SUGARS, RELATIVE WATER CONTENT, AND GROWTH AFTER PLANTING OF DORMANT LODGEPOLE PINE SEEDLINGS

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Abstract
Dormant 3-yr-old lodgepole pine seedlings (Pinus contorta var. latifolia) were stored for 3–4 mo in air-tight plastic bags at 2 ± 1 C in the dark. Groups of 40–50 seedlings were removed from storage and grown in a greenhouse for 5 wk. Needle and root samples were taken at the time of planting and 5 wk later to determine their relative water content (RWC) and sugar contents. The upper needles had a 3–10% higher RWC than the lower needles. Comparisons between actively growing versus nonactive classes of seedlings demonstrated that new root growth after planting was not related to the hydration of the needles at the time of planting. Contents of free sugars (glucose, fructose, sucrose, stachyose, raffinose, galactose, and xylose), starch, and pectic sugars (arabinose, galactose, xylose, and mannose) were all reduced during the 5-wk growth period. Differences in subsequent root activity were not related to differences in root sugar contents at planting; however, sucrose content in actively growing root systems was significantly higher than in roots with no new growth 5 wk after planting. The supply of sucrose from the shoot after planting appeared to be associated with the occurrence of new root growth in stored lodgepole pine seedlings. Damage during storage to photosynthetic or sugar transport systems in the shoot may have caused inadequate export of sucrose to the root system after planting, which in turn reduced the root regeneration capacity.