EFFECTS OF THE PHYSICAL-PROPERTIES OF SPHAGNUM PEAT ON THE NURSERY GROWTH OF CONTAINERIZED PICEA-MARIANA AND PICEA-GLAUCA SEEDLINGS

Containerized black spruce (Picea mariana [Mill.] B.S.P.) and white sp ruce (Picea glauca [Moench] Voss) seedlings were grown from seed in Sp hagnum media at two different degrees of humification (light and moder ate) and at two artificially created textural grades (with or without particles < 1.3 mm). During the 26-week growing period, the water cont ent in the media was maintained at 60% of container capacity. At the e nd of the growing period, white spruce seedlings grown in the peat med ia enriched in fine particles (< 1.3 mm) had a greater height, diamete r, and root and shoot dry mass than those grown in peats deprived of f ine particles. The degree of humification per se had little influence on growth. Black spruce seedlings, on the other hand, showed only a sm all increase in height with the addition of fine particles. Significan t (p < 0.05) linear relationships were found between physical properti es of the media and final morphological measurements of white spruce: between easily available water and both height (R = 0.97) and shoot dr y weight (R = 0.98), and between air volume and stem diameter (R = -0. 95). Water relations parameters of black spruce and white spruce were largely unaffected by differences in the physical properties of the pe at media.