NITROGEN FERTILIZATION FOR THE NURSERY PRODUCTION OF AUSTRALIAN RED CEDAR

Fertilization is one of the most important cultural practices in the production of seedlings, significantly influencing the quality and establishment of new stands. As the production of Toona ciliata var. australis lacks information on their nutritional requirements, especially nitrogen, this work evaluated the effect of different nitrogen concentrations and application intervals on the production of seedlings of this species, determining the most appropriate concentration. The seedlings were fertilized with 0, 250, 500, 1000, 2000 and 4000 mg L-1 of nitrogen (N), at intervals of 7 and 14 days till the end of the experiment. Increases in height, diameter, dry shoot and root mass, and Dickson quality index were observed as the concentration increased and decreased in higher concentrations, showing a negative quadratic regression in all variables, except the height/diameter ratio, which showed a higher value as N concentration increases. A higher growth showed by the Dickson quality index was achieved using the concentration of 2060 mg L-1. The absence of nitrogen and the concentration of 4000 mg L-1 limits the development of the seedlings, regardless of the interval. It is therefore recommended to use 2060 mg L-1 every 7 days for the production of Toona ciliata var. australis.