No abstract

Survival, phenology, and growth performance of 2 + 0 Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and noble fir (Abiesprocera Rehd.) seedlings planted at 1500 m in the Oregon Cascade Range were determined following a lifting on November 7 with 7 months of cold storage or lifting on March 1 with 3 months of cold storage. Storage temperature remained between 1 and 2 °C. There was no difference in Douglas-fir survival attributable to the lifting – cold-storage treatments during the first two growing seasons. The first-season survival of noble fir stored for 7 months was superior to that of those stored for 3 months, but no difference was evident after the second growing season. Timing of bud burst did not differ significantly among treatments for either species. However, the rate of bud burst was significantly greater for noble fir seedlings lifted in November and stored 7 months than for those lifted in March and stored 3 months. No difference in the rate of bud burst was observed between treatments for Douglas-fir. Shoot/root ratio for both species and treatments decreased significantly in the first growing season, but did not change significantly in the second growing season. Regardless of species, no differences were found in height growth or diameter increment between the two lifting – cold-storage treatments for the two consecutive growing seasons. The results suggest that Douglas-fir and noble fir seedlings originating from high-elevation seed sources can be lifted in fall and cold stored for 7 months without adverse effects on seedling performance.

Applieatlon. Results of this study show that container-grown true fir seedlings respond dynamically to treatments inducing terminal bud dormancy. To induce dormancy in healthy planting stock, the seed source should be considered. The proper induction treatment (moisture-temperature-photoperiod combination) may vary according to seedling age. Moisture-stress treatment of young seedlings should be avoided.Abstraet. Twelve-week-old container-grown seedlings of noble fir (Abies procera Rehd.) and Shasta red fir (A. magnifica A. Murr. var. shastensis Lemm.), both high-elevation species, were grown under controlled environments in a study of induction of terminal-bud dormancy. Eight treatment combinations of "long" (15 h) or "short" (11 h) photoperiods, "warm" (25*/20 *C) or "cool" (18"/12 *C) thermoperiods, and "dry" (-1.2 MPa) or "wet" (-0.6 MPa) moisture regimes were imposed upon seedlings for 12 weeks. Treatment factors significantly affecting the induction of dormancy in terminal buds of seedlings were identified over time. The results suggest that seedlings responded dynamically to dormancy cues. The "warm/dry" and "cool/wet" combinations induced dormancy in the first 2 weeks in noble fir and in the first week in Shasta red fir. "Short-day/warm" and "long-day/cool" combinations enhanced dormancy induction in weeks 3 to 4 in noble fir and in weeks 1 to 7 in Shasta red fir. "Short" days and "cool" thermoperiods independently hastened dormancy induction in noble fir in weeks 5 through 12.

Survival, phenology, and growth of containerized noble fir (Abiesprocera Rehd.) and Shasta red fir (Abiesmagnifica A. Murr. var. shastensis Lemm.) seedlings were measured in response to dormancy induction chilling, and postplanting irrigation treatments. Temperature, photoperiod, and moisture were varied to induce dormancy. Seedlings were not chilled during the first winter, but received natural chilling during the second winter. In the first growing season (no winter chilling), terminal buds did not flush, but remained alive and inactive. Buds on lateral branches flushed and extended normally. In the second season (natural winter chilling), all terminal buds and lateral buds flushed. Dormancy induction treatment did not significantly affect budbreak, survival, or growth. However, postplanting drought simulation significantly reduced height, diameter, and aboveground biomass. The results demonstrate that the terminal buds of planted, nonchilled seedlings of these true fir species can remain inactive through an entire season and then resume growth once their chilling requirements are fulfilled.

Two vegetation management methods, paper mulching and spot-spraying with glyphosate, were combined with a root-dipping treatment, Terra Sorb®, to test effects on seedling survival and height growth on a harsh site in Oregon. Survival of Douglas-fir (Pseudotsuga menziesii) seedlings was significantly higher after the third growing season when competing vegetation had been controlled with mulch or glyphosate during the first two growing seasons. Seedlings retreated with paper mulch and glyphosate before the second growing season had 36 and 25% higher survival than those that were not retreated. None of the seedlings was retreated before the third season; after this season, survival of seedlings treated twice with glyphosate was 26, 23, and 21% higher than seedlings receiving one glyphosate treatment and one or two mulch applications, respectively. There were no differences in seedling height growth among treatments. Rootdipping with Terra Sorb® did not influence survival or growth. West. J. Appl. For. 1:108-111 Oct. 86.