Viability of Picea abies Seedlings with Damaged Roots and Shoots

Cold stored, one-year-old Norway spruce seedlings were manipulated to obtain seedlings with different viabilities. Either half or whole root systems were submerged in boiling water for five minutes, or 40 or 75 % of the shoot volume was cut away. The seedlings were grown in a climate chamber, and transpiration rates were estimated daily for 20 days after treatment by weighing individual seedlings. Rates of transpiration and photosynthesis were also measured by porometry after 20 days. Root and shoot growth was assessed after 21 days. Buds of treated seedlings broke earlier than the buds of untreated ones. The transpiration rate increased with time for the undamaged seedlings, while the severely damaged seedlings transpired at a uniform low rate throughout the experiment. Root growth capcity ' Tailed to detect the different magnitudes of root damage, whereas the reduction in both transpiration and photosynthesis rates did. Transpiration rates estimated by weighing correlated linearly with those measured by porometer after 20 days, and both correlated with the rate of photosynthesis and the shoot volume. Also, the dry weight of roots grown during the experiment (root growth capacity) correlated significantly with the rate of photosynthesis.