein an Lipiden armes pflanzliches Organ, stellen diese Verbindungen doch nur ungef?hr 0,1% der Frischsubstanz dar. Die wesentlichen Lipide der Knolle sind reich an unges?ttigten Fetts?uren (60–80%), wobei die Linols?ure vorherrscht (Tabellen 1 und 2). Man hat festgestellt, dass im Verlauf der Lagerung bei 10°C und 18°C eine nennenswerte Erh?hung im Gesamtgehalt an Fetts?uren im Knollenfleisch erzeugt wird. Diese Erh?hung findet vor allem w?hrend der raschen Wachstumsphase der Keime statt, also ziemlich lange Zeit nach Ende der Keimruhe der Knollen. Diese Erh?hung setzt sich fort bei den bei 10°C gehaltenen Knollen bis zum Stadium der Inkubation oder der beginnenden Knollenbildung. Dagegen ist bei den bei 18°C aufbewahrten Knollen eine Verminderung der Gesamtmenge der Fetts?uren w?hrend dieser Periode festzustellen; diese Tatsache ist wahrscheinlich auf ein physiologisches Ungleichgewicht der Zellen zurückzuführen, das von einem starken Wasserverlust der Knollen herrührt (Abb. 3). Was die Knollen betrifft, die bei niedriger Temperatur aufbewahrt wurden (0°C und 4°C). so hat man ein Ansteigen des Gesamtgehaltes an Fetts?uren bemerkt (begleitet von einer Abnahme des Grades der S?ttigung der Lipide). Dieser Steigerung folgt ein starker Abfall w?hrend des letzten Monates der Lagerung. Für diese Tatsache kann eine Erkl?rung gefunden werden, sei es in der Unregelm?ssigkeit des Funktionierens der Zellen bei tiefen Temperaturen, sei es in einer wachsenden Degradation der Lipide durch die Lipasen (Abb. 3). Das Studium der Lagerung von Kartoffelknollen unter verschiedenen Atmosph?ren hat interessante Ergebnisse gebracht. Das mit Sauerstoff angereicherte Gemisch (37%) hemmte teilweise das L?ngenwachstum der Keime und die apikale Dominanz; die mit 20% CO2 belastete Luft verhindert die Keimung vollst?ndig und führt zum Tod der Knolle. Dagegen beschleunigt die mit 6% CO2 belastete Luft die Keimung, f?rdert die frühere Knollenbildung der Stolonen und erzeugt pro Trieb eine gr?ssere Anzahl von Tochterknollen. Ein solches Ergebnis k?nnte für die landwirtschaftlich Praxis von Interesse sein. Man hat zu Beginn der Keimung ein Ansteigen des Gesamtgehaltes an Fetts?uren im Fleisch von Knollen, die in mit 6% CO2 angereicherter Luft gelagert wurden, festgestellt. Auf diesen Zuwachs folgt eine Abnahme. Wenn die Luft mit 20% CO2 angereichert war, ging der Gesamtgehalt an Fetts?uren, wenn er w?hrend einer gewissen Zeit auch beinahe gleich blieb, nachher doch deutlich zurück. Dagegen stieg in nennenswerter Weise der Gesamtgehalt an Fetts?uren im Fleisch von Knollen, die bei normaler Luftzusammensetzung und in sauerstoffarmer Atmosph?re gelagert wurden; in mit Sauerstoff angereicherter Luft (O2:37%) f?llt der Gehalt an diesen S?uren stark (Abb. 5). Die Wirkung der ‘Rindite’, einem Mittel zur Brechung der Keimruhe, auf die Weiterentwick lung der Fetts?uren des Parenchyms der Kartoffelknolle ist sehr deutlich. Sie bewirkt eine wachsende Synthese von Lipiden, besonders in der aktiven Wachstumsperiode der Keime. Dieses Ansteigen des Gesamtgehaltes an Fetts?uren betrifft besonders die unges?ttigten Fetts?uren und auch die Palmitins?ure. Diese Zunahme der Lipid-Synthese k?nnte auf eine allgemeine, durch ‘Rindite’ hervorgerufene Beschleunigung des Kohlenstoff-Stoffwechsels zurückgeführt werden (Abb. 7 und 8).
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18.
Shortening dormancy of seed potatoes by storage temperature regimes   总被引：1，自引：0，他引：1  
Summary Four experiments (three with four cultivars, one with twenty cultivars) investigated the effect of different storage temperature regimes on the duration of dormancy of seed potatoes harvested immature. Regimes included constant temperatures (18 and 28°C), hot pre-treatments (20 days at 28°C and subsequently 18°C) and cold pre-treatments (20 days at 2°C and subsequently 18°C). Compared with 18°C, storage at 28°C slightly prolonged dormancy of some cultivars with a genetically short dormancy and shortened dormancy by up to 45 days in cultivars with a long dormancy. Some tubers of one cultivar lost their ability to sprout after storage at 28°C for 90 days. A hot pre-treatment shortened dormancy by 2–3 weeks on average, for all cultivars examined. A cold pre-treatment shortened dormancy by 2 weeks on average in some cultivars with a short dormancy and in all cultivars with a long dormancy.  相似文献   

19.
The present study investigated the effects of elevated carbon dioxide concentration ([CO2]) and air temperature on the germination of seed bulbils and the seedling vigour of two Chinese yam lines. Plants were grown under two [CO2] levels, ambient and elevated (ambient + 200 μmol mol?1), and two mean air temperature regimes, 22.2 °C (ambient + 1.4 °C) and 25.6 °C (ambient + 5.2 °C). Elevated [CO2] did not affect bulbil germination under both air temperature regimes. During the early growth stage, the dry weight (DW) of leaves, vines, shoots, roots, belowground parts (roots + tubers) and whole plants were higher under elevated [CO2] than ambient [CO2] for both lines under the low- and high-temperature regimes. The values of vigour indexes (index I = germination % × seedling length and index II = germination % × seedling DW) were also higher under elevated [CO2] than ambient [CO2] for both lines. These results indicated that Chinese yam seedlings respond positively to elevated [CO2] during the early growth stage. The above:belowground DW ratios were lower under elevated [CO2] than ambient [CO2] in seedlings with very small new tubers for both yam lines, indicating that elevated [CO2] strongly affected the root growth in the early growth stage. The DWs of post-treatment seed bulbils were higher in the elevated [CO2] under both air temperature regimes. The results showed that Chinese yam used a smaller amount of the reserves in seed bulbils under elevated [CO2] than under ambient [CO2].  相似文献   

20.
Summary The influence of storage temperature (pre-storage, 3 °C, 7 °C, and 9 °C) and controlled atmospheric (CA) conditions (7 °C, 2% O2, 10% CO2) were evaluated relative to the physiology and mechanical failure properties of potato tubers (Solarium tuberosum L. cv. Shepody). Mechanical properties of the tuber tissue differed by storage treatment although the physical properties could be generally explained by the measured relative turgor of the tissue. Models typically ascribe lower tissue toughness to greater tissue turgor. In this study, prior to storage tubers exhibited characteristics of greater tissue toughness (20.3 MPa) in conjunction with high relative tissue turgor (as measured by shock wave speed, 115 m/s). It appears that tubers prior to storage have quantitatively stronger tissue compared to tubers after storage regardless of hydration level. CA storage altered tissue mechanical properties as well as carbohydrate content and had physiochemical characteristics of tubers stored at 3 °C;. Idaho Agricultural Experiments Stations paper no.00710, Moscow, ID, USA.  相似文献   

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