Crescimento de mudas de Gon?alo-Alves (Astronium fraxinifolium) sob diferentes fontes e doses de nitrogênio

摘要

Degradation of cerrado and the loss of its biodiversity require the revegetation of the areas in this biome, where there are species with little known potential of economical and environmental use. The objective of this work was to evaluate the effect of different sources and levels of nitrogen on growth of seedlings of Gon?alo-Alves(Astronium fraxinifolium), tree species native from cerrado, threatened of extinction. The experiment was carried out in a greenhouse, at UNESP/Campus of Ilha Solteira. The soil used (Red Latosol) was collected from 0.0 to 0.20m layer in Selvíria (MS). The utilized sources of N, ((NH4)2SO4, NH4NO3 and Ca(NO3)2), were applied at doses of 0; 50; 100; 150 and 200 mg dm-3. The N applied as Ca(NO3)2 presented the best results for the soil used. Gon?alo-Alves seedlings growth was not influenced by the N sources, but it responded to the doses of N. Height, stem diameter, content of leaf chlorophyll, fresh and dry matter weights of the aerial section, weights of fresh and dry matter of root system, total dry matter weight, as well as IQD and ratio of weight of dry matter of aerial section and root system presented maximum value for doses which ranged from 59.0 to 72.5 mg dm-3 N, suggesting the dose of 72.5 mg dm-3, as sufficient for a satisfactory growth of seedlings of Gon?alo Alves.