Aboveground Structures Research Articles

원삼국~백제 한성기 취락의 저장 양상 변화

In the process of state formation, storage methods can change according to political, economic, and social transformations. This study aims to identify such changes in storage methods, storage amounts, and stored crops by comparing and analyzing various types of archaeological evidence, such as crop remains, pottery, storage pits, and above-ground structures from sites of the central region of the Korean Peninsula dating the Proto-Three Kingdoms to Baekje’s Hanseong period. The results of the analysis revealed that, in the Gyeonggi region, the tendency to store crops indoors was weakened by the Hanseong period. However, in major settlements, this tendency persisted, and the use of external storage facilities increased, with rice becom-ing a significant crop for external storage. In the Yeongseo region, the change in indoor storage methods was not as distinct as in the Gyeonggi region, but there was a noticeable change in external storage patterns. Overall, the use of deep storage pits increased, new storage crops were added, and the use of external storage facilities increased somewhat in the Namhan River basin. Analyzing the reasons for these changes based on contemporary contexts, it was found that both the Gyeonggi and Yeongseo regions were influenced by changes in agricultural production methods. In the case of the Gyeonggi region, the in-creased complexity of society, such as the intensification of social stratification and the dif-ferentiation of site functions, also influenced storage strategies.

Ground motion amplification by twin circular tunnels for obliquely incident seismic waves: Effects of saturated poroelastic soil parameters

Underground structures can significantly affect the ground motion and further influence the seismic design of aboveground structures around them. Although this issue has been well recognised and studied, it is not thoroughly addressed as a large number of factors are involved. This paper focuses on ground motion amplification induced by twin circular tunnels embedded in saturated poroelastic soil. The saturated poroelastic soil is modelled as a two-phase medium to consider parameters characterising the fluid phase. Three-dimensional scattering features of the twin tunnels for obliquely incident seismic waves are numerically investigated by a 2.5D finite element and boundary element hybrid model. It is shown that the presence of the twin tunnels can lead to significant modifications of the free-field motion, in terms of its magnitude and distribution. The three-dimensional oblique incidence scenario presents a more general perspective on the ground motion amplification. Moreover, the effects of saturated poroelastic soil parameters on the ground motion amplification, including soil permeability, groundwater levels, and the degree of saturation, are parametrically investigated. The differences in ground motion amplification patterns between the saturated poroelastic and dry poroelastic soil scenarios are notable, highlighting the effects of parameters characterising the fluid phase.

Study on the Effect of Burial Depth on Selection of Optimal Intensity Measures for Advanced Fragility Analysis of Horseshoe-Shaped Tunnels in Soft Soil

Seismic intensity measures (IMs) can directly affect the seismic risk assessment and the response characteristics of underground structures, especially when considering the key variable of burial depth. This means that the optimal seismic IMs must be selected to match the underground structure under different buried depth conditions. In the field of seismic engineering design, peak ground acceleration (PGA) is widely recognized as the optimal IM, especially in the seismic design code for aboveground structures. However, for the seismic evaluation of underground structures, the applicability and effectiveness still face certain doubts and discussions. In addition, the adverse effects of earthquakes on tunnels in soft soil are particularly prominent. This study aims to determine the optimal IMs applicable to different burial depths for horseshoe-shaped tunnels in soft soil using a nonlinear dynamic time history analysis method, and based on this, establish the seismic fragility curves that can accurately predict the probability of tunnel damage. The nonlinear finite element analysis model for the soil–tunnel interaction system was established. The effects of different burial depths on damage to horseshoe-shaped tunnels in soft soil were systematically studied. By adopting the incremental dynamic analysis (IDA) method and assessing the correlation, efficiency, practicality, and proficiency of the potential IMs, the optimal IMs were determined. The analysis indicates that PGA emerges as the optimal IM for shallow tunnels, whereas peak ground velocity (PGV) stands as the optimal IM for medium-depth tunnels. Furthermore, for deep tunnels, velocity spectral intensity (VSI) emerges as the optimal IM. Finally, the seismic fragility curves for horseshoe-shaped tunnels in soft soil were built. The proposed fragility curves can provide a quantitative tool for evaluating seismic disaster risk, and are of great significance for improving the overall seismic resistance and disaster resilience of society.

