Controlled-release fertilization for optimizing the production of African mahogany (Khaya senegalensis) seedlings
Name: SANNAWÁ DA GRAÇA FERREIRA
Publication date: 12/02/2026
Examining board:
Name |
Role |
|---|---|
| CRISTIANE COELHO DE MOURA | Examinador Interno |
| GABRIEL SOARES LOPES GOMES | Examinador Externo |
| MARCOS VINICIUS WINCKLER CALDEIRA | Presidente |
| MAURÍCIO NOVAES SOUZA | Examinador Externo |
Summary: The expansion of African mahogany (Khaya) in the Brazilian forestry sector has intensified due to its high-value timber characteristics. Among species of the genus, Khaya senegalensis stands out for its development in sandy soils and drought resistance. In this context, the success of forest plantations depends primarily on seedling quality, which ensures greater field growth. Therefore, understanding the nutritional requirements during the initial cultivation phase is essential, especially given the scarcity of studies on this species. Thus, the objective was to determine, for each controlled-release fertilizer (CRF) formulation used, the dose capable of optimizing the initial growth of seed-derived seedlings of K. senegalensis. Three experiments were conducted, each corresponding to a CRF formulation with six-month release (NPK 17-43-00, NPK 16-08-12, and NPK 18-05-09). In each experiment, seven doses were applied (2, 4, 6, 8, 10, 12, and 14 g L¹), with four replications, and experimental units composed of 14 seedlings grown in 280 cm³ tubes. A control treatment without CRF was also included, common to all three experiments and maintained under the same experimental conditions. The experiments were arranged in a completely randomized design (CRD) in the nursery of the Federal Institute of Espírito Santo (Ifes), Alegre campus, ES, Brazil. The variables evaluated at 120 days—when seedlings were considered suitable for planting, with shoot height (H) of 25 to 30 cm and stem diameter (SD) of 5 to 10 mm—were shoot dry mass (SDM), root dry mass (RDM), total dry mass (TDM), sturdiness index (SI), total indirect chlorophyll content measured using the SPAD index, and morphological traits of the root system (length, surface area, projected area, average diameter, and volume). Shoot height and stem diameter were measured monthly up to 180 days using the remaining seedlings, marking the end of the evaluation period, which began 30 days after sowing. Data were analyzed using R statistical software. The Shapiro–Wilk test (5%) was applied to verify residual normality, followed by analysis of variance (ANOVA). Variables with significant ANOVA results were subjected to polynomial regression models, and maximum technical efficiency doses (MTED) were estimated from the fitted equations. The sturdiness index was identified as an excellent indicator of seedling quality, being easy to measure and interpret; therefore, it was used for dose recommendation: 11.57 g L¹ for formulation 16-08-12; 10.78 g L¹ for formulation 17-43-00; and 10.41 g L¹ for formulation 18-05-09. It was concluded that the use of controlled-release fertilizers is an effective practice for improving the quality and initial growth of Khaya senegalensis seedlings, contributing to the advancement of forest seedling production in Brazil.
Keywords: controlled-release fertilizer; forestry; nursery production; forest nutrition.
