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.     

The relationship between specific gravity and percentage dry matter in potato tubers

Specific gravity and percentage dry matter were determined for 1269 potato samples taken over a period of six years. The correlation coefficient between these properties over the whole material was 0.912 and the regression equation was: % dry matter = ?217.2 + 221.2 (specific gravity). When the material was broken down into smaller, logically defined groups, such as a single cultivar, regression lines often deviated from this general line, although in most cases the correlation coefficients were still quite high. This means that the quantitative relationship between specific gravity and dry matter content was not sufficiently stable to serve as a general measure of prediction under all conditions. It seems probable that various production areas of the United States will have to develop the line which is best suited to their conditions, and that some cultivars may require separate lines.     

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.     

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.     

A common regression for estimating dry-matter content of carbohydrate-containing commodities from specific gravity

For nine commodities that consist primarily of carbohydrates and water, corrections for intercellular space permit highly significant correlations between percent dry matter and corrected specific gravity. Drymatter contents for all commodities ranged from about 3 to 36%. Throughout this range the commodity mean values fall approximately on the regression line for specific gravity of sucrose solutions on dry matter percentage of the solutions, and the individual regressions often nearly coincide with the sucrose regression. It is suggested that, when intercellular space is accounted for, the sucrose regression is representative of commodities that consist primarily of water and carbohydrates.     

Specific gravity and dry matter content of potato

Summary Data obtained from 516 pairs of specific gravity and dry matter determinations were used to derive a relationship for estimation of dry matter content of potatoes grown in India.     

Dry matter content and mineral composition of potatoes grown in Cyprus

Summary The specific gravity and dry matter content of 193 tuber samples (cultivars: Arran Banner, Spunta, Up-to-Date, Cara) from crops grown at Kokkinochoria, the major potato growing area of Cyprus, were related to each other as follows: Dry matter (%)=−269.59+268.24×specific gravity. This regression accounted for 82.4% of the variation; the fiducial limits (P<0.05) for single determinations of specific gravity were±1.54 percentage units. The mineral contents of the tubers were similar to those reported in other countries.     

花生籽粒比重与生态特性的研究

不同花生品种籽粒比重有差异，花生籽粒比重和生育日数、结荚日数呈正相关，和开花与结荚日数二者比值呈显著负相关，结荚日数长有利于增加花生籽粒比重。在花生营养生长时期长日照、高温、较小温差，生殖生长时期短日照、低温和较大温差有利于干物质积累。花生籽粒比重的变化与品种的遗传和干物质积累时的气候因素有关。     

Alasclear: A high quality scab resistant potato

Alasclear was released from the breeding program at Palmer to provide Alaskan potato growers with a variety as resistant to potato scab as Ontario and of much better quality than that variety. Alasclear has a clear skin and is very acceptable at harvest for chip manufacture. Ninety days from planting it accumulated high dry matter as indicated by 1.089 specific gravity. It continues to increase to 1.102 specific gravity over a period of 120 days.     

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.     

Effect of irrigation applied at different growth stages and length of irrigation period on quality characters of potato tubers

Summary Potatoes were irrigated at three growth stages: (1) planting-stolon initiation. (2) stolon initiation-tuber bulking, and (3) tuber bulking, when available soil water dropped to 25%, 50% and 75%, bringing it up to field capacity; and irrigation ceased 0, 10 and 20 days before maturity. Significant increases in specific gravity, dry matter, starch content, chip yield and significant decreases in protein content and oil absorption rate of chips were observed due to the frequent irrigation at growth stages 1 and 2. No significant effect on chip colour was attributed to irrigation during the early growth stages. Frequent irrigations at the final growth stage were found to have deleterious effects on specific gravity, dry matter, starch content and chip yield especially when irrigation continued until maturity.     

Simple linear relationship between dry matter,specific gravity,and tissue specific gravity in a diploid potato breeding population

Summary Two hundred clones were randomly selected in 1988 and in 1989 from a hybrid population ofSolanum phureja andSolanum stenotomum to determine the relationship between specific gravity (SG) and percent dry matter (%DM), and between tissue specific gravity (TSG) and %DM. The objectives were: (1) to determine the dry matter prediction equation for a diploid potato population, (2) to determine whether estimates of %DM and efficiency of selection for %DM could be improved by measuring TSG, and (3) to determine the influence of year on the estimates. In 1988 the prediction equation for the relationship between %DM and SG was %DM=198.71 (SG-191.30,r=0.85. Ranges and means for the variables were: (1) %DM: 16.99–32.67, mean 25.16; (2) SG: 1.054–1.122, mean 1.089. In 1989 the relationship of %DM and SG was predicted as %DM=194.46(SG)-187.53,r=0.87; whereas the relationship of %DM and TSG was predicted as %DM=196.77(TSG)-192.91,r=0.87. Ranges and means for the variables were: (1) %DM: 10.68–34.57, mean 21.32; (2) SG: 1.030–1.122, mean 1.074; (3) TSG: 1.046–1.141, mean 1.089. Slopes were not significantly different between any of the prediction equations, but intercepts were significantly different. Estimates of %DM were not improved by measuring TSG. Year did influence the relationship between %DM and SG.     