KozhukhovaE.I., MustafinKh.Kh., SemenovV.A., UchanevaE.N. Reconstructing Ethnocultural Processes in the Sausken Valley (Tuva) during the Later Half of the 1st Millennium BC

The article represents findings of the group research devoted to reconstructing ethnocultural processes of the second half of the 1st millennium BC (Sausken Terrain Feature, Tuva). The research comprehensively studies local population groups who left behind their burial monuments in Eerbek River Valley. The study engages geneticist, ancient technologies experts, anthropologists and archaeologists. Kurgans of the middle and late Uyuk-Sagly Culture (5th–2nd century BC) were excavated in 2011–2016 by Tuva archaeological expedition arranged by the Russian Academy of Sciences Institute for the History of Material Culture. Nearly all burials in the kurgans had been robbed back in the ancient days. The study analyses above-ground structures and internal layouts of the kurgans, the burial ritual and tools (weapons, mirrors, belt accessories, bone items, embellishments). It allows to conclude that the kurgans have varying cultural attributions. The research also implies instrumental process analysis of glass and stone beads, chromatography of fabrics and proteomic analysis of archaeological leather. The paper reveals radiocarbon dating (14C) and correlations with other burial monuments of the Scythian Tuva. Craniological materials analysed allow to determine populations that could have been related to the aliens who arrived at the Eerbek River Valley in the Uyuk times. The Ozen-Ala-Belig groups differ from their peers from other territories in Tuva. It might be explained through the Uyuyk migrants mixing with the Eerbek Valley people who had been living there since the late Bronze Age. The paleogenetic study of 19 items especially focuses on researching the Y-chromosome DNA. For many researched samples the study determines haplogroups Q1b1a3-L330 and R1a1a1b2-Z93 (or its subgroups). The area of spread for these haplogroups is Soviet Central Asia, Central Asia, West and South Siberia. One samples is assigned to I2a1b1-M223 haplogroups with the area of spread in the Balkans and South-Eastern Europe. The obtained findings may indicate that the Western and Eastern nomads kept in touch during the researched period. The archaeological, anthropological and genetic data lead to a conclusion that the Scythian cultures in the given region is complex and multi-faceted.

Correlation Analysis of Tunnel Deformation and Internal Force in the Earthquake Based on Tunnel Inclination

An increasing number of studies have shown that the seismic response of shield tunnels differs from that of aboveground structures. While the seismic response of aboveground structures is mainly influenced by the peak acceleration and frequency of the earthquake, the seismic response of shield tunnels is more influenced by the ground displacement due to the surrounding soil layers. In this study, it is not appropriate to follow the seismic concept of aboveground structures. Dynamic time-history analysis is a powerful and effective method to study the seismic response of tunnels in the typical subway in this paper. The analysis results show that the overall levelling of the tunnel will not affect the tunnel too much, and the seismic response of the tunnel is mainly related to the relative displacement of the ground around the tunnel. The analysis results show that the internal force of the tunnel and the tunnel inclination have a good linear relationship, and the tunnel inclination can be used to measure the magnitude of the seismic response of the tunnel. In the seismic design of shield tunnels, the inclination of the tunnel can be taken into account to evaluate the change in the internal forces of the tunnel during earthquakes, which avoids the need for complex dynamic time-history analysis and greatly improves the efficiency of the seismic design of shield tunnels.

