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  • Author or Editor: D. G. Richardson x
  • Journal of the American Society for Horticultural Science x
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Mature `Anjou' pears (Pyrus communis L.) continuously stored at 20 °C or -1 °C before transfer to 20 °C exhibited differences in the sequence of ripening events up to 100 days. Pears continuously held at 20 °C showed little change in ripening characteristics (chlorophyll, firmness, titratable acidity) for 14 to 28 days, then these characteristics decreased at a daily rate of 1.4% thereafter. A 40% increase in soluble polyuronides paralleled the firmness loss, while ACC did not exceed 0.5 nmol·g-1 until the 84th day, and internal ethylene did not exceed 0.2 μL·L-1 until after 90 days, whereas ACC oxidase activity (and total protein) peaked after 63 days. `Anjou' pears stored at -1 °C showed no changes in chlorophyll, firmness, protein, or total polyuronides for at least 84 d. Despite essentially no change in firmness during -1 °C storage, there was a slow but steady increase (≈15 %) in soluble polyuronides. ACC oxidase activity, expressed as ethylene production, rose to 71 nL·g-1·h-1 and the ACC content increased to almost 1.0 nmol·g-1 by the 84th day. Internal ethylene slowly increased and levelled to 1 μL·L-1 by the 56th day. Satisfaction of a chilling requirement thus appears to favor the development of ethylene synthesis capacity, which on transfer from cold storage to higher temperatures results in enough internal ethylene to rapidly drive the associated ripening mechanisms. Fruit for which the chilling requirement (≥70 days at -1 °C) was met softened in response to accelerated internal ethylene production on transfer to 20 °C for 7 days. However, pears that were not chilled or partially chilled did not sustain the increased ACC levels or ACC oxidase activity. Chemical name used: 1-aminocyclopropane-1-carboxylate (ACC).

Free access

Abstract

A technique is described whereby osmotic potential, turgor potential and total fruit water potential can be determined quickly in the field with the aid of a pressure bomb, a hand held refractometer, and a percent soluble solids to osmotic potential conversion chart. A unique inverse linear relationship between percent soluble solids and osmotic potential was found for each fruit species. Application of this technique to rain cracking of ‘Napoleon’ sweet cherries (Prunus avium L.) shows that cracking is not strictly related to percent soluble solids, osmotic, turgor, or fruit water potential. This suggests that the degree of cuticular permeability, cuticular strength, cell wall strength or other factors may be of greater importance in determining cracking susceptibility than water potential parameters.

Open Access

Abstract

Several compounds were used to desiccate tops of onion (Allium cepa L.) prior to harvest. Most chemicals at various rates and timings caused an increase in postharvest disease and sprouting. Endothall at 1.1 kg active ingredient/ha had storage losses comparable to the control. Paraquat substantially elevated storage decay at all rates, but there was less increase from Ethephon and Stoddard Solvent. Disease in storage was not correlated with neck moisture as affected by spray treatments. Phenolic concentration in neck tissue studied for several treatments was weakly and negatively correlated with subsequent disease in storage.

Open Access

Abstract

Fruit quality of ‘Starkspur Golden Delicious’ apples (Malus domestica Borkh.) on 6 rootstocks [Seedling, Mailing (M) 1, M ailing Merton (MM) 106, M 7, OAR 1, M 26] grown in a high density orchard at 2 levels each of K and N was studied at 3 harvest dates and after 6 months of 0°C storage from 1980 to 1982. Fruit on OAR 1 rootstock had greater soluble solids, more yellow color at harvest and after storage and were relatively firmer at harvest, but were smaller than those from other rootstocks. Fruit on M 7 had lower soluble solids than most of the other rootstocks at harvest time. Fruit from MM 106 had a lower incidence of breakdown in storage than most others. Crop load influenced both harvest and storage quality. Fruit on M 26, which had a light crop in 1981, were larger, yellower, and had higher soluble solids, and also had more storage breakdown (about 20%) and bitterpit (about 12%) than other rootstocks. Rootstocks or fertilizers did not affect fruit respiration. Little effect of K fertilizer was found on any quality indices, whereas high N treatments produced greener fruit than did low N.

Open Access

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