Performance of potato minitubers in a controlled environment after different storage periods

Summary Minitubers of cultivars Agria and Liseta were harvested from the same plantlets on three dates. After each harvest, tubers were dried (1 day), cured (13 days) and cold stored at 2 °C in darkness and 80 % RH. Their performance was studied 65, 128, 191, 254, 317, 380, 443, 506 and 569 days after harvest. Minitubers (1–2 g) were planted in pots and grown for 8 weeks in a controlled environment. After 191 days of storage their growth was still extremely poor. In both cultivars, tallest plants and largest leaf areas per plant were observed in plants from tubers from the second and third harvests that had been stored for 317 days. Highest stem numbers, yields (total dry matter, tuber fresh weight) and harvest indices were achieved with 443 days storage with cv. Agria and 569 days storage with cv. Liseta. Tubers from the first harvest behaved slightly differently.     

Post-harvest characteristics of potato minitubers with different fresh weights and from different harvests. II. Losses during storage

Summary Storage losses were studied in minitubers of cvs Agria and Liseta, using five fresh weight classes (<0.50 g, 0.5–0.99 g, 1.00–1.99 g, 2.00–2.99 g, ≥3.00 g), and three successive harvests of the same plantlets. After each harvest, tubers were dired at room temperature (1 day), curred at 18 °C (13 days) and stored at 2 °C (540 days). Two kinds of storage losses were considered: (a) losses of entire tubers because of deterioration, and (b) fresh weight losses of the other tubers. Both kinds of losses were higher in cv. Liseta, in tubers with lower fresh weights and in tubers from the first harvest. Almost all minitubers ≥0.5 g from later harvests and from both cultivars survived storage for 1.5 years. Deterioration occurred mainly from 6 to 12 months of storage. Tubers which deteriorated during cold storage had already shown high weight losses during curing.     

Post-harvest characteristics of potato minitubers with different fresh weights and from different harvests. I. Dry-matter concentration and dormancy

Summary Dry-matter concentration and dormancy were studied in minitubers of cvs Agria and Liseta, using five fresh weight classes (<0.50 g, 0.50–0.99 g, 1.00–1.99 g, 2.00–2.99 g and ≥3.00 g) and three successive harvests of the same plantlets. The average dry-matter concentration increased with tuber weight for tubers from the second and third harvests. In minitubers ≥0.5 g, dry-matter concentration was higher in tubers from later harvests. The dormant period (days from harvest to 50% sprouting) was longer in minitubers with lower than higher weights, and longer in tubers from the first harvest than from later harvests. A cold-storage period of 6 weeks, starting 14 days after harvest, reduced the dormant period by an average of 11 days.     

Sugar and dry matter changes in potatoes stored in a clamp in a mountainous region of Northern Greece

Summary Potato tubers (cvs Fina, Marfona and Spunta) were stored in a clamp in the region of Mount Vermion in Northern Greece (altitude about 1400 m) from October 1985 to April 1986. No sprout inhibitor was applied. Tubers were analysed for dry matter and sugar content at 2–4 month intervals. Cultivar and date of sampling had a no significant effect on dry matter but had a significant effect on the total and reducing sugar contents. A significant interaction between cultivar and date of sampling was observed for dry matter and sugars. A continuous increase of total and reducing sugars from October to April was found in tubers of cv. Marfona. In tubers of cvs Fina and Spunta the total and reducing sugars increased, significantly only until March, and thereafter decreased.     

Specific Gravity, Dry Matter Concentration, pH, and Crisp-making Potential of Ethiopian Potato (Solanum tuberosum L.) Cultivars as Influenced by Growing Environment and Length of Storage Under Ambient Conditions