DESIGN METHODS AND FEATURES OF FOUNDATIONS OF HIGH-RISE BUILDINGS

The article large loads applied to the foundations of high-rise buildings from above-ground structures, as well as their high sensitivity to swaying, create their own peculiarities in the calculation and design of the foundations of high-rise buildings, which have not yet been sufficiently studied and require further research. In this regard, the study of these issues is relevant and has practical significance. The article proves that the pressure on the foundation of high-rise buildings is significantly higher than that of buildings up to 75 m high, which requires special laboratory and field studies; the features of geotechnical research, current standards, and excessive loads (1–2 MPa) are considered. High sensitivity to foundation deflections is ensured by increasing the dimensions (depth and width) of the compressed structure. The study examined the problems of calculation and design of foundations of high-rise buildings. The identified features of high-rise buildings require the development of geotechnical research, basic principles of calculation and design. It has been proven that in order to assess the accuracy of determining individual soil parameters, soil samples should be placed in devices that allow sealing the soil sample, as well as measuring pore and total pressure in order to restore the original state of the soil.

Interaction-performance-driven design of negative-stiffness friction pendulum systems for aboveground structure–connected underground structure–soil system with ground motion effects

Within the transit-oriented development framework, aboveground structure–connected underground structures (ASUS) have been widely constructed in urban areas; however, abrupt stiffness changes and complex soil–structure interactions could cause structural damage or business disruption after earthquakes. In this study, to address these challenges, a novel approach is proposed that employs negative stiffness, damping elements, and friction pendulum bearings to enhance the overall performance of ASUS. An interaction-performance-driven design procedure and parameter selection methodology are developed to simultaneously upgrade multiple performance aspects of ASUS. A mechanical model of the negative stiffness amplification system-enabled friction pendulum system (NSAS-FPS) is constructed. The theoretical basis of the equivalent negative stiffness and enhanced energy dissipation effects is elucidated, and a finite element model of the NSAS-FPS-incorporated soil–ASUS interaction system is established. Extensive parametric, robustness, and correlation analyses against short/long-period ground motions are conducted to provide a comprehensive performance assessment framework. Then, an interaction-performance-driven design principle aimed at multiperformance upgrading of aboveground and underground structures is developed with proposed parameter selections and applied in a case study. These results indicate a significant improvement in vibration control for both aboveground and underground structures when utilizing NSAS-FPS compared to utilizing conventional FPSs with the same design. By following the proposed design procedure and parameters, the NSAS-FPS demonstrates enhanced efficiency in isolating energy dissipation and robustness in seismic isolation, as well as resistance against overturning, irrespective of variations in structural masses and functionalities. While the advantages of the NSAS-FPS include its ability to mitigate the effects of stochastic earthquakes, the extent of the performance improvement may decrease during long-period earthquakes. Therefore, the velocity characteristics of seismic excitations need to be carefully incorporated into the NSAS-FPS design, particularly when targeting specific demands for the isolation-layer performance within ASUS.

The dosage- and size-dependent effects of micro- and nanoplastics in lettuce roots and leaves at the growth, photosynthetic, and metabolomics levels

The occurrence of microplastics (MPs) and nanoplastics (NPs) in soils potentially induce morphological, physiological, and biochemical alterations in plants. The present study investigated the effects of MPs/NPs on lettuce (Lactuca sativa L. var. capitata) plants by focusing on (i) four different particle sizes of polyethylene micro- and nanoplastics, at (ii) four concentrations. Photosynthetic activity, morphological changes in plants, and metabolomic shifts in roots and leaves were investigated.Our findings revealed that particle size plays a pivotal role in influencing various growth traits of lettuce (biomass, color segmentation, greening index, leaf area, and photosynthetic activity), physiological parameters (including maximum quantum yield - Fv/Fmmax, or quantum yield in the steady-state Fv/FmLss, NPQLss, RfdLss, FtLss, FqLss), and metabolomic signatures. Smaller plastic sizes demonstrated a dose-dependent impact on aboveground plant structures, resulting in an overall elicitation of biosynthetic processes. Conversely, larger plastic size had a major impact on root metabolomics, leading to a negative modulation of biosynthetic processes. Specifically, the biosynthesis of secondary metabolites, phytohormone crosstalk, and the metabolism of lipids and fatty acids were among the most affected processes. In addition, nitrogen-containing compounds accumulated following plastic treatments.Our results highlighted a tight correlation between the qPCR analysis of genes associated with the soil nitrogen cycle (such as NifH, NirK, and NosZ), available nitrogen pools in soil (including NO3− and NH4), N-containing metabolites and morpho-physiological parameters of lettuce plants subjected to MPs/NPs. These findings underscore the intricate relationship between specific plastic contaminations, nitrogen dynamics, and plant performance.

