A fertilização azotada de pés-mãe de Eucalyptus globulus Labill.: efeito no crescimento

Abstract

To asses the effect of N fertilization on the growth of E. globulus stock plants, a nitrogen fertilization experiment was performed. During 3 years, stock plants of 2 clones (HD161 and CN5) were fertilized with complete nutrient solutions containing 5 different levels of N (50, 100, 200, 400 and 800 mg N L-1). Total biomass, leafbiomass, leaf area and number of shoots produced during the 3 years period were measured. Increasing levels of applied nitrogen till 400 mg N L-1 led to a significant increase of both biomass and shoot production. However, these productions were not significantly affected when N fertilization increased from 400 to 800 mg N L-1. Increasing levels of applied nitrogen also led to an increase of: i) total leaf area ii) specific leaf area (29% increase) and iii) leaf area ratio (13% increase), showing that with a higher N availability stock plants tend to improve their photosynthetic apparatus. Results show that nitrogen is a fundamental nutrient for the growth of E globulus stock plants and, as a consequence, nitrogen fertilization must be optimized. The maximum growth of E. globulus mother plants was achieved with 400 mg N L-1.