Field harvest damage affects potato tuber respiration and sugar content

Field and laboratory experiments demonstrate that damage to potato tubers increased tuber respiration, which declined with time. Measurement of tuber respiration with an infra-red gas analyzer can be a sensitive indicator of amount of tuber damage in actual field harvests. Damage of tubers had no effect on total sugar content but decreased sucrose content when measured ten days after harvest.     

Yield and relationships among tuber size,sucrose and chip color in six potato cultivars on various harvest dates

Cultivars were harvested biweekly for yield, weekly for sucrose determinations, and stored for chipping. At the last harvest Crystal was highest in total and marketable yield. Specific gravity was higher in Lemhi, Russet Burbank, and Norchip than in Kennebec, Crystal and Dakchip. Storage tests showed Norchip had superior chipping color to other cultivars. Dakchip had better color after short rather than after long-term storage, while the opposite was true for Kennebec and Russet Burbank. Lemhi and Crystal were marginal in color throughout storage. Sucrose (mg sucrose/g fresh tuber) expressed as a sucrose rating (SR) ranged from 1.2 to 11.9 among the various cultivars and harvest dates. Correlation between SR’s and tuber size within cultivars ranged from ?.91 to ?.97. Variability in sucrose content of immature tubers explained 70% of the variability in chip color among cultivars after storage from four to six months. Sucrose levels may be used to predict relative chipping quality of various cultivars after moderate to long-term storage if measured during early tuber development when differences in sucrose concentration are greatest among cultivars.     

Small tuber studies of sugar accumulation in potatoes

Small potato tubers, less than 1 cm in diameter, responded in a manner typical of larger tubers and accumulated sucrose and reducing sugars during storage at 1°C. Prolonged soaking (50% submerged) was used as a method for introducing metabolic inhibitors into intact, small tubers. Judging from the effects on respiration, cycloheximide was absorbed within 25 h. Cycloheximide treatment inhibited the sucrose and reducing sugar accumulation associated with storage at 1°C     

Specific gravity,potato chip color and tuber mineral content as affected by soil moisture and harvest dates

In 1966 and 1967 the chipping quality of three potato varieties was studied using three moisture regumes, two nitrogen levels, and three harvest dates. Specific gravity and chip color of potatoes freshly harvested and of those stored 10 days, along with chip color differences between the two periods, were tested. Of the three varieties tested — Anoka, Kennebec, Irish Cobbler — Anoka§ specific gravity was least depressed by soil-moisture stress and its chip color least affected by time of chipping; all tubers, however, chipped darker after being stored. High soil temperatures were associated with low specific gravities and dark chips. In 1966 irrigation tended to lower soil temperature, resulting in lighter chip color for potatoes harvested from irrigated than from nonirrigated plots; also color was lighter at the first than at the later harvests. In 1967, when air temperatures were consistently lower and rainfall nearly adequate, chip color was lighter for potatoes harvester later in the season. Nitrogen levels did not influence chip color. Moisture regimes and varieties influenced mineral content of tubers more consistently for the two years than did harvest dates or nitrogen levels. Specific gravity did not correlate significantly with chip color.     

Effect of variety and location on the glycoalkaloid content of potatoes

Significant differences in tuber glycoalkaloid (TGA) content were found among five commercial varieties and B5141-6 grown at 39 different locations in 28 states. Line B5141-6 had the highest average TGA content, 29.3 mg/100 g in 1970 and 28.1 mg/100 g in 1971. Average TGA contents in 1970 of Kennebec, Russet Burbank, Katahdin, Irish Cobbler, and Red Pontiac were 9.7, 7.9, 7.9, 6.2, and 4.3 mg/100g, respectively. There were also significant location effects. Possible causes of high TGA levels are discussed.     

Hill to hill variations in tuber yield of potatoes in Alberta

The hill to hill variation in tuber yield and mainstem number was studied on 18 potato farms. There were up to 14-fold differences in the tuber yield per hill among plants of Norland, Russet Burbank, Norchip, Carlton and Alaska Red. The mainstem number was more variable than tuber weight per hill in Norland, Russet Burbank and Alaska Red. However, the opposite was true in Norchip and Carlton. In nearly all comparisons, the number of tubers per hill was less variable than tuber weight and mainstem number per hill. The total variation in tuber weight found in about 50% of the samples could be explained by the variance of hills within rows. Even in samples where an added variance component due to differences among rows was present, relatively more variation occurred within than among rows. The correlation coefficients between the number of mainstems and tuber weight per hill were positive but significant (P&< 0.05) only in Norland and Norchip. The correlation coefficients between the number of mainstems and number of tubers per hill were also positive but slightly higher and significant (P<0.01) in all 5 cultivars. The coefficient of determination values indicated that variation in cut seed piece weight explained only about 10% of the total variation in tuber weight harvested per hill. At a spacing of 30 cm within the row, a major proportion of hill to hill variation in tuber yield had to be explained by factors other than the seed piece weight.     

