ABSTRACT. Among the most relevant aspects of seed production, mechanical damage may affect seed germination and reduce health and vigor. This study introduces a noninvasive high-resolution imaging procedure for evaluating the mechanical damage to maize seeds and the effects on seed germination. Seeds with different levels of mechanical damage were evaluated using a benchtop micro-computed tomography system (micro-CT) and digital X-ray equipment. The two-dimensional transaxial, coronal and sagittal micro-CT sections were used to inspect the seed anatomy and the mechanical injuries in the internal seed tissue. Germination tests were performed using paper towel rolls (25°C for 7 days) in which the seedling length was evaluated on a daily basis, and the seedling dry biomass was measured at the seventh germination day. The micro-CT cross-sectional images allowed an efficient spatial characterization of the mechanical damage inside the seeds. On average, mechanically damaged seeds produced seedlings with a length 24% shorter and a dry biomass 65% less than that of the undamaged seeds. We concluded that the micro-CT technique provides an efficient means to inspect mechanically damaged maize seeds and allows for a reliable association with germination response.

A geração e o armazenamento de resíduos de construção civil e demolição (RCD) constituem-se em um problema ambiental, pois representam mais de 50 % do total de resíduos sólidos gerados nos médios e grandes centros urbanos. Porém, como o calcário é uma das principais matérias-primas utilizadas na fabricação do cimento e da cal hidratada e, consequentemente, de concretos, argamassas e reboques, a reciclagem desses materiais pode fornecer, em princípio, um subproduto com potencial para correção da acidez dos solos. Este estudo teve o objetivo de avaliar a utilização de resíduos de construção e demolição reciclados como corretivos de acidez do solo. Utilizaram-se RCD-R provenientes de concretos, argamassas e reboques (material cinza), que foram caracterizados inicialmente por fluorescência e difratometria de raios-X. O desempenho dos RCD-R cinza como corretivo de acidez foi avaliado pela produção de matéria seca da alfafa (Medicago sativa cv. Crioula) e pela medida dos atributos químicos do solo. Os resultados sugerem que os RCD-R cinza (origem de concretos) apresentam características interessantes para utilização como corretivos da acidez de solos, porém em concentrações superiores a 24 t ha-1, quando aplicados em área total.

The production and storage of construction and demolition residues (CDR) consist in an important environmental issue because they represent more than 50 % of total solid waste that has been produced in large and medium-sized urban centers. However, as limestone is one of the major raw materials used in cement and hydrated lime products in the preparation of concrete and mortar, recycling this material can, in principle, provide a subproduct with potential to be applied to correct soil acidity. This study aimed to evaluate the use of recycled construction and demolition residues (RCD-R) as soil acidity corrective. The material was collected at a commercial recycling plant and consisted mainly of concrete and mortar (gray material), which was initially characterized by X-ray fluorescence and X-ray diffraction. The performance of gray RCD-R for soil pH correction was evaluated by the chemical properties of a medium-textured soil treated with this residue and the dry matter production of alfalfa (Medicago sativa cv. Crioula). Results suggest that the RCD-R used has promising characteristics to be applied as correction material of the soil pH, but at doses higher than 24 t ha-1.

ABSTRACT X-ray computed microtomography (microCT) is one of the most advanced non-destructive techniques enabling the reconstruction of wood anatomical structure and its products. This work applied the microCT to the analysis of wood anatomy of Amburana cearensis and Pinus sp. Through microCT it was possible to obtain images of the macro and microscopic wood structure of the two species, followed by the characterization, description and comparison to the literature. The advantages of microCT are discussed in relation to the preparation of histological slides, providing the integrity of wood, panels, charcoal, paper samples, etc.

RESUMO A microtomografia computadorizada de raios X (microCT) é uma das mais avançadas técnicas de análise não destrutiva e possibilita a reconstrução da estrutura anatômica da madeira e de seus produtos. O trabalho aplicou a microCT na análise da anatomia da madeira de Amburana cearensis e de Pinus sp. A microCT possibilitou a obtenção de imagens da estrutura macro e microscópica da madeira das duas espécies, permitindo a sua caracterização, descrição e comparação com a da literatura. As vantagens da microCT, em relação à confecção de lâminas histológicas, mantendo a integridade das amostras de madeira, painéis, carvão, papéis, etc. são discutidas.