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Jennifer L. Emerson, John Frampton, and Steven E. McKeand

1 Graduate research assistant. 4 To whom reprint requests should be addressed; e-mail . 2 Professor. 3 Professor and co-director of the NCSU Tree Improvement Cooperative. We thank the Christmas tree growers who maintained

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Jennifer L. Emerson, John Frampton, and Steven E. McKeand

future tree improvement and breeding were made from this progeny test series after the fifth year in the field. Based on previous results, selection can be effective in Fraser fir after just four years in the field ( Arnold and Jett 1995 ; Arnold et al

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M.E. Ostry

White pine blister rust (Cronartium ribicola J.C. Fisch.) (WPBR) was discovered on Ribes L. in New York in 1906, although it was accidentally introduced from Europe on pine (Pinus L.) seedlings. The spread of this destructive fungus has changed the forests in North America. After decades of reduced planting because of the concern over the impact of WPBR, white pine (Pinus strobus L.) is now being restored in the lake states of Minnesota, Wisconsin and Michigan. Although the potential for growing white pine is high on many sites, the disappearance of a seed source because of logging and fires means that reestablishment of white pine to these areas will require active management. A series of plantings have been established on three national forests in Minnesota and Michigan to evaluate various silvicultural treatments intended to minimize the incidence of WPBR and to compare the performance of seedlings selected for disease resistance to nonselected planting stock.

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Jenny Knoth, John Frampton, and Ray Moody

The authors gratefully acknowledge Christmas tree growers Dale Taylor and Tom Wright for their maintenance and culture of the field trials. The Nursery and Tree Improvement Program of the South Carolina Forestry Commission and the

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Roger J. Arnold, J.B. Jett, and William T. Huxster

1 Graduate Research Assistant. 2 Professor. 3 Professor, retired. This research was supported by the North Carolina State Univ.–Industrial Tree Improvement Program, the North Carolina Division of Forest Resources, and the North Carolina

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Kourosh Vahdati, James R. McKenna, Abhaya M. Dandekar, Charles A. Leslie, Sandie L. Uratsu, Wesley P. Hackett, Paola Negri, and Gale H. McGranahan

1 Present address: Department of Horticultural Sciences, Faculty of Agriculture, University of Tehran, Karaj, Iran. 2 Present address: USDA Forest Service/Hardwood Tree Improvement and Regeneration Center, Purdue University, West Lafayette, IN 47907

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Paula M. Pijut and Melanie J. Moore

1 To whom reprint requests may be addressed. Current address: USDA Forest Service, North Central Research Station, Hardwood Tree Improvement and Regeneration Center, Purdue Univ., Dept. of Forestry and Natural Resources, 1159

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Larry J. Shoemake and Michael A. Arnold

Ninety seedlings from each of seven half-sib families of sycamore (Platanus occidentalis L.) were grown to marketable size in 9.1-liter containers in College Station, Texas. Dry matter partitioning was assessed with 10 seedlings each of four half-sib families grown in 4.7-liter containers. Half-sib families included selections native to Brazos County, Texas, and Putnam County, Tenn., and four half-sib families from the Westvaco Corp. (WV) or Texas Forest Service (TFS) tree improvement programs. Families could be separated into three groups with TFS-09 attaining a significantly greater height than other families, while Brazos-D, Brazos-C, and TFS-24 were intermediate and WV-10 and WV-14 were shortest. Contrary to previous field production studies, a weak inverse correlation (R 2 = –0.19, P > 0.01) was observed between the number of cuts required to remove multiple leaders and plant height, perhaps due to episodic shoot elongation in south Texas conditions vs. a single flush in northern regions. Corrective pruning removed more dry matter from TFS-09 than from Brazos-D, Brazos-C, and Putnam seedlings. Total dry weights of TFS-09 and Brazos-C were greater than WV-14 or Putnam seedlings.

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Ying Yang, Xian-Ge Hu, Bingsong Zheng, Yue Li, Tongli Wang, Anket Sharma, Huwei Yuan, and Jian-Feng Mao

MicroRNAs (miRNAs) are short noncoding RNAs (20–25 nucleotides) that regulate gene expression posttranscriptionally. However, identification and characterization of miRNAs remain limited for conifer species. In this study, we applied transcriptome-wide miRNAs sequencing to a conifer species Platycladus orientalis, which is highly adaptable to a wide range of environmental adversities, including drought, barren soil, and mild salinity. A total of 17,181,542 raw reads were obtained from the Illumina sequencing platform; 31 conserved and 91 novel miRNAs were identified, and their unique characteristics were further analyzed. Ten randomly selected miRNAs were validated by quantificational real-time polymerase chain reaction. Through miRNA target predictions based on psRNATarget, 2331 unique mRNAs were predicted to be targets of P. orientalis miRNAs that involved in 187 metabolic pathways in KEGG database. These targets included not only important transcription factors (e.g., class III homeodomain leucine zipper targeted by por-miR166d) but also indispensable nontranscriptional factor proteins (i.e., por-miR482a-3p regulated nucleotide-binding site leucine-rich repeat protein). Interestingly, six miRNAs (por-miR16, -miR44, -miR60-5p, -miR69–3p, -miR166b-5p, and -miR395c) were found in adaptation-related pathways (e.g., drought), indicating their possible involved in this species’ stress-tolerance characteristics. The present study provided essential information for understanding the regulatory role of miRNAs in P. orientalis and sheds light on their possible use in tree improvement for stress tolerance.

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James R. McKenna and Lynn Epstein

1 To whom reprint requests should be addressed at his current address: Dept. of Forestry and Natural Resources, USDA-Forest Service, Hardwood Tree Improvement and Regeneration Center, Purdue Univ., Forestry Building, 195