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  • Author or Editor: D. G. Richardson x
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Abstract

Forward stepwise multiple regression equations were developed from seasonal leaf and fruit mineral analyses to predict quality parameters for ‘Starkspur Golden Delicious’ apple (Malus domestica Borkh.) during 1980–82. Quality parameters were evaluated both at harvest and after 6 months of 0°C storage. Soluble solids, skin ground color, and titratable acidity were strongly predictable as early as June or July. However, an August analysis was most predictive. For titratable acidity, a combination of both leaf and fruit minerals produced stronger predictions than leaf or fruit minerals alone in each individual year. Soluble solids, skin ground color, and bitterpit were more accurately predicted by fruit analyses. Fruit size was important in regression equations for firmness, but was not essential for other parameters. Although between-year predictions were not as good as within-year predictions, regression equations could successfully place fruit in high or low categories for most quality parameters.

Open Access

Abstract

A comparative study in 1979 and 1980 between ‘Anjou’, a long-keeping winter pear and ‘Bose’, a shorter keeping winter pear (both Pyrus communis L.) revealed that ethanol-insoluble matter, titratable acids, soluble solids, proteins, and free amino acids in fruit of both cultivars during fruit development, maturation, and storage period fluctuated from season to season and were not associated with their difference in postharvest life. Malic acid was the major fraction of organic acids in both cultivars, and it declined at a faster rate in ‘Bosc’ than in ‘Anjou’ during storage at −1.1°C. The amounts of citric, oxaloacetic, and fumaric acids were higher in ‘Bosc’ than in ‘Anjou’ and were maintained at constant levels throughout the storage period. Internal ethylene in both cultivars early in fruit development was about 0.3 ppm and decreased rapidly to below 0.07 ppm during late fruit development and harvest period. For 2 seasons, ‘Bosc’ was capable of ripening after less than 20 days of chilling at −1.1°C when its internal ethylene increased to 0.2 ppm, while ‘Anjou’ required at least 50 days of chilling to develop the ripening capacity coincident with an internal ethylene above 2.0 ppm. Internal ethylene accumulated in ‘Bosc’ about 8 times faster than in ‘Anjou’ during the first 60 days of storage at −1.1° and reached an equilibrium at 40 ppm for ‘Bosc’ and only 5 ppm for ‘Anjou’ during the remaining storage period. After any corresponding period of cold storage, both ethylene and CO2 productions of ‘Bosc’ at ripening temperature of 20° were higher than those of ‘Anjou’, and ‘Bosc’ also required fewer days to reach the climacteric peaks than did ‘Anjou’.

Open Access

Abstract

Excised Cornus stolonifera Michx. stems cultured axenically in a liquid medium were acclimated to cold when subjected to short photoperiods and low temperatures. Foliate explants acclimated effectively and defoliated ones did not when they were cultured on White's medium which contained 0.083 M sucrose. Several other concentrations of sugars (0, 0.01, 0.1, and 0.5 M glucose and 0, 0.01, 0.05, and 0.1 M sucrose) did not enhance cold acclimation of foliated explants. The exogenously supplied sugars reduced stem growth, promoted leaf abscission, and enhanced the development of typical autumnal red coloration in leaves and stems. The highest sugar concentration (0.5 M glucose) caused death of the explants.

While a minimal level of photosynthate (sugar) is almost certainly required for the active metabolic phases of cold acclimation in hardy woody species, our studies provided no evidence that sugars bear a direct causal relationship to cold acclimation.

Open Access

Kernel oil content increased while moisture content decreased during development. Oil concentration of varieties was between 59.6% and 67%, at harvest and the major lipid class was triglycerides. Oleic acid increased from 10% to become the most abundant fatty acid at harvest (74%). Linoleic increased from about 4% to around 30% early in the season but then decreased although it finally represented a high proportion of total fatty acids (19-22%). Total vitamin E increased as oil content increased. α-tocopherol was the major form of vitamin E and its concentration increased to around 400μg/g oil throughout the season and was almost 90% of total vitamin E. β-tocopherol was only a minor constituent and decreased from the beginning to around 10-20 μg/gm of oil at the end. Γ-tocopherol increased during the first stage of growth and then decreased during the second and third stages.

Free access

Oil content, fatty acid and vitamin E composition of seventeen varieties of hazelnuts, thirteen types of nuts, and seven different oil seeds were determined as part of a larger study on Hazelnut kernel quality. Alpha-tocopherol was the predominant (90%) tocopherol in all hazelnut varieties. In other nuts α- and Γ-tocopherols were predominant Delta-tocopherol was found in some kinds of nuts but it was not found in hazelnuts. All four kinds of tocopherols were found in oil seeds and tocotrienols were found in some. Hazelnuts are a rich source of α-tocopherol. Oil concentration varied among hazelnut cultivars and ranged from a low of 57.9% in Hall's Giant to 67% in Tombul. Macadamias were the highest in oil content (76.9%). Oleic acid and linoleic acid comprised more than 90% of the fatty acid composition in most nuts.

Free access