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  • Author or Editor: K.B. McRae x
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Root hardiness for the apple (Malus domestica Borkh.) rootstocks M.26, MM.106, MM.111, M.7A, and M.7EMLA at - 8 and - 11C and trunk survival for the tender cultivar Gravenstein and the hardy cultivar Wealthy at -25 and -35C were evaluated both destructively (tissue examination) and nondestructively (regrowth measurement the following season). No differences in root survival were detected at -8C by either method; at - 11C, MM.111 rated better than the others, while regrowth was higher on M.26, MM.111, and M.7A than on MM.106 or M.7EMLA. Root survival did not differ for the scions at either temperature, but regrowth was greater for `Gravenstein' than Wealthy' at both temperatures. Trunk tissue survival at -25C was consistently lowest for scions on M.7EMLA, and regrowth was less than on M.26 and MM.111. At -35C there were no significant rootstock effects. For the scions, lateral wood tissue survival at -25C was highest for Wealthy', but the weight of the new growth did not differ. At -35C bark tissue survival and regrowth was greater for Wealthy' than for `Gravenstein'. Evidence is presented in support of the occurrence of reciprocal effects. Correlation between the two methods was highest for root exposure at - 11C and for the assessment of trunk bark.

Free access

Abstract

Chrysanthemum X morifolium Ramat. cvs. Yellow Paragon and Copper Ann, when grown as pot plants, produced more flowering stem breaks and greater flower weight in crops planted in January and February (spring) than in those grown under similar greenhouse conditions in October and November (fall). Spring crops also showed longer vegetative dry weight, shorter stem breaks, and earlier flower development. Supplemental high-pressure sodium (HPS) irradiation resulted in a larger increase in flower weight and number of flowering breaks in the fall than in the spring. Flower development was hastened by HPS irradiation only in the fall. Split-night temperatures did not delay flowering and resulted in a relatively small reduction in flower weight and number of flowering breaks in the spring. Unacceptable delays and degradation of flower quality occurred with this treatment in the fall and HPS was only partly successful in restoring acceptable quality and time to harvest.

Open Access

Abstract

The mortality of European red mite [Panonychus ulmi (Koch)] eggs on fruit of ‘McIntosh’ apple (Malus domestica Borkh.) in storage increased with continuing exposure to low O2 (1.5% CO2 + 1.0% O2) or conventional controlled atmospheres (5.0% CO2 + 3.0% O2) and with elevated storage temperatures to 7.5°C. Lethality was sufficient to provide commercial control for overwintering populations. Susceptibility of red mite eggs differed among years and orchards within years.

Open Access

Abstract

Reduced O2 storage (3.0 or 1.0%) significantly increased mortality of overwintering apple rust mite (Aculus schlechtendali (Nal.)) and European red mite (Panonychus ulmi (Koch)) egg populations on ‘Mcintosh’ apples (Malus domestica Borkh.). High levels of mortality can be achieved during the usual commercial storage period for apples in 1.0% O2 atmospheres. Addition of CO2 decreased red mite survival at 3% O2 storage.

Open Access

The apple industry worldwide would benefit from an improved and standardized description of fresh-apple textural quality. The description proposed here is unique in that it integrates structural, sensory, and consumer information. To demonstrate its benefits, 24 apple cultivars [Malus ×sylvestris (L.) Mill. var. domestica (Borkh..) Mansf.] were sampled over two harvest seasons and analyzed using microstructural and sensory techniques. Cultivars were selected to cover a range of known sensory textures, and microstructural profiles were compiled in parallel with sensory and instrumental studies. Each cultivar was pre pared for conventional scanning electron microscopy (SEM) observation using standard methods. Representative fruit from each cultivar were photographed at three magnifications to visualize fruit architecture, tissue relationships, and size, shape, and arrangement of cells within layers to compile the microstructural profile. A trained sensory panel evaluated the cultivars for crispness, surface coarseness, sponginess, hardness, juiciness, degree of melting, mealiness, and skin toughness while a consumer panel rated liking. This information was compiled into a texture profile. The microstructural and texture profiles were then combined into a cultivar profile for each sample. Cultivar profiles were collected to form a database; subtle similarities and differences among the 28 market-quality samples were interpreted and noted. With this technique, those structures with similar sensory properties can be identified with some form of microscopy. Clarifying and predicting the parameters that are related to textural quality in new cultivars will streamline the introduction process.

