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James N. Moore, Roy C. Rom, Stanley A. Brown and Gerald L. Klingaman

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A.S. Devyatov

Growth and fruiting of apple trees in twin-row tree-belts were studied during 5 years after planting the orchard. Distance between belts was 4 m, between rows in a belt was 1 m, between trees in row 3 or 1.5 m, giving tree densities of 1335 or 2670 trees/ha, respectively. Control was a single-row planting 4 × 3 or 4 × 1.5 m, producing densities of 833 or 1665 trees/ha. Trees were trained as hedgerow in treatments with a density of 1335 or 833 trees/ha. Each tree in a twin-row belt had a separate crown with narrow passage between trees. This passage was cut through every year. Fruiting of `Tellisaare' began at 2nd leaf, `Antey' at 3rd, and `Spartan' at 4th leaf after planting. Total yield for 3 years in the highest density treatment of single-row planting of `Antey' and `Tellisaare' was >50 t·ha–1 and in twin-row orchard construction from 36 to 57 t·ha–1, depending on orchard density. The two-fold increase in orchard density from 1335 to 2700 trees/ha raised yield of `Antey' by 58% and `Tellisaare' by 33%. Single-row treatment with a tree density of 1665/ha averaged 17.1–17.5 t·ha–1 without great expenditure on pruning of trees. The fruit quality was very high in all treatments.

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Mushtaq Sarwar and Robert M. Skirvin

Adventitious shoots were regenerated from apple (`Wijcik', `McIntosh', `Macspur', `M-26' and `Mutsu') by excising leaves from in vitro-grown shoots, cutting them into three sections, and plating them onto regeneration media. Cultures were kept in the dark for 1 to 4 weeks and then moved to light for further shoot development. MS medium supplemented with thiadiazuron (2-3 μM) and napthaleneacetic acid (5 μM) produced the highest number of shoots per leaf segment. `Wijcik' and `M-26' regenerated best from big leaves, whereas `McIntosh' and `Macspur' regenerated best from small leaves. Shoot formation was enhanced by 3 to 4 weeks of dark treatment and by placing the leaf on medium with its abaxial surface uppermost. The cut surface of leaf segments produced the most regeneration sites. In vitro adventitious shoots were transferred to various concentrations of BA (5, 10, 15, 20, 25 and 30 μM to screen them for BA tolerance and to predict their adult growth habit. These shoots will be rooted and transferred to greenhouse and field conditions for long-term evaluations.

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Baolin Zhang and Leonard P. Stoltz

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Usman Siswanto and Frank B. Matta

This study was established to determine the influence of scion/stock combination on leaf area, yield efficiency, and fruit quality attributes in effort to identify the most suitable scion/stock combination for Mississippi. Twenty-nine scion/stock combinations were grown at the Pontotoc Ridge-Flatwoods Research and Extension Center, North Mississippi. The treatments were arranged in a completely randomized design (CRD) with six single tree replications. `Jon-A-Red' on Mark produced the smallest leaf area, while the largest leaf area was produced by the combination of `Royal Gala' on MM106 and `Blushing Golden' on M7A. Scion/stock combinations significantly affected yield efficiency, fruit yellow pigment dvelopment, firmness and fruit mineral composition. Scion cultivars on Mark resulted in the highest yield efficiency, except `Empire'. `Ultra Gold' and `Braeburn' on Mark and `Blushing Golden' on MM111 led to yellow pigmentation in the highest category. Meanwhile, `Braeburn' on Mark was among the scion/stock combinations that produced the firmest fruit. And fruit from trees on Mark consistently had high calcium (Ca) levels. After 7 years, `Royal Gala' on Mark produced the highest yield efficiency. `Braeburn' on Mark resulted in both the firmest fruit and the highest fruit Ca concentration.

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Brent K. Harbaugh, John W. Scott and David B. Rubino

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Brent K. Harbaugh and John W. Scott

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Alan W. Meerow, Rhoda McMaster and Cameron McMaster

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J.W. Scott, B.K. Harbaugh and E.A. Baldwin

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Usman Siswanto and Frank B. Matta

The performance of spur-type apple cultivars was evaluated on MM.111, MM.106, M.7A, M.26, and Mark rootstocks. Shoot growth, leaf area, and total nonstructural carbohydrate (TNC) were affected by scion cultivar and rootstock. Empire on Mark stock had less shoot growth. Ultra Mac on M.7A produced smaller leaf area. `Braeburn' on Mark stock exhibited higher TNC content. Scion cultivar and stock influenced fruit weight and yield, L: D ratio, SSC, pH, and the content of N, P, K in leaves and fruit. `Braeburn' on M.7A, M.26, and MM.111 produced greater yield per tree. L: D ratio was higher in `Ultra Gold' on MM.106. `Ultra Gold' and `Jon-A-Red' had higher SSC on Mark. `Empire' and `Ultra Gold' on M.7A resulted in higher juice pH. `Empire' on MM.106 produced heavier fruit and higher N content in leaves and fruit. `Ultra Mac' on M.7A showed higher P and K content in the fruit.