Increasing doses of resin-coated controlled release fertilizers (CRF) were compared with conventional fertilization and treatment without fertilizer. Five species of tree seedlings were used: the pioneers Guazuma ulmifolia (mutambo), Eucalyptus grandis and Pinus caribaea var. caribaea, the early secondary Peltophorum dubium ("canafístula") and the climax Calycophyllum spruceanum ("mulateiro"), grown in greenhouse. The seedlings were tilled in plastic tubes of 50 cm³ capacity, receiving as substrate a mixture of 50% earthworm humus, 30% decomposed eucalypt bark, and 20% carbonized rice husk (by volume). At 125 days after sowing the seedlings of G. ulmifolia, E. grandis and P. dubium submitted to conventional fertilization presented greater growth in height and shoot dry weight (stem plus leaf), in comparison with the CRF treatments. However, for these same species, root dry weight of the seedlings submitted to conventional treatment was not statistically different from that of the seedlings with the two largest doses of CRF (4.28 and 6.42 kg/m³ of substrate) and the root/shoot ratio was greater for dose 6.42 kg/m³, compared with the conventional treatment for the two former species. Calycophyllum spruceanum and Pinus caribaea var. caribaea showed little development for all treatments at 125 days.
Seedlings; nursery; controlled-release fertilizer and nutrition
