A simple device for the determination of potato tuber specific gravity

A simple device consisting of a plastic rack with suspended wire basket was developed. This device when used in conjunction with a top loading balance greatly facilitates the determination of the specific gravity of individual tubers.     

French fry quality related to specific gravity and solids content variation among potato strips within the same tuber

The solids content of adjacent potato strips cut from known locations within the tuber was found to differ significantly. These strips were identified and processed according to commercial practice. The finish fries were subjectively scored for quality. Yield and oil uptake were calculated. The solids content of individual strips from a 20 tuber sample out of a single 100 lb. bag ranged from 12% to 29%. The whole tubers ranged from 18% to 23% solids. Strips below 17% solids were shriveled, limp and soggy after processing while strips above 22% solids were rigid and crisp with a mealy interior. Oil uptake was not related to solids content. However, yield of par-fries and to a lesser extent of finish-fries increased as solids content increased.     

Alturas: A multi-purpose, Russet potato cultivar with high yield and tuber specific gravity

‘Alturas’, a late-maturing, high-yielding, russet potato cultivar with high tuber specific gravity, was released in 2002 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington. Originally selected for dehydration processing, its cold-sweetening resistance also makes it suitable for processing out of storage into french fries and other frozen potato products. Culinary quality is high, with larger tubers suitable for fresh market if heavily russeted skin is not essential. Alturas consistently produced greater total and U.S. No. 1 yields than ‘Russet Burbank’ and ‘Ranger Russet’ in southern Idaho trials. Across other western trial sites, total yields of Alturas have on average been 29% and 14% greater than Russet Burbank and Ranger Russet, respectively. Alturas is resistant to Verticillium wilt (Verticillium dahliae) and early blight (Alternaria solani). Compared with Russet Burbank and Ranger Russet, Alturas is less susceptible to corky ringspot and foliar and tuber infection by late blight (Phytophthora infestans). It also is less susceptible to tuber net necrosis and Fusarium dry rot than Russet Burbank, and is more resistant to common scab (Streptomyces scabies) than Ranger Russet. However, Alturas is more susceptible to infection by PVY and PVX than Ranger Russet. Total nitrogen application recommendations for Alturas are approximately 40% less than those for Russet Burbank. Alturas requires 15% to 20% more water during the growing season than does Russet Bur-bank.     

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.     

Selection for chip quality and specific gravity of potato clones: possibilities for early generation selection

Summary Ten cultivars contrasting in chip quality were grown in the field and in the glasshouse to evaluate three different methods for chip quality assessment. Specific gravity was also measured. The glasshouse culture simulated growth of seedlings and the field culture represented growth of advanced breeding lines. Differences between cultivars for chip quality and specific gravity could be established in both environments. Although ranking of the cultivars in both environments was not identical, both good and bad genotypes could be identified. It seems that mild selection for specific gravity and chip quality among glasshouse-grown seedlings can be exercised. If tubers of glasshouse-grown plants are too small to slice chips, Reflocheck Glucose test strips offer a satisfactory alternative to frying chips. Crip in UK     

Variation in specific gravity of potato tubers

Specific gravity of tubers from the Irish Cobbler, Kennebec, Norgold Russet, Norland, Red Pontiac, Russet Burbank, Snowflake, and Viking varieties grown at 2 locations over 3 years were determined by the brine solution method. The usual differences in specific gravity were noted between varieties and locations. There was a narrow range in specific gravity of individual tubers within lots of Norland and Russet Burbank, and a wide range within lots of Kennebec and Snowflake, with the remaining varieties intermediate. Low variation of tubers within a variety as measured by standard deviation did not indicate low or high specific gravity. Varieties with low variation tended to remain low from one year to the next.     

Raritan,a potato with high specific gravity

Raritan (F5459) is a new netted potato variety named and released by Rutgers University. It is the progeny of a cross made within the Potato Breeding Program of the Canada Department of Agriculture, and later released to Rutgers University for development and introduction. Raritan is unique in its ability to produce tubers of high specific gravity under the relatively high temperatures prevailing in New Jersey. Its baking, mashing, and french frying qualities have been good in most trials.     

Uniformity among virus-free clones of ten potato cultivars

Heat therapy and meristem tip propagation were used to develop two or three virus-free clones of 10 cultivars from the following sources: Epicure from British Columbia and Scotland; Katahdin, Kennebec, Keswick, Red Pontiac and Sebago from British Columbia and New Brunswick; Norchip from Alberta, Quebec and Washington; Norland from Alberta, British Columbia and North Dakota; Red La Soda from British Columbia, Nebraska and North Dakota; and White Rose from British Columbia and North Dakota. Tests prior to treatment showed that all but one of the stocks were infected with potato virus X and/or potato virus S but in only five of the ten cultivars were all clones infected with the same virus or viruses. Field trials with the virus-free clones, which extended over four years, showed that one of the Norchip clones produced fewer tubers per plant than two other clones in three years of the four years, but no consistent differences in yield or specific gravity of tubers were found among the clones of any of the 10 cultivars.     

