No description available.

The ontogeny of vascular cambium and the wood formation in the 8 month-old Pinus radiata have been examined. The results showed that the procambium develops from the subapical meristem parenchyma, which is converted to pro cambial cells by periclinal division about 0.5 mm from the shoot tip. The interfascicular cambium originates from the interfascicular parenchyma, which is also derived from the subapical meristem. Transverse sections show that the interfascicular parenchyma convert to interfascicular cambial cells requires activation by the fascicular cambium. The vascular cambium was established by the fascicular cambium connecting with the interfascicular cambium. Compression wood formation is related to the plantlet's response to stress. The magnitude and distribution of compression wood is related to whether the stem is free-growing, staked vertically, or tied to an inclined stake, the three situations generating 27%, 14% and 49% compression wood as assessed by image analysis of thin sections. Stiffness, density, tracheid length, cell numbers/mm2, and percent cell wall area were tested for plantlets of clones 8 and 31 grown under three treatments. Compared to the free grown plantlets, the angled plantlets were shorter, thinner, contained more compression wood with thicker cell walls and more cells/mm2, and had shorter denser tracheids to formed weaker wood. By contrast the tied plantlets were taller and thinner, having fewer cells/mm2 with each tracheid being longer and less dense (thinner cell walls), but of similar stiffness to the free grown ones. Compression wood was stiffer than opposite wood because of its higher density, and the angled plantlets were weaker than the free and tied plantlets due to their shorter tracheids. Stiffness is related to density in angled plantlets, and related to tracheid length in the free and tied plantlets. Tracheid length is negatively related to density, cells/mm2, and percent cell wall. Density is related to percent cell wall and cells/mm2, and the percent cell wall and cells/mm2 related each other. Stiffness, microfibril angle, density, and maximum crushing strength have been studied for 1 and 2 year-old seedlings from seedlots 10 and 28. The results indicated that stiffness increased and microfibril angle decreased from one year-old to two year-old material. A relationship between maximum crushing strength and density and a negative relationship between stiffness and microfibril angle existed in two years old plantlets. Stiffness and maximum crushing strength related each other in both one and two years old plantlets. Overall, this work proved to be a scoping trial. While the results could have been anticipated in general terms they do provide a useful description of very young wood. The extent of compression wood varied greatly between treatments, but even in the best case (tied) it takes up a significant proportion of the stem cross-section. However, the technical challenges, especially in the measurement of mechanical properties in such small samples remains a formidable challenge.

Thesis (Ph. D.)--University of Wisconsin, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 67-70.

No description available.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1956. / Bibliography: leaves 93-108.

Plant growth and development is largely controlled in regions of totipotential cells around the plant body called meristems. The well characterized shoot and root apical meristems are responsible for vertical growth, in which many key players have been well studied. Lateral (secondary) growth is controlled by the vascular and cork cambiums, which are much less understood. A rapid growth of interest in a new model angiosperm tree, poplar, has facilitated the study of the two cambiums, specifically into their regulation at the genomic and proteomic levels. This study describes recent work carried out to explore the genetic regulation of secondary growth in poplar. Two genes have been identified that were previously not associated with the process of secondary growth. The first, a gene lacking annotation (FM#2), was identified through the investigation of a mutant from an activation-tagged population of poplar. This mutant showed aberrant secondary growth, with an increase in the phloem:xylem ratio. It also developed a thick, rough bark, and was subsequently named corky. Constructs to recapitulate this phenotype have been produced to allow the link between the gene FM#2 and the corky phenotype to be firmly established. The second gene was identified through a reverse genetics strategy to test if the Arabidopsis shoot apical meristem regulator, CLAVATA1 also played a role in the regulation of the vascular cambium. When it was downregulated in Arabidopsis, a significant increase in secondary growth was observed. Antisense and hairpin-RNAi constructs were produced to attempt downregulation of the gene in poplar using both traditional Agrobacterium-mediated transformations, and the recently developed strategy of induced somatic sector analysis. / Thesis (Master, Biology) -- Queen's University, 2008-09-23 16:35:26.603

