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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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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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Steven G. Russell, Sylvia M. Blankenship, and Walter A. Skroch

A field study was initiated in 1981 in western North Carolina to determine the influence of eight groundcover management systems on quality of `Redchief Red Delicious' apple (Malus domestica) grafted onto rootstock of M VIIA. Management systems included: bare soil, Secale cereale mulch, minimal cultivation, Festuca arundinacea, Dactylis glomerata, Poa pratensis, Muhlenbergia schreberi and Rubus sp. Thus far, fruit quality data indicate that fruits produced in plots of cool-season grasses are smaller and less mature than those produced in vegetation-free plots or plots of warm-season grasses. A negative correlation was noted between high fruit quality and water deficit stress as measured by water potential and stomatal conductance.

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Steven G. Russell, Sylvia M. Blankenship, and Walter A. Skroch

A field study was initiated in 1981 in western North Carolina to determine the influence of eight groundcover management systems on quality of `Redchief Red Delicious' apple (Malus domestica) grafted onto rootstock of M VIIA. Management systems included: bare soil, Secale cereale mulch, minimal cultivation, Festuca arundinacea, Dactylis glomerata, Poa pratensis, Muhlenbergia schreberi and Rubus sp. Thus far, fruit quality data indicate that fruits produced in plots of cool-season grasses are smaller and less mature than those produced in vegetation-free plots or plots of warm-season grasses. A negative correlation was noted between high fruit quality and water deficit stress as measured by water potential and stomatal conductance.

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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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Todd M. Morrissey and William A. Gustafson Jr.

A study was designed to determine if current dormant-bud cryopreservation techniques investigated on woody plants, such as apple (Malus domestica), gooseberry (Ribes), blueberry (Vaccinium corymbosum) and pear (Pryus communis) etc., could be applied to certain nut tree species for long-term preservation. Pecan (Carya illinoinensis) and black walnut (Juglans nigra) were exposed to prefreezing temperatures ranging from -10° C to -40° C and then directly immersed in liquid nitrogen for 2 hrs. Dehydration by prefreezing was not sufficient for bud survival in pecan. Bud survival was increased by dehydrating stem sections prior to prefreezing. Prefreezing at -30° or -40° C was suitable for survival of black walnut.

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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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Jayson K. Harper and George M. Greene II

This study quantifies the discounts and premiums associated with various quality factors for processing apples (Malus domestica Borkh.). Discounts and premiums were estimated using a hedonic price model and quality data from a total of 137 samples representing three processing apple cultivars (45 `York Imperial', 43 `Rome Beauty', and 49 `Golden Delicious'). Price discounts in the sample were statistically significant for fruit size, bruising, bitter pit, decay, misshapen apples, and internal breakdown. Commonly cited defects, such as insect damage and apple scab, did not cause significant price discounts.

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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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C. Chervin, J. Raynal, N. André, A. Bonneau, and P. Westercamp

The effects of ethanol vapors, controlled atmosphere (CA) storage, and a combination of both on superficial scald development on `Granny Smith' apples (Malus ×domestica Borkh.) are reported. The major result was that ethanol vapors, applied in cold storage, prevented scald development over a week at 20 °C in apples that had been CA-stored for 4 months, then left for 1 month in cold air storage. Interrupting CA storage aimed to reproduce industry practices when fruit in part of storage rooms has to be sold and the remaining fruit is held in air for later sale. The estimated cost and further development of this method are discussed.