Abstract
Qualitative and quantitative analyses of soluble sugars were conducted on needle and root samples of 17-month-old white spruce seedlings grown for the last 5 months at 50°, 70°, 80°, 90°, and 100 °F soil temperatures under continuous light in a greenhouse at an air temperature of 70 °F. Additional samples were taken when seedlings grown under these conditions were transferred for 1 month to a cold room at 34 °F under continuous light. Shoot and root growth was also studied on newly germinated seedlings exposed to soil–air temperatures of 65°–70°, 70°–70°, 80°–70°, and 90°–70 °F under continuous light for 8 months.An increase in sugars per unit dry weight, a greater apical growth, and a higher shoot–root ratio were associated with the 50°–70 °F and 65°–70 °F soil–air temperatures. The seedlings exposed for 1 month to soil–air temperatures of 34°–34 °F showed a considerable increase of soluble sugars, especially of the higher oligosaccharides from the raffinose family, when compared with those grown at 70 °F air temperature and varying soil temperatures. When seedlings are exposed to low temperatures, even at the period of budbreak, the change in the composition and amount of sugars is similar to that established under natural conditions in the fall.