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  • Author or Editor: David C. Smith x
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The cutleaf hazelnut [Corylus avellana L. f. heterophylla (Loud.) Rehder] is an ornamental form with strongly dissected leaf morphology. Its stigmas express incompatibility allele S20 but none of the other 25 S-alleles was detected with fluorescence microscopy. Three seedlings from a cross of the cutleaf hazelnut and VR6-28 lacked S20 and were investigated further. Each expressed an allele from the parent VR6-28 (S2 S26), S26 in OSU 562.031 and OSU 562.048 and S2 in OSU 562.049. S2 and S26 are low in the dominance hierarchy, so we expected the new allele from the cutleaf hazelnut to be expressed in their pollen. Unexpectedly, fluorescence microscopy showed that pollen of all three selections was compatible on their cutleaf parent and on each other, and furthermore, self-pollinations showed the excellent germination and long parallel tubes in the styles that are typical of a compatible pollination. Controlled self- and cross-pollinations in the field verified the self-compatibility of two selections. Cluster set for self-pollinations was very high (75-90%) and within the range observed for compatible cross-pollinations. Furthermore, the frequency of blank nuts was low (<10%). The second allele in the cutleaf hazelnut is designated S28, and its presence in seedlings of `Cutleaf' is indicated by the absence of S20. Controlled pollinations in the field also showed that selection OSU 562.069 (S2 S28) from the cross `Cutleaf' × `Redleaf #3' was self-compatible. Fluorescence microscopy showed that two additional seedlings were self-incompatible [OSU 367.052 (S1 S28) and OSU 367.076 (S6 S28)] while a third [OSU 706.071 (S9 S28)] was self-compatible. Self-compatibility may be limited to genotypes that combine S28 with a second allele that is low in the dominance hierarchy.

Free access

`Barcelona' hazelnut (C. avellana L.) shoots were girdled and stool layered in a factorial design with three tissue removal (leaf, bud and meristem removal) and two hormone (with or without 750 ppm IBA) treatments. Percent rooting, rooting grade (0 to 5), shoot length, shoot diameter, and total number of buds were determined. Average percent rooting was >90% for all treatments. Girdling alone gave as high percent rooting as hormone application. The main effect of IBA was on root quality rather than percent rooting. About 75% of the hormone-treated rooted layers could be directly planted (grades 3 to 5), compared to 44% for the control, but shoot length, shoot diameter and total number of buds decreased with IBA application. Bud removal did not affect average percent rooting while meristem removal reduced it slightly. The percentage of layers having grades 3 to 5 was lower for the meristem and bud removal treatments than for leaf removal. Our results support the adoption of stool layerage with girdling and IBA application for the production of strong, well-rooted trees suitable for planting directly in the orchard.

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The cutleaf hazelnut [Corylus avellana L. f. heterophylla (Loud.) Rehder] is grown as an ornamental for its distinct leaf shape. Its leaves are slightly smaller, more deeply lobed, and more sharply toothed than those of standard hazelnut cultivars. When the cutleaf hazelnut was crossed with cultivars with normal leaves, all seedlings had normal leaves. When seedlings were backcrossed to their cutleaf parent, half of the seedlings expressed the cutleaf trait, and when crossed with each other in pairs, 25% of the seedlings were cutleaf. These segregation ratios indicate that the cutleaf trait is conferred by a single recessive gene for which the symbol cf is proposed. Progenies segregating simultaneously for leaf shape and color indicate that the cutleaf locus is independent of the locus controlling red leaf color and of the locus controlling a chlorophyll deficiency, which appears to be identical to that previously observed in seedlings of `Barcelona'.

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The contorted hazel, Corylus avellana `Contorta', is an ornamental tree prized for its grotesquely twisted trunk and branches. `Contorta' was discovered in a hedgerow in England about 1863 and has been commercially propagated by layerage or graftage because it was thought to not breed true from seed. We investigated the inheritance of contorted growth habit in the course of our work breeding hazelnuts. Crosses between normal growth habit cultivars and `Contorta' produce all normal seedlings. Sib matings of compatible normal seedlings of `Contorta' produce offspring in the proportion of 3 normal: 1 contorted. The backcross of a normal `Contorta' seedling to `Contorta' gives progeny in the ratio of 1 normal: 1 contorted, indicating control of the trait by a single recessive gene.

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Tyvek housewrap (Du Pont, Wilmington, Delaware), an air-infiltration barrier for use in house construction, has been put to a novel use for making pollination bags for breeding hazelnuts (Corylus avellana L.). Bagged flowers are used in making crosses and incompatiblity testing and remain receptive for up to 3 months. Tyvek has outperformed paper and plastic materials we have tried in terms of durability and cost. Tyvek is a spun-bonded, nondirectionally oriented film of highdensity polyethylene fibers that is permeable to water vapor and air, but is water resistant and pollen-proof, and can be made into bags of any size needed.

Free access

Abstract

Hazelnut kernels from which the pellicle can be removed easily by dry heat are highly desirable for the international kernel market. Cultivars vary from no to complete pellicle removal after heating. Nut samples of 951 seedlings representing 62 parental combinations were roasted at 130°C for 13.5 min, rubbed, and scored for degree of pellicle removal. Narrow sense heritability, estimated by regression of progeny means on midparent values, was 48% (±10%). This moderately high heritability estimate indicates that selection of easy-to-blanch seedlings should result in rapid progress.

Open Access