IRRIGATION AND NITROGEN FERTILIZATION EFFECTS ON THE QUALITY OF Tabebuia serratifolia Vahl Nich SEEDLINGS

Abstract

The good development of seedlings in the nursery has a direct influence on the success of planting in the field, since the presence of nutrients in the substrate, especially nitrogen, phosphorus and potassium, has a great impact on the final quality of the seedlings. The amount of water required for irrigation can vary according to the species, and both the lack and excess of nutrients can affect the growth of seedlings positively or negatively. Thus, the objective of this study was to determine the quality of yellow ipê seedlings as a function of different irrigation depths and doses of nitrogen fertilization. The experiment was conducted in a greenhouse at the Center of Agricultural Sciences of the State University of the Tocantina Region of Maranhão, in Imperatriz - MA. The experimental design was in randomized blocks, in a 3 × 3 factorial scheme, with five replications. The treatments consisted of three irrigation levels (50%, 100% and 150% of ETo) and three nitrogen doses (0, 100 and 200 mg.dm⁻³), using ammonium sulfate as the source. After 100 days from the beginning of the treatments, height (H), stem diameter (DC), fresh shoot mass (MFPA), fresh root mass (MFR), total fresh mass (MFT), dry shoot mass (MSPA), dry root mass (MSR) and total dry mass (MST) were evaluated. The Dickson Quality Index (IQD), which evaluates the quality of the seedlings based on their morphological characteristics, was also calculated. The best results for all variables analyzed were observed in the seedlings treated with 200 mg.dm⁻³ of N and irrigated with 100% of ETo, which also presented the highest IQD.