Digital applications for preserving archaeological sites and tourism management

Cultural heritage is an important part of our life, a resource for the identity and the cohesion of communities. The paper aims to identify possible solutions for cultural heritage management of the archaeological sites and monuments from Dobrogea. The authors documented and researched above-ground archaeological structures, analysing their characteristics and suggesting solutions for conservation and promoting of archaeological heritage. The rapid development of digital technologies like augmented reality can help us finding cost-effective solutions for archaeology and cultural heritage tourism.

REINFORCEMENT OF FOUNDATION IN CRAMPED SETTINGS

According to the analysis, deformations haven't stopped in most buildings even after repairs or strengthening of above-ground structures, leading to partial or complete destruction [1].

Investigation of the stress-strain state of foundation structures in determining the vertical stiffness of piles using different software systems

The results of numerical modeling of the interaction between a multi-storey building on a pile foundation and the soil base in the "Lira-SAPR" software are presented. A comparison of the stress-strain state of foundation structures was performed using different methods for determining vertical stiffness (Rz) in single-node FE 57 (this element is designed to model the behavior of a pile together with the surrounding soil, similar to FE 56, and can implement the interaction with the "SOIL" system). Piles were modeled by a chain of single-node FE 57 connected by vertical bars.
 In the first variant, the calculation of the building was performed in the "Lira-SAPR" software. To determine the vertical stiffness in FE 57, a soil model with physical-mechanical characteristics was created, and layering was defined according to the engineering-geological cross-section in the "SOIL" system. The calculation of vertical stiffness took into account mutual influence and the model of the conditional foundation.
 In the second variant, the determination of vertical stiffness (Rz) in FE 57 was carried out using the "Plaxis 3D" software. The overall model of above-ground structures, foundations, and all necessary loads were created in the "Lira-SAPR" software. Subsequently, an export to "Plaxis 3D" was performed, where the soil was previously modeled as a three-dimensional soil mass (with characteristics and strengths of layers similar to those created in the "SOIL" system) using the "Hardening soil" behavior model. After the import into "Plaxis 3D," the analysis of the "Soil-Foundation-Structure" system was conducted, and the obtained values of vertical stiffness (Rz) in FE 57 were exported back to "Lira-SAPR". After the export of "refined" values of vertical stiffness to "Lira-SAPR", a general static analysis and comparison of the stress-strain state of foundation structures with the first calculation variant was performed.
 It was established that the vertical stiffness in FE 57 in the first variant is higher than in the second, accordingly, the total displacements for the first variant are smaller. The importance of using the connection between "Lira-SAPR" and "Plaxis 3D" or other specialized geotechnical software complexes was demonstrated to obtain more accurate results of the interaction of the "Soil-Foundation-Structure" system due to the possibility of using nonlinear soil models to better describe the behavior of the foundation.

Change in strength parameters of dusty-clayey soils depending on the time of dynamic load impact and soil type

The method of high frequency vibratory driving and extraction of sheet piles is frequently utilized in the conditions of structurally unstable soils in St. Petersburg. However, with this method of installation (extraction) of sheet piles in the surrounding soil mass it arises oscillations that are transmitted to nearby buildings and housing, capable of causing dangerous phenomena in their undergroud and aboveground structures, mainly related to differential settlement of foundations. The prediction of additional settlement of buidings in the surrounding area from vibro-driving/extraction of sheet piles is a complex, multi-factor task, and the level of the structural displacement of building, which is the main controlled parameter for the influence of dynamic loading on the foundation soil, according to the current regulatory documents Territorial Building Codes50-302-2004, Departmental Building Codes490-87, Russian State Standard 52892-2007 is merely an indirect criterion for assessment. To obtain a more accurate assessment of the development of additional settlements in buildings during high-frequency vibratory pile driving and sheet pile extraction, it is necessary to take into account not only the duration and frequency of the impact, but also the properties and type of soil itself. The purpose of this reseach was to study changes in the strength parameters of silty-clay soils depending on the time of dynamic loads impact, the type and consistency of the soil itself, as well as changes in parameters depending on the “rest” time of the soil base after exposure to vibration. The article presents the results and shows the tendency to reduce the parameters of soil strength after the application of dynamic load and the dependence of their change on the time of impact, on the type and consistency of the soil. It has been determined the dependence of changes in the strength parameters of the soil conditionally upon the "rest" time of the soil mass as a result of thixotropic re-storation, which will determine the economic attractiveness for the accident-free technology of this method.

