Formulations and doses of controlled-release fertilizers in the production of African mahogany seedlings (Khaya anthotheca)
Name: MARNELA DA CARIDADE MANUEL
Publication date: 25/02/2026
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 establishment of high-quality seedlings is one of the primary prerequisites for the success of forest plantations, with fertilization playing a decisive role in the production of vigorous and well-formed plants. In this context, the present study aimed to evaluate the growth and quality of Khaya anthotheca (Welw.) C.DC. (African mahogany) seedlings in response to different formulations and application rates of controlled-release fertilizers (CRF). The experiments were conducted under greenhouse conditions at the Federal Institute of Espírito Santo (Ifes), Alegre campus, located in the district of Rive. A completely randomized design (CRD) was adopted, considering three CRF formulations (16-08-12, 17-43-00, and 18-05-09), each evaluated in an independent experiment. For each formulation, eight CRF rates (0, 2, 4, 6, 8, 10, 12, and 14 g L¹) were tested, applied to seedlings grown in tubes with a volume of 288 cm³. Each experiment consisted of four replicates per treatment, totaling 32 experimental units per formulation. Each experimental unit comprised 14 seedlings, resulting in 56 seedlings per treatment and 448 seedlings per experiment. Sowing was performed directly in the tubes using a commercial substrate, with two seeds sown per container. Seedling height (H) and collar diameter (CD) were measured monthly, starting at 30 days after sowing and continuing until the end of the experimental period. Final evaluations were carried out at 150 days after sowing for the 16-08-12 and 18-05-09 formulations, and at 180 days for the 17-43-00 formulation, in accordance with the criteria used to define seedling quality, whereby height should range from 20 to 35 cm and collar diameter from 5 to 10 mm. At the final evaluation stage, the following variables were assessed: seedling height (H), collar diameter (CD), robustness index (H/CD), shoot dry mass (SDM), root dry mass (RDM), total dry mass (TDM), chlorophyll a and b content, root length, mean root diameter, and root system volume. Growth models were fitted based on the monthly H and CD data. The variables H, CD, H/CD ratio, chlorophyll a and b, leaf area, SDM, RDM, and TDM obtained at the end of the experiments were subjected to analysis of variance (ANOVA) at a 5% significance level. When significant differences among treatments were detected, polynomial regression models were fitted to describe the response of the variables as a function of CRF rates. From the fitted regression equations, the rate of maximum technical efficiency (MTE) was determined for each variable. The results demonstrated that the application of CRF in the 16-08-12, 18-05-09, and 17-43-00 formulations positively influenced the growth of Khaya anthotheca seedlings, promoting consistent increases throughout the evaluation period. Growth curves for seedling height indicated that the 16-08-12 and 18-05-09 formulations reached the target height defined by the methodology at 120 days after sowing across all treatments, except for the control (no CRF application). For the 17-43-00 formulation, the target height was reached at 150 days. Regarding collar diameter, growth curves showed that seedlings reached the target diameter at 120 days in all treatments for the three formulations, except for the control. For the variables height, collar diameter, leaf area, chlorophyll content, total dry mass, and root system attributes, the rates of maximum technical efficiency ranged from 8 to 10 g L¹ across the three formulations evaluated. All three CRF formulations proved effective in enhancing the growth and quality of Khaya anthotheca seedlings under nursery conditions. From a practical standpoint, based on seedling height, collar diameter, and robustness index (H/CD), the application rate of 8 g L¹ provides optimal technical efficiency.
Keywords: initial growth; plant nutrition; morphophysiology; seedling production; Khaya anthotheca.