Relationships between tuber size and time of harvest to hollow heart initiation in Dryland Norgold Russet potatoes

In four years of field trials approximately75% of hollow heart was initiated in tubers between 5.1 and 7.6 cm in diameter. Only rarely was hollow heart initiated in tubers less than 3.8 cm. The frequency of hollow heart was approximately nine times greater in medium sized tubers (6.4 to 7.6 cm) and 34 times greater in large tubers (over 7.6 cm) than in small tubers (5.1 to 6.4 cm). The number of tubers with hollow heart increased linearly through the last five weeks of the growing season. Hollow heart during the four years ranged from 4200 to 31900 tubers/ha or 2.9 to 13.0% of all tubers over 2.5 cm. There were consistent increases in tuber growth between harvests in each season, inferring an absence of severe plant stress and supporting the hypothesis that hollow heart was due to tissue tension associated with tuber enlargement.     

Some effects of planting depth and time and height of hilling on Kennebec and Sebago potatoes

Kennebec and Sebago potatoes were grown under level culture and various hilling treatments at two planting depths. These treatments were applied at planting time or after tuber-set, or both. There were no differences in total yield but lower marketable yields were obtained under level culture due to the increased amount of sunburn. Hilling after tuberset caused the range of tuber-set to be displaced upwards so that the uppermost tubers were at a nearly constant depth below the soil surface, regardless of the height of hill applied. Hilling after tuber-set also tended to produce tubers of higher specific gravity than hilling only at planting.     

Furrow vs hill planting of sprinkler-irrigated russet burbank potatoes on coarse-textured soils

Surface water runoff from the hill, where potatoes are planted, to the furrow may exacerbate potato drought sensitivity. Planting into furrows and constructing midrow ridges may improve water use efficiency and relieve water stress on potato by directing water toward, not away from, the plants. A 3-year field study was conducted to compare yields and tuber size distributions of furrow- and hill-planted potato (Solanum tuberosum L., ‘Russet Burbank’) on coarse-textured, well-drained soils under sprinkler irrigation. A split-plot experimental design with main plots of row orientation (N-S vs E-W) and subplots of planting method (hill and furrow) combined with two planting depths was used at two central North Dakota sites. Except for planting method and limiting the post-emergence cultivation in the furrow treatments, all cultural practices (fertilizer, irrigation, etc.) were identical and corresponded with conventional practices for hill planted potato. Row orientation did not affect yield for any tuber size category. Averaged over 3 years, furrow-planted potato produced 24% larger tubers (188 vs 151 g), 31% smaller yield for tubers <113 g (4.99 vs 7.21 Mg ha^?1), 28% smaller yield for tubers 113 to 170 g (8.14 vs 11.3 Mg ha^?1), 8% larger yields for tubers 170 to 283 g (18.0 vs 16.6 Mg ha^?1), 103% larger yields for tubers 283 to 454 g (10.9 vs 5.36 Mg ha^?1), 341% larger yields for tubers >454 g (2.65 vs 0.60 Mg ha^?1), and 10% larger total yields (46.2 vs 41.9 Mg ha^?1) compared with hill-planted potato. There were no differences in tuber specific gravity. Preliminary soil water measurements indicated an inter-row water-harvesting effect for furrow planting compared with hill planting. The furrow-planting method may offer significant potential for ameliorating the drought sensitivity of potato.     

Influence of pre-sprouting on tuber number,size and yield of King Edward potatoes

Summary Experiments show that sprouting treatment, seed size and spacing affect the number and size of tubers produced. Early sprouting gives fewer sprouts per set and hence plants per hill than late sprouting. The number of tubers produced is directly related to the number of plants. Sets with few sprouts (plants) produce fewer tubers than sets with many sprouts. Small seed produces fewer plants and hence tubers than large seed. The size of the tubers is inversely related to tuber numbers. In 1960 unsprouted seed produced fewer and larger tubers than pre-sprouted seed butPhytophthora infestans was not experienced. Early sprouting, small seed and wide spacing increased tuber size, but early sprouted seed planted closely gives a higher yield of ware than late sprouted seed planted further apart. Pre-sprouting results in earlier emergence and tuber set but does not necessarily increase the yield of ware. If early drought occurs, presprouting may increase the proportion of mishapen tubers.

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Zusammenfassung Versuche haben ergeben, dass Vorkeimung, Gr?sse der Saatknollen und Pflanzabstand die Anzehl und Gr?sse der erzeugten Knollen beeinflussen. Frühkeimung gibt weiiger Triebe je Pflanzknolle und somit Pflanzen je Staude als Sp?tkeimung. Die Anzahl der erzeugten Knollen steht in direktem Verh?ltnis zu der Zahl der Pflanzen, Pflanzknollen mit wenig Trieben (Pflanzen) liefern weniger Knollen als Saatgut mit vielen Trieben. Kleine Saatknollen ergeben weniger Pflanzen und somit Knollen als grosse Saatknollen. Die Gr?sse der Knollen steht in umgekehrtem Verh?ltnis zu der Knollenzahl. Im Jahre 1960 ergaben ungekeimte Saatknollen weniger und gr?ssere Knollen als vorgekeimte Saatknollen, jedoch kam kein Befall vonPhytophthora infestans vor. Durch Frühkeimung, kleine Saatknollen und weiten Pflanzabstand wurde die Knollengr?sse gesteigert; vorgekeimte Saatknollen bei enger Pflanzung ergaben jedoch einen h?heren Ertrag an Verbrauchskartoffeln als sp?tgekeimte, die in gr?sserem Abstand gepflanzt waren. Vorkeimen bewirkt früheren Aufgang und Knollenansatz, erh?ht jedoch nicht unbedingt den Ertrag an Verbrauchskartoffeln. Wenn früh Trockenheit eintritt, kann das Vorkeimen Ursache eines gr?sseren Anteils an missgebildeten Knollen sein.

