The relationship of cell size,intercellular space,and specific gravity to Bruise depth in potatoes

Cell size, specific gravity and intercellular space (IS) of 11 potato varieties were measured and compared with depth of bruising to determine if these factors are related to bruising. Rate of application of supplemental fertilizer did not change IS or tissue specific gravity. Variations in fertility level, moisture content of soil and temperatures during the periods of tuber growth and maturation caused only small differences in tissue specific gravity and IS. Depth of bruising, cell size, and IS differed among varieties. Analysis showed bruise susceptibility of tubers of different varieties was highest for tubers having low specific gravity, large cell size and high IS.     

Relationship of clonal mean to the uniformity and stability of tuber specific gravity in potatoes

Regression analysis of plot mean and plot standard deviation for specific gravity of tubers from 190 unreplicated 12-hill breeding plots, was used to study the relationship of mean and within-plot uniformity. Using two data sets from the Western Regional Potato Variety Trial, regression analysis of clone mean for specific gravity within a location on overall location mean was used to study the relationship of mean and inter-location stability. A highly significant (p>0.01) but very weak (r²=0.04) positive coefficient of determination existed between plot means and plot standard deviations. No relationship was found for mean specific gravity of clones and their stability across different environments. The results suggest that selection of high specific gravity combined with uniformity and/or stability is a feasible goal for breeding programs.     

Stability of high specific gravity genotypes of potatoes under high temperatures

An initial population of PHU-STN hybrid diploid potatoes was screened in 1978 at the Mountain Horticultural Crops Research Station, Fletcher, N.C. for high specific gravity and tuber production. Sixty clones were selected for testing under high temperatures at two North Carolina coastal locations. Twenty-seven clones maintained a relatively high specific gravity and acceptable tuber production under these high temperatures. The other 33 either were low in specific gravity or produced few, if any, tubers. Specific gravity was lower at the two coastal locations than at the Mountain Horticultural Crops Research Station. The 27 relatively stable, high specific gravity clones were retested in 1980 along with seven additional clones included for the first time. Severe high temperatures resulted in low survival rates and low specific gravity. However, eight clones maintained a relatively high specific gravity in relation to the rest of the population.     

Relationship of specific gravity to sugar accumulation in stored Norgold and Russet Burbank potatoes

Studies were made on the influence of growing season and low fertility on reducing sugar accumulation in storage of the stem and bud portions of Russet Burbank and Norgold Russet potatoes separated into different specific gravity groups. The stem portion of Russet Burbank had a significantly different intercept and slope of regression line (between specific gravity and reducing sugar accumulation) than the bud portions of the same tubers indicating higher reducing sugar accumulation in the stem portion as well as differences in behavior as to amount accumulated at the different specific gravity levels. No significant difference in sugar content or behavior at the different specific gravity levels was obtained between stem and bud portions of Norgold Russet. Growing season did not cause significant differences in total sugar content or slope of the regression lines within the stem or bud portions of Russet Burbank. Low fertility level resulted in significantly higher sugar accumulation in the stem portion of Russet Burbank as compared to adequate fertility and there was also a trend toward less influence of specific gravity on sugar accumulation at the lower fertility level. Low specific gravity Russet Burbank potatoes tended to be more variable in sugar accumulation from year to year and also had wider differences in sugar accumulation between stem and bud portions than high specific gravity potatoes.     

Nitrogen and potassium fertilization of potatoes: Yield and specific gravity

Potassium and N fertilization is often required for maximum potato (Solanum tuberosum L.) production. Nitrogen, K, and K-sources (KCl, K₂SO₄ are known to affect yield and quality of potatoes but N and K interactions as affected by K-source have not been defined. This study evaluated the N*K and K-source interactions on Russet Burbank tuber yields and specific gravity (SG) in two irrigated field experiments. Nitrogen rates of 0, 112, 224 or 336 kg ha^-1 were combined with selected K rates of 0,112, 224 or 448 kg ha^-1 as either KC1 or K₂SO₄ in an incomplete factorial. A multiple linear regression model was fit to the data and used to predict yield and SG for a complete factorial for each K-source. Both N and K applications increased yields independent of K-source. Nitrogen decreased yields at the 336 kg ha^-1 rate. Potassium increased yields up to 448 kg K ha^-1. Both K-sources decreased SG a similar amount with N application; without N, KC1 decreased SG but K₂SO₄ did not. Nitrogen also decreased SG. Petiole NO₃-N and K concentrations were positively related to yields and negatively to specific gravities. The petiole K concentration 100 days after planting should be above 4.5 for highest tuber yields. The N*K*K-source interaction was important for yields at low available N and for SG at adequate N availabilities. This study showed that N or K fertilizers can be applied according to their respective soil test concentration and the crop’s requirement, generally without consideration of K-source.     

The influence of fertilizers on the specific gravity of potatoes grown in Minnesota

American Journal of Potato Research - Specific gravity measurments were obtained for samples of potatoes from 37 fertilizer experiments in the Red River Valley of Minnesota and on sandy soils near...