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  • Author or Editor: David H. Picha x
  • Journal of the American Society for Horticultural Science x
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Abstract

The quantity and pattern of carbohydrate change during curing and storage differed among 6 sweet potato [Ipomoea batatas (L.) Lam] cultivars. ‘Travis’ contained the most total sugar and ‘Whitestar’ the least on a dry weight basis. Sucrose, the major sugar in raw sweet potatoes, sharply increased during curing (10 days at 32°C; 90% RH), and generally continued to increase in 4 orange-flesh cultivars during 46 weeks of 15.6° storage. Sucrose concentration decreased in 2 white-flesh cultivars after curing, followed by an increase after 14 weeks of storage. Glucose concentration was slightly higher than fructose in all cultivars except ‘Centennial’, which had similar monosaccharide concentrations. The pattern of monosaccharide change during curing and storage varied with cultivar, but generally increased during curing and the first 4 weeks of storage, followed by stabilization or a slight increase. Alcohol-insoluble solids (AIS) decreased with increasing lengths of storage in the 4 orange-flesh cultivars, which was attributed to continuous starch degradation. AIS increased during the first 4 or 14 weeks of storage in the 2 white-flesh cultivars, followed by a decrease during longer periods of storage.

Open Access
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Abstract

Yellow shoulder (YS) expression was associated with differences in composition, respiration rate, and ethylene evolution between the yellow and normal red tissue in tomato (Lycopersicon esculentum Mill.) fruit. The YS tissue was higher in pH, dry matter, alcohol-insoluble solids (AIS), calcium content, respiration rate, and ethylene evolution than the red blossom-end tissue. The YS tissue had less phosphorus, potassium, citric acid, and a lower titratable acidity than the red tissue. Expression of YS was not associated with imbalances in fructose, glucose, malic acid, nitrogen, or magnesium concentration. Substantial YS development occurred in fruit of nonuniform ripening gene cultivars allowed to vine-ripen. Yellow shoulder was alleviated by harvesting fruit in the mature-green stage and room-ripening.

Open Access
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Abstract

External chilling injury symptoms, primarily surface pitting followed by secondary fungal decay, developed in six sweet potato [Ipomoea batatas (L.) Lam] cultivars after an exposure to 7°C for 2 weeks or more followed by storage at 15.6°. Internal chilling injury symptoms, primarily darkening of the cambium and vascular bundles, were observed in noncured ‘Whitestar’ and ‘Rojo Blanco’ roots after exposure to 7° for 3 weeks and in ‘Centennial’ after exposure to 7° for 4 weeks followed by storage at 15.6°. ‘Jewel’ was the cultivar most tolerant to low temperature. Chilling injury and respiration rate were greater with increasing lengths of exposure to 7° and were greater in noncured than cured roots. Enhanced sucrose and total soluble sugar content occurred at 7° compared to 15.6°. The primary sugar responsible for low-temperature sweetening was sucrose, but there was considerable variation among cultivars in the extent of low-temperature sweetening and specific sugar changes.

Open Access
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Abstract

In the article “Weight Loss in Sweet Potatoes During Curing and Storage: Contribution of Transpiration and Respiration”, by David H. Picha (J. Amer. Soc. Hort. Sci. 111:889–892, November 1986), Figs. 1 and 2 were reversed. The correct figures and captions are printed below.

Open Access
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Abstract

Fruit of 2 cherry tomato (Lycopersicon esculentum var. cerasiforme Alef.) cultivars [‘Large Red Cherry’ (‘LRC’) and ‘Small Fry’ (‘SF’)] and 2 large-fruited tomato (Lycopersicon esculentum Mill.) cultivars (‘Duke’ and ‘Sunny’) were harvested green, ripened at 23°C, and analyzed for sugars and organic acids 6 days after breaker stage. Both fructose and glucose concentration decreased in ‘LRC’ and ‘SF’ fruit with less-mature harvested fruit. Maturity at harvest had no effect on the concentration of either sugar in ‘Duke’ or ‘Sunny’ fruit. ‘LRC’ had the highest fructose and glucose concentration among cultivars. Increased citric acid concentration was found with less-mature harvested fruit, except in ‘LRC’. Malic acid concentration within cultivars was similar in the fruit harvested more mature, but decreased with less-mature fruit in ‘Duke’ and ‘Sunny’. ‘LRC’ and ‘SF’ fruit had more citric and malic acid than ‘Duke’ or ‘Sunny’. Cherry tomato cultivars had a higher percentage of locular tissue than the large-fruited cultivars.

Open Access
Author:

Abstract

Cured sweet potatoes [Ipomoea batatas (L.) Lam] were stored successfully at 15.6°C and 90% RH for up to a year without sprouting. Contribution of respiration and transpiration to total weight loss was determined during curing and storage in 6 cultivars. Respiration rate was highest the day of harvest, decreased during curing, and continued to decrease at a slower rate during the first several months of storage, whereafter it remained constant (except for slight increases during the last several months in 2 cultivars). Respiration contributed more to total weight loss during the latter periods of storage than during curing or the first months in storage. Transpiration, however, was the major source of weight loss. The highest rate of weight loss occurred during curing, followed by a gradual rate of loss during storage. Total weight loss of cured roots after 50 weeks of storage ranged from 6.7% (‘Rojo Blanco’) to 16.1% (‘Travis’).

Open Access

The quantity and pattern of carbohydrate-related changes during storage root development differed among six sweetpotato cultivars [Ipomoea batatas (L.) Poir. `Beauregard', `Heart-o-Gold', `Jewel', `Rojo Blanco', `Travis', and `White Star']. Measurements were taken for individual sugars, total sugars, alcohol-insoluble solids (AIS, crude starch), and dry weight (DW) at 2-week intervals from 7 to 19 weeks after transplanting (WAT) in two separate years. Sucrose was the major sugar during all stages of development, representing at least 68% of total sugars across all cultivars and dates. Pairwise comparisons showed `Heart-o-Gold' had the highest sucrose content among the cultivars. Sucrose content increased by 56% for `Heart-o-Gold' over the 12 weeks of assay, ranking first among the cultivars at 17 and 19 WAT and possessing 27% more sucrose than the next highest ranking cultivar, `Jewel', at 19 WAT. Fructose content profiles varied among and within cultivars. `Beauregard' showed a consistent increase in fructose throughout development while `Whitestar' showed a consistent decrease. The other cultivars were inconsistent in their fructose content profiles. Glucose content profiles were similar to those for fructose changes during development. The relationship between monosaccharides was fructose = 0.7207 × glucose + 0.0241. Cultivars with the highest fructose and glucose content could be selected by breeders after 13 WAT. Early clonal selection for high sucrose and total sugars is less promising because substantive changes in clonal rank occurred for sucrose and total sugars after 15 WAT. Cultivars ranking the highest in total sugars had either more monosaccharides to compensate for a lower sucrose content or more sucrose to compensate for a lower monosaccharide content. The relationship between DW and AIS was similar (AIS = 0.00089 × DW), and DW and AIS increased with time for most cultivars. Cultivars with high DW and AIS can be selected early during storage root development.

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