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Résumé Des essais ont démontré que la prégermination, la grosseur des plants et leur espacement influencent le nombre et la grosseur des tubercules récoltés. Une germination précoce donne moins de pousses par plant, c’est-à-dire moins de plantes par touffe qu’une germination tardive. Le nombre de tubercules obtenus est directement proportionnel au nombre de plantes. Les plants portant peu de pousses (peu de plantes) produisent moins de tubercules que les plants qui présentent des pousses nombreuses. Les petits plants donnent moins de plantes et donc moins de tubercules que les gros plants. La grosseur des tubercules obtenus est indirectement proportionnelle à leur nombre. En 1960, les plants non prégermés produisirent des tubercules moins nombreux et plus gros que les plants prégermés, mais il n’y eut pas d’attaque dePhytophtophthora infestans. La germination précoce, le petit format des plants et leur grand espacement faisaient augmenter la grosseur des tubercules, mais les plants prégermés et plantés et plantés serré donnaient un plus haut rendement en tubercules de consommation que les plants germés tard et espacés davantage. La prégermination occasionne une levée plus précoce et une tubérisation également plus précoce, mais n’augmente pas nécessairement le rendement en tubercules de consommation. En cas de sécheresse au début de saison, la prégermination peut accro?tre le nombre de tubercules difformes.

     

The effect of tuber size on the susceptibility of potatoes to metoxuron

Summary Field and pot experiments to determine whether the tuber size of volunteer potatoes affected their susceptibility to foliar applications of metoxuron are reported. The reduction in haulm weight of plants from small tubers (2–3 cm diameter) was greater than that of plants from large ones (4–5 cm diameter). This greater control was related to the lower vigour at spraying of the plants from the small tubers. It is suggested that these results could explain the variability in the level of control of volunteer potatoes achieved by metoxuron in carrot crops.     

Influence of chilling on potato tuber respiration,sugar, O-dihydroxyphenolic content and membrane permeability

The response of four potato cultivars to various temperatures was evaluated in respect to respiration, sugar and phenolic content, and ion leakage from cut tissue sections. Respiration decreased with decreasing temperature from 20° to 0°C but after 24 hours at 0°C began to increase and reached a maximum after 10 days at 0°C, then drifted downward. No distinct break in an Arrhenius plot of the respiration data from 20° to 0°C was observed. Reducing and non-reducing sugars did not change initially between 20° and 0°C and did not increase until after 6 or 7 days at 0°C. The magnitude of the increase in sugars varied between cultivars. Only one cultivar significantly increased in phenolic content during chilling. Ion leakage remained constant from 20° to 0°C then showed a transient increase within 24 hours at 0°C. A sustained increase in leakage did not occur until after 10 days at 0°C. Cultivars varied in the rate and magnitude of the increase. The respiratory rise could not be attributed to an increase in sugar content or an increase in membrane permeability. Also, the initial increase in sugars preceded the sustained increase in ion leakage. Differences observed between cultivars in the parameters measured were not considered sufficient to explain differences in chilling sensitivity.     

Effect of seed tuber and seed piece size on growth and incidence of hollow heart in Norgold Russet potatoes

Small seed pieces decreased yield and number of tubers. Both seed tuber and seed piece size affected the percentage of tubers with hollow heart. Hollow heart increased from 14 to 22% as the seed tuber size increased from 57 to 228 g and decreased from 27 to 19% as the seed piece size increased from 28 to 57 g. The least hollow heart (11%) occurred in tubers of plants grown from 57 g whole seed pieces and the most (26%) in tubers of plants grown from 228 g seed tubers cut into 28 g seed pieces. Hollow heart was positively correlated with the mean tuber size and negatively correlated with the number of mainstems per hill, total yield, and total number of tubers.     

The relationship between tuber size and hollow heart in Norgold Russet potatoes

Hollow heart (HH) when found in potatoes is predominately in the largest tubers. Various tuber lots of cv Norgold Russets ranged from 3.4 to 55.9% HH by weight. In the lot with the least HH approximately 43% of the tubers over 8.89 cm in diameter were hollow compared to 0.2% of those between 3.81 and 5.07 cm. By first removing the very largest, followed by successively smaller tubers there was a continuous reduction in HH in all tuber lots. There were only small differences among the five years in the effect of sizing on HH, and these appeared to be associated with yield differences among years. Figures illustrate the specific effect of removing progressively smaller tubers on the amount of HH remaining.