Free access

Abstract

The addition of 1.0% (wt/vol) ammonium peroxydisulfate to 0.125%, 0.25%, and 0.50% (wt/vol) ethephon sprays, applied before harvest to rutabaga (Brassica napus, Group Napobrassica Mill. cv. Laurentian) nearing commercial size, defoliated a greater percentage of leaves than would be anticipated from the effects of the individual components. Defoliation expressed on the logit scale was a linear function of the square root of the ethephon concentration, if ethephon was applied with or without ammonium peroxydisulfate. Chemical name used: (2-chloroethyl) phosphonic acid (ethephon).

Open Access

Abstract

An ethyl acetate extract of ground apples (Malus domestica Borkh.) was concentrated and purified for a specific (β-galactosidase inhibitory function. Vacuum infusion of either H2O or the extract restricted initial C2H4 evolution from apples but had no effect on fruit soluble solids and titratable acid levels in apples held at 20°C. Infusion of the extract did not affect the mean CO2 evolution from ‘McIntosh’ apples over a 5-day period but reduced the rate of CO2 evolution over time. Vacuum infusion of the extract containing the (β-galactosidase inhibitor resulted in retention of fruit firmness in ‘McIntosh’ and ‘Gravenstein’ apples held at 20°.

Open Access

Abstract

Storage of ‘McIntosh’ apples (Malus domestica Borkh.) in low O2 atmospheres (1.5% CO2 + 1.0% O2) maintained fruit firmness by an average of 0.86 kg over 40 grower lots, compared with the same fruit stored in conventional controlled atmospheres (5% CO2 + 2.8% O2). Low O2 storage resulted in fruit which were higher in titratable acids and were significantly crisper, more acid, and juicier to sensory panelists. Fruit maturity at harvest was a significant factor in determining the losses of firmness and titratable acids in low O2 storage.

Open Access

Abstract

The initial storage of ‘McIntosh’ apples in a low-oxygen atmosphere (LO) of 1.5% CO2 plus 1.0% O2 at 3°C for as little as 1.25 months reduced the rate of titratable acids loss and the rate of apple softening in subsequent storage in the standard controlled atmosphere of 5.0% CO2 plus 3.0% O2 at 3°. With total storage time of 7.5 months, the initial LO storage effect on titratable acid loss was observed in 2 of the 3 years studied, whereas the effects on firmness loss were consistent over 3 crop years. ‘Spartan’ apples stored initially in LO at 0° were determined by a trained panel to retain crispness and hardness in subsequent standard controlled atmospheres of 3.0% CO2 plus 2.5% O2 at 0°, with the highest ratings obtained for durations of 3.0 months in LO and 4.5 months in standard atmospheres, whereas ‘Golden Delicious’ apples stored for 4.5 months in LO plus 3.0 months in 3.0% CO2 plus 2.5% O2 at 0° were determined to be the crispest and hardest. Extended storage of ‘McIntosh’ in LO increased the incidence of flesh browning in the 1981 crop year but decreased the incidence of senile brown core in the 1983 crop year. Storage of ‘McIntosh’ apples initially in LO for 2 to 5 months followed by the standard atmosphere reduced the risk of flesh browning resulting from low-oxygen injury and retained up to 90% of the firmness retention imparted by continuous LO storage.

Open Access

Abstract

Storing ‘McIntosh’ apples (Malus domestica Borkh.) initially in 1.0% or 1.5% CO2 plus 1.0% O2 at 3°C (LO) was more effective in retarding firmness loss than initial storage in 4.5% or 5.0% CO2 plus 3.0% O2 at 3° (SCA), indicating that early exposure to LO suppressed the subsequent rate of softening in SCA. ‘McIntosh’ firmness retention, determined 1 day after storage and after 7 days at 20°, decreased with fruit maturity for all LO and SCA storage regimens, but mature fruit tended to soften more rapidly in SCA after being exposed initially to LO. Initial storage in SCA for >75 days with subsequent storage in LO (in 1984) did not result in firmer apples than those stored continuously in SCA. The initial exposure period in LO needed to induce retention of apple firmness depended on cultivar and temperature. For ‘McIntosh’, ‘Spartan’, and ‘Golden Delicious’ cultivars, respectively, maximum post-storage fruit firmness was reached after 7.5, 4.5, and 1.5 months of initial exposure to LO at 0° and after 4.5, 3.0, and 3.0 months at 3°. Poststorage evolution of CO2 and C2H4 and the severity of senescent disorders generally decreased with continuing storage in LO, but the incidence of low-O2 injury increased. Poststorage ethanol evolution increased with exposure to 1.0% O2 in ‘McIntosh’ apples stored at 0°, and ‘Spartan’ apples held at either 0° or 3°. Chemical name used: butanedioic acid mono(2,2-dimethylhydrazide) (daminozide).

Open Access