The effect of nitrogen on growth and architecture of Fraxinus pennsylvanica 'Patmore' (green ash) in Field-grow containers at two sites in Manitoba, Canada

Abstract

Fraxinus pennsylvanica var. subintegerrima (Vahl) Fern. 'Patmore' green ash was established at two sites in southern Manitoba. Four levels of N fertilizer (4.5–400 ppm) were applied during two growing seasons. Growth and development of the trees was dependent on the site and local environmental conditions. At Morden, the annual height growth increment was greater with lower levels of N applications and declined at higher levels, while at Winnipeg higher levels resulted in greater growth. Stem diameter changes followed a similar pattern. The numbers of lateral shoots per parent shoot were only weakly affected by N treatment and any differences appeared to be an indirect effect of parental shoot length. The Field-grow containers at the Winnipeg site were installed in crass-sod which penetrated the containers and appeared to result in competition for N resources. The Morden site was kept cultivated and thus there was no such competition. At Morden, it is possible that wicking from the surrounding soil may have moved excessive salts into the containers resulting in high conductivity values and toxicity. Key words: Field-grow, biomass, roots, architecture, fertilization, Fraxinus pennsylvanica