Features of stabilization of soft soils at the base of emergency deformed buildings using finely powdered injection materials in low pressure mode

At present, the strengthening of the soil base is often performed by high-pressure injection - injection of a solution under pressure that exceeds the structural strength of the soil (hydraulic fracturing mode). High-pressure injection makes it possible to successfully solve various geotechnical problems, but it has a number of disadvantages, first of all, the uncertainty of the shape and size of injection bodies created in the soil mass, as well as the impossibility of predicting the final deformation and strength characteristics necessary for design. It should be noted that directly from the production of injection works in the uncontrolled hydraulic fracturing mode, unpredictable technological deformations (rise followed by uneven settlement) of the Objects are observed, the base of which is stabilized, as a result of which crack formation processes in above-ground structures and fragmentary destruction of load-bearing elements develop. The article considers the possibility of solving the problem of predictable increase in the mechanical properties of stabilized soils on the example of a pilot production site in the central region of St. Petersburg. The proposed method makes it possible to ensure the absence of technological deformations from the production of injection works by using the author's kinematic scheme for the production of works and the use of modern solutions based on fine binders in the impregnation mode with an element of soil microfracture, that is, in the mode of controlled hydraulic fracturing at a reduced injection pressure of the injection solution.

Main characteristics of burial complexes of Central Kazakhstan in the Late Bronze Age

The main factual basis of the research comprised the materials of 25 necropoleis of the Late Bronze Age examined in the Karaganda and Ulytau regions of Central Kazakhstan. The total number of the investigated burials amounts to 167 individual structures. There were 190 burials recorded. Since the 2000s, nine cemeteries belonging to the Late Bronze Age have been investigated. There were 72 burial structures studied, including one of the eight largest mausoleums in the region — Karazhar-tas, excavated in 2016–2017. All known burial structures were divided into three groups: surface stone boxes, boxes imbedded in the bedrock, and ground graves, which, according to the characteristic above-ground structures, were divided into ten types of burial structures. It has been noted that for the first group of the burials, the most characteristic are quadrangular funeral structures erected using the masonry technique. The second group is dominated by quadrangular fences built from vertically set slabs, less often from stone laid on flat. The third group is clearly dominated by a ring-shaped layout in the form of the stones selected according to their dimensions, laid in a circle. The most numerous appeared to be the first group, for which the charac-teristic feature is the arrangement of the burial chambers in the form of stone boxes raised above the ground. The less repre-sentative was the second group with subsurface burials, including those that had a form of composite stone boxes. The third group comprised the burials in ground graves. It is assumed that in the first two groups, the westward orientation of the interred is predominant, with a certain role of the northeastern sector. The third group is characterised by the invariable orientation of the deceased in a southward direction with the sleeping position of the skeleton laid on the right side.

Foliar non-structural carbohydrates and resprouting ability of woody species in a tropical dry forest