A study was conducted to investigate the influence of genotype, growing environment and storage period on postharvest quality of seven released potato cultivars grown at Adet (2240 masl), Chilga (2270 masl), and Dabat (2620 masl), northwest Ethiopia in 2006. Cured tubers of each cultivar from each location were stored at ambient conditions for 8 weeks in a locally constructed dark room in Adet, the location with the highest temperatures. The quality of the tubers and the crisps prepared from them was evaluated at weekly intervals. Tubers from cvs Jalenie, Guassa, and Zengena had a high specific gravity (1.088–1.094) and dry matter percentage (26.2–27.1%) when grown in Dabat and Chilga, and a lower specific gravity (1.064–1.072) and dry matter percentage (22.3-22.7%) when grown in Adet. These cultivars produced crisps with a taste value of 8 (like very much) when grown in Chilga and Dabat and of almost 7 (like moderately) when grown in Adet. There was a progressive reduction in specific gravity, dry matter percentage, and taste of crisps with increase in storage time. Cultivars with higher dry matter concentration maintained a better quality than cultivars with a lower dry matter concentration. Across growing locations and cultivars, 57% of the crisps samples were white to cream colored, 33.3% light tan and 9.5% dark tan after 1 week of storage, whereas after 6 weeks of storage none of the cultivars produced white cream colored crisps. It is reasonable to conclude that cvs Jalenie, Guassa, and Zengena can produce tubers with a high dry matter percentage under Chilga and Dabat conditions, from which acceptable crisps can be prepared from tubers stored up to 6 weeks under ambient conditions.     

Comparative performance of three small seed tuber sizes and standard size seed tubers planted at similar stem densities

Summary Small seed tubers of 1–5 g, 5–10 g and 10–20 g were planted at the same sprout densities as standard size seed tubers of 40–60 g in order to give similar stem densities. Early ground cover by foliage, total yield, and yield of tubers >45 mm were consistently greater in plots planted with larger seed tubers. The effect of seed tuber size on yield and tuber number per stem varied between years but 1–5 g seed tubers always gave lower yields per stem than larger seed tubers. Reducing the spacing between rows from 90 cm to 60 cm and maintaining the same sprout density was more effective in increasing yields from small seed tubers than increasing sprout density from 20 to 40 sprouts per m² by reducing plant spacing within the row.     

Resistance of tubers from different potato cultivars to soft rot caused byErwinia carotovora subsp.atroseptica

Mechanically harvested tubers of 14 potato cultivars grown on both loamy sand and silt loam soils were evaluated for resistance to bacterial soft rot caused byErwinia carotovora subsp.atroseptica. Cultivars were also assayed for calcium and dry matter content to determine possible correlations with soft rot resistance. Resistance of potato tubers to bacterial soft rot was assayed after harvest by inoculating tubers and determining percent surface area decayed after four days in a mist chamber. Tubers of the cultivars differed widely in resistance to bacterial soft rot. The ranking of the resistance of tubers from different cultivars to bacterial soft rot was similar for both soils, although disease severity in tubers from a particular soil type varied with the season. Of the cultivars tested, tubers of Butte, Russet Burbank, and Nor-gold Russet were ranked as the most resistant, whereas tubers of Redsen, Norchip, Norland and Belchip were rated as the most susceptible. Tubers of Rhinered, Red La Soda, Superior, Pontiac, Atlantic, and Nooksack were intermediate in resistance. Neither calcium concentration in medullar tissues nor dry matter of potato tubers alone could be correlated with ranking of the cultivars with respect to severity of bacterial soft rot. However, a multiple linear regression model incorporating both variables indicated that tubers with a high content of both calcium and dry matter were likely to be less susceptible to bacterial soft rot than were tubers with lower percentages of these variables.     

The Relationship Between Soil Temperature and Sugar Ends in Potato

Sugar ends is a serious defect in processed potatoes. Among the more important factors associated with the development of sugar ends are soil temperature and soil moisture, particularly during early tuber bulking. This 2-year study was designed to examine the effects of soil temperature on the development of sugar ends. Soil temperature was recorded in different zones (0–10 cm and 10–20 cm depths) of potato rows oriented in north–south and east–west directions. At harvest, tubers from four sections in each field were hand excavated from each quadrant of the hill. The rows were divided vertically through the center and horizontally at the 10-cm depth. Tubers from each quadrant were weighed and then evaluated for fry color after 3 months of storage. Temperature profiles within the different regions of the row showed considerable variation throughout the season. Row orientation had a slight effect on soil temperature, but soil depth appeared to be more important. The deeper portion of the row (below 10 cm) was generally cooler throughout the day. East and north facing portions of rows also tended to be cooler than the opposite side that was exposed to more solar radiation. The highest yields and highest incidence of tubers with sugar ends tended to be found in areas below 10 cm in depth. These results contradict the notion that soil temperature is the primary factor leading to development of sugar ends. Therefore, individual tuber growth rate and temperature exposure of the entire plant may be more important in causing the development of sugar ends than was previously thought.     

