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  • Author or Editor: L. J. Kushman x
  • Journal of the American Society for Horticultural Science x
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Abstract

Individual fruit pH, total acidity (AC as %), soluble solids (SS as %), and SS/AC ratios correlated significantly with anthocyanin contents of ‘Wolcott’, ‘Morrow’, ‘Jersey’, and ‘Tifblue’ blueberries as measured by light transmission (ΔOD740-800 nm). Fruit orientation with respect to the light path influenced readings. The relationships of the light transmission values to the quality indices differed among cultivars.

Open Access

Abstract

‘Wolcott’ blueberries were harvested at 8 stages of development (small, deep green to overripe) on 3 dates in 1963 and on 4 dates in 1964 from 2 plantings in eastern North Carolina. As the fruit developed, per cent acid decreased while pH, per cent soluble solids, sugar (per cent of fresh weight and mg/berry), soluble solids/acid ratio (SS/A), anthocyanin content and berry weight increased. Acid content (mg/berry) increased during early stages but decreased rapidly during later stages of development. Anthocyanin content (mg/cm2 of berry surface) was significantly correlated with sugar/acid ratio and SS/A ratio. An increase in incidence of decay of 10 punctured or bisected fruit samples after 9 to 11 days at 70°F, or 21 days at 32° plus 6 days at 70°, was associated with an increase in ripeness. In culture solutions with acid and sugar levels paralleling those of fruit of various degrees of ripeness, growth of both Alternaria and Botrytis spp. decreased as the level of acid in culture solution increased. Thus, the acid composition of blueberry fruit appears to afford a mechanism of resistance to decay-producing organisms. This indicates a potential for selecting varieties with high-keeping quality through selection of clones high in acid. The increase in anthocyanin (Acy) content as berries develop indicates a potential means of sorting blueberries electronically, according to their Acy content.

Open Access

Abstract

One hundred 2-year old ‘Wolcott’ blueberry plants were grown in sand culture with 5 levels each of N, P, K, Ca, and Mg and fruited in 1962 and 1963 in the greenhouse. The content of each of the 5 nutrient-elements in the leaves varied widely. Level of N affected the number of leaves and fruit per plant (+, −), fruit size (−), acidity (−), and ripening date (+), and the fruit-to-leaf ratio (F/L) of the bush (+). Foliar levels of P greater than 0.40% were associated with foliar interveinal chlorosis and abscission; low levels of P were associated with few leaves, a high F/L, and low berry weight. Leaves containing between 0.28 and 0.36% K showed foliar deficiency symptoms of K. High K was associated with high fruit acidity. No effects of nutrition upon the keeping quality of fruit were noted. High F/L had a greater effect than treatments upon fruit and was related to late ripening, low soluble-solids, and small size of the berries. With bushes having a high F/L, fruit weight and soluble solids decreased as the harvest season progressed until the ratio was between 1 and 2; thereafter, soluble solids content increased. Content of soluble solids varied inversely with per cent of crop ripening at a given time until a F/L between 1 to 2 was reached.

Open Access
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Abstract

Intercellular space measurements of ‘Nugget’ and ‘Centennial’ sweetpotatoes were significantly different due to variety, evacuation and holding periods, and the interaction of curing with evacuation and holding periods but not different because of curing alone, root length, dry-matter content, or uncorrected specific gravity. To determine intercellular space accurately, evacuation time should be no less than 10 min and holding in water after evacuation no less than 15 min.

Open Access

Abstract

‘Nugget’, ‘Gem’, ‘Goldrush’ and ‘Centennial’ sweet potato cultivars were grown for 3 yr at 3 locations in North Carolina. Root samples were collected at peak harvest (about October 1) each year and examined for intercellular space (IS). At 1 location each year a collection was made 3 wk prior to peak harvest, at peak harvest, and 3 wk after peak harvest. Cultivars differed significantly from one another in IS at harvest and averaged 6.26, 7.32, 8.41 and 9.85 ml/100 ml of root for ‘Nugget’, ‘Gem’, ‘Goldrush’ and ‘Centennial’, respectively. Over the 3-yr period IS did not differ significantly due to location, time of harvest, or years.

