Efeito de recipientes na produção de mudas de Acnistus arborescens (L.) Schltdl. (fruto-do-sabiá) e Platypodium elegans Vogel (uruvalheira)

Abstract

This study stands out for its integrated evaluation of the effect of container design and effective depth on the root architecture of native forest species with contrasting ecological strategies, in a real-world, low-technology context. In this context, four different containers (plastic bag, biodegradable ellepot tube, cylindrical plastic tube, and pyramidal rootmaker® tube) were evaluated on the growth of seedlings of two forest species (A. arborescens and P. elegans). Furthermore, the incorporation of morphological and functional analyses of the root system, obtained through scanning, broadens the understanding of the effects of the containers beyond traditional indicators of shoot growth. The work was carried out in the forest nursery of the Federal Institute of Minas Gerais, São João Evangelista Campus (IFMG-SJE). As each container used has its own support structure, it was not possible to establish the experiment in traditional designs, and the treatments were established in the nursery in the form of "plots," where four experimental replicates per treatment were arranged, composed of three seedlings in each replicate. At 180 days after sowing, the following variables were obtained: total height (Ht, cm), stem diameter (Dc, mm), Ht/Dc ratio, shoot dry mass (MSPA, g/plant) and root dry mass (MSR, g/plant), as well as root surface area (cm²) and root volume (cm³) using a root scanner. All analyses applicable to this experimental setup and used to compare treatments were the Kruskal-Wallis test and the Bonferroni Post Hoc multiple comparisons test (equivalent to mean comparison tests) at a 5% significance level, using the R software. The results demonstrated that the containers significantly influenced the growth of the shoot and root system of the seedlings, with distinct responses among the species. For A. arborescens, the Root Maker ® pyramidal tube promoted root development, resulting in more balanced seedlings with lower height/diameter and shoot/root ratios, desirable characteristics for establishment in degraded areas. For P. elegans, deeper, cylindrical containers promoted greater root growth, reflected in higher surface area and root volume values, consistent with the species' taproot pattern. The performance of forest seedlings is more related to the suitability of the container design, the effective depth of root exploration, and the ecological characteristics of the species than solely to the substrate volume. Therefore, the choice of container should be carefully considered and contextualized to the nursery's operational conditions and the species' requirements, aiming to maximize seedling quality and the efficiency of forest restoration projects.