Substâncias húmicas na produção e qualidade de mudas de Acacia mangium

Abstract

Tropical acacias are cultivated worldwide, including in Brazil. These trees offer multiple uses, including timber production, charcoal production, and the restoration of degraded areas. Therefore, it is crucial to explore technologies that accelerate seedling growth and improve their quality for the establishment of robust plantations. Given this, the objective of this study was to evaluate the use of humic substances in the production and quality of Acacia mangium seedlings. The experiment was conducted in randomized blocks, testing six doses of humic substances (0, 10, 20, 30, 40, and 50 mL L⁻¹) with four replicates. Sixty days after sowing, the seedlings received the humic substance solution, at the tested doses, applied directly to the substrate. At 120 days after sowing, the following were measured: stem diameter, total height, relative chlorophyll index, maximum root length and volume, shoot and root dry mass per seedling, and the Height/Diameter, Shoot/Root ratios and Dickson Quality Index were calculated. The application of humic substances to the substrate of Acacia mangium seedlings resulted in changes in all parameters analyzed. For each parameter analyzed, there was an optimal dose that provided the greatest growth. Thus, it can be concluded that the use of humic substances applied to the substrate of Acacia mangium seedlings interferes with their formation. The doses at which the best parameters were obtained ranged from 10.0 to 21.1 mL L-1. This influence is more pronounced for the development of the root system. And, for the seedling quality parameters, the use of humic substances provides quality seedlings, and the dose to be applied varies with the parameter that is intended to be optimized.