Open Access

Abstract

On 15 occasions, either Wolcott, Jersey, Morrow or Murphy cultivars of highbush blueberry (Vaccinium corymbosum L.) were harvested by commercial hand-pickers and over-the-row mechanical harvesters in eastern NC during 1970 and 1971. Compared with hand-harvesting, machine-harvesting reduced yield of marketable ripe fruit 19 to 44%. Compared with commercially hand-harvested fruit, machine-harvested fruit was 10 to 30% softer in compression tests; and when held for 7 days at 21°C, the fruit developed 11 to 41% more decay. Machine-harvested fruits sorted on a commercial cleaner were softened still more and developed 5 to 10% more decay than fruit mechanically harvested but not sorted.

Fifty times as many canes were damaged by mechanical harvesting as by hand-harvesting.

Open Access

Abstract

The 3-monoarabinosides and 3-monogalactosides of delphinidin (Dp), petunidin (Pt), malvidin (Mv), and peonidin (Pn) as well as small amounts of the 3-monoglucosides of Dp, Pt, Mv, Pn, and cyanidin (Cy) were isolated from ripe blueberry fruit, variety ‘Croatan’. Small amounts of the 3-monogalactoside of Cy were present also. None of these 14 anthocyanins (Acy) were acylated. The major Acy were (in descending order): Mv-3-galactose, Dp-3-galactose, Dp-3-arabinose, Pt-3-galactose, Pt-3-arabinose and Mv-3-arabinose.

Open Access

Abstract

A method is described and test results reported for sorting blueberries with low-frequency vibration. Separation was dependent on fruit firmness which is affected by roughness of handling and other softening factors.

Firmness, as measured by compressing blueberries 0.2 cm between flat plates, statistically explained 58 to 72% of the variation in frequency for removal of berries from a vibrating trough with constant energy input. When comparing ripeness with frequency for sorting, light transmittance (∆OD; 740-800 nm) values, which indicate anthocyanin pigment concentration, explained only 10% of the variation in sorting frequency.

Berries of several cultivars and harvest dates were vibration sorted and tested for susceptibility to decay. Sorting frequency statistically explained 75% of the variation in decay level. Thus, the vibration method should be suitable for sorting blueberries into groups of different shelf life.

Open Access

Abstract

An Instron Universal Testing Machine was modified to measure firmness of blueberry fruit. Each blueberry was compressed between 2 flat surfaces for 1/4 its diameter at 1 cm/minute. Compression curves were linear. Small, green, unripe blueberries were extremely firm, softened appreciably as they ripened from the green to red stages but softened relatively little thereafter. Smaller blueberries tended to be slightly more firm than larger ones. Firmness varied from one harvest to another within a year and from one year to another. The firmness of fruit of some cultivars was almost double that of others. Firmness as measured by the Instron compared well (r = 0.70* and 0.81 *) with field (“chewing” or mastication) scores made by the breeder as part of his regular program. Blueberries dropped upon hard boards softened (bruised) in proportion to the distance of fall. Small increments (10.2 cm or 4-inch) of fall softened blueberries as much as large increments (40.6 cm or 16-inch) as long as the total distance (sum of increments) of fall was constant. Regardless of cultivar, size, ripeness, or initial firmness, the firmness of blueberries after a standard fall (8 drops of 40.6 cm or 16 inches each) can be predicted if their initial firmness (X) is known (Y = −0.590 + 0.627X). Bruised blueberries decayed more than those not bruised. Firmness of blueberries decreased when they were warmed and increased when they were cooled; this effect was a reversible, physical phenomenon.

Open Access

Abstract

Fruit of 104 clones and 75 seedlings of highbush blueberries were assayed for acidity, soluble solids, and keeping quality. From this group, 9 clones were selected to represent 4 extreme soluble solids and acid classes. These 9 clones were harvested over 2 years at 2 North Carolina locations. The previously reported relationships between high fruit acidity (Ac) or low soluble solids-to-acid ratio (SS/Ac) and high keeping quality (low DK) were extended from a few cultivars to a population of representative blueberry genotypes. Approximately 80% of the decay variability can be accounted for by various soluble solids and acid measures indicating that a soluble solids and acid measure would be useful to the breeder for segregating clones into those of poor, intermediate and good keeping quality. Suggested clonal discriminatory Ac, SS/Ac and pH x SS levels were proposed, and the possibility of field screening of blueberry clones for keeping quality potential was examined.

Open Access