Influence of intercellular space differences due to variety and storage upon tuber specific gravity-dry matter relationship

At each of two locations in two years, five varieties of potatoes were examined for specific gravity—intercellular space relationships. At harvest intercellular space differred consistently among varieties and decreased during two months' storage at 40 F. Changes in weight, volume, and intercellular space were used to explain that changes in tuber specific gravity may or may not reflect changes in dry matter content and that differences and changes in intercellular space are of sufficient magnitude to account for most of the discrepancies between recently published regressions of dry matter on specific gravity developed without correction for intercellular space. A coordinated study is proposed to establish the correctness of this postulation. Estimation of dry matter content of white potatoes from specific gravity determinations is a widely accepted practice. The accuracy of the estimation has been questioned because of the relatively large error of estimation (±1.5 to 2%) usually encountered (24), the wide divergence of regressions (1, 6, 15, 16, 18, 19, 23), and the frequency with which discrepancies have been noted between specific gravity and quality (14). Recent recommendations call for “Improved accuracy in the quick estimation of solids either by specific gravity or other means” and clarification of the “effect of temperature and period of storage on changes in ... specific gravity” (25). The tests reported here were undertaken to obtain corroborating evidence for the estimation of dry matter content of sweet potatoes from root specific gravity after correction for intercellular space (IS), (8, 12). Sweet potatoes, as well as several other commodities, contain relatively large amounts of IS (8, 11) but when this is accounted for, a reasonably consistent relationship exists that appears to be nearly identical to the regression for the specific gravity of sucrose solutions (8). The work with sweet potatoes showed that 1 ml of IS produced a buoyancy equivalent to the weight in water of 2.38 g of dry matter (12). Although white potatoes contain relatively small amounts of IS on the average, amounts of 1% (1ml/100ml) and more have been reported (2, 8, 15, 16). Nissen, in Denmark, reported that varieties differed in IS and that for greatest accuracy the IS should be accounted for (15, 16). Most workers in the United States, however, have ignored the influence of IS upon the accuracy of the methol of estimating dry matter content from tuber specific gravity, although several have speculated that IS contributed to variation in this relationship (1, 18). The tests reported here indicate that varieties may differ with reasonable consistency in IS at harvest in much the same manner as sweet potatoes (17), and that these differences and changes in IS during storage may be large enough to account for most of the discrepancies observed in the relationship between tuber specific gravity and dry matter content.     

Grav-o-tater: A computer apparatus for measuring specific gravity

An apparatus was developed which automates the determination of specific gravity of potatoes. Samples of potatoes are lowered and raised into and out of a tank of water by means of a pneumatic cylinder. Weight in air and weight in water of the samples are determined by an electronic scale and transmitted to a microcomputer. The computer converts the data to specific gravity readings, stores the information in its memory, and presents the results on a monitor. The device can process samples at a rate of 120 per hour.     

Nitrogen fertilization and irrigation affects tuber characteristics of two potato cultivars

Nitrogen fertilization, irrigation, and cultivars affect tuber characteristics such as tuber size, specific gravity, and N concentration. Few studies, however, have investigated the interaction of irrigation and N fertilization on the tuber characteristics of potato cultivars, particularly in Atlantic Canada. The objective of this on-farm study, conducted at four sites in each of three years, 1995 to 1997, was to determine the effects of supplemental irrigation and six rates of N fertilization (0-250 kg N ha^-1) on the number of tubers per plant, the average fresh tuber weight, tuber N concentration, nitrate (NO₃-N) concentration, and specific gravity of the cultivars Shepody and Russet Burbank. Nitrogen fertilization increased the average fresh tuber weight, tuber N and N0₃-N concentrations, and decreased specific gravity. Effects of increasing N fertilization on tuber characteristics were often more pronounced for Shepody than for Russet Burbank, and for irrigated than for non-irrigated conditions. Shepody had greater average fresh tuber weight and tuber N concentration, lower specific gravity, and fewer tubers per plant than Russet Burbank. Supplemental irrigation increased the average fresh tuber weight and the number of tubers per plant, but it had a limited effect on specific gravity and tuber N and NO₃-N concentrations. Tuber NO₃-N con centration and specific gravity were strongly related to tuber N concentration, which in turn depended primarily on N fertilization. Incidents of lowest specific gravity and highest NO₃-N concentration occurred with a relative yield close to or equal to 1.0. We conclude that the risks of low specific gravity and high tuber NO₃-N concentration are greater when fertilization exceeds the N requirements to reach maximum tuber yield.     

