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• 1. [Article] Physiological and anatomical studies of several groups of Douglas-fir (pseudotsuga menziesii (Mirb.) Franco) seedlings which demonstrated differential survival potential under drought stress

  Several hundred two year old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were planted in an enclosure designed to permit control of soil moisture. The seedlings came from five seed sources ...

  Citation × Citation Citation Abstract Copy Title: Physiological and anatomical studies of several groups of Douglas-fir (pseudotsuga menziesii (Mirb.) Franco) seedlings which demonstrated differential survival potential under drought stress Author: Heiner, Terry Charles, 1941- Several hundred two year old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were planted in an enclosure designed to permit control of soil moisture. The seedlings came from five seed sources in southern Oregon and one seed source in northwestern Oregon. Mortality terminal and lateral budburst, and soil moisture were recorded during the growing season. The final death count showed that the mortality of the northwest Oregon seed source (84%) differed significantly (at the 1% level) from that of four southern Oregon seed sources (ca 44%) and that the mortality of all differed significantly from that of a fifth southern Oregon source (30%). The purpose of this study was to determine what anatomical, morphological, and physiological characteristics were associated with survival. Root length, calcium-potassium ratio, cuticle thickness, shoot-root ratio, and root surface area are not correlated with mortality. A relation between mortality and the amount and rate of budburst was found. The low bud activity and high mortality of the northwest Oregon seedlings may be an expression of their physiological condition. Earlier bud activity by the southern Oregon seedlings may be a response to a lower minimum temperature, and is a survival advantage in areas with severe summer drought. Title: Physiological and anatomical studies of several groups of Douglas-fir (pseudotsuga menziesii (Mirb.) Franco) seedlings which demonstrated differential survival potential under drought stress Author: Heiner, Terry Charles, 1941- Several hundred two year old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were planted in an enclosure designed to permit control of soil moisture. The seedlings came from five seed sources in southern Oregon and one seed source in northwestern Oregon. Mortality terminal and lateral budburst, and soil moisture were recorded during the growing season. The final death count showed that the mortality of the northwest Oregon seed source (84%) differed significantly (at the 1% level) from that of four southern Oregon seed sources (ca 44%) and that the mortality of all differed significantly from that of a fifth southern Oregon source (30%). The purpose of this study was to determine what anatomical, morphological, and physiological characteristics were associated with survival. Root length, calcium-potassium ratio, cuticle thickness, shoot-root ratio, and root surface area are not correlated with mortality. A relation between mortality and the amount and rate of budburst was found. The low bud activity and high mortality of the northwest Oregon seedlings may be an expression of their physiological condition. Earlier bud activity by the southern Oregon seedlings may be a response to a lower minimum temperature, and is a survival advantage in areas with severe summer drought. Close