THE EFFECT OF NITROGEN ON GROWTH AND ARCHITECTURE OF FRAXINUS-PENNSYLVANICA PATMORE (GREEN ASH) IN FIELD-GROW CONTAINERS AT 2 SITES IN MANITOBA, CANADA

Fraxinus pennsylvanica var. subintegerrima (Vahl) Fern. 'Patmore' gree n ash was established at two sites in southern Manitoba. Four levels o f N fertilizer (4.5-400 ppm) were applied during two growing seasons. Growth and development of the trees was dependent on the site and loca l environmental conditions. At Morden, the annual height growth increm ent was greater with lower levels of N applications and declined at hi gher levels, while at Winnipeg higher levels resulted in greater growt h. Stem diameter changes followed a similar pattern. The numbers of la teral shoots per parent shoot were only weakly affected by N treatment and any differences appeared to be an indirect effect of parental sho ot length. The Field-grow containers at the Winnipeg site were install ed in grass-sod which penetrated the containers and appeared to result in competition for N resources. The Morden site was kept cultivated a nd 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.