Record Details
Fungi associated with Douglas-fir seed during cone development, seed processing, and storage
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Fungi associated with Douglas-fir seed during cone development, seed processing, and storage |
| Names |
Gordon, Lewin Roland
(creator) Roth, Lewis F. (advisor) |
| Date Issued | 1967-04-06 (iso8601) |
| Note | Graduation date: 1967 |
| Abstract | The Pacific Coast form of Douglas-fir in natural forest succession is an intermediate species thriving in the Coast Range and Cascade Mountains of the Pacific Northwest. This species constitutes 26 percent of the standing timber in the United States, and 24 percent of the nation's annual timber harvest. Characteristics of the timber type and its management in addition to utility are: an irregular seeding habit; clear-cutting as the popular harvest practice; and the rapid intrusion of brush into cut-over areas to the detriment of tree regeneration. These factors demand immediate and successful restocking of deforested areas. Such restocking of cut-over lands with the desired Douglas-fir requires a constant supply of quality seed. Successful seed storage resulting in minimum subsequent reduction of vitality of seed and seedlings may be more nearly achieved through fuller knowledge of the effects of storage on the fungi normally occurring in the seed and on their activities. This study was undertaken to disclose and identify fungi occurring on seed of Douglas-fir, and to determine the effects of different common storage treatments on the seed microflora. To this end, cones collected from four Douglas-firs on the eastern periphery of the Coast Range in Oregon were briefly soaked in a five percent solution of Clorox prior to storage. A similar group was untreated. Seed were extracted from both groups at intervals and stored at different temperatures. Periodically, stored seed were plated on potato dextrose agar following surface sterilization in 30 percent hydrogen peroxide. Fungi growing from the seed were identified and tabulated. Twenty-six species were identified, including a number of known seed pathogens. Occurrence of the five most prevalent isolates was analyzed statistically. All were found to become significantly more numerous with delay of extraction of seed from the cones following harvest. These organisms decreased numerically with time of storage at room temperature, but never reached the level found in promptly extracted seed. However, when seed was stored in the refrigerator at minus 16°C, the fungal flora was soon reduced below the level occurring in the promptly extracted seed of the controls. This was true of seed held for both short and long periods of storage at room temperature, preceding refrigeration. Prevalence of different organisms varied widely between trees, but differed little between filled and empty seed. Both Clorox treatment of cones and detergent treatment of seed, preceding sterilization, contributed to a reduced fungal flora. Many of the fungi became associated with the seed very early in cone development, and fungal floras differed little between extracted and naturally shed seed. The following conclusions were reached. Refrigerated storage reduces the fungal flora of mature seed. Douglas-fir seed should be artificially extracted from the cones immediately after harvest. Additional investigation of surface sterilization of cones prior to seed extraction is warranted. Sterilized seed for experimental purposes can be readily obtained by a combination of refrigerated storage, detergent soak and hydrogen peroxide sterilization. Knowledge of the effects of fungi in seed during and after storage is needed in order to determine the desirability of seed sterilization prior to storage. |
| Genre | Thesis/Dissertation |
| Topic | Douglas fir |
| Identifier | http://hdl.handle.net/1957/47804 |
