Root and shoot growth, assimilate partitioning and cell proliferation in roots of Sitka spruce (Picea sitchensis) grown in filtered and unfiltered chambers.

Rooted cuttings of clonal Sitka spruce (Picea sitchensis (Bong.) Carr.) were grown from April to October in 1 m long tubes sunk into the ground inside open top chambers. The same experiment was repeated in each of two consecutive years using a different clone of Sitka spruce each year. Air was either passed directly into the chambers (ambient air) or passed over charcoal filters which removed the majority of gaseous pollutants before entering the chambers (filtered air). Ambient pollution did not appear to influence the growth of Sitka spruce at least over the experimental period used. No significant differences were found between plants exposed to ambient or filtered air in terms of shoot and root dry mass, needle dry mass, root length, carbohydrate content of roots and needles, and in the percentage of meristematic cells close to the apex in each phase or interphase or undergoing mitosis.