OREGON STATE UNIVERSITY
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My teaching and research focuses on woody nursery and landscape plants. I teach spring and fall woody plant identification courses, growth and development of horticultural crops, and plant propagation. Research in my lab is closely aligned with the nursery industry to try and develop new plants that work well in production and serve the needs of growers and gardners alike. As the nursery industry grows an incredible diversity of crops, we try to address a diverse suite of plants from low growing shrubs or groundcovers to large shade trees. This interest in serving the needs of the industry has led me to intitiate projects on 33 genera to date - a number that is always on the rise.
My research program involves several areas of ornamental plant breeding and cultivar development. Of primary interest is the development of sterile forms of nonnative species that are of economic importance to Oregon growers to prevent escape from cultivation. Primary techniques to achieve sterility/reduced fertility include develoment of triploids using ploidy manipulation, as well as mutagenesis by exposing seeds or meristems to physical and chemical mutagens.
My lab conducts fundamental research in traditional genetics, cytogenetics, molecular genetics, and genomics to support the applied breeding program with the goal of developing plants that are attractive to consumers, easy for growers to produce, and resilient in modern landscapes. The end goal being to develop new cultivars that have increased insect and disease resistance combined with superior aesthetics.
- Tyler HoskinsTyler is a native Oregonian who has degrees from Clackamas Community College, George Fox, and Virginia Tech. The latter is where he honed his expertise in managing water and nutrients in soilless substrates of nursery crops - earning his M.S. with former Oregon State professor, Jim Owen. Tyler expertly manages the growing operation for the breeding program from propagation, to containers, field production, irrigation, and fertilization.
Adigun McLeod: Ploidy manipulation of different lines of industrial hemp
Cara Still: Reproductive behavior and pollinator attration of Buddleja cultivars
Sunny Green: Pollen analysis and crossability of Vaccinium
Current
Past
Ribes sanguineum 'Oregon Snowflake'
Cotoneaster ×suecicus 'Emerald Sprite' PP31,719
Cotoneaster ×suecicus 'Emerald Beauty' PPAF
*Lattier, J.D. and R.N. Contreras. 2020. Segregation of flower color and eyespot in althea. J. Amer. Soc. Hort. Sci. (in press but published online ahead of issue) https://doi.org/10.21273/JASHS04824-19.
Contreras, R.N. and *Shearer, K. 2020. Exposing seeds of Galtonia candicans to ethyl methanesulfonate (EMS) reduced inflorescence height, lodging, and fertility. HortScience. https://doi.org/10.21273/HORTSCI14775-19.
*Chen, H., J.D. Lattier, K. Vining, and R.N. Contreras. 2020. Two SNP markers identified using GBS are associated with remontancy in a segregating F1 population of Syringa meyeri ‘Palibin’ x S. pubescens ‘Penda’ Bloomerang®. J. Amer. Soc. Hort. Sci. 145(1): https://doi.org/10.21273/JASHS04847-20.
*Petter, J., P. Ries, A. D’Antonio, and R.N. Contreras. 2020. A Tree Selection Survey of Tree City USA Designated Cities in the Pacific Northwest. Arboriculture & Urban Forestry. (in press).
*Petter, J., P. Ries, A. D’Antonio, and R.N. Contreras. 2020. How are managers making tree species selection decisions in the Pacific Northwest of the United States? Arboriculture & Urban Forestry. 46(2):148-161.
Hoskins, T. and R.N. Contreras. 2020. Exposing seeds of Sarcococca confusa to increased concentrations and durations of ethyl methanesulfonate reduced seed germination, twinning, and plant size. HortScience 54(11):1902-1906. https://doi.org/10.21273/HORTSCI14428-19
Graebner, R.C., H. Chen, R.N. Contreras, K.G. Haynes, and V.R. Sathuvalli. 2019. Identication of a high frequency of triploid potatoes from tetraploid x diploid crosses. HortScience 54(7)1159-1163.
Vining, K.J., I. Pandelova, K. Hummer, N. Bassil, R.N. Contreras, K. Neill, H. Chen, A.N. Parrish, and B.M. Lange. Genetic diversity survey of Mentha aquatica L. and Mentha suaveolens Ehrh., mint crop ancestors. Genetic Resources and Crop Evolution 66(4):825-845.
Contreras, R.N. and L. Meneghelli. 2016. In vitro chromosome doubling of Prunus laurocerasus 'Otto Luyken' and 'Schipkaensis'. HortScience 51(12):1463-1466.
Schwartz, B.M., R.N. Contreras, K.R. Harris-Schultz, D.L. Heckart, J.B. Peake, and P.L. Raymer. 2013. Discovery and characterization of a turf-type triploid seashore paspalum. HortScience 48(12):1424-1427.
Schwartz, B.M., K.R. Harris-Schultz, R.N. Contreras, C.S. Hans, W.W. Hanna, and S.R. Milla-Lewis. 2013. Creation of artificial triploid and tetraploid centipedegrass using colchicine and breeding. Intl. Turfgrass Soc. Res. J. 12:327-334.
Schwartz, B.M., K.R. Harris-Schultz, C.S. Hans, R.N. Contreras, and S.A. Jackson. 2013. Creation of hexaploid and octoploid zoysiagrass using colchicine and breeding. Crop Science 53:2218-2224.
Contreras, R.N. and J.M. Ruter. 2009. Sulfuric acid scarification of Callicarpa americana (Lamiaceae) seeds improves germination. Native Plants J. 10(3):283-286.
Contreras, R.N. and T.G. Ranney. 2008. New opportunities for breeding fragrant rhododendrons. J. Amer. Rhododendron Soc. 62(4):201-202.
Contreras, R.N., T.G. Ranney, S.R. Milla-Lewis, and G.C. Yencho. 2007. Investigating parentage and hybridity of three azaleodendrons using amplified fragment length polymorphism analysis. HortScience 42(3):740-743. https://doi.org/10.21273/HORTSCI.42.3.740