Comparison of seasonal development of tuber specific gravity among seven potato clones

Specific gravity of potato tubers provides an estimate of starch content of which uniformly high levels are important for product quality. The objectives of this study were to document the relationship between the level of specific gravity and the variability among tubers and to model the seasonal development o f specific gravity for seven potato clones. Individual determinations were made on twenty tubers from each plot using the weight-in-air, weight-in-water method on each of eight harvest dates spanning the tuber growth period. For each plot, the mean and standard deviation of specific gravity were calculated and used to define the correlation between specific gravity level and tuber-to-tuber variability and to construct a predictive model of the seasonal specific gravity developmental pattern. As the season progressed, tuber-to-tuber variability of specific gravity increased for some clones but not for others. A positive correlation existed between tuber specific gravity mean and its standard deviation for four of the seven clones in 1991 and five in 1992. Correlation coefficients were generally low, suggesting only a weak association between specific gravity and its standard deviation. Tuber specific gravity developed in a similar seasonal pattern for the seven clones. It generally started low, reached a maximum approximately seven to eleven weeks after tuberset, at which time some clones showed a tendency to decline through the remainder of the season. Quadratic regression equations provided an adequate model to describe specific gravity development for all seven clones over the tuber growth period. Statistical contrasts were used to test for differences in equation parameters, including line coincidence, line slope, and intercept. The model showed that initial specific gravity level at tuber set, the rate of early season increase, as well as the length of time from tuber set to specific gravity maximum, varied by clone and determined the level of specific gravity at season’s end.     

Non-starch polysaccharides and the texture of French fried potato

Gel Filtration of the non-starch polysaccharides extracted from high and low specific gravity potatoes gave similar elution patterns. It is suggested that excessive degradation of the high molecular weight polysaccharides in low specific gravity potatoes, during frying, is an important reason for the poor textural qualities of low specific gravity french fries.     

The germplasm release of B0718-3 and B0767-2: Two late blight resistant potato clones

Two potato breeding selections were released by the United States Department of Agriculture, Agricultural Research Service on November 14, 1996, as germplasm that is highly resistant to current populations ofPhytophthora infestans (Mont.) deBary, the causal organism of potato late blight: B0718-3 and B0767-2. These two clones have been evaluated for their reaction toP. infestans in replicated plots at Presque Isle, Maine since 1990. B0718-3 is a netted white-skinned selection with good yields but low specific gravity. It is both male and female fertile and crosses readily with tetraploid Tuberosum. B0767-2 is a russet-skinned selection that is low yielding and low in specific gravity. It has not been successfully crossed; however, it may have some potential use in somatic hybridizations. Neither B0718-3 nor B0767-2 process into acceptable colored chips. Genetic material of this release has been deposited in the National Plant Germplasm System where it is available for research purposes, including development and commercialization of new cultivars.     

