Application of 3D magnetic resonance microscopy to the anatomy of woody tissues

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Microwave modification can increase the permeability of wood by delaminating and rupturing its anatomical microstructures at their weak points. A high degree of intensity of microwave modification can cause significant structural damage to the microstructures of wood, resulting in poorer strength properties. The objective of this study was to evaluate the changes in the anatomical structure of Norway spruce (Picea abies (L.) Karst.) heartwood and sapwood after microwave modification in order to develop the most effective treatment in terms of applied energy without causing significant structural damage. Analysis with light and scanning electron microscopy were performed to evaluate the effect of microwave treatment for two different energy intensities, moderate and high intensity. The results indicated structural changes in the tracheid cells. Microscopy showed varying degrees of modification within the wood microstructure, with the heartwood samples showing a greater anatomical distortion compared to their sapwood counterparts. Furthermore, the samples were subjected to pycnometric density measurements, which indicated a reduction in skeletal and absolute density after microwave modification, for both high and moderate intensity treatment on sapwood and heartwood samples. With increasing microwave energy, a gradual increase in specific pore volume and porosity percentage of the samples were also detected.

Section: Light Microscopy and Scanning Electron Microscopymentioning

confidence: 99%

Effects of Different Energy Intensities of Microwave Treatment on Heartwood and Sapwood Microstructures in Norway Spruce

Ganguly

Balzano

Petrič

et al. 2021

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“…Extreme drought stress could also provoke the occurrence of tyloses in the vessels of the latest formed xylem, very soon after vessel formation. Indeed, tyloses in sapwood can be linked to vessel embolism or can be a consequence of a traumatic event [68][69][70]. Tyloses block vessels in the outer sapwood crucial for water conduction, and therefore they might affect tree survival.…”

Section: Cambial Activity and Xylem Incrementmentioning

confidence: 99%

Xylem and Phloem Formation Dynamics in Quercus ilex L. at a Dry Site in Southern Italy

Balzano

Čufar

Micco

2021

Quercus ilex L. dieback has been recently reported at numerous Mediterranean sites. Wood and phloem formation dynamics and tree-ring series of anatomical traits can be used to evaluate growth conditions of trees. We monitored cambial activity in Q. ilex trees growing at a site in southern Italy in order to assess how xylem and phloem production are affected by harsh seasonal climatic variation during a dry year. We followed xylogenesis by counting the number of cambial cells and detecting the occurrence of post-cambial cells throughout the year. As phloem did not show clear growth rings and boundaries between them, we followed the development of phloem fibres—their morphological traits during development and the distance from the cambium served as a reference point to evaluate the phloem production during the year. We detected a multimodal pattern in cambial activity, with wood production in three periods of the year and consequent formation of intra-annual density fluctuations (IADFs). The lowest production of xylem cells was observed in the dry late spring and summer period (likely due to the low water availability), while the highest occurred in autumn (the wettest period). Although we could not differentiate between early and late phloem, the analysis of phloem traits was useful to follow the dynamics of phloem production, which is generally difficult in Mediterranean tree species. We found cambial production of phloem throughout the year, even in the periods without xylem production. The results showed that if tree growth was constrained by environmental limitations, the ratio between xylem to phloem cells decreased and, in the most severely affected trees, more cells were formed preferentially in the phloem compared to xylem. We also briefly report the way in which to solve technical problems with tissue preparation due to extreme hardness and to the peculiar structure of Q. ilex wood and outer bark.

“…Due to its structure and high moisture content, wood is a convenient material for studying of changes in moisture distribution after injury by MRI. With suitably selected MRI parameters the MR signal obtained from the observed wood tissue is directly proportional to the amount and distribution of water [29][30][31][32].…”

Section: Magnetic Resonance Imaging and Wood Moisture Determinationmentioning

confidence: 99%

Influence of Mechanical Wounding and Compartmentalization Mechanism on the Suppression of Invasive Plant Species Using the Example of Cherry Laurel (Prunus laurocerasus)

Plavčak

Mikac

Merela

2021

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Natural habitats increasingly face the introduction and spread of non-native species. Under the right conditions, non-native species can become invasive over time. This issue is now being addressed by many experts and researchers who are using and developing various approaches and methods to limit and eliminate or suppress problematic plant species. Many invasive plants are already spreading uncontrollably in urban and forestry areas, causing health hazards, environmental and economic damage and negatively impacting natural ecosystems. The use of chemical agents is generally limited, so our only option to control and suppress the problematic species is mechanical removal. In this research suppression by tree stem wounding, i.e., incomplete girdling, was used. This type of injury causes the plant to lose its vitality, become weaker after first year and then die within a few years. Using a research approach, we chronologically monitored the response of cherry laurel (Prunus laurocerasus L.) stem tissue to mechanical wounding of the incomplete girdling. Magnetic resonance imaging (MRI) and light microscopy were used for monitoring moisture content and anatomical changes in different periods after injury. The results of the study showed that cherry laurel, with an intense wound tissue response and other changes, is a species with good compartmentalization potential. The rapid and intense tissue response to injury requires high energy and nutrient consumption and consequently leads to a loss of vigour and mechanical stability, which may result in plant destruction. Results revealed that mechanical wounding by incomplete girdling is a successful method for suppression of non-native and invasive cherry laurel.