Search Results (4)

South American wood and wood-based products play major roles in the global forest sector. Most research related to Paraguayan wood is focused on forest restoration, urban arborization, silviculture, and botanical taxonomy. Often overlooked but of major importance is the cellular structure of the trees that comprise remaining forests in Paraguay. Wood greatly contributes to forest value, yet wood anatomy studies remain novel in the country. To further document Paraguayan wood anatomy, two downed species of multipurpose Myrtaceae trees were sampled from a subtropical semi-deciduous forest in Areguá, Central Paraguay. In this article, heartwood xylem anatomy was observed and documented using low-cost methodology to support the regional realities of the emerging field in rural communities, especially local Paraguayan peoples. This included specific gravity, density, and basic light microscopic features. Sample material was processed near the pith at breast height to display cellular features in the transverse, radial, and tangential planes. Four features were measured with light microscopy and ImageJ: tangential vessel element diameter, vessel element length, ray seriation, and ray height. Results showed structural similarity between species, with diffuse porosity, solitary pores, simple perforation plates, alternate intervessel pits, and apotracheal diffuse parenchyma in aggregates. These results represent the first sampling of Myrtaceae from Paraguay in a methodology that can be easily replicated by the native population, thereby enabling further wood anatomy studies in the region. Full article

The multiple structures of xylem vessels in Magnolia provide stable and efficient water transport channels. The structural parameters of xylem vessels were studied in wood sections and in macerated materials. The results showed that the xylem vessels of Magnolia contained a helical thickening structure and a pit structure of a secondary wall, and the end walls had a scalariform perforation plate. The helical thickening and scalariform perforation plate increased the flow resistance of the vessel, and the pit structure decreased the flow resistance of the vessel. There was a close positive correlation between the flow resistance of the vessels and the helical width, the helical height, the thickness of the scalariform perforation plate, the number of holes in the scalariform perforation plate, the length of the pit canal, and the pit spacing. In addition, there was a negative correlation between the flow resistance of the vessels and the helical spacing, the pit vertical diameter, and the pit domain length. Among these structural parameters, the helical height, the number of holes, and the length of pit canal had a greater influence on the flow resistance. The pit structure caused the vessel to produce radial water transport. The radial transmission efficiency increased with the increase in the pit domain length. With no pit membrane in the pit structure of Magnolia, the radial transmission efficiency would be between 43.99% and 53.21%. Full article

Drip irrigation has become an application trend of water-saving irrigation technology due to its excellent water-use efficiency. However, the energy dissipation form of the commonly used labyrinth channel is relatively simple, and the corresponding energy dissipation mechanism research is inadequate. This article proposes a new kind of channel structure of drip irrigation emitters based on the structure of scalariform perforation plates in plant xylem vessels. We establish a total of 16 sets of orthogonal structure schemes. Using numerical simulation and physical experiments, the hydraulic performance and energy dissipation mechanism of the perforated drip irrigation emitters (PDIE) are studied. The results show that the flow index of PDIE is 0.4665–0.5266. The hydraulic performance of PDIE in the high-pressure zone is the best, and the flow index is 0.4665–0.5046. As the pressure increases, the velocity of the flow of the upper perforation increases rapidly, the flow ratio decreases, the flow index decreases, and the hydraulic performance improves. To further verify the energy dissipation mechanism, a lower flow ratio and a better hydraulic performance were obtained through appropriately expanding the upper part of the upper perforation inlet to the channel boundary. The research sheds new insights for optimizing the hydraulic performance of PDIE. Results reported here provide a theoretical basis for the structural design of drip irrigation emitters and the energy dissipation mechanism research. Full article

After the nuclear power plant accident in Fukushima, radionuclides were deposited over a large area of local forest. However, almost nothing is known about radionuclide infiltration into trees. Here, we used poplar seedlings as a model to show that radiocesium can enter directly into leaves and bark, moving via ray cells through the symplastic pathways to the xylem and concentrating around the meristems, cork, and vascular cambium. During induced potassium incorporation and reduced seasonal growth, the radiocesium in the meristems of stems mainly passes into abscission tissues such as leaves and heartwood. There is no turnover of radiocesium after it enters the heartwood. Full article