The nature of the relationship of electronic capacitance meter readings to pastures on offer in short swards

The residual standard deviations and distribution of residuals around five models were used to investigate the relationship between recordings from an electronic pasture probe and dry matter harvested from annual pastures (predominantly subterranean clover) at low levels of green feed on offer. Pasture material harvested was that considered to have the greatest influence on the probe i.e., within 5 cm of it.
The following conclusions were drawn. When measuring short dense green pastures yielding up to 3000 kg dry matter ha^-1 the model best describing the relationship is a split line. Curvilinear models are better than a linear model; however, both single linear and curvilinear models give biased estimates particularly near the middle and at the lower end of the range.
The best fitted model is discussed in terms of the structure of the sward and the probe.     

Aspects of nitrogen fertilizer rate on tuber dry-matter content of potato cv. Record

Summary Effects of three rates of fertilizer nitrogen, viz. 80, 160 and 240 kg N/ha, on tuber yield and dry-matter percentage in potato cv. Record were compared in two experiments. Crop nitrogen uptake increased with application rate but total uptake differed between experiments. Tuber yield was highest following application of 160 or 240 kg N/ha but differences between these two rates were not significant. Tuber dry-matter percentage was reduced in one experiment with increasing nitrogen rate, but in the second experiment final dry- matter percentage was highest following application of 240 kg N/ha. In all treatments, positive linear relationships were found between dry matter percentage and mean fresh weight of tubers >30 mm, but within experiments, the regression coefficients were generally reduced by increased crop nitrogen uptake.     

Relations between specific gravity,dry matter content and starch content of potatoes

Summary Published relations between specific gravity, dry matter content and starch content are summarized in the form of regression equations and a diagram. It is suggested that, for the potato literature, uniformity of presentation of results and of conversion equations used would be desirable.     

种植密度与马铃薯块茎大小的分布 Ⅰ.密度与块茎生长的关系

种植密度是影响马铃薯块茎生长发育的主要因素之一。主栽品种 Mira 和783-1各3种密度的试验结果表明,随着单位面积播种密度的增加,单位面积上的主茎数及块茎数目均增加,而块茎的平均重量及大中薯率则减少。单位面积上的光能截获量与植株干重、块茎干重和块茎的平均重量均呈极显著的直线相关。Mira 和783-1的光能转化系数分别为1.444克干重/兆焦和1.106克干重/兆焦。分配到块茎的干物质比率随着块茎的生长而增加,最终两品种的干物质转化率均为85%左右。而密度对各品种的光能转化率及块茎干重分配率均无显著影响。因此,种植密度主要是通过对单位面积上块茎数量的控制来影响块茎所获得的屯合产物的数量及块茎的生长发育。     

施氮量对不同基因型小麦产量和干物质累积的影响

为了解基因型和施氮量对冬小麦产量和干物质累积的影响,以土壤肥力不同的温县大尚、赵堡为试验地点,在0、150、300 kg·hm-2施氮水平下研究了施氮量对15个基因型小麦产量和干物质累积的影响。结果表明,以籽粒产量差异的显著性关系为标准进行聚类分析,可将15个小麦品种分为高产、中产、低产三个类型。在3个施氮水平下,豫麦49198在两地都表现为高产,适应性和稳产性好,但两地没有共同的中产和低产品种类型。不同基因型小麦在整个生育期内干物质累积都呈“慢－快－慢”的动态模式,不同基因型小麦在开花和成熟期干物质累积量差异显著。氮肥对小麦干物质变化率影响最大的时期是开花期,最小的是分蘖期;在3个施氮水平下,各时期干物质增加率在基因型间差异不显著,然而两地都表现为在开花和成熟期干物质增加率最大的是高产基因型,最小的是低产基因型;施氮使高产基因型小麦的花后干物质转移率及花后干物质转移对籽粒产量的贡献率下降。     

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.     

A comparison of tuber shape and tissue composition of potato genotypes

Summary Seven tuber attributes were measured for a number of cultivars and breeding lines: two shape indices for the length and flatness of the potato, one index for the narrowness of the pith, three volume parameters for the relative proportion of cortical, perimedullaryand pith zones of the potato, and specific gravity. The three index traits, specific gravity and volume of the pith zone showed highly significant genotype x year interactions. Significant genotypic and seasonal effects were usually detected for the three volume traits and specific gravity. The percentage volume of the cortical and perimedullary zones showed no genotype x year interactions. Correlations between the traits were estimated, and a factor analysis was performed based on the correlation matrix. One factor appeared to control the negative allometric relationship between the percentage volumes of the cortical and perimedullary zones, and another factor indicated the relationship between the length and flatness indices of the potato. The negative association of the percentage volume with the narrowness index of the pith and positive association between the length of tuber and narrowness of the pith suggested that long potatoes having narrow pith were inclined to have a smaller volume of pith. Factor analysis can be used to identify genotypes with desirable tuber attributes.     

STUDIES IN THE DIGESTIBILITY OF HERBAGE

Data from 291 digestion trials have been used to derive regression equations relating the organic-matter digestibility of herbage to the nitrogen percentage of its dry matter and to the nitrogen percentage in the organic matter of the resulting faces.
The residual errors are very high and it is shown that the deviations from the lines are not randomly distributed but have a seasonal trend. The seasonal biases have been calculated, and the inclusion of month of cutting as a factor is found to improve the two regressions to some extent. Monthly regressions have also been calculated. Even with these, however, the errors are still too high for many practical purposes.