Efeito de diferentes substratos no desenvolvimento inicial de mudas de Handroanthus impetiginosus (Mart. ex DC) Effect of different substrates on the initial development of Handroanthus impetiginosus (Mart. ex DC) seedlings

This study aimed to assess the influence of the seasonality on the bark tannins content of Acacia mangium trees grown in the Northeastern Brazilian Region and the effect of soil preparation on the results. Two experimental plots of 1.0 ha each were submitted to different soil preparation methods, with two different intensities. The experimental design consisted of four treatments, two types of soil preparation and, two different bark collection seasons (end of the rainy and dry seasons). The bark of the trees was collected in each treatment and the contents of condensed tannins were determined. For each experimental treatment, 15 trees were harvested and debarked. Bark material was submitted to extraction with hot water, obtaining the total solids content (TSC), Stiasny index (I), and the condensed tannins content (CTC). There was no influence of the soil preparation method on the TSC, I, and CTC. However, there was a significant difference in these parameters for tree bark collected in the rainy season, with higher values. The less intensive soil preparation method is recommended due to its lower cost, and bark should be collected at the end of the rainy season for the best yield of condensed tannins.

Enterolobium contortisiliquum (Vell.) Morong., known as tamboril, is a promising species in the recovery of degraded areas. However, it presents integument dormancy in its seeds and it is necessary to find methods to overcome it. Therefore, the present study aimed to evaluate the dry heat efficiency on the viability and vigor of E. contortisiliquum seeds, as an alternative and practical method for overcoming dormancy. The experiment was conducted in the house of vegetation of the Specialized Agricultural Sciences Academic Unit of the Federal University of Rio Grande do Norte. The fruits, obtained from different matrices located in the municipality of Macaíba-RN, were manually processed. The heat treatments obtained through a drying oven during five minutes used: 60 (T1), 80 (T2), and 105ºC (T3), the mechanical scarification (T0) of the seeds were used as a mediating treatment of the efficiency of the others. The emergency, first emergency count, and the emergency speed index were evaluated. Observing the results obtained, the best performance corresponded to the scarified seeds. The thermal treatments in dry heat were not efficient to overcome the dormancy of E. contortisiliquum seeds when compared with the traditional method of mechanical scarification. However, the methodology presents practicality in its execution which can be considered advantageous. Therefore, new studies with different combinations of time and temperature for the species are encouraged.

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This study aimed to determine the concentration of condensed tannins in the bark of Mimosa tenuiflora (Willd) Poir trees. Additionally, the physical-mechanical properties of cross-laminated timber (CLT) panels bonded with an adhesive based on M. tenuiflora tannins were assessed. Bark was collected from five trees. The adhesive formulation was synthesized by mixing powdered tannins, paraformaldehyde, and water at 50 °C under continuous stirring. Bark tannins extract in its pristine state without any previous chemical treatment or modification was employed to synthesize the adhesive. Viscosity, pH, solids content, and gel time of the adhesive formulation were determined. CLT panels were manufactured with Eucalyptus spp. wood. The bonding performance was assessed by determining the physical (apparent density and water absorption) and mechanical (modulus of elasticity – MOE, modulus of rupture – MOR, and shear strength) properties of the CLT panels. Condensed tannins content in the M. tenuiflora bark was 23.4%. Adhesive properties were pH = 3.93, TS of 50.64%, gel time of 460 s, and 6,000 cP for viscosity. Values of MOE, MOR and shear strength were 4,411, 16.18, and 1.06 MPa, respectively. The M. tenuiflora tannins are promising for the formulation of adhesives to bond CLT.

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Nos últimos anos tem-se utilizado cada vez mais tubetes biodegradáveis para produção de mudas florestais, pois esse tipo de material, além de não gerar resíduo no ambiente também diminui as chances de dano ao sistema radicular da planta no momento do plantio. Assim, o objetivo do estudo foi avaliar a utilização de três tipos de recipientes, sendo um nãobiodegradável e dois biodegradáveis na produção de mudas de Enterolobium contortisiliquum. As sementes foram semeadas em sacos plásticos para mudas com 1.960 cm³ de volume, e em cilindros de bambu de 589 cm³ de volume com e sem duas aberturas laterais opostas de 6 cm 2. Após 60 dias de semeio observou-se que o plantio em sacos plásticos resultou em maiores área foliar, altura, peso seco da biomassa aérea e diâmetro do colo, mas não apresentou maior peso seco do sistema radicular, o que influenciou em menor valor do Índice de Qualidade de Dickson. Assim, a produção de mudas em recipientes biodegradáveis a partir de bambu, como as utilizadas neste trabalho, não resultou em maiores ganhos de desenvolvimento das mesmas, além da reduzida praticidade do uso em condições de viveiro comercial.

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