© 2000 by Institute of Chartered Foresters
Species and seasonal variability in the sensitivity of seedling conifer roots to drying and rough handling
1 Forestry Commission Research Agency, Northern Research Station, Roslin, Midlothian, UK
The ability of the fine root system of 2-year-old bare-rooted Picea sitchensis (Bong.) Carr. of Queen Charlotte Islands, Oregon and Alaskan provenances, Pseudotsuga menziesii (Mirb.) Franco, Larix kaempferi (Lamb.) Carr. and Pinus sylvestris L. to withstand standard drying and rough handling treatments was tested at regular intervals from September 1990 until April 1991. Electrolyte leakage was used to quantify the damage to the fine roots. Stressed seedlings had significantly (P < 0.001) greater leakage values than untreated seedlings and dried seedlings had significantly (P < 0.001) greater leakage values than roughly handled seedlings, but the responses varied with species and lifting date. After drying, leakage values increased in the order P. sitchensis (Oregon and Queen Charlotte Islands), P. sylvestris, L. kaempferi, P. sitchensis (Alaskan), P. menziesii. Leakage values after rough handling increased in the order P. sitchensis (Alaskan and Queen Charlotte islands), L. kaempferi, P. sitchensis (Oregon), P. sylvestris, P. menziesii. Leakage values were greatest in early September. During September and October there was a rapid downward trend in leakage. From December to February, leakage values decreased very slowly. In March leakage values of untreated and roughly handled seedlings increased slightly but decreased further in dried seedlings. These results indicate that great care must be taken during autumn planting to protect bare-rooted seedlings, particularly P. menziesii, from drying and to a lesser extent rough handling. Fine root leakage values following drying and rough handling had a significant linear relationship with the logarithm of the number of days required for the terminal bud to burst.