Post-harvest decay of second growth-induced glassy tubers of potato (Solanum tuberosum L.) cv. Bintje in relation to their specific gravity

Summary After the induction of second growth, tubers may develop physiological rot following complete starch depletion. Tubers from two crops were graded into specific gravity classes after harvest and the development of decay was monitored during storage for 9 weeks. Most decay took place within the first 5 weeks. Tubers with a specific gravity<1.010 usually decayed completely. About 80% of tubers with a specific gravity>1.020 remained intact. In the specific gravity class 1.010–1.020 more than 50% of the tubers were affected, but they did not all decay completely.     

Variation in pathogenicity on potato tubers and sensitivity to thiabendazole of the dry rot fungusFusarium avenaceum

Summary The majority of isolates ofFusarium avenaceum caused dry rot on potato tubers; many were as pathogenic asF. coeruleum. Pathogenicity ofF. avenaceum was not related to the plant species from which the isolates originated. Tubers of potato cv. Cara were more susceptible than those of cvs Romano or Maris Piper. Temperature (5–15° C) had no effect on lesion depth but lesions tended to be slightly wider at the lowest temperature. Two isolates (of 61) from wheat and white lupin had a moderate level of resistance to thiabendazole. The results are discussed in relation to the control of dry rot in stored potato tubers.     

Effect of gibberellic acid and multiple harvests on production and reproductive value of seed potatoes produced above ground on stem cuttings

Summary Potato plants of cvs Eersteling and Bintje were grown from stem cuttings and induced to form aerial tubers for use as seed. Spraying the plants with gibberellic acid in concentrations of 10, 25 and 50 mg/l to induce stolon formation in the leaf axils led to a decrease in the number of tubers formed per plant. Multiple harvesting of the largest tubers from plants treated with gibberellic acid or not, approximately doubled the number of tubers formed but halved their individual weight compared with only one harvest at plant senescence. After a storage period of about 1 year, with their vigour declining, the aerial tubers were planted in the field. Aerial seed tubers taken from multiple harvests during the previous year produced the same number of tubers as plants grown from above-ground tubers harvested at plant senescence only, but the tuber yields declined with earlier harvesting when small (5–13 mm) aerial tubers were used, compared to larger (14–19 mm) tubers.     

Effects of nitrogen,phosphorus and potassium fertilizer treatments on weight loss and changes in chemical composition of potato tubers stored at 4°C

Summary Pot and field experiments were carried out to test fertilizer treatments on the behaviour of potato tubers stores at 4°C and ≥90% relative humidity for 6 months. Weight losses (separated into water and dry matter) were enhanced after N and K fertilization and decreased by increasing P supply. Glucose and fructose contents were reduced at harvest by high N-fertilizer rates compared to no or low fertilization, but throughout storage reducing sugar accumulation was increased, sucrose reduction was decreased and ascorbic acid was increased. K fertilization affected the chemical composition of the tubers somewhat similar to that of nitrogen fertilization. High initial nitrate content of the tubers seemed to be increased and low nitrate values were decreased during storage. The tubers from pot experiments showed similar changes but of greater magnitude.     

Nitrogen and Italian ryegrass 5. Growth up to 14 weeks: residual effects

In a field experiment with Italian ryegrass residual effects of N applied in late April at four rates, 28, 84, 140 and 196 kg ha^?1, and of different dates of first harvest ranging from 1 to 14 weeks after N application, were studied. The harvests after the first added about 10 kg dry matter yield and about 0.16 kg N yield for each extra kg N applied in April. Residual response was similar for each increment of applied N. A positive residual response to N was obtained in May of the year following N application despite high winter rainfall. N content of herbage during part of the summer was reduced by extra N applied in April although N yield was increased. The reduction in N content was accompanied by a reduction in P and K content, these latter elements having been applied only once and at a uniform rate on all plots. Loss of N, P and K from the crop, when a period of more than about 9 weeks regrowth was allowed prior to the first harvest, was not recouped at subsequent harvests. Residual marginal recovery of N in Aberystwyth was no higher than in comparable experiments in Cambridge although marginal recovery of N at the first harvest had been appreciably lower in Aberystwyth than in Cambridge.     

