Dormancy

Dormancy is a resting stage in plants. Tissues that are predisposed to grow under favorable conditions do not do so during dormancy because of internal inhibitions. The conditions of dormancy include a series of different physiological phases, each of which has different attributes and requirements. Research consistently shows that proper physiological condition, particularly dormancy, has a critical effect on reforestation success. The objective for seedling storage and transportation is to maintain seedlings in a relatively deep dormancy phase where they have as much resistance to environmental stress as possible. Trees that have broken dormancy will deteriorate rapidly in storage, even under the best conditions.

Trees break dormancy due to environmental changes that affect their metabolism. Controlling temperature and light intensity is essential when maintaining dormancy. When seedlings become active, they will respire. Seedling respiration can be checked by placing the crown in a small, airtight plastic bag. If moisture forms on the inside lining of the bag in 30 minutes or less, the seedling is active and respiring, even though no other physical indicators may be evident. Storage temperatures must be lower that 34 °F to prevent active respiration.

Once seedlings have broken dormancy, new root tips may grow. They are extremely sensitive to damage. If seedlings exhibit more than occasional root tip elongation and cannot be planted within 1 to 2 days, they should be destroyed. Physical signs of activity are noted by yellow-white root tips, bud swelling, or buds that have burst. When dormancy is broken and roots are pruned or damaged, the seedling must repair the damage (by building callus tissue) before it can devote significant energy to regenerating new roots. This effort will slow development of new roots after planting, while using stored carbohydrates needed for new growth and further increasing the risk of mortality or reduced growth. Every effort must be made to maintain dormancy in storage.