Abscisic acid (ABA) was synthesised in dehydrating leaves and roots of willow (<I>Salix dasyclados</I>) and exogenous ABA in the xylem stream was shown to cause decreases in stomatal conductance. A transient decrease in leaf water potential occurred if water was entirely withheld from roots on one side of a willow plant. This was avoided if roots from all sides of the plant were watered and only root tips were allowed to dehydrate. Partial stomatal closure and decreased leaf extension rate then occurred without any initial perturbation in leaf water potential or leaf ABA. The drying event was associated with an increased content of ABA in root tips and xylem sap. The effects were reversible on either rewatering or excision of the affected root tips. It was concluded that partial dehydration of root tips caused partial stomatal closure and decreased leaf extension, and that changes in the ABA content of root tips and the xylem sap were consistent with a possible causal role for root-sourced ABA in the regulation of leaf physiology in response to root water deficit. Stem-girdling experiments indicated that a major pathway of ABA transport, between leaves on different stems in the shoot system, was in the phloem, without an apparent involvement of transport in the xylem. Damage to the shoot apex caused an increase in stomatal conductance. This was associated with a decreased content of ABA in the xylem sap and in fully extended leaves. It is suggested that these changes may have been associated with a possible import of ABA from mature leaves into the growth sites of axillary shoots. Results are discussed within the context of water deficit and the growth and survival of individual stems in a willow plantation.

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ABSTRACT This pilot study examines the knowledge about tree root systems amongst five tree planting professionals. The aim is to find out the professionals’ collective knowledge of the nature of root systems of various trees used in green areas. Furthermore; to explore how the professionals adapt landscaped green areas to the tree root properties in a sustainable manner. Questions: Which tree species have special root properties to consider and how do the professionals utilize this knowledge? And: How do the professionals in general adjust planting according to the root systems of trees in areas to create sustainable green environments? Interviews with the professionals were performed. Four of the five interviewees expressed that they had no root systems in mind when they chose trees to an area. However they considered properties such as wet soil, clay soil, sandy soil and the urban environment when they decided on the trees for an area. The interviewees discussed 22 different trees and their root systems and what kind of adaptations in landscaping they would make for the special root features to create sustainable tree plantings. As a result of the information a list was compiled and the collective knowledge of landscaping amongst the professionals was gathered into themes. These themes were then divided in to four headings: nutrition, root ball, design and soil conditions. In addition, all of the interviewees agreed that the most important thing for tree planting is to select the right tree species for the right soil. / SAMMANFATTNING Syftet med den här intervjustudien är att ta reda på en grupp yrkesverksammas samlade kunskap om rotsystemens olika egenskaper hos träd och sedan utforska hur de yrkesverksamma anpassar anlagda gröna miljöer till trädens rotegenskaper på ett hållbart sätt. Fem personer som arbetar med trädplantering intervjuades för att besvara studiens tre frågeställningar om rotsystemen hos träd. De två första frågeställningarna gällde: Vilka träd har särskilda rotegenskaper att ta hänsyn till och vilka anpassningar i anläggandet gör yrkesverksamma för de respektive trädens rotsystem? Utifrån intervjusvaren sammanställdes en lista där 22 träd med särskilda rotegenskaper presenteras tillsammans med vilken typ av anpassning de yrkesverksamma rekommenderar. Den tredje och sista frågeställningen var; Hur arbetar de yrkesverksamma generellt med rotsystem hos träd i anläggningar för att skapa hållbara gröna miljöer? Frågeställningen utmynnade i fyra huvudområden som beskriver hur de yrkesverksamma arbetar med näring, rotklump, design och mark för att skapa hållbara gröna miljöer. Slutligen svarade fyra av de fem informanterna att de inte hade rotsystemet i tanke när de valde träd till en plats. Trots det tog alla hänsyn till egenskaper som t.ex. blöt mark, lerjord, sandjord och urban miljö när de valde träd till en plats. Därutöver var alla var överrens om att artvalet är viktigt när träd ska planteras i en anläggning, dvs. rätt träd på rätt jord.

Fir tree root forms are one way to retain turbine blades in turbine disks. These features are ruled surfaces that span the entire thickness of the disk and are usually machined by broaching. With increasing use of new heat resistant and difficult-to-machine materials, mechanical machining methods exhibit severe problems with tool wear and surface integrity. To mitigate these problems, thermal material removal processes such as Wire Electrical Discharge Machining (WEDM) are being considered in the aerospace industry. Developments in turbine design have led to a root form geometry in the form of an arc across the thickness of the disk in order to decrease the contact stress by increasing the contact area between blade and disk. A curved surface such as this cannot be produced by conventional WEDM as it is not a ruled surface. A novel WEDM process is being developed where an arc shaped curve is formed from an axially moving wire to allow for the production of such curved surfaces. / Thesis / Master of Applied Science (MASc) / Turbine blades are attached to turbine disks with specially shaped, straight slots called Fir Tree Root Forms (FTRF) that can be cut with broaching tools. Broaches wear out quickly because the disk is made of very difficult to cut material and the aerospace industry is starting to use Wire Electric Discharge Machining (WEDM), instead of broaching, to cut these slots since it can easily cut the material used. New turbine disk designs have curved slots, which can not be cut with a straight broach or wire, and a new process is therefore being developed which uses an arc-shaped wire to cut the desired curved shapes.

Patterns of trees’ endogenous rhythmic growth (ERG) and paralleled C allocation shift between root and shoot systems have been studied, but there is still a need to understand their impact in shaping soil microbiomes. Moreover, the impact of plants on soil microbial communities can be modulated or overweighed by time-induced plant and/or seasonal changes. Thus, we intended to analyze the structure of soil microbiomes as response to simultaneous alternated host tree root and shoot flushes and time-induced changes within one vegetation period at two sites in Central Germany. In this study, we utilized oak phytometers (Quercus robur L., clone DF159) as host trees, and made use of their ERG, whereby consecutive root and shoot flushes make a complete growth cycle. We studied two complete growth cycles during the same vegetation period, performed a non-destructive soil sampling and applied high-throughput amplicon sequencing of the bacterial 16S gene and the fungal ITS2 region. As C allocation shifts between the tree root and shoot, released root exudates and consequently the nutrient availability alternate for soil microorganisms. We therefore anticipated different microbial communities in the host tree root zone along the growth cycles until autumnal leaf senescence. In our results, the bacterial community exhibited a directional change over time along the vegetation period. In contrast, the fungal community appeared sample specific. Our findings enlarge the current understanding of the temporal microbial assembly in the host tree root zone.