马铃薯丰产植株光合产物日变规律的研究(一)——干物率及其日变化

马铃薯丰产砰体植株的叶片、茎秆、块茎的干物率在整个生育期间,始终低于一般群体,其日变化规律两群体相同,均表现昼高夜低的变化趋势,但茎秆和块茎不明显。全生育期,茎秆干物半始终低于叶片和块茎,叶片干物半生育前期高于块茎,生育后期低于块茎。叶片干物率的高低与植株长势呈正相关关系。因此,叶片干物率的高低是衡量植株生长状况和内部代谢强弱的重要生理生化指标。     

The immediate effect of gamma irradiation upon the sugar content of potatoes previously stored at 2, 4.5, 6, 10 and 15.5°C

Summary The sugar content of samples of potatoes, cv. Majestic, was varied by storage for 4 weeks at 2, 4.5, 6, 10 and 15.5°C, before irradiation with 10 krad. With initial sucrose contents of 0.14–0.37% FW (tubers from 4.5–15.5°C) the marked temporary increase in sucrose, as reported previously, was observed, reaching a maximum after 3–7 days before falling rapidly to a level rather higher than in non-irradiated tubers. Tubers from 2°C, with 1.4% sucrose, showed an immediate drop in this after irradiation, succeeded within 3 days by a rise to values not significantly different from the controls. Irradiation caused a significant increase in reducing sugar content, for a period of up to 7 days in sweetened tubers, but for 21 days or more in unsweetened tubers. Previous storage at the different temperatures had some permanent residual effect upon the sugar content of the controls during subsequent storage for up to 90 days at 10°C.     

Effect of Nitrogen Rate on Growth,Yield, Economics and Crisps Quality of Indian Potato Processing Cultivars

A field study was conducted during 2000–2001 and 2001–2002 at the Central Potato Research Institute Campus, Modipuram, India, in order to increasing the processing-grade tuber yield of India’s first ever developed processing potato cultivars, Kufri Chipsona-1 and Kufri Chipsona-2. Tuber yield and post-harvest quality characteristics were evaluated in response to five N levels (0, 90, 180, 270 and 360 kg N ha^-1). The crop growth traits (stem number, plant height and compound leaf number) responded positively to N application, whereas the effect of N fertilization on processing-grade tuber number, total tuber number per ha and tuber number per plant was quadratic. There was a steady increase in tuber weight per plant, processing-grade tuber yield, total tuber yield and biomass yield in response to N application. Kufri Chipsona-1 produced a 23.6% higher tuber yield per plant than Kufri Chipsona-2. Agronomic N use efficiency decreased linearly with increased N doses. Specific gravity and tuber dry matter percentage responded positively to N application, while crisps colour (at harvest and after storage) and reducing sugars remained unaffected. Cultivar was the major factor that influenced the tuber quality parameters (specific gravity, crisps colour). Higher values of these quality traits were observed in Kufri Chipsona-2 as compared to Kufri Chipsona-1. Net income and benefit cost ratio (B:C) indicated that Chipsona cultivars should be fertilized with 270 kg N ha^-1 for realizing higher processing-grade yields and desirable quality tubers.     

High temperature storage of potato (Solanum tuberosum L.) for processing — a feasibility study

Tubers of three potato cultivars were stored at room temperature (20–39°C, 30–75% RH), under an insulated storage run on passive evaporative cooling (16–30°C, 70–90% RH) and a refrigerated storage (2–4°C, 90–95% RH) for 14 weeks and studied periodically for storage losses, reducing sugar content and dry matter percent of tubers, in order to explore the possibility of storing potatoes for processing at higher temperatures. Physiological losses in tubers remained less than 10% until 12 weeks of storage under evaporatively cooled storage. Reducing sugar contents increased by only 52.4–242.1% in tubers stored in evaporatively cooled storage as compared to 90.5–484.2% increase in tubers stored in refrigerated storage until 14 weeks. Potatoes stored in evaporatively cooled store were more suitable for processing into chips and french fries due to lower physiological losses and lower reducing sugar content of tubers.     

