ROOT EXPOSURE OF WHITE SPRUCE NURSERY STOCK

Two lots of 2-0 white spruce (Picea glauca (Moench) Voss) in soil blocks were brought into the greenhouse in February. The first lot, called "active" was left in the greenhouse for 10 days before transplanting. The second lot, called "dormant" was left in the greenhouse for 3 days before transplanting. The seedlings were then washed from the soil, graded, and exposed to the air on nets, some in the greenhouse, some in an adjacent laboratory. The exposure varied from 0 (immediate planting), to ½, 1, 1½, 2 and 2½ hours. After planting, the seedlings were grown in the greenhouse for four months, then removed from the soil and measured.The results showed greater mortality from root exposure of the "active" seedlings. The mortality increased with the length of exposure. Growth also was inhibited most within the "active" stock. However, growth was reduced even in the "dormant" stock by root exposures of ½ hour or longer. Differences due to location in greenhouse or laboratory during root exposure were not significant.