Sugar-end in Russet Burbank potatoes

Tissue selected from the stem- and bud-end of reconditioned tubers having sugar-end disorder was compared by color after frying and chemical composition to tissue removed from the two ends of tubers without sugar-end disorder taken directly from cold storage at 45 F, and after reconditioning 3 weeks at 70 F. Chemical analyses of selected tissue suggested that the dark finish-fry color at the stem-end of sugar-end tubers following reconditioning at 70 F was due to the inability of the physiological systems within the tissue to convert reducing sugars to starch and/or to use these sugars in the respiratory process. Of the components analyzed, only a high reducing sugar content was associated with a dark finish-fry color. Neither sucrose nor free amino acid content was associated with the sugar-end disorder. Extending the reconditioning period at 70 F for sugar-end tubers did not lower the reducing sugar content or the darkening of the stem-end tissue on frying.     

Internal quality of Russet Burbank potatoes following chilling

Russet Burbank potatoes were chilled at 25 F (?3.8 C), 27.5 F (?2.5 C), or 30 F (?1.1 C) for various periods of time and were then held at 45 F (7.2 C) for one or four weeks before testing. Susceptibility to injury was quite variable between the two crops and among tubers of the same lot exposed to the same treatment. The greatest amount of low temperature breakdown occurred in tubers chilled at 27.5 F (?2.5 C) for 10 hours. Flesh color, reducing sugar content, mealiness, and amount of sloughing in tubers that survived chilling were not markedly different from those in control samples although certain trends were observed indicating that the quality of chilled tubers was beginning to deteriorate. Chilling increased yellowness of flesh color in most treatments and darkness in several. Chilled tubers had a reducing sugar content slightly to moderately higher than the controls. They sloughed less than the controls and tended to be less mealy     

Field performance of transgenic Russet Burbank and Lemhi Russet potatoes

Transformed Russet Burbank and Lemhi Russet clones which contained three different transgene constructs were evaluated for performance under field conditions in Idaho. The transgenic lines were characterized over two growing seasons, using plants grown from both greenhouse produced minitubers (first year) and field grown seed (second year). Individual clones were evaluated for a variety of agronomic and quality properties. Many of the transformed clones showed reduced yield and increases in percent malformed and undersized tubers. Other characteristics, such as specific gravity and fry color, showed less variability. The variation observed in non-transgenic clones regenerated from tissue culture was less than that of the transformed lines. Out of an original population of 57 transgenic lines in tissue culture, maintenance of key agronomic and quality properties of the parental material was observed in only four clones. These results suggest that experiments designed to generate transgenic lines for the marketplace should be initiated with a large number of transgenic clones.     

Seed performance of Russet Burbank potatoes

A three-year study of three planting dates and four harvest dates of Russet Burbank seed potatoes was made to determine their effect on plant vigor, virus leaf roll infection, yield, size distribution and quality. Yields decreased significantly with delayed harvest of the seed crop. The incidence of late season virus leaf roll based on visual symptoms increased significantly with delayed harvests. The risk of a late season virus leaf roll infection increased when a later harvest was combined with a late planting. Seed taken from the earlier harvested plots consistently had earlier and more uniform emergence, the greatest vigor and the highest yields. The effect of planting date and harvest date had little effect on size distribution and no effect on specific gravity.     

Specific gravity of Russet Burbank potatoes

Variability in specific gravity of Russet Burbank potatoes was documented in a single 32 hectare field. Maximum variation was 40 units among individual tubers within hills (one unit equals one part in 1000th of specific gravity measurement) and 15 units among hills. Field site variability of 10–15 units was common between sampled grid lines in the field; but bulked samples (truckloads) reduced the sampled variability to 8–10 units. When the samples were taken from bulked lots as opposed to single hill samples, the variability decreased. Grower lots, which were pooled samples from several truckloads, showed specific gravity differences of 2–7 units even though all lots were from the same field. These variations among specific gravity samples should be taken into account when considering total solids content in any lot of potatoes. Degree of russetting of the skin and hollow heart also influenced specific gravity measurements. Measured differences between peeled and unpeeled lots of 10 units in specific gravity corresponded to 2% difference in total solids content. Statistically, the variance of the peeled lot was one half that of the unpeeled lot, therefore, to minimize the measured differences due to skin type, peeled potatoes could be used for the specific gravity measurements.     

Factors influencing reconditioning of Russet Burbank potatoes

Studies were made to determine factors which influence reconditioning of Russet Burbank tubers. Tubers from plants grown under low fertility were more difficult to recondition than tubers from plants adequately fertilized. Low specific gravity potatoes were also more difficult to recondition than high specific gravity potatoes even though the initial sugar content was approximately equal. The stem portion of Russet Burbank tubers lost considerably less sugars than the bud portion during the reconditioning process. It appears that factors which are responsible for high sugar development are also responsible for difficulty in sugar loss. Results also indicate greater difficulty in reconditioning early in the storage period with the loss of sugars becoming easier as the storage season progressed into spring.     