玉米籽粒几个物理性状的遗传与配合力分析

用14份玉米自交系采用7×7不完全双列杂交设计组配的49个F1组合为供试材料,研究了玉米籽粒几个物理性状的遗传规律和配合力效应。结果表明,粒宽和容重主要受加性基因效应影响;千粒重和比重加性效应及非加性效应同等重要;粒长主要受非加性效应影响。同一物理性状在不同自交系间其GCA效应有较大差异,其中自交系5003的粒长GCA效应最高,533粒宽和比重GCA效应均为最高,千粒重和客重GCA效应最高者分别为425和48—2。     

Chemical composition of potatoes. VII Relationship of the free amino acid concentrations to specific gravity and storage time

Prior to storage, Maine-grown Katahdin potatoes were sorted into five specific gravity classes. Samples of three classes (high, intermediate, and low) were stored in individual boxes at 38 F for eight months, 45 F for one month, and 50 F for one month. New York-grown Katahdins were sorted into specific gravity classes periodically after removal from storage. Both lots were analyzed periodically for free amino acids (including the amides). In general, an inverse relationship was found between total solids and free amino acids calculated on a dry weight basis in Maine-grown and New York-grown Katahdin potatoes. In most cases little difference was found on the fresh-weight basis. Changes in the amino acids during storage were quite random. The differences found in the amino acid values between samples due to sorting for specific gravity before and after placing in storage were minor.     

南阳彩色小麦籽粒性状分析初报

为给小麦新品种的种植、加工和开发利用提供科学依据,以南阳灰麦、蓝麦,普通紫麦和硬质紫麦为材料,对南阳彩色小麦品种中的籽粒形状、千粒重、容重、比重等性状指标进行了测定。结果表明,南阳彩色小麦尤其是友麦、蓝麦和硬质紫麦籽粒较长,属于瘦长型籽粒品种。千粒重属中等水平;容重除蓝麦外,其余都达不到一等小麦的要求;比重也比普通小麦偏低．因而这些性状限制了南阳彩色小麦在食品加工上的某些应用,但综合其营养价值和保健功能,这些品种在我国传统食品和功能食品上仍有较大的开发前景。     

The influence of storage conditions on various properties of potatoes

Change in weight and, to a lesser degree, in specific gravity of tubers during storage was much more dependent on relative humidity than on temperature. Katahdin usually lost more weight and showed a greater increase in specific gravity than Russet Burbank. The increase in weight loss of cured tubers in the course of the storage period was nearly always linear. The increase in specific gravity was often particularly pronounced at the end of the storage period. Black spot susceptibility decreased during the storage season and was sometimes affected by temperatures as well as relative humidity. In the cases that these influences were significant, colder and drier storage conditions resulted in less susceptible tubers than higher temperatures and relative humidities, but the differences were small. In one year out of three Russet Burbank was more susceptible than Katahdin, once the opposite was true, and once there was no difference between them. Susceptibility to damage, which decreased during the storage period in two out of three years, was greater at lower temperatures and higher humidities than under warmer or drier storage conditions. Variety differences were not consistent.     

Evaluation of potato clones for severity of Verticillium wilt, yield and specific gravity in Maine

In 1994 and 1995, the effect of Verticillium wilt, caused byVerticillium dahliae andV. albo-atrum, on tuber yields, number and weight of U.S. No. 1 and B size tubers, and specific gravity was studied in northern Maine, an area with a short growing season. Seven clones (four resistant and three susceptible) were evaluated in a split-plot design with three replications. Clones were the whole-plot factor, and seed pieces in sub-plots were either uninoculated or inoculated with 50 ml of 4 × 10⁴ cfu/mlVerticillium spp. at planting. Individual plants were scored for Verticillium wilt symptoms before harvest on a 1= <3% wilt to 10= >97% wilt. Differences among clones for wilting and specific gravity were significant. The inoculation treatment had no effect on any of the tuber traits measured. However, there were significant clone x inoculation interactions for most tuber traits. Reductions in yield, weight and number of U.S. No. 1 potatoes, and specific gravity were greater in the Verticillium wilt susceptible clones than in the resistant clones. These results suggest that breeding clones with resistance toVerticillium spp. will reduce yield losses, while maintaining tuber size and specific gravity under disease pressure.     

