Title: Effect of mycorrhizae and light environment on growth and physiology of Fraxinus excelsior planted as a street tree.

Summary: This study evaluated the effectiveness of mycorrhiza in improving growth, health, and leaf gas exchange of ash trees planted as street trees growing in two different light environments. In spring 2005, 54 Fraxinus excelsior were planted along both sides of a road characterized by high traffic and air pollution. Treated trees were inoculated with species-specific strains of mycorrhizae-forming fungi derived from root samples taken in Tuscany (Italy) or Germany. Untreated controls were not inoculated. Shoot growth, stem diameter, bud break date, leaf yellowing, and abscission date were recorded. Leaf gas exchange was measured with a portable infrared gas analyzer and chlorophyll fluorescence was measured three times per year with a portable fluorimeter. Chlorophyll content was measured once per year with a SPAD-meter. Root samples were collected from all plants and analyzed in order to measure myzorrhyza intensity and frequency on inoculated and control roots. The effect of inoculums with specific and commercial mycorrhyza and effects of light environment on plant growth and physiology will be discussed.

Alessio Fini, PhD, University of Florence, Horticulture, Novate Milanese, MI, Italy

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