Storage temperature for maintenance of internal quality in Idaho Russet Burbank potatoes

Idaho-grown Russet Burbank potatoes treated with a sprout inhibitor were stored at 42 F, 45 F, and 48 F for 11 months. Monthly quality evaluations showed that tubers stored at 42 F were less mealy, contained more reducing sugars, and were yellower in color than those stored at 45 F or 48 F. The latter two treatments were not significantly different in mealiness and were generally similar in yellowness of color. Tubers stored at 48 F had less reducing sugars than those stored at 45 F. Although all treatments resulted in a gradual darkening of the potatoes during storage, differences in grayness among the three storage treatments were minor from a practical standpoint. It is suggested that a storage temperature no lower than 45 F be used to maintain the internal quality of Russet Burbank potatoes.     

Effect of simulated hail damage on yield and quality of Russet Burbank potatoes

The yield and quality response of Russet Burbank potatoes to simulated hail damage was dependent upon the amount of damage and on the growth stage at which the damage occurred. Plots of Russet Burbank potato plants were subjected to 0%, 10%, 25%, 50%, 75%, or 100% defoliation at 3, 5, 7, 9, 11, or 14 weeks after emergence. A motorized flail was used to simulate the complex damage that occurs during a natural hail storm. Early season simulated hail damage, when the plants were mainly vegetative, caused yield losses proportional to the degree of damage. Simulated hail damage during the early phases of tuber growth caused minor yield losses (< 5%) at low defoliation levels but severe losses at the higher levels with proportional loss of tuber quality. Defoliation later in the season resulted in progressively less reduction of both yield and quality. At or near maturity, late season simulated hail damage caused insignificant losses unless the stems were damaged enough to prevent nutrition and carbohydrate translocation into the tubers.     

Response of Russet Burbank potatoes to ethephon sprays

Ethephon ((2-chloroethyl)phosphonic acid) was sprayed on the foliage of Russet Burbank potatoes at tuber initiation in four separate field trials over two years. Rates were 0, 61, 122 and 183 g ai/ha. Total yield, yield of U.S. No. 1’s, hollow heart and brown center generally decreased at higher ethephon rates. Yield of undersized tubers increased. Ethephon sprays generally decreased specific gravity but the effect was minor and not consistent. In three of the four plantings where hollow heart and brown center in the untreated controls exceeded 8 t/ha, the low rate of ethephon increased the yield of non-hollow tubers ≥56 g in size.     

Sensory evaluation as a tool in breeding potatoes for French fries and flakes

Standardized sensory evaluation of advanced breeding clones developed in the research program of the Horticulture Department at North Dakota State University has been conducted annually since 1980. Procedures used by the USDA-ARS Potato Research Laboratory for processing tubers into partially fried french fries or flakes are described along with the procedures used for finish-frying of the fries and rehydrating the flakes in preparation for sensory evaluation in the Food and Nutrition Department at North Dakota State University. Following brief training, panelists evaluate the fries and flakes from each clone in triplicate for color, flavor, and texture. Procedures for determining length of fries and limpness of fry strips are described. Samples of 334 clones prepared as french fries and 135 clones prepared as flakes have been evaluated. Examples are given of types of data collected with interpretation of results in relationship to their use in the breeding program.     

Effect of seed piece population on the yield and processing quality of Russet Burbank potatoes

The effect of seed piece population on tuber yield, size distribution and processing quality of Russet Burbank potatoes grown under nonirrigated conditions in southern Manitoba from 1983 to 1987 was determined. Seed pieces were planted at 21.7, 26.3, 33.3 and 45.5 thousand seed pieces per hectare, and plant emergence generally exceeded 90% of the seed piece population. Marketable tuber (greater than 5 cm in diameter) yields were not affected by seed piece population. As population increased, however, the number of harvested tubers increased and average tuber size decreased, which resulted in a decreased yield of premium tubers (greater than 284 g) and an increased yield of small tubers (less than 5.0 cm in diameter). Specific gravity, the incidence of hollow heart in maingrade (5 cm in diameter to 284 g in weight) and premium tubers, and fry color were not significantly affected by seed piece population. In the one trial tested, sucrose content decreased as population increased, however, this was not reflected in improved fry color after storage.     

