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• 1. [Article] The effect of age on transpiration rates of Douglas-fir seedlings (Pseudotsuga menziesii (Mirb.) Franco)

  The objective of this study was to determine the effect of age on rates of transpiration by Douglas-fir seedlings. Seeds were collected from a xeric site (Goldendale, Washington) and a mesic site (Forks, ...

  Citation × Citation Citation Abstract Copy Title: The effect of age on transpiration rates of Douglas-fir seedlings (Pseudotsuga menziesii (Mirb.) Franco) Author: Geppert, Rollin Roger The objective of this study was to determine the effect of age on rates of transpiration by Douglas-fir seedlings. Seeds were collected from a xeric site (Goldendale, Washington) and a mesic site (Forks, Washington). The seedlings were grown in a cold frame and in a growth chamber for periods of two, four, eight, and sixteen weeks. Although much interaction occurred between age, seed source, and growing condition, significant differences were delineated for each of the three variables. For both the Forks and Goldendale seedlings, the transpiration rates were not found to decrease significantly with increasing age. At a given age, four, eight, or sixteen weeks, the Forks seedlings grown in the cold frame, in general, had the highest rates of transpiration. The effect of seed source was found to be significant when the seedlings were grown in the cold frame. Under these conditions the seedlings from Forks, Washington, had a significantly higher rate than the seedlings from Goldendale, Washington. The effect of conditioning on transpiration resulted in the seedlings grown in a cold frame having a significantly higher rate than those grown in a growth chamber. Title: The effect of age on transpiration rates of Douglas-fir seedlings (Pseudotsuga menziesii (Mirb.) Franco) Author: Geppert, Rollin Roger The objective of this study was to determine the effect of age on rates of transpiration by Douglas-fir seedlings. Seeds were collected from a xeric site (Goldendale, Washington) and a mesic site (Forks, Washington). The seedlings were grown in a cold frame and in a growth chamber for periods of two, four, eight, and sixteen weeks. Although much interaction occurred between age, seed source, and growing condition, significant differences were delineated for each of the three variables. For both the Forks and Goldendale seedlings, the transpiration rates were not found to decrease significantly with increasing age. At a given age, four, eight, or sixteen weeks, the Forks seedlings grown in the cold frame, in general, had the highest rates of transpiration. The effect of seed source was found to be significant when the seedlings were grown in the cold frame. Under these conditions the seedlings from Forks, Washington, had a significantly higher rate than the seedlings from Goldendale, Washington. The effect of conditioning on transpiration resulted in the seedlings grown in a cold frame having a significantly higher rate than those grown in a growth chamber. Close

• 2. [Article] The effect of internal and external moisture stress on the transpiration rate of Douglas-fir seedlings (Pseudotsuga menziesii (Mirb.) Franco)

  The objective of this study was to examine the transpirational behavior of Douglas-fir seedlings from two origins,, each grown in two environments, and subject to a range of moisture stress. Forks and ...

  Citation × Citation Citation Abstract Copy Title: The effect of internal and external moisture stress on the transpiration rate of Douglas-fir seedlings (Pseudotsuga menziesii (Mirb.) Franco) Author: Unterschuetz, Phillip The objective of this study was to examine the transpirational behavior of Douglas-fir seedlings from two origins,, each grown in two environments, and subject to a range of moisture stress. Forks and Goldendale, Washington were the mesic and xeric seed origins respectively. One-half of the seedlings from each origin was grown in a growth chamber and the other half in a cold frame. The transpiration rate, soil moisture stress, and plant moisture stress were measured on each seedling at the age of six weeks. Tri-variate response surfaces were developed for each seed origin-preconditioning combination of seedlings. There were no apparent differences in the transpirational response of the seedlings of the seed source-preconditioning combinations to soil moisture stress. There were highly significant differences in transpirational behavior among seedlings of the several factor combinations in response to plant moisture stress. Those seedlings grown in a cold frame had consistently higher subsequent transpiration rates regardless of the plant moisture stress. Xeric origin seedlings had higher subsequent transpiration rates at moderate plant moisture stress than did the mesic origin seedlings. The transpiration rates of the seedlings from the two origins were at parity between ten and 12 atmospheres plant moisture stress. Above 12 atmosphere plant moisture stress, the xeric source seedlings transpired less than the mesic source seedlings. The observed transpirational behavior of the xeric source seedlings was seen to be a distinct ecological advantage. Title: The effect of internal and external moisture stress on the transpiration rate of Douglas-fir seedlings (Pseudotsuga menziesii (Mirb.) Franco) Author: Unterschuetz, Phillip The objective of this study was to examine the transpirational behavior of Douglas-fir seedlings from two origins,, each grown in two environments, and subject to a range of moisture stress. Forks and Goldendale, Washington were the mesic and xeric seed origins respectively. One-half of the seedlings from each origin was grown in a growth chamber and the other half in a cold frame. The transpiration rate, soil moisture stress, and plant moisture stress were measured on each seedling at the age of six weeks. Tri-variate response surfaces were developed for each seed origin-preconditioning combination of seedlings. There were no apparent differences in the transpirational response of the seedlings of the seed source-preconditioning combinations to soil moisture stress. There were highly significant differences in transpirational behavior among seedlings of the several factor combinations in response to plant moisture stress. Those seedlings grown in a cold frame had consistently higher subsequent transpiration rates regardless of the plant moisture stress. Xeric origin seedlings had higher subsequent transpiration rates at moderate plant moisture stress than did the mesic origin seedlings. The transpiration rates of the seedlings from the two origins were at parity between ten and 12 atmospheres plant moisture stress. Above 12 atmosphere plant moisture stress, the xeric source seedlings transpired less than the mesic source seedlings. The observed transpirational behavior of the xeric source seedlings was seen to be a distinct ecological advantage. Close