Glycoalkaloid accumulation during tuber development of early potato cultivars

Summary Plants of early potato cultivars were sampled at successive harvests during tuber development and individual tubers were analysed for α-solanine and α-chaconine using high-performance liquid chromatography. Mean tuber total glycoalkaloid concentration (α-solanine plus α-chaconine) per plant decreased with time and statistically significant differences between cultivars were observed in the patterns of decline during tuber growth. The mean tuber ratio of α-chaconine to α-solanine increased during tuber development and was also affected by genotype. Total glycoalkaloid concentration for individual tubers of marketable sizes (up to 50 g fresh weight) exceeded the safety limit of 20 mg per 100 g fresh weight for cultivars Home Guard and British Queen but not for Rocket. These differences were attributable to differences in both rates and patterns of glycoalkaloid accumulation during tuber development, although in all cultivars results were consistent with glycoalkaloid accumulation occurring in the expanding peripheral cell layers of tubers for a considerable period after tuber initiation.     

Evaluation of potato clones for resistance to tuber and stem rot induced byErwinia chrysanthemi

Tubers of 149 clones ofSolarium tuberosum subsp.andigena (andigena) from four self-pollinated (S₁) families (Jak 072, 702440, 700718 and Och 5331) obtained from true seed were rated for resistance toErwinia chrysanthemi. The clones were classified into four arbitrary categories based on disease reaction: resistant, intermediate, susceptible, and very susceptible. In family Jak 072, 23% of the clones were resistant and 61% intermediate. In family Och 5331, 22% of the clones were susceptible and 67% very susceptible; and in families 702440 and 700718, 38% and 29% of the clones were intermediate and 45% and 40% were susceptible, respectively. Tubers of 11 clones chosen to represent each one of the four categories were inoculated withE. chrysanthemi (Ech), E. carotovora subsp.carotovora (Ecc) andE. carotovora subsp.atroseptica (Eca). Clones responded similarly toEch andEca. However,Ecc induced significantly more rot thanEch orEca, presumably favored by the temperature of incubation (25°C). Clones Jak 072-17 and Jak 072-18 were resistant to the three bacterial pathogens. Above ground stems of 6 of the 11 selected clones inoculated withEch were susceptible to stem rot. No correlation was found between the response of tubers and above ground stems to tuber and stem rot induced byEch.     

Differences in tuber rot development for North American clones ofPhytophthora infestans

The relative aggressiveness ofPhytophthora infestons clones in potato tubers was compared in three trials using 7 to 24 isolates of 2 to 4 clones. Visible rot developed slowly at 13C with isolates of the US-1 genotype, the only significant clone found in North America prior to 1979, but substantially faster with most isolates of the newer clonal genotypes US-6, US-7 and US-8. Certain US-7 isolates were similar to US-1, and US-6 isolates also had a broad range of aggressiveness. Secondary infection byFusarium sp. increased rot development in many instances, but this effect was not clone-related. Differences in rot development may affect potato storage or late blight disease transmission.     

Dry matter accumulation in potato clones under seasonal high temperature conditions in Pakistan

The effects of seasonal high temperatures on potatoes were investigated under field conditions near Peshawar, Pakistan. Five potato clones (A79196-1, Desiree, DTO-28, LT-1, Russet Burbank) were grown during the spring season at two locations. Canopy development, vine dry weight and tuber dry weight were determined at 13-day intervals, starting 68 days after planting (DAP). Tuber yield was higher in heat tolerant clones compared to heat susceptible clones. Location significantly affected tuber dry weights. Tuber dry weights of Russet Burbank were consistently lower than those of DTO-28. Ground canopy cover of DTO-28 occurred earlier and reached maximum at 75 DAP, compared to 90 DAP for Desiree. DTO-28, because of its high tuber yield under cool as well as hot temperatures, and its relatively early bulking, should be a promising clone for a short duration crop in hotter regions.     

The relationship between bruising and specific gravity in some potato varieties

Summary Tubers of known specific, gravity (SG) of seven potato varieties were subjected to a mechanical force and the volume of bruised tissue which developed was measured. The mean SG of tubers which bruised was higher than of those which did not. No significant varietal differences in bruise volume were found; the genetic component influenced only the proportion of tubers which bruised. Correlations between SG and bruise volume were generally not significant.     

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.     

Influence of potato specific gravity on yield and oil content of chips

Tubers from bulk samples of Norchip potatoes were separated into specific gravity groups by weighing each tuber in air and then in water. Forty-nine chipping samples were assembled according to specific gravity from the segregated tubers (1.060 to 1.110 specific gravity). Chip yield increased and chip oil content decreased linearly through a specific gravity of 1.110. The contribution of specific gravity to chip yield was demonstrated by expressing chip yeild on a zero percent oil basis. For all lots of Norchips tested, the specific gravity distribution was similar, and all standard deviations (s) were the same (0.0064). Using s, a table of tolerances was compiled for estimation of the appropriate sample size for routine specific gravity determinations.