Mechanical Properties Of Plants Research Articles

Analysis of the structure and portion-intermittent movement of the threshed material in the threshing-separating tract

The article considers a number of models for describing threshing technology, which is associated with a variety of physical and mechanical properties of plants under different threshing conditions. The analysis of determining the position of a site with a relatively high resistance to the movement of plant mass is carried out, which may allow taking constructive measures to increase the speed of stems and reduce their damage for threshing machines of different sizes. The main components of the threshing medium in the threshing space are stems and grains. When studying the regularities of the threshing and separation processes, various models of the components of the threshed mass are used, reflecting to varying degrees the essential aspects of the phenomena under study. The given models of the threshed mass expand our understanding of the picture of what is happening in the threshing space.

Axial variation in flexural stiffness of plant stem segments: measurement methods and the influence of measurement uncertainty

BackgroundFlexural three-point bending tests are useful for characterizing the mechanical properties of plant stems. These tests can be performed with minimal sample preparation, thus allowing tests to be performed relatively quickly. The best-practice for such tests involves long spans with supports and load placed at nodes. This approach typically provides only one flexural stiffness measurement per specimen. However, by combining flexural tests with analytic equations, it is possible to solve for the mechanical characteristics of individual stem segments.ResultsA method is presented for using flexural tests to obtain estimates of flexural stiffness of individual segments. This method pairs physical test data with analytic models to obtain a system of equations. The solution of this system of equations provides values of flexural stiffness for individual stalk segments. Uncertainty in the solved values for flexural stiffness were found to be strongly dependent upon measurement errors. Row-wise scaling of the system of equations reduced the influence of measurement error. Of many possible test combinations, the most advantageous set of tests for performing these measurements were identified. Relationships between measurement uncertainty and solution uncertainty were provided for two different testing methods.ConclusionsThe methods presented in this paper can be used to measure the axial variation in flexural stiffness of plant stem segments. However, care must be taken to account for the influence of measurement error as the individual segment method amplifies measurement error. An alternative method involving aggregate flexural stiffness values does not amplify measurement error, but provides lower spatial resolution.

Decay Process Characteristics and Fungal Community Composition of Salix psammophila Sand Barriers in an Arid Area, Northern China

With the increase in setting years in deserts, Salix psammophila sand barriers with different degrees of lodging damage caused by decay are losing wind-prevention and sand-fixation properties. In this study, we focus on the change in chemical properties of soils, and physical and mechanical properties of plants along different setting years; meanwhile, the change in fungal communities has been analyzed using high-throughput sequencing technology. The results show that a change in physical and mechanical properties and the loss of primary chemical components led to the degradation of the protective properties of the barrier to different degrees. After five years of setting, the physical parameters of basic density and shrinkage rate decreased by 44.04% and 28.68%, respectively, and the loss of the modulus of rupture mechanical index declined by 62.72%. After seven years of setting, the mechanical indexes of the modulus of rupture decreased by 76.95%. Five and seven years represented important inflection points in the decay process. Sordariomycetes (53.75%) and Eurotiomycetes (19.78%) were the main fungal groups present during the decay of the sand barrier. The basic density, moisture content, cellulose, and lignin of the sand barrier were the main driving factors affecting the distribution of fungal communities. The mechanism on fungal community to the decay of sand barriers still needs further studies to keep the function of sand barriers in fragile desert ecosystems.

The Results of the Laboratory Studies of Harvesting the White Lupine by a Stripper Header with Fingers for Large Seed Crops

Introduction. Agricultural machinery and devices used for harvesting white lupines do not provide a complete collection of seeds, which leads to the violation of agricultural requirements for the harvesting of leguminous crops. It is necessary to find new technological and technical solutions to reduce losses of seeds during this process. The most perspective solution to the problem of white lupine harvesting is the application of industrial flow line technology together with the improvement of the method to comb standing plants by a stripper header. Materials and Methods. The article presents the design of a laboratory setup with experimental working bodies, which allows simulating the process of harvesting white lupines by separating the seed part of plants in the field. The empirical method based on the theory of multi-factor experiment was used to substantiate the parameters and operating modes of the stripper header with fingers for large seed crops. The algorithm and results of experimental studies to determine the completeness of seed collection are presented. Results. The results of the laboratory studies of the stripper header with fingers for largeseeded crops to determine the qualitative indicators for the completeness of the collection of white lupine seeds are presented. It is determined that the maximum completeness of seed collection is 99.5%. Discussion and Conclusion. In studying the technological process of harvesting white Degas lupine seeds by a combing header with fingers for large-seeded crops under laboratory conditions, the physical and mechanical properties of plants were experimentally studied, their morphological characteristics were clarified, and the regimen-technological parameters of the harvesting header were determined to ensure seed loss within agrotechnical requirements (0.5%).

A new perspective on mechanical characterisation of Arabidopsis stems through vibration tests

The mechanical properties of plants are important for understanding plant biomechanics and for breeding new plants that can survive in challenging environments. Thus, accurate and reliable methods are required for the determination of mechanical properties such as stiffness and Young's modulus of elasticity. Much attention has been paid to the application of static methods to plants, while dynamic methods have received considerably less attention. In the present study, a dynamic forced vibration method for mechanical characterisation of Arabidopsis inflorescence stems was developed and validated against the conventional three-point bending test. Compared to dynamic tests based on free vibration, the current method allows to determine simultaneously more than one natural frequency, thus increasing the overall accuracy of the results. In addition, this method can be applied to the top parts of the stems that are more flexible, and where application of the three-point bending test is often limited. To demonstrate one of the potential applications of this method, it was applied to evaluate the influence of turgor pressure on the mechanical properties of Arabidopsis stems. Overall, the new dynamic testing approach has been shown to provide reliable data for the local mechanical properties along the Arabidopsis inflorescence stem.

