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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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Shawn A. Mehlenbacher and Maxine M. Thompson

A chlorophyll deficiency expressed as yellowing of leaves was observed in hazelnut (Corylus avellana L.) progenies. Segregation ratios approximated 3 green: 1 yellow, indicating control by a single recessive gene designated chlorophyll deficient #1, for which the symbol c, is proposed. `Barcelona', `Butler', `Compton', `Lansing', Willamette', and the ornamental selection `Redleaf #3' are heterozygous. Pedigree analysis strongly suggests that all heteroxygotes inherited the recessive allele from `Barcelona'. A cross of `Barcelona' with the yellow-leafed ornamental Corylus avellana L. var. aurea Kirchn. produced no yellow-leafed seedlings, indicating that the chlorophyll deficiencies from these two sources are controlled by different loci. Progenies segregating simultaneously for this trait and the gene controlling presence of anthocyanin indicated that the two traits are inherited independently. Seedlings deficient in chlorophyll but with anthocyanin were able to survive under field conditions, while leaves of yellow-leafed seedlings lacking anthocyanin became scorched and the trees died.

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Thomas J. Molnar, Sara N. Baxer, and Joseph C. Goffreda

An eastern filbert blight resistance screening technique was developed that reduces the time required to identify susceptible Corylus avellana L. seedlings from the previously reported 14 to 16 months after inoculation to 6 to 7 months. To accomplish this, hazelnuts were harvested at maturity, treated with GA3, germinated, and grown for about 8 weeks at 24 °C day/18 °C night with 16-hour daylengths. Seedlings were then moved to a humidity chamber and inoculated with ascospores of Anisogramma anomala (Peck) E. Müller 3 times over 2 weeks by misting until run off with a solution of 1 × 106 ascospores/mL in sterile distilled water. Following inoculation, seedlings were returned to the original greenhouse for 8 weeks and then were moved to a 10 to 15 °C day/5 to 10 °C night greenhouse with natural daylengths for 4 weeks. They were then moved to a 4 °C cold room for 8 weeks to receive chilling. Afterwards, seedlings were returned to a greenhouse at 24 °C day/18 °C night where stromata development was visible in 4 to 6 weeks.