Location: Floral and Nursery Plants Research
Project Number: 8020-21000-086-002-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2023
End Date: Aug 31, 2028
Objectives of this research include: 1) collect open-pollinated seed from California incense-cedar from 13 geographically and/or climatically diverse provenances throughout its native distribution; 2) conduct a common garden experiment to identify California incense-cedar populations and/or individual trees with superior cold-hardiness, disease resistance, vigor, and ornamental qualities (e.g., excurrent form, compact growth, green winter color, etc.); and 3) preserve the newly characterized incense-cedar accessions in the Woody Landscape Plant Germplasm Repository. The goal of this research is to increase genetic diversity of conifers used in Eastern U.S. landscapes by introducing broadly adaptable incense-cedar selections.
Thirty incense-cedar seedlings from open-pollinated seeds collected from each of 13 provenances, ranging from Mount Hood National Forest in Northern Oregon to Cleveland National Forest in Southern California, will be planted in a common garden at the Otis Floyd Nursery Research Center in McMinnville, TN. Provenances identified by the ARS investigator will span 10 Ecoregions and be diverse in elevation, latitude, average minimum winter temperature, annual rainfall, and soil fertility. Trees will be planted with 2 m spacing within and between rows in a randomized complete block design with 13 provenances, six blocks, and five seedlings per block per provenance. Height, width, caliper, and winter survival will be determined once annually. Leaf chlorophyll content of recently matured foliage from each plant will be measured twice during the summer and twice during the winter to identify populations or individuals that remain green during winter. During the growing season, plants will be monitored once every three to four weeks for signs of disease and arthropod pests. Continuous data (e.g., height, width, chlorophyll content) will be analyzed via ANOVA. Ordinal data, such as cold-hardiness and disease severity, will be analyzed via Generalized Linear Mixed Model ANOVA using a Beta distribution.