The aim of the study was to examine the effects of application of plant-growth regulators (PGR) on the growth of paulownia plants and evaluate their usefulness in paulownia nurseries. The experiment ...was carried out on the paulownia interspecific hybrid (Paulownia elongata × Paulownia fortunei) ‘Oxytree’. Micropropagated plants grown in pots were sprayed with PGR solutions. Gibberellins (GAsub.3, GAsub.4+GAsub.7), 6-benzyladenine (BA), triclopyr (TPA), ethephon (ETH), daminozide (DA), prohexadione-Ca (PH), and trinexapac-ethyl (TE) were used. They were included in commercial products (Florgib 245 mg dmsup.−3, Gibb plus 11 SL 5 cmsup.3 dmsup.−3, Globaryll 100 SL 1.5 cmsup.3 dmsup.−3, Topper 10 ST 200 mg dmsup.−3, Agrostym 480 SL 2 cmsup.3 dmsup.−3, B-Nine 85 SG 2 g dmsup.−3, Regalis plus 10 WG 2.5 g dmsup.−3, Moddus 250 EC 1 cmsup.3 dmsup.−3, respectively). None of the studied preparations modified positive correlations between the longitudinal vs. transverse growth of stems and growth of leaves. Not only GAsub.3, GAsub.4+GAsub.7, but also BA (cytokinin) and unexpectedly TE (retardant) stimulated stem elongation and thickening. Furthermore, the effect of TE lasted longer than influence of GAsub.x and BA. Leaves of TE-treated plants were distinguished by a higher chlorophyll a/b ratio, and a lower relative chlorophyll content and efficiency of photosystem II (Fsub.v/Fsub.m, Fsub.v/Fsub.0). TPA strongly deformed the stems and leaves of liners. Other regulators (ETH, DA, PH) retarded the diameter growth of stems and leaf expansion. Some results obtained by GAsub.x, BA, and especially by TE treatment, might be beneficial for paulownia grown as ornamental and/or timber tree.
The remarkable development of timber construction technologies in recent decades has led to an increase in the number of timber buildings worldwide, including multi-storey buildings. The design of ...timber buildings, especially those of greater height, is relatively demanding and, even in the context of architectural expression, has certain constraints due to the specific structural and physical properties of this material. Thus, it is important for designers to have an overview of existing timber structural systems and their specificities to be able to make the right design decisions during the design process. Unfortunately, there is a lack of scientific literature that systematically addresses the essential features of contemporary timber structural systems. Within the aims of this paper to provide the systematic review of contemporary structural systems, both the scientific and professional literature are comprehensively reviewed. This paper presents a systematic classification and description of the following structural systems of timber buildings: all-timber and hybrid timber structural systems with an additional description of constituent structural elements, while examples of completed multi-storey timber buildings are also given for each structural system. The findings provide a broader view of the knowledge of contemporary solutions of timber structural systems and their application, thus representing a novelty in the field of timber construction review.
Throughout the last two decades the timber building sector has experienced a steady growth in multi-storey construction. Although there has been a growing number of research focused on trends, ...benefits, and disadvantages in timber construction from various technical perspectives, so far there is no extensive literature on the trajectory of emerging architectural typologies. This paper presents an examination of architectural variety and spatial possibilities in current serial and modular multi-storey timber construction. It aims to draw a parallel between architectural characteristics and their relation to structural systems in timber. The research draws from a collection of 350 contemporary multi-storey timber building projects between 2000 and 2021. It consists of 300 built projects, 12 projects currently in construction, and 38 design proposals. The survey consists of quantitative and qualitative project data, as well as classification of the structural system, material, program, massing, and spatial organization of the projects. It then compares the different structural and design aspects to achieve a comprehensive overview of possibilities in timber construction. The outcome is an identification of the range of morphologies and a better understanding of the design space in current serial and modular multi-storey mass timber construction.
The authors present a novel transcendental hysteresis model based on the piecewise definition of arctangent functions. The definition of the shape parameters of the arctangent functions originates ...from the features of the experimental hysteresis curves directly. In the first step, the authors present this model's application to the experimental cyclic response of cross‐laminated timber (CLT), light‐timber frame (LTF) shear walls, and a steel angle bracket. Then, the response of a plywood‐coupled laminated‐veneer lumber (LVL) shear wall is used for validation purposes. The paper introduces the arctangent‐based model, labeled Atan model, by illustrating some possible shortcomings of hysteresis models with pinching. The paper concludes with a simple demonstration of these issues in the case of a Bouc‐Wen class hysteresis model, the extended energy‐dependent generalized Bouc‐Wen (eegbw) model. The numerical instabilities of the eegbw model are used to endorse the advantages of the proposed formulation in modeling complex structural arrangements, like wood joints and structural systems. The proposed model originates from the analysis of the experimental response of wood joints. However, it can be of more general application, and the particular reference to wood joints does not preclude other application fields.
As an important timber genus with high economic and ecological values, Populus is a model for dissecting the genetic architecture of growth traits in perennial forest trees. However, the genetic ...mechanisms of longitudinal growth traits in poplar remain incompletely understood. In this study, we conducted longitudinal genetic analysis of height and diameter at breast height (DBH) in eleven-year poplar clones using ultra-deep sequencing datasets. We compared four S-shaped growth models, including asymptotic, Gompertz, logistic, and Richard, on eleven-year height and DBH records in terms of five metrics. We constructed the best-fitting growth model (Richard) and determined poplar ontogenetic stages by virtue of growth curve fitting and likelihood ratio testing. This study provides some scientific clues for temporal variation of longitudinal growth traits in Populus species.
PDF
