Efeito do nitrogênio no estado nutricional e na produção de biomassa em minicepas de Eucalyptus dunnii Maiden

Abstract

The aim of this study was to evaluate the nutritional state and the biomass production of ministumps of Eucalyptus dunnii Maiden submitted to fertirrigation with nitrogen different forms and doses. The clonal minigarden of 90 days seedlings was cultivated in the commercial substrate of pine sp bark and vermiculite (tubes of 55 cm3). Different forms of nitrogen were tested in the concentration of 0.4 g L-1 (NO3-, NH4+ and NO3- + NH4+), the nitrogen sources were: KNO3, (NH4)2SO4 and NH4NO3, respectively. In the dose test an unique source (NH4NO3) was used in the following concentrations of N: 0.2; 0.4 and 0.6 g L-1. Each ministump was weekly watered with 10 mL of the tested solution. At 42 days of experiment, foliar samples were collected for determining the nutritional state. At 157, 185 and 216 days, minicuttings was collected for determination of the biomass production. None of tested nitrogen forms and doses showed negative effect on foliar nutritional state of the minicuttings. The dry biomass production was bigger for the NO3- +NH4+ form and for 0,6 g L-1 dose. In conclusion, the NO3- +NH4+ N form and the 0,6 g L-1 N were recommended. Bigger N doses can be able to increase the biomass production in the clonal minigarden of E. dunnii.