Food Reserves and Seasonal Growth of Douglas-Fir Seedlings

Seasonal growth of tops and roots and concomitant trends in food reserves were observed biweekly on Pseudotsuga menziesii (Mirb.) Franco seedlings of two seed sources growing in a Pacific Northwest forest nursery. A general pattern of alternating root, diameter, and shoot growth wasfound. Rapid root growth did not coincide with rapid shoot elongation, but preceded and followed it. Increased root activity was strongly correlated with lowered reducing sugar concentrations in seedling roots of the faster growing source. Sucrose and raffinose increased markedly during earlywinter and were apparently converted to starch in spring prior to growth. Concentrations of reducing sugars, crude fat, and protein nitrogen changed little with season. Implications of this information on timing of lifting, storage, and transplanting of seedlings are discussed.