Effects of nitrogen fertilization and in-row seedpiece spacing on yield of three potato cultivars in Prince Edward Island

AC Novachip and NorWis were recently introduced as new potato (Solanum tuberosum L.) chip cultivars on Prince Edward Island (P.E.I.), Canada. Variability of nitrogen application and in-row seedpiece spacing, required for maximum yield, exist among cultivars presently grown in P.E.I. This study was conducted to determine the N rate and in-row seedpiece spacing required for optimum production of AC Novachip and NorWis compared to the standard cultivar Norchip, and also, to determine the effects of treatments and harvest dates on AC Novachip. Treatments included N applied at 90, 134, and 179 kg/ha with in-row seedpiece spacings at 20.3, 25.4 and 30.5 cm. In addition to the 120 day harvest for all three cultivars, treatments for AC Novachip were also harvested at 80 and 100 days after planting. For the 120 day harvest, yield of Canada No. 1 size tubers was higher for NorWis compared to Norchip while yields for AC Novachip and Norchip were similar. Nitrogen application had no effect on yields of AC Novachip. Similar to Norchip, increasing the rate of applied N more than 134 kg/ha resulted in little or no increase in yields of NorWis. Yields of Canada No. 1 size tubers decreased as in-row spacing increased for AC Novachip and were greater at 25.4 compared to 30.5 cm spacing for Norchip. In-row seed-piece spacing had no affect on Canada No. 1 size tuber yields of NorWis. Increasing the days to harvest increased the yields of AC Novachip. Nitrogen rate or in-row spacing had no effect on Canada No. 1 yields of AC Novachip at the 80 and 100 day harvests. The results of this study suggest that little gain in yield of Canada No. 1 size tubers for NorWis, similar to the standard cultivar Norchip, can be obtained with N application more than 134 kg/ha or for AC Novachip by increasing the rate of N from 90 to 179 kg/ha. Unlike NorWis yields of AC Novachip and NorWis are reduced when in-row seedpiece spacing is increased from 25.4 to 30.5 cm.     

Growth and Tuberization of Hydroponically Grown Potatoes

Three hydroponic systems (aeroponics, aerohydroponics, and deep-water culture) were compared for the production of potato (Solanum tuberosum) seed tubers. Aerohydroponics was designed to improve the root zone environment of aeroponics by maintaining root contact with nutrient solution in the lower part of the beds, while intermittently spraying roots in the upper part. Root vitality, shoot fresh and dry weight, and total leaf area were significantly highest when cv. Superior, a medium early-maturing cultivar, was grown in the aeroponic system. This better plant growth in the aeroponic system was accompanied by rapid changes of solution pH and EC, and early tuberization. However, with cv. Atlantic, a mid-late maturing cultivar, there were no significant differences in shoot weight and leaf area among the hydroponic systems. The first tuberization was observed in aeroponics on 26–30 and 43–53 days after transplanting for cvs Superior and Atlantic, respectively. Tuberization in aerohydroponics and deep-water culture system occurred about 3–4 and 6–8 days later, respectively. The number of tubers produced was greatest in the deep-water culture system, but the total tuber weight per plant was the least in this system. For cv. Atlantic, the number of tubers <30 g weight was higher in aerohydroponics than in aeroponics, whereas there was no difference in the number of tubers >30 g between aerohydroponics and aeroponics. For cv. Superior, there was no difference in the size distribution of tubers between the two aeroponic systems. It could be concluded that deep-water culture system could be used to produce many small tubers (1–5 g) for plant propagation. However, the reduced number of large tubers above 5 g weight in the deep-water culture system, may favor use of either aeroponics or aerohydroponics. These two systems produced a similar number of tubers in each size group for the medium-early season cv. Superior, whereas aerohydroponics produced more tubers than aeroponics for the mid-late cultivar Atlantic.     

A non-destructive method for rapid evaluation of boiling quality of potato tubers

A non-destructive method for rapid evaluation of boiling quality of potatoes has been developed. The method is based on the degree of sloughing, after-cooking darkening and colour of tuber fractions (cores of 1.3 cm in diameter) cooked in test tubes at 118°C for 25 min. Using sixteen potato cultivars, with 20–30% dry matter content, boiling quality results obtained by the new method were compared to sloughing and after-cooking darkening values obtained by boiling quartered tubers in aluminum sauce pans on a standard electric stove. The correlation coefficient between sloughing data obtained by the two methods was 0.912 (P< -0.001). The new method has proven to be simple, reproducible and highly suitable for evaluating a large number of potato samples. This should make it attractive for routine use by potato breeders.