Diverse disturbances contribute to biomass loss in tropical dry forests (TDF), of which slash-and-burn agriculture (SBA) may be the most severe; it is practiced by large populations of residents. Plant species capable of resprouting in response to such disturbances often possess above-ground structures that survive and mobilize resources for resprouting, in addition to below-ground structures. In Brazilian TDF, woody species regenerating from stem pieces that persist after SBA events are common. In this study, we evaluated the foliar concentrations of non-structural carbohydrates (NSC) and mineral nutrients during the first six months after an SBA event in all species that resprouted within the experimental area. Almost all the species resprouted exclusively from the stems. The measured nutrient concentrations did not change drastically after an SBA event. Two patterns were observed with respect to NSC concentrations among the species. Half of the studied species exhibited high concentrations of NSC before the SBA event, which gradually decreased three and six months after the disturbance. In contrast, the remaining species maintained consistent NSC concentrations throughout the study period. The cost of building new leaf tissue was similar for all species before the SBA event. However, after disturbance, the species invested different amounts of carbon into the new leaves. Those species that decreased NSC leaf concentration after SBA showed the highest regrowth intensity through the number of new tillers. Our results suggest that the intense translocation of NSC from the leaves before SBA may support the increased activity of the buds present in the remaining stem piece.

Impacts of Surface Deformation Induced by Underground Mining of Metal Mines on Above-Ground Structures: A Case Study

The surface deformation caused by underground mining seriously affects the normal life and personal safety of local residents and also causes unfavorable factors for the safe and efficient exploitation of underground resources. While the study of surface deformation caused by underground mining of metal mines requires a large amount of measured data as support, the measured data is particularly scarce, which severely hinders the study of surface deformation caused by underground mining. In this paper, in order to study the impact of underground mining on surface structures in metal mines, we take the Fu Lao Zhuang Iron Mine in Anhui Province, China, as the research object and put forward a comprehensive measurement method based on the flat plate beam theory. Using empirical formulas combined with the methods of thickness-to-span ratio and the relaxation coefficient, etc., we carry out numerical simulation calculations for the displacement of the surface triggered by the mining of the ore body by using FLAC3D software. We calculate the maximum inclination deformation, curvature, and horizontal deformation values of the ground surface by referring to the displacement and deformation with reference to the displacement and deformation formula; the maximum tilt deformation, curvature, and horizontal deformation values of the ground surface are calculated, and finally, the permissible values of the design specifications are combined to make a judgment. The research results of this paper put forward the prerequisite for improving the surface deformation induced by underground mining.

Soil denudation in the northwestern Negev (Israel) following the Late Byzantine – Early Islamic period

During the 5th and 6th centuries, the economic hinterland of the city of Gaza encompassed a network of settlements that supplied the city with agricultural produce. Water was collected in underground cisterns from rooftops and courtyards. While almost nothing remained of the above-ground structures since the settlements collapsed, soil erosion exposed these cisterns, which now serve as well-preserved indicators of the location and levels of the houses - that supplied the water. The study examines to what extent the land abandonment in the late Byzantine - early Islamic period resulted in denudation and soil property changes. We hypothesize that the abandonment of settlements and agriculture intensified soil erosion and amplified gully development. Approximately 140 cisterns were mapped in the study area, mainly north of the ephemeral Nahal Gerar stream. The height of the cisterns above the ground was used to calculate the denudation rate (DR) since abandonment. Findings indicate that over relatively flat terrains (1–5 %), cisterns protrude 0.5–1.2 m above the surface. Considering abandonment in the 6th or 11th century, DR was calculated as 0.35–0.85 mm/yr or 0.5–1.2 mm/yr, respectively. Over steeper slopes (10–12 %), along river banks and incised gullies, extensive bank erosion occurred, leading to the exposure of cisterns up to 2.5 m; DR = 1.8 to 2.5 mm/yr, depending on the abandonment time. The settlements' distribution and the surface topography directly correlate: in settled areas, Terrain Roughness Index (TRI) values are higher compared to other areas with the same lithology and rainfall amount. Following abandonment, decaying houses resulted in the complete disintegration of mud bricks, increasing the proportion of fine soil fractions. Cisterns acted as sedimentation basins, trapping surface-derived sediments and debris, including degraded brick material. This process influenced the mechanical composition of soils, affecting soil erosion and land degradation.