Quality tests of potato varieties in Australia

Color, texture and flavor were scored and specific gravity and dry matter contents were determined over a 13-year period on 262 varietal samples of potatoes grown in Australia. Statistical analyses of these results showed highly significant differences in each of the three culinary factors, just significant differences in dry matter content and no significant differences in specific gravity. There was a close linear relationship between dry matter content and specific gravity but the latter was shown to be an unreliable index of culinary quality. A pronounced mutual agreement which existed amongst the three culinary factors suggests that a reliable objective method for any of them would be an advantage in early screening tests of newly developed varieties.     

Variance components for yield and specific gravity in a diploid potato population after two cycles of recurrent selection

The potato(Solanum tuberosum L.) processing industry needs cultivars with high tuber specific gravity and acceptable color of processed product. All of the cultivars with high specific gravity currently grown in the U.S. are very closely related, which increases their genetic vulnerability and results in inbreeding as efforts are made to improve these traits. The use of diploidSolanum sp. in breeding may resolve these problems. The purposes of this study were (1) to estimate narrow-sense heritability for yield and specific gravity in random-mating diploid hybrid potato populations ofS. phureja - S. stenotomum (PHU-STN) following two cycles of recurrent selection, (2) to examine phenotypic variances for yield and specific gravity following two cycles of recurrent selection within PHU-STN, (3) to compare the yield and specific gravity of individual PHU-STN clones with Atlantic, and (4) to screen these PHU-STN clones for the presence of 2n pollen. Four clones from each of 72 maternal half-sib families were evaluated for yield and specific gravity in replicated field tests in 1990 and 1991. A second selection cycle, using a randomly mated population obtained from the highest specific gravity clone in each maternal half-sib family, was similarly evaluated for yield and specific gravity in replicated field tests in 1995 and 1996. Narrow-sense heritability for specific gravity was estimated as 0.37 ± 0.25 and 0.43 ± 0.27, in the first and second selection cycles, respectively, with a 27% decrease in phenotypic variance. Narrow-sense heritability for yield was estimated as 0.60 ± 0.26 and 0.06 ± 0.24, in the first and second selection cycles, respectively, with a 73% decrease in phenotypic variance. There were significant correlations between yield and specific gravity in 1990 (r=0.32) and 1996 (r=0.37), but not 1991 (r=0.08) and 1995 (r=0.05). These results indicate that additional breeding efforts in this PHU-STN population could result in improvements in specific gravity. However, the amount of variation for yield in this population is decreasing and may indicate that the yield potential of this population is rapidly approaching its limit. In the second selection cycle, many of the 288 clones were significantly higher in specific gravity than the high-specific-gravity cultivar Atlantic, but none were higher yielding. Fifty-eight clones from the second selection cycle produced at least 5% 2n pollen. When used in tetraploid x diploid hybridizations, this diploid population could furnish new genetic material to the tetraploid potato germplasm base for simultaneously increasing specific gravity and yield.     

The relation between storage conditions and changes in weight and specific gravity of potatoes

Weight losses of potatoes during storage were closely related to the product of average water vapor pressure deficit of the air between the tubers and the duration of storage in weeks. Shortly after harvest, the water loss per cm² skin area per hour per mm Hg VPD was five to seven times as high as later in the storage period. Temperature, through its influence on respiration did not appreciably affect weight loss, but had in several cases a clear effect on specific gravity. In those cases the relations between specific gravity and either weight loss or the product of storage duration and VPD were close only if the influence of storage temperature was eliminated.     

Shear press determinations of the raw product as a possible tool for quality measurement of potatoes

Texture determinations were made with a Food Technology Corporation shear press on Russet Burbank and Norgold tubers as they grew and developed from July 1 until October 15, 1970. Shear force reading increased as Russet Burbank tubers grew and increased in dry matter content. However, no increase in shear force was obtained with growth and development of the Norgold variety. Tubers harvested in the Fall were placed in 48 F storage and separated into specific gravity groups in increments of 0.005 with a brine solution. As specific gravity of the Russet Burbank variety increased, shear force readings also increased. Shear force of the Norgold Russet did not change with specific gravity changes. A very high correlation was obtained between raw shear force readings of specific gravity groups (Russet Burbank) and processed frozen french, fries of the same lots which were finish fried and shear force readings made within 3 minutes after removal from the fryer. Again, the correlation between raw shear force readings and finish fry readings of Norgold Russet was very poor, although the finish fry product readings increased as specific gravity increased.     

