Water requirement and growth indicators of forest tree species seedlings produced with automated irrigation management

Abstract

The lack of information regarding the water requirement of tree species promotes water waste in the seedlings production in nurseries. Water requirement, the growth plant factors and water efficiencies for height and diameter were determined for Schizolobium parahyba (Vell.) Blake, Cytharexylum myrianthum Cham. and Ceiba speciosa Ravenna seedlings, under greenhouse conditions and automated irrigation management. We used sewage sludge biosolids as substrate in the seedling phase (280 cm-3 tube), and sandy soil material in the initial pot growth phase (18 dm-3 pot). In the seedlings phase, four water replacement levels were applied to the substrate, by drip irrigation, meaning average replacement ranging from 40 (V1) to 100% (V4) of species water requirement. Seedlings developed properly and 80 days after emergency, S. parahyba, C. myrianthum and C. speciosa seedlings received, respectively, 2.40, 1.08 and 0.85 L per plant, for V4. After growth phase (230 DAE), the total water volumes were, respectively, 70.0, 50.3 and 52.7 L per plant. Under adequate water supply, there were rapid recovery and growth of the species, even for the seedlings which showed different height and diameter in the tube phase. The growth plant factors values found were below 0.5 for all species indicating low sensibility to growth, both in height and in diameter, in response to water deficit. Water efficiency indicators point to distinct trends between the two phases, and C. speciosa present higher values of water efficiencies for height (80.7 and 17.0 cm L-1) and diameter (2.1 and 0.5 mm L-1) in both phases.