Performance of the suspension method in large cross-section shallow-buried tunnels

Large cross-section tunnel construction induces ground surface settlements, potentially endangering both subterranean projects and nearby above-ground structures. A novel tunnel construction method, known as the suspension method, is introduced in this paper to mitigate surface settlement. The suspension method employs vertical tie rods to establish a structural connection between the initial tunnel support system and the surface steel beam, thereby exerting effective control settlements. To analyze the performance of the proposed method, systematic numerical simulations were conducted based on the practical engineering of Harbin Subway Line 3. The surface settlement and vault settlement characteristics during construction are investigated. The results show a gradual increment in both surface and vault settlement throughout the construction process, culminating in a stabilized state upon the completion of construction. In addition, compared to the double-side drift method and the Cross Diaphragm Method (CRD) method, the suspension method can obviously reduce the surface settlement and vault settlement. Moreover, the surface settlements and the axial force of tie rods were continuously monitored during the construction process at the trial tunnel block. These specific monitoring measurements are illustrated in comparison to numerical analysis results. The monitored results show great agreement with the numerical predictions, confirming the success of the project. This research can serve as a valuable practical reference for similar projects, offering insights and guidance for addressing ground surface settlements and enhancing construction safety in the domain of large cross-section tunneling.

The transcription factor HSFA7b controls thermomemory at the shoot apical meristem by regulating ethylene biosynthesis and signaling in Arabidopsis

The shoot apical meristem (SAM) is responsible for overall shoot growth by generating all aboveground structures. Recent research has revealed that the SAM displays an autonomous heat stress (HS) memory of a previous non-lethal HS event. Considering the importance of the SAM for plant growth, it is essential to determine how its thermomemory is mechanistically controlled. Here, we report that HEAT SHOCK TRANSCRIPTION FACTOR A7b (HSFA7b) plays a crucial role in this process in Arabidopsis, as the absence of functional HSFA7b results in the temporal suppression of SAM activity after thermopriming. We found that HSFA7b directly regulates ethylene response at the SAM by binding to the promoter of the key ethylene signaling gene ETHYLENE-INSENSITIVE 3 to establish thermotolerance. Moreover, we demonstrated that HSFA7b regulates the expression of ETHYLENE OVERPRODUCER 1 (ETO1) and ETO1-LIKE 1, both of which encode ethylene biosynthesis repressors, thereby ensuring ethylene homeostasis at the SAM. Taken together, these results reveal a crucial and tissue-specific role for HSFA7b in thermomemory at the Arabidopsis SAM.

Importance of controlling mesocotyl elongation in the development of rice seedlings intended for mechanical transplantation.

The mesocotyl facilities the emergence of deep-sown rice. However, the effects of mesocotyl elongation on mechanically transplanted rice seedlings remain unclear. In this study, the indica three-line hybrid rice Chuanyou 6709 (CY6709) and the indica conventional rice Guichao II (GCII) were selected as experimental materials. The seedlings were grouped based on mesocotyl lengths of 1.0 and 2.0cm (M1 and M2, respectively), and seedlings without mesocotyl elongation were used as a control (M0). Seedling morphology, root morphology and physiology, and dynamic changes in soluble sugar and protein, malondialdehyde (MDA), and antioxidant enzyme activity in the mesocotyl were evaluated. The results showed that the elongation of mesocotyl is not conducive to improving the quality of mechanically transplanted seedlings, resulting in weak seedlings and poor root coiling force. The mesocotyl lengths of the seedlings showed a single peak with increasing seedling age, which gradually disappeared. The longer the mesocotyls, the slower their senescence. The MDA content of M2 was significantly lower than that of M1, and the activities of soluble sugar, soluble protein, and antioxidant enzymes of M2 were higher than those of M1, implying that seedlings with longer mesocotyls yielded lower-quality seedlings, reducing their suitability for mechanized transplantation. Compared with those of M0, the root-shoot ratio, stem base width, leaf age, leaf area, white root number, root coiling force, root length, root surface area, and root volume of M1 and M2 were reduced. Therefore, in the raising of rice seedlings, excessive elongation of the rice mesocotyl is not conducive to optimum root growth and development of aboveground structures for seedlings that are suitable for mechanized transplantation. Controlling the mesocotyl elongation can facilitate the cultivation of high-quality mechanically transplanted seedlings.