EXTRATO DE ALGA E FORMAS DE APLICAÇÃO NA PRODUÇÃO E QUALIDADE DE MUDAS DE Khaya senegalensis

Abstract

The extract of the algae Ascophyllum nodosum has stood out as a plant biostimulant, promoting an increase in the quality of physiological processes through the supplementation of growth hormones, amino acids, nutrients, induction of resistance, and promotion of plant growth. However, the action of this biostimulant can be affected by the species, dose, and method of application. Among the forest species of commercial interest for the production

of high-value-added wood, African mahogany (Khaya senegalensis) stands out. Thus, the objective of this work was to evaluate the extract of the algae Ascophyllum nodosum, and its method of application, on the formation and quality of Khaya senegalensis seedlings. In the experiment, a randomized block design was used, in a 5 x 2 factorial scheme, testing five doses of the Ascophyllum nodosum algae extract, in two application methods: on the substrate and by foliar application, with four replications. The treatments were applied 50 days after sowing, and 110 days after application, the following were measured: stem diameter, total height, number of leaves, leaf area, root length, root volume, root dry mass, shoot and total dry mass, height-to-diameter ratio, and Dickson quality index. Only stem diameter, total height, and height-to-diameter ratio showed no influence from the interaction between the studied factors. However, individually, both the dose and the method of application of the seaweed extract affected seedling development. Application via substrate provided higher values for stem diameter (4,8 mm) and total height (12 cm), while for the height-to-diameter ratio, only the applied dose influenced the results, with 13,2 mL L-1 providing the best outcome. Application via substrate provided better seedling performance, except for the number of leaves. The values for number of leaves, root volume, root dry mass, and total dry mass increased with the applied dose, while for leaf area, the 24 mL L⁻¹ dose showed a result 30.9% higher than the control. For root length, the 17,2 mL L⁻¹ dose showed the best performance, reaching 14,1 cm. The highest value for shoot dry mass (1,7 g) was obtained with the 24,3 mL L⁻¹ dose, while for the Dickson quality index parameter, the 26,4 mL L⁻¹ dose had the best result. It was concluded that the use of Ascophyllum nodosum extract influences the formation of African mahogany seedlings, favoring their development and quality. The application of the extract directly to the substrate provided higher morphometric parameters than those obtained by foliar application.