Some factors influencing shear force determinations of Norgold Russet and Russet Burbank potatoes

Norgold Russet did not increase in shear force readings with growth and development as did the raw product of Russet Burbank which showed a progressive increase in readings with growth during the latter half of the season. Seasonal differences were apparent with Russet Burbank, but not for Norgold Russet during the 3 years of this study. Higher shear force readings were recorded with an increase of specific gravity of Russet Burbank, but not for Norgold Russet. Low fertility level resulted in slightly higher shear force values possibly because of enhanced maturity. No major influence of moisture stress was evident. Higher shear force values resulted from longer periods of storage and with higher storage temperatures of Russet Burbank within the range of 34F to 45F.     

Preconditioning and storage of chemically immature Russet Burbank and Shepody potatoes

Russet Burbank and Shepody potatoes of different chemical maturities (i.e. varying sucrose concentrations) at harvest were preconditioned by holding at 15 C for various durations to lower the concentration of reducing sugars to levels acceptable for processing as french fries out of 8 C storage. In chemically immature tubers (i.e. those harvested with a high sucrose), sucrose declined after harvest and stabilized in storage regardless of the preconditioning period. However, there was a temporary small increase in sucrose after harvest in more chemically mature tubers. The concentrations of the reducing sugars glucose and fructose were low at harvest, usually < 1.0 mg g^?1, but increased rapidly during the first 30 to 45 d of storage in tubers with more than 2.0 mg g^?1 sucrose at harvest. Preconditioning for up to 70 d at 15 C either limited the increase in reducing sugars or lowered them more rapidly during storage than when preconditioned for only 14 d. Fresh weight loss of Russet Burbank and Shepody was greater in physically and chemically immature tubers compared to more mature tubers. Extended preconditioning of Russet Burbank and Shepody resulted in minimal additional weight loss.     

Petiole analysis and the nitrogen fertilization of Russet Burbank potatoes

The effect of nitrogen rates on the yield of Russet Burbank potatoes was studied in field experiments in Idaho. Petioles were sampled at the 6-to-8 leaf stage and thereafter at two week intervals until mid August. Petiole nitrate concentrations were very high early but decreased rapidly as the season progressed and declined to a very low level as the plants matured. The nitrate content of the petioles reflected the amount of N applied to both locations. Nitrogen applications increased total yield and the quantity of the larger size tubers. A highly significant correlation was found between the early season petiole nitrate concentrations and total yield. Suggested ranges of petiole nitrate concentrations were developed as a guide to efficient N fertilization of Russet Burbank potatoes in Idaho.     

Factors influencing incidence of internal brown spot in Russet Burbank potatoes

Studies were conducted to determine factors influencing incidence of internal brown spot (IBS) in Russet Burbank potatoes. A significant decrease in the incidence of IBS occurred as planting date was delayed from March 31 to May 12. IBS increased during storage particularly at the higher storage temperature and in larger tubers. Foliar application of maleic hydrazide (MH) significantly reduced IBS from a high of 33% of tubers to less than 10%. The incidence of IBS in tubers was lower in the field as well as in storage from plants sprayed with MH. Tubers with high specific gravity had greater incidence of IBS than low gravity tubers. Results indicate that IBS is a physiological disorder influenced by factors affecting growth of tubers.     

Dry matter content of apical and basal portions of Russet Burbank potatoes

Studies were made over a 4-year period of some factors affecting the dry matter content of the apical and basal portions of growing Russet Burbank potatoes. The greatest difference between portions was obtained from tubers of the normally irrigated plots of 1969. The amounts in the two portions in 1970 were nearly equal throughout the growing season. The major differences between the 2 years was a slightly cooler June and warmer maximum temperatures in July of the 1970 growing season. Moisture stress, particularly, early in the stage of tuber development (1972 season) caused a switch in amount of dry matter in the apical and; basal portions. Stress later in the development stage (1969 season) did not cause a switch. Fertility level was not as influential as moisture stress in affecting the ratio of dry matter in the two ends, whether under stress or normal moisture conditions.     

Response of Russet Burbank potatoes to soil fumigation and nitrogen fertilizers

Two field studies were conducted to determine the effects of soil fumigation on the response of Russet Burbank potatoes (Solanum tuberosum L.) to NH₄-N or NH₄NO₃ fertilizers. In one study fumigation increased yields but N source had no effect. In the other study fumigation had no effect but NH₄-N provided higher yields than NH₄NO₃. Microbial studies indicated that although populations of nitrifying bacteria were initially altered by fumigation, nitrification rates were similar to those in non-fumigated soil. In a controlled environment study in which potatoes were grown in fumigated field soil, neither N source nor fumigation had any effect on growth or yield. These studies indicated that fumigation had no effect on the response of potatoes to NH₄-N or NH₄NO₃ fertilizers.