Les arbres sont capables de contrôler leur forme et de résister à la gravité grâce à leur aptitude à produire du bois sous tension en périphérie. Il est connu que cette précontrainte se développe durant la phase de maturation des fibres de bois mais le mécanisme sous jacent de génération de cette contrainte n'est pas encore clairement identifié et compris. Cette étude se focalise sur la formation du bois à deux échelles : i) à l'échelle du tissus, le processus et la chronologie de la formation du bois de tension, du bois opposé et du bois normal ont été étudiés sur des peupliers élevés en pleine terre et ii) à l'échelle de la paroi, la formation de la couche secondaire dans le bois de tension a été étudiée sur de jeunes peupliers inclinés artificiellement. Les résultats montrent que, du coté du bois de tension d'arbres fléchis, le nombre de cellules cambiales au début de la saison de croissance, et ainsi le nombre total de cellules produites au final, augmente comparé au bois opposé et normal. Le nombre de cellules produites du coté du bois opposé est clairement réduit suite à une baisse de l'activité cambiale de ce coté. En conséquence, les arbres fléchis présentent une croissance excentrique. La phase de lignification commence plus tard dans le bois opposé comparé au bois normal et de tension, mais aucune différence significative n'est constatée entre le bois normal et le bois de tension. Le développement de la couche dite G dans le bois de tension commence peu de temps après le début de la lignification. Bien que le nombre total de cellules produites du coté du bois de tension des arbres fléchis est en moyenne plus important que pour les arbres droits, le nombre total de cellules produites globalement dans un cerne de croissance des arbres fléchis est comparable à celui des arbres droits. Ceci est une conséquence directe de la forte réduction du nombre total de cellules produites du coté du bois opposé pour les arbres fléchis. L'inclinaison a aussi un effet évident sur l'épaississement de la couche cellulaire des jeunes peupliers. L'évolution de l'épaisseur de la couche secondaire et de la couche G a été mesurée, du cambium au bois mature, dans des échantillons, prélevés à différentes dates après inclinaison, issus de plusieurs arbres. Les mesures sur des fibres de bois produites avant inclinaison montrent l'épaississement progressif habituellement observé de la paroi secondaire au cours de la saison de croissance. Après la date d'inclinaison, l'épaisseur de la paroi secondaire diminue de façon marquée du bois normal vers le bois de tension alors que l'épaisseur total de la paroi augmente, comparé au bois normal, avec le développement d'une couche G épaisse. Néanmoins, même après la formation de la couche G, l'épaisseur de la couche secondaire continue d'augmenter au cours de la saison de croissance. L'observation montre que l'épaississement de la couche G est plus rapide que celui de la couche secondaire. Le développement de la couche G non lignifiée pourrait être une stratégie économe, mais efficace, pour la production rapide de contrainte de croissance importante chez les feuillus. / Trees can control their shape and resist gravity thanks to their ability to produce wood under tensile stress at their periphery. This prestress is known to be produced during the maturation of wood fibres but its generation mechanism remains unclear. This study focuses on the wood formation process at two levels: i) at the tissue level, the process and timing of tension wood, opposite wood and normal wood formation were investigated on field grown poplar trees and ii) at the cell wall level, the formation of the secondary wall in tension wood was studied in artificially tilted poplar saplings. Results showed that the number of cambial cells at early growing season, and thus the total number of cells produced in the end, on the tension wood side of bent trees increased compared to opposite and normal wood. The total number of opposite wood cells produced obviously decreased as a result of a lower cambial activity on this side. Consequently, one can observe pith eccentricity in the bent trees. The lignification phase starts latter in opposite wood than in tension and normal wood, however no obvious differences were observed between tension and normal wood. The so-called G-layer (gelatinous layer) formed soon after the start of the lignification in tension wood. Although the total number of cells produced on tension wood side was more important than the averaged one produced in upright trees, the total number of cells produced in the whole growth ring of bent trees was similar to the one produced in upright trees. This was the result of a huge reduction in the number of cells produced on the opposite wood side of bent trees. Tilting also had obvious effect on the wall thickening of young poplar. The thickness of the secondary wall layer and G-layer were measured, from cambium to mature wood, in several trees sampled at different times after tilting. Measurements on wood fibres produced before tilting show the usual progressive increase of secondary wall thickness during the growing season. After the tilting date, the secondary layer thickness decreased markedly from normal wood to tension wood while the total thickness increased, compared to normal wood, with the development of a thick G-layer. However, even after the G-layer formation, the secondary layer thickness continues to increase during the growing season. G-layer thickening was observed to be faster than secondary layer thickening. The development of the unlignified GL is proposed to be a low cost but efficient strategy for a fast generation of high tensile stress in hardwood trees.

This paper describes an interactive computer program which simulates daily cell growth and differentiation in a single radial file of tree cells. The growth processes are controlled by 22 model parameters, half of which are constants, the remainder time-dependent. The program user specifies the constants and the form of the time variations desired. The program computes daily values for the time-dependent parameters, and applies these values to the calculation of cell diameters, cell division, cell wall thickness, and ring width for each day of the growing season. Output is in tabular and graphical form. The tabular listing consists of the cell diameter at each position in the radial file, and for the xylem it also prints cell wall thickness and a relative density for each cell. The graphical output plots cell diameter, wall thickness, and relative density vs. file position. The program was designed primarily as an instructional tool and has been used for this purpose with good results. Because of its flexibility it has potential for research, and some possibilities for such use are discussed.

This thesis examines the ethnobotany, physiology, anatomy, and nutritional value of edible lodgepole pine (Pinus contorta Douglas ex Louden var. latifolia Engelm. ex S. Watson ) cambium. Many First Peoples of the Pacific Northwest historically used lodgepole pine cambium. It was so popular among interior First Peoples of British Columbia that it was considered a universal food. Even though harvesting and consumption of pine cambium is diminishing in popularity today, I was able to learn from some Tsilhqot‟in First Peoples on Redstone Reserve who had prior experience with pine cambium. Nutritional analysis of lodgepole pine cambium revealed the tissues to be high in protein and sugar as well as a suite of micronutrients, which contribute to overall immunity and electrolyte balance. While lodgepole pine cambium is considered a sweet, seasonal treat by many First Peoples it is evident through my analysis that there are added nutritional benefits beyond the pleasure of consumption. This research illustrates an important case study of an endangered traditional food, which can be integrated into modern diets today. It also explores the integration of multiple disciplines of knowledge to inform this subject matter, providing multiple dimensions to understanding cambium production, timing of harvest, and benefit of consumption. / Graduate