Physiological changes in seedlings of Eucalyptus grandis (Hill) ex Maiden submitted to nitrogen fertilization and ethylene

Fertilization and hardening during seedling production are extremely important to promote morphophysiological changes that enhance growth and minimize the stress damage after field planting. This experiment aimed to evaluate nitrogen fertilization during production of Eucalyptus grandis (Hill) ex Maiden seedlings and to quantify morphometric changes. The experiment was conducted in a greenhouse located at 24 degrees 33 `S and 54 degrees 04' W in a randomized complete block design in a factorial scheme with an additional control (3 x 4+1) composed by three regimes of fertilization (100 mg L-1 conventional N, 100 mg L-1 exponential N and zero N) applied for three months (nine applications) and four ethylene applications of 1000 mg L-1 more one control without application of plant regulator with six replicates of five plants per plot. Fertilization, both exponential or conventional, as well as the weekly application of ethylene, induced physiological changes ofEucalyptus grandis seedlings during hardening. Fertilization regimes presented similar effects with two ethylene applications, reducing phosphorus and potassium levels and stimulating the accumulation of lignin in the cell wall of roots. There was no effect of the fertilization regimes and the ethylene application on the survival of Eucalyptus grandis seedlings.