Transplanting shock in white spruce; effect of cold-storage and root pruning on water relations and stomatal conditioning

White spruce Piceae glauca (Moench) Voss] seedlings were pre-conditioned by cold storage and root pruning and a study was made of the effects of conditioning on root regeneration and stomatal adaptation following transplanting.
Root pruning (0 to 75% of the initial root area) of dormant seedlings immediately prior to transplanting did not confer any detectable physiological advantage in either cold-stored or freshly-lifted seedlings. Transpiration rates and stomatal resistance were not greatly affected by root pruning in the 6 week period after planting and root pruning did not greatly alter the response to drought.
Cold-stored seedlings appear better able to avoid transplanting shock and an early drought despite delayed root growth as evidenced by a) a delay in flushing of new shoot growth and b) pre-conditioning of the stomatal apparatus which reduced water loss after planting and when moisture was limiting. Seedlings freshly-lifted in the spring did not show these adaptive responses and their stomata were poorly adapted to reduce water loss in the post-planting period after a drought.