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  • Author or Editor: Olusola Lamikanra x
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Abstract

The development of individual anthocyanins (Acy) in black muscadine grapes (Vitis rotundifolia Michx) during maturity was followed. Most of the grapes investigated contained the nonacylated 3,5-diglucoside of delphindinin (Dp), cyanidin (Cy), petundin (Pt), Peonidin (Pn), and malvidin (Mv) when pigment extracts were separated on a reverse phase HPLC C18 column. Dp was the most abundant anthocyanin (Acy) in most cultivars at maturity. The development of individual Acy, which is indicative of the nature of enzyme activity, occurred at different rates for each of the cultivars. A very high flavonoid 3' hydroxylase activity was indicated by the fact that, in most instances, Dp content was higher than those of the other Acy at the onset of pigmentation, including Cy, which is the precursor of the other pigments. The total Acy content at maturity ranged from 12 to 338 mg/100 g of berries.

Open Access

Fluorescence microscopy was used to examine the unilateral intersubgeneric incongruity of muscadine grape (Muscadinia Planch.) × bunch grape (Euvitis Planch.). Pollen grains of bunch grape hydrated and germinated on the stigmas of muscadine grape. Healthy pollen tubes of the bunch grape also penetrated the stigma and entered into the style without obstacles. However, most bunch grape pollen tubes were arrested in the style near the stigma, and few bunch grape pollen tubes were found at the base of the style. Barriers to the intersubgeneric crosses apparently occurred before fertilization; abortion of pollen tubes in the style was the major cause of failure for the cross of V. rotundifolia Michx. × Euvitis.

Free access

Gibberellic acid (GA3), a plant growth regulator used routinely in the production of seedless bunch grapes, was sprayed on the seeded muscadine grape cultivar Triumph. GA3 at 100, 200, and 300 mg·L-1 was sprayed on the leaves and fruit clusters at late bloom; a second spray followed 1 week later. The sprayed vines produced more than 20% seedless berries and the size of the berries with seeds increased significantly. GA3 application in commercial muscadine grape production may have potential benefits.

Free access

Two morphologically distinct types of grapes belonging to the subgenera Euvitis and Muscadinia in the genus Vitis are cultivated in the United States. The former is commonly called bunch grapes while the latter is usually called muscadine. Genetic diversity among these grapes was investigated using RAPD markers. Sixteen grape cultivars, with parentage including V. rotundifolia Michx., V. vinifera L., and several American Vitis species, were used for the RAPD analysis. A total of 156 RAPD markers was produced from 19 random primers, over 90% of which was polymorphic among the muscadine and the bunch grapes. Polymorphisms were lower within each subgenus. Relationships between these two subgenera were estimated based on band-sharing and cluster analysis. The average genetic distance between the bunch and the muscadine grape cultivars was 0.45. The results based on DNA analysis agree with isozyme data obtained from a separate study, which demonstrated that muscadine grapes share very few common alleles with American bunch grapes and European grapes.

Free access

Muscadine grapes (Vitis rotundifolia Michx.), native to the southeastern United States, have a distinct flavor, and grocers are interested in marketing them as table grapes. Two studies using 'Fry' muscadines were conducted to assist the muscadine industry in providing quality table grapes. Study 1 (1998 and 1999) evaluated density sorting and relationships between maturity, color, soluble solids, firmness, shelf life, and sensory evaluation of grapes. Study 2 (1998) determined the effect of storage on quality attributes of different maturities of grapes and evaluated use of polyethylene bags to extend their storage. Density separation successfully sorted grapes by maturity. Muscadine berry color may allow for visual or electronic sorting to eliminate immature fruit. Sensory panelists could distinguish differences in maturities for all sensory attributes. In 1999 maturities 3 and 4 (≈24-33 soluble solids: acid ratio) were preferred overall by panelists. As maturity increased, soluble solids and pH increased, and acidity decreased. Firmness decreased as maturity and storage at 2 °C increased. Percent decay increased with maturity and storage time. Grapes stored in polyethylene bags had reduced decay. A chart developed from the 1999 data related berry color to soluble solids: acid ratio, soluble solids, tartaric acid, and pH. Data from these studies can be used by industry to establish harvest parameters and enhance marketability of 'Fry' muscadine grapes.

Free access