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Margaret Worthington and John R. Clark

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Molly Felts, Renee T. Threlfall and Margaret L. Worthington

Understanding how human perception is related to physicochemical attributes strengthens identification of ripeness and marketability parameters for peaches and nectarines [Prunus persica (L.) Batsch]. Six peach and nectarine cultivars (Amoore Sweet, Bowden, Effie, Loring, Souvenirs, and White River) and three advanced breeding selections (A-827, A-850, and A-865) were harvested from trees grown at the University of Arkansas System Division of Agriculture Fruit Breeding Program in Clarksville, AR. Physical and chemical characteristics of the genotypes at harvest were as follows: fruit weight of 134.4 to 330.2 g, firmness of 7.8 to 35.8 N, soluble solids of 7.5% to 14.7%, pH of 3.3 to 4.8, titratable acidity of 0.2% to 1.1%, total sugars of 1.7 to 10.4 g/100 g, and total organic acids of 0.1 to 0.9 g/100 g. Overall, A-865 had the lowest fruit weight (134.0 g) and pH (3.3), and the highest firmness (35.8 N), soluble solids (14.7%), titratable acidity (1.1%), total sugars (10.4 g/100 g), and total organic acids (0.8 g/100 g). ‘White River’ had the largest fruit (330.2 g) and pit (11.06 g). A-850 (63.6) had the highest soluble solids/titratable acidity ratio, and ‘Bowden’ (12.7) had the lowest. A trained descriptive sensory panel (n = 10) was used to create a lexicon for Arkansas-grown fresh-market peaches and nectarines. The panel evaluated the fruit for aroma (n = 4), external appearance (n = 8), internal appearance and pit attributes (n = 6), basic tastes (n = 3), aromatics while eating fruit (n = 5), feeling factors (n = 2), and texture (n = 6). Principal component analysis explained 63.4% of the data variance attributed to texture and acidity. Of all of the physicochemical attributes, firmness had the most significant correlations with the descriptive sensory attributes, followed by fruit weight. Firmness was negatively correlated (r = −0.70 to 0.81) to fruit size, fuzziness, amount of bruises on the flesh, pit size, and moisture release, and positively correlated (r = 0.68–0.84) to sourness, green/unripe aromatics, flesh hardness, flesh crispness, and fibrousness between the teeth. Fruit weight was positively correlated (r = 0.67–0.75) to fruit and pit size, overripe aromatics, and moisture release. Significant correlations between descriptive sensory appearance, basic tastes, aromatics, and texture attributes with physicochemical attributes provide an indication of ripeness and marketability parameters for peaches and nectarines. These descriptive attributes are quality factors that impact consumer purchases and perception of fresh-market peaches and nectarines.

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John R. Clark, Margaret Worthington and Taunya Ernst

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Molly Felts, Renee T. Threlfall, John R. Clark and Margaret L. Worthington

Understanding how consumer perception is related to physiochemical attributes assists in the identification of harvest and marketability parameters for muscadine grapes (Vitis rotundifolia Michx.). Three muscadine cultivars (Ison, Nesbitt, and Summit) and three advanced breeding selections (AM-9, AM-74, and AM-83) were harvested from vines at the University of Arkansas System Division of Agriculture Fruit Research Station in Clarksville, AR. The physiochemical (physical and composition) and sensory attributes (descriptive) of the genotypes were evaluated at harvest. Significant differences between genotypes were observed for berry weight (9.25–14.38 g), soluble solids (12.73% to 15.40%), pH (2.88–3.33), titratable acidity (0.54% to 1.01%), soluble solids/titratable acidity ratio (13.12–28.49), skin firmness [0.85–1.48 Newtons/millimeters (N·mm−1)], and flesh firmness (0.89–2.14 N). Total sugars (6.17–9.75 g/100 g) and total organic acid (0.50–0.84 g/100 g) levels were not significantly different for these genotypes. A trained descriptive sensory panel (n = 8) evaluated the fruit attributes for aroma (n = 9), external appearance (n = 7), internal appearance (n = 3), basic tastes (n = 3), aromatics (n = 10), feeling factors (n = 2), and texture (n = 7). The descriptive sensory panel detected differences among genotypes for external appearance, internal appearance, and basic taste attributes, more specifically with desirable attributes rather than unfavorable. However, the panelists found no differences among genotypes for texture attributes. Of the physiochemical attributes, total sugars had the most significant correlations with the descriptive sensory attributes, followed by soluble solids/titratable acidity ratio. Total sugars were correlated to 12 attributes (three aromas, two exterior appearances, two basic tastes, four aromatics, and one feeling factor) and soluble solids/titratable acidity was correlated to five attributes (one aroma, one basic taste, two aromatics, and one feeling factor). A lexicon of terms for descriptive sensory attributes for fresh-market muscadine grapes was established. This lexicon can be used for other research and breeding efforts, as well as establishing the relationship between the physiochemical and descriptive sensory attributes.

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Jason D. Zurn, Katie A. Carter, Melinda H. Yin, Margaret Worthington, John R. Clark, Chad E. Finn and Nahla Bassil

Confirming parentage and clonal identity is an important aspect of breeding and managing germplasm collections of clonally propagated, outcrossing crops, like blackberry (Rubus subgenus Rubus). DNA fingerprinting sets are used to identify off-cross progeny and confirm clonal identity. Previously, a six-simple sequence repeat (6-SSR) fingerprinting set was developed for blackberry using a small number of samples. The usefulness of the 6-SSR fingerprinting set for pedigree confirmation had not been evaluated. Therefore, it was used in this study to validate parentage for 6 and 12 biparental populations from the University of Arkansas (UA) and US Department of Agriculture Agricultural Research Service (USDA-ARS), Horticultural Crops Research Unit (HCRU) breeding programs, respectively. Twenty-seven of the 489 individuals in these breeding populations were identified as off-cross. The 6-SSR fingerprinting set was sufficient for parentage confirmation; however, a total of 61 plants distributed across 28 sets of genotypes could not be distinguished from each other. An 8-SSR fingerprinting set with improved resolution was subsequently developed and used to evaluate 177 Rubus accessions from the USDA-ARS National Clonal Germplasm Repository, UA, and USDA-ARS HCRU programs. The 8-SSR fingerprinting set distinguished all samples expected to have unique genotypes and identified differing DNA fingerprints for two sets of accessions suspected to have identical fingerprints. Cluster analysis grouped the accessions from the eastern and western US breeding programs based on geography and descent. Future work will focus on establishing a database of DNA fingerprints for germplasm identification and for determining pedigree relationships between blackberry accessions.