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Salih Kafkas, Yıldız Doğan, Ali Sabır, Ali Turan, and Hasbi Seker

( Rehder, 1947 ; Kasapligil, 1972 ; Mehlenbacher, 1991 ; Thompson et al., 1996 ). The commercially important European hazelnut ( Corylus avellana L.) is native to most of Europe, Turkey, and the Caucasus mountains, and wild populations can be found in

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Ryan J. Hill, David R. King, Richard Zollinger, and Marcelo L. Moretti

The natural form of European hazelnut ( Corylus avellana L.) is a multistemmed bush. Hazelnuts can be trained into single-trunk trees, which facilitates mechanized orchard maintenance and harvest, increasing yield ( Mehlenbacher and Smith, 1992

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William M. Proebsting, Nahla V. Bassil, and David A. Lightfoot

Propagation of Corylus avellana stem cuttings may be limited by either root initiation or bud abscission. We divided juvenile shoots of 3 varieties growing in layering beds in mid-July into 4 or 5 3-node cuttings with leaves at the upper two nodes, except that terminal cuttings had one expanded leaf. Cuttings were treated with 5 mM IBA in 50% EtOH, a mixture of A. rhizogenes strains A7 + 22 or left untreated. IBA and bacteria stimulated rooting of cuttings from all shoot positions. Rooting of the terminal cuttings (<50%) was less than that of the sub-terminal cuttings (>80%). Bud retention was <50% on terminal cuttings, nearly 100% on sub-terminal cuttings. Using juvenile stock plants of various varieties, sub-terminal cuttings treated with Agrobacterium or 5 mM IBA may yield 70-90% cuttings with both roots and buds, Agravitropic roots, characteristic of genetic transformation, were observed on Agrobacterium-treated cuttings. Dot blots probed for TL-DNA were negative, however.

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William M. Proebsting, Nahla V. Bassil, and David A. Lightfoot

Propagation of Corylus avellana stem cuttings may be limited by either root initiation or bud abscission. We divided juvenile shoots of 3 varieties growing in layering beds in mid-July into 4 or 5 3-node cuttings with leaves at the upper two nodes, except that terminal cuttings had one expanded leaf. Cuttings were treated with 5 mM IBA in 50% EtOH, a mixture of A. rhizogenes strains A7 + 22 or left untreated. IBA and bacteria stimulated rooting of cuttings from all shoot positions. Rooting of the terminal cuttings (<50%) was less than that of the sub-terminal cuttings (>80%). Bud retention was <50% on terminal cuttings, nearly 100% on sub-terminal cuttings. Using juvenile stock plants of various varieties, sub-terminal cuttings treated with Agrobacterium or 5 mM IBA may yield 70-90% cuttings with both roots and buds, Agravitropic roots, characteristic of genetic transformation, were observed on Agrobacterium-treated cuttings. Dot blots probed for TL-DNA were negative, however.

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Paolo Boccacci, Roberto Botta, and Mercè Rovira

The European hazelnut ( Corylus avellana L.) is one of the world's major nut crops. Its geographic distribution extends from the Mediterranean coast of North Africa northward to the British Isles and the Scandinavian Peninsula, and eastward to

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Nahla V. Bassil, B.J. Rebhuhn, David W.S. Mok, and Machteld C. Mok

Development of optimum protocols for micropropagation of C. avellana is particularly important due to the threat of Eastern Filbert Blight and the need for rapid increase of resistant varieties and advanced selections. Therefore, efforts were directed at in vitro establishment, multiplication and rooting, starting with buds from mature trees. The frequency of shoot formation from buds was highest in August but varied with the genotype. Medium containing high Ca levels was more effective in preventing bud necrosis than MS medium. Multiplication rates of 4-7 new shoots/propagule were obtained over a 6-week culture period. Rooting of some genotypes could be accomplished by inclusion of 1 or 3 μM β- indolebutyric acid (IBA) in the medium. Other genotypes responded better to a dip of shoot bases in 1-10 mM IBA for 10 sec., followed by a passage on auxin-free medium. Large numbers of healthy plantlets have been produced for transfer to soil.

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Xiaoling Yu and Barbara M. Reed

Multiplication and elongation of shoot cultures established from mature trees of hazelnut cvs. Nonpareil and Tonda Gentile Romana were affected by changes in basal medium, carbon source and concentration, cytokinin and agar concentration. Explants on DKW medium produced significantly more shoots than those on Anderson medium or modified woody plant medium for chestnut. Explants on DKW medium with 3% glucose or fructose gave more and longer shoots than those with the other carbon sources. Cytokinins 6 benzylaminopurine (BA) and zeatin were more effective in producing shoots than kinetin and 2iP. On BA supplemented medium, the best multiplication rate was obtained with 1.5 - 2.0 mg/l. Explants grown on 0.4% agar produced more shoots than those on 0.6%, however, prolonged culture on 0.4% agar caused vitrification of lower parts of the plants. Shoot multiplication rates of these two cultivars were similar, but `Nonpareil' produced longer shoots than `Tonda Gentile Romana'.

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Francis Y. Kwong and H. B. Lagerstedt

Abstract

Branch treatments with (2-chloroethyl)phosphonic acid (ethephon) on fruiting filbert trees showed that ethephon was equally effective in accelerating nut drop from bagged and treated clusters. Ethylene production in husks increased significantly after ethephon application to leaves. Ethylene production did not differ between husk applications and leaf-plus-husk applications of ethephon. Results from radioactive-tracer studies showed the presence of radioactivity in stem tips, buds, and husks when 14C-ethephon was applied to leaves. The data indicate that ethephon, or its active derivative, translocates rapidly in the filbert, as shown by radioactivity and ethylene evolution, being completed within 1 day of foliar application.

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M. M. Thompson, P. Romisondo, E. Germain, R. Vidal-Barraquer, and J. Tasias Valls

Abstract

A common evaluation system for filberts has been developed by research leaders of breeding programs in U. S., France, Italy, and Spain. The system incorporates important horticultural or economic traits and is independent of specific breeding objectives. To minimize the influence of site and season on certain traits, especially phenological traits, a standard set of well-known cultivars was established, against which all other clones are compared. Ratings are recorded numerically so the data can be readily computerized.