OAC Temagami: A new red-skinned white fleshed table potato cultivar

OAC Temagami is a new potato cultivar with red skin and creamy white flesh. Tubers are round in shape. When evaluated over three years at three sites in Ontario, it had higher specific gravity and culinary quality than Chieftain. OAC Temagami has the same maturity and comparable yield to Chieftain. It is recommended for fresh market use in Ontario.     

OAC Ruby Gold: A new red-skinned yellow fleshed table potato cultivar

OAC Ruby Gold is a new potato cultivar with red skin and yellow flesh. Tubers are oblong in shape. When evaluated over three years at three sites in Ontario, it had higher specific gravity and culinary quality than Chieftain. OAC Ruby Gold has the same maturity and slightly lower yield than Chieftain. It is recommended for fresh market use in Ontario.     

Texture of French fried potato: Quantitative determinations of non-starch polysaccharides

Contents of high, intermediate and low molecular weight, non-starch polysaccharides of low specific gravity (LSG: 1.062–1.070) potatoes were determined to be 32.3, 28.9 and 32.2%, respectively. Respective figures for high specific gravity (HSG: 1.102–1.106) potatoes were 42.3, 22.2 and 29.1%. Frying caused severe degradation of high molecular weight polysaccharides (MWP) and reduced the original levels in LSG potatoes from 32.3% to 21.3% (34% degradation) and in HSG potatoes from 42.3% to 37.8% (10.6% degradation). HSG fries, therefore, had almost twice the levels of high MWP than LSG fries (37.8 VS 21.3%). Contents of intermediate and low MWP in HSG fries (25.3 and 30.3%, respectively) were lower than those in LSG fries (34.2 and 37.6%, respectively). These differences are suggested to be one of the important factors governing the textural qualities of french fries.     

Genotypic stability analysis of eight potato varieties tested in a series of ten trials

Genotypic stability analyses were carried out for five characteristics of eight potato varieties which had been tested in the New Brunswick Variety Trial in the past ten years, 1961–1970. Special attention was paid to three economic traits, i.e., marketable yield, specific gravity and dry matter yield. General adaptability was defined in this paper as having average genotypic stability and above-average mean performance. Kennebec showed the best general adaptability of marketable yield, Hunter for specific gravity and Netted Gem dry matter yield. No variety was ranked at the top for both marketable tuber yield and specific gravity. Some implications of this study on potato breeding are discussed.     

Determination of silage face surface area on commercial California dairy farms

Analysis of exposed silage face surface area was conducted to better understand and provide feed management recommendations as well as evaluate potential compliance needs related to volatile organic compound emissions. Policy was developed by the San Joaquin Valley Air Pollution Control District (District) to restrict exposed surface area of silage piles to 199·7 m² per farm if only one pile was exposed or 399·5 m² per farm if more than one pile was exposed. Exposed surface area on piles of silages at 20 dairies was quantified to determine impacts of these surface area restrictions. Herd size ranged from 490 to 7,200 milking cows, and the number of exposed piles ranged from one to four per farm as maize and/or wheat silage. Surface area of piles was quantified based on pile measurements and geometric shapes. The measured value was compared to the estimated value using the District ‘online calculator’. The District calculator used inputs for base length and height with assumed constant relationships between base and top lengths. Five of 43 piles had >199·7 m² of exposed surface area. Sixteen of 20 dairies with more than one exposed surface complied with the exposed surface area restriction. On average, the District calculator overestimated surface areas by 11·6% ± 14·8 (range ?57·7 to 38·4%). Pile measurements and use of geometric shapes provide a more precise method to quantify exposed surface area. This will be of particular use for those operators who utilize the District calculator and find their exposed areas out of compliance.