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Joshua D. Klein and Susan Lurie

Apple (Malus domestica Borkh. `Grand Alexander') fruit were stored immediately at 0C after harvest or after being held at 38,42, or 46C for 72,24, or 12 h, respectively. Half of each fruit lot was dipped in 1.5 % CaCl before storage. Heating did not appreciably affect Ca uptake into epidermal or cortical tissue. Calcium and heat treatments acted synergistically in reducing the severity of superficial scald and in retaining fruit firmness after 5 months of storage, relative to nontreated or nonheated Ca-dipped fruit.

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D.C. Elfving

Dormant heading-back of terminal extension shoots on scaffold limbs on 2-year-old `Empire'/M.26 EMLA apple trees (Malus domestica Borkh.) in Apr. 1985 increased shoot growth from 1- and 2-year-old limb sections. Removing competing shoots to restore a single terminal extension shoot on each scaffold on half the trees in each pruning treatment in May 1985 had little influence on shoot growth. Annual trunk enlargement was reduced in 1985 and 1986 by heading-back pruning in 1985. Trunk cross-sectional area in Fall 1989 remained smaller for trees only headed back once, in 1985. Yields were decreased in 1986 through 1989 by heading-back treatments applied in 1985.

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Karim H. Al-Juboory and Jabar H. Al-Niami

Leaves of wild apple (Malus domestica Borkh) were excised from in vitro grown shoots transversely cut into halves and plated onto petri dishes containing regeneration media. Cultures were kept in the dark for three weeks before adventitious shoots were observed. Callus from leaf explants produced adventitious shoots after 3 months of in vitro culture. Callus were cultured on Nitsch and Nitsch medium supplemented with a range of BA (0.0–2.0 μm) and NAA (0.0–10 μm). BA at 10 μm combined with NAA (0.5 μm) proved most effective for stimulating shoot proliferation of cultured apple. Plantlets from tissue culture were easily transferred to the greenhouse environment.

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Karim H. Al-Juboory and Jabar H. Al-Niami

Thidiazuron (TDZ) and benzylamino purine stimulated shoot proliferation on shoot tip explants of wild apple (Malus domestica Borkh) when incorporated in Murashige and Skoog (MS) medium at concentrations of 1.0–10 μm. Shoot numbers obtained with TDZ were greater than the number produced when using BA in the medium but the shoots were shorter than with BA. Increasing TDZ levels increased shoot proliferation with 10 μm. Apple shoots were successfully rooted on MS medium with 2.0 mg·L–1 NAA and then transferred to a mixture of 1 peat: 1 perlite: 1 soil and acclimatized for potting.

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Seung-Ryeul Shin, Jae-Kyun Byun, and Kyung-Ho Chang

β-Galactosidase was purified from apple, Malus domestica Borkh, cv. Fuji by gel filtration, CM cellulose ion exchange chromatography, and characterizied by means of several biochemical methods. One form of β-Galactosidase was detected and the Km and Vmax values were calculated to be 0.035 and 0.036 mM with para-nitrophenyl-β-D-galactoside lmM/15min., respectively. The β-galactosidase was active between pH 3 and 7 with the optimum pH of about 4-5. The stable temperature for β-galactosidase was lower than 45°C with 30°C optimum. The β-galactosidase activities were inhibited by Ag*. EDTA and SDS.

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Stephen J. Tancred, Aldo G. Zeppa, Mark Cooper, and Joanne K. Stringer

A major objective of the apple (Malus domestica Borkh.) breeding program in Stanthorpe, Australia, is to develop early ripening, high-quality cultivars. The heritability and inheritance of ripening date was investigated. Regression of offspring on midparent harvest dates and estimation of best linear unbiased predictions for parents were used to demonstrate that apple harvest date is highly heritable. Predominantly, additive genetic components of variance are responsible for the variation. Despite the existence of some specific combining ability variance and some non-normal family distributions, the best strategy for a breeder to predict the harvest date of progeny is to calculate the mean harvest date of parents.

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E.W. PAVEL and T.M. DEJONG

The fruit growth of three peach (Prunus persica (L.) Batsch cvs. `Spring Lady', `Flamecrest', `Cal Red') and two apple cultivars (Malus domestica Borkh. cvs. `Cox Orange', `Golden Delicious') was measured weekly during the 1988 growing period. Seasonal patterns of fruit relative growth rate calculated on a dry weight basis were very similar for both species. Changes in nonstructural carbohydrate composition of peach mesocarp and apple pericarp were correlated with the two physiological phases of sink-activity of the relative growth rates Changes in sucrose concentrations seemed to coincide with increasing dry matter accumulation for both species, even though fructose was a dominant sugar in apples.

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Shiow Y. Wang and Miklos Faust

The glycolipids, phospholipids, and sterols were determined in normal and watercore-affected apple (Malus domestica Borkh. cv. Delicious). Fruit with watercore contained higher amounts of glycolipids, phospholipids, and sterols. The ratios of unsaturated to saturated fatty acids and (18:3) to (18:1 + 18:2) were lower in watercore-affected tissue than in normal tissue. The ratio of free sterols to phospholipids was higher, whereas the ratio of phosphatidylcholine to phosphatidylethanolamine was lower in watercore-affected apple. Membrane lipids were altered in watercore-affected fruit.

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Richard J. Campbell, Kendrick N. Mobley, Richard P. Marini, and Douglas G. Pfeiffer

The relationship between SPAD-501 meter readings (SPAD) and total chlorophyll content (TCHL) was evaluated for `Delicious' apple (Malus domestica Borkh.) leaves grown in various environments. Regression models were developed between SPAD and TCHL for each of six separate experiments and were evaluated for statistical coincidence. SPAD was linearly related in a positive manner to TCHL in five of the six experiments; however, models differed between experiments, particularly between field- and greenhouse-grown trees. Thus, the relationship between SPAD and TCHL must be determined for each experiment.

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Xuetong Fan and James P. Mattheis

Climacteric `Fuji' apples (Malus ×domestica Borkh.) were treated with water, 0.45 mmol·m–3 1-methylcyclopropene (MCP), 2 mmol·L–1 methyl jasmonate (MJ), or both MCP and MJ. Fruit were kept at 20 °C for 17 days after treatment. Ethylene production, respiration, and color change were all inhibited following MCP treatment. Ethylene production following MJ treatment fluctuated below and above that of controls, but was representative of postclimacteric apples at all times. Rates of respiration and color change were enhanced by MJ, even when fruit were previously treated with MCP. The results indicate that MJ can enhance rate of color change and respiration in apple fruit independently of ethylene action.