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• 1. [Article] Water relations and the root regeneration response of Douglas-fir

  The effect of lifting date and root-pruning treatments on water potential, root regeneration, and shoot growth of six-month-old and three-year-old Douglas-fir seedlings bare-root transplanted into a growth ...

  Citation × Citation Citation Abstract Copy Title: Water relations and the root regeneration response of Douglas-fir Author: Cobb, Cheryl Anne The effect of lifting date and root-pruning treatments on water potential, root regeneration, and shoot growth of six-month-old and three-year-old Douglas-fir seedlings bare-root transplanted into a growth chamber, and sawdust bed, respectively, was studied. Root growth in six-month-old and three-year-old seedlings was highest in February and August respectively. Survival was highest in November for seedlings of both ages. The time to first root growth, water potential four weeks after transplanting, and survival were correlated. The possibility that the maintenance of plant turgor above the critical level necessary to allow root growth is important for survival of an actively growing transplant is discussed. The effect of root-pruning on transplant water potential, root growth and survival varied with season. In a second study six-month-old Douglas-fir seedlings were subjected to eight drying cycles in which the seedlings were allowed to dry to a -15 bar water potential before watering. Root growth, water potential, and survival of transplants were measured under stressed and control conditions. Water potential, soil moisture content and survival of seedlings subjected to a prolonged drying period were recorded. Preconditioning treatments were effective in increasing drought resistance under stress conditions. Reductions in shoot elongation, dry matter production, and early bud set were noted. Though inadvertant watering of the transplants made conclusions impossible, survival data and' data collected prior to watering indicate that root growth and survival were improved by the treatment. Title: Water relations and the root regeneration response of Douglas-fir Author: Cobb, Cheryl Anne The effect of lifting date and root-pruning treatments on water potential, root regeneration, and shoot growth of six-month-old and three-year-old Douglas-fir seedlings bare-root transplanted into a growth chamber, and sawdust bed, respectively, was studied. Root growth in six-month-old and three-year-old seedlings was highest in February and August respectively. Survival was highest in November for seedlings of both ages. The time to first root growth, water potential four weeks after transplanting, and survival were correlated. The possibility that the maintenance of plant turgor above the critical level necessary to allow root growth is important for survival of an actively growing transplant is discussed. The effect of root-pruning on transplant water potential, root growth and survival varied with season. In a second study six-month-old Douglas-fir seedlings were subjected to eight drying cycles in which the seedlings were allowed to dry to a -15 bar water potential before watering. Root growth, water potential, and survival of transplants were measured under stressed and control conditions. Water potential, soil moisture content and survival of seedlings subjected to a prolonged drying period were recorded. Preconditioning treatments were effective in increasing drought resistance under stress conditions. Reductions in shoot elongation, dry matter production, and early bud set were noted. Though inadvertant watering of the transplants made conclusions impossible, survival data and' data collected prior to watering indicate that root growth and survival were improved by the treatment. Close