Stink Bug Communication with Multimodal Signals Transmitted through Air and Substrate

This review represents complex mechanisms and processes of multimodal communication in stink bugs. During reproductive behavior the airborne and substrate-borne signals enable mate recognition, mediate directionality of movement, eliminate rivals and motivate partners for copulation. Species specific characteristics prevent hybridization at various levels of mating behavior. Male sex and/or aggregation pheromones as uni- or multicomponent signals attract mates to land on the same plant and there, trigger females to call males by vibratory signals, transmitted through the plant. Communication during courtship runs at short distance with visual, airborne, substrate-borne and contact chemical and mechanical signals. Abdomen vibrations produce the main repertoire of female and male calling, courtship and rival vibratory signals. To increase their informational value, stink bugs tune signal frequency, amplitude and temporal characteristics with mechanical properties of plants. The airborne component of species non-specific and high amplitude signals, produced by body tremulation and wing buzzing enables communication contact between mates standing on mechanically isolated plants. Female vibratory signals increase the amount of male emitted pheromone and the latter keeps female calling. Interaction, synergy and characteristics of visual, contact chemical and vibratory signals, exchanged during courtship remain under-investigated. Female and male competition for access to copulation in imbalanced sex conditions is characterized by duetting with rival song vibratory signals. Different receptors in and on different parts of the body are able to detect with high sensitivity multimodal airborne and substrate-borne communication signals. The relevance of the multimodal communication for the reproductive success of stink bugs is discussed.

Unraveling the impact of Pto4CL1 regulation on the cell wall components and wood properties of perennial transgenic Populus tomentosa

Cell wall components and structure impact the physical and mechanical properties of plants, thereby affecting wood applications. Lignin is the most abundant biopolymer after cellulose in the wood cell wall and can be modified by certain lignin biosynthesis enzymes. 4-Coumarate: coenzyme A ligase(4CL) is an important lignin biosynthesis enzyme. To demonstrate the impact of the regulation of Pto4CL1 from poplar on wood properties, we analyzed the composition and anatomy of 5-year-old Pto4CL1-modified poplar cell walls, assessing the density, strength, volume shrinkage, and impact toughness of the transgenic trees. These results showed that the up-regulation of Pto4CL1 increased the lignin content to 46.65% from 33.11% in the control plants, while hydrophilic polysaccharides such as cellulose, hemi-cellulose, and pectin decreased. In contrast, the down-regulation of Pto4CL1 resulted in a reduction in lignin content to 27.39%, and the content of cellulose and hemi-cellulose showed compensatory variation. Raman spectroscopy showed that the change in lignin in the transgenic events was embodied in the deposition and concentration of lignin in the secondary cell wall. Moreover, the increased lignin content caused significantly increased wood strength and slightly increased wood density. In contrast, a reduction in lignin content resulted in a significant decrease in wood strength and a slight decrease in wood density. However, the Pto4CL1-modified trees had similar stiffness to the control group. We also found a significant decrease in volume shrinkage and increase in impact toughness in the low-lignin events. These results indicate that Pto4CL1 regulation alters the chemical composition of plant cell walls and these changes affect the physical and mechanical properties of the wood.

Criterial models of the stem separation process when harvesting rice

The problem of determining the influence of several major environmental factors on the value of grain losses during rice stem separation by a vibratory grain divider is considered. It makes it possible to establish the grain loss dependences upon varying the divider's parameters obtained for polynomial and criterial models, as well as enables to confirm the advantage and feasibility of using a vibratory grain divider on windrowers for rice harvesting. The criterion equations of the stem separation process by a vibratory grain divider are developed and the dependences of the change in the loss values behind the divider when cutting upright and lodged rice are obtained. They confirm the results of statistical studies, but to a greater extent illustrate information about the stem separation process. For this research, a classical theory of similarity and modeling was used, which made it possible to develop a model construction method taking into account physical and mechanical properties of plants when they are cut with windrowers on upright and lodged agricultural backgrounds with losses in the divider zone and under the windrow in the harvest field.

Evaluation of Hydro-Mechanical Properties and Root Architecture of Plants for Soil Reinforcement

Plant helps to stabilize the masses of soil via hydrological and mechanical means. The effects of vegetation on soil depend on the overall root growth, architecture and its hydro-mechanical functions. Three leguminous plants, Leucaena leucocephala, Pterocarpus indicus and Peltophorum pterocarpum were evaluated in terms of their hydro-mechanical characteristics and root architecture for soil reinforcement. The results show that L. leucocephala exhibited the highest hydrological properties such as diurnal transpiration, water absorption capacity and soil matric suction (SMS). Regarding mechanical characteristics, L. leucocephala exhibited the highest root tensile strength and cellulosic components in the root. Interestingly, L. leucocephala also showed a higher root length, volume and tips than Pterocarpus indicus and Peltophorum pterocarpum . The SMS was strongly (r = 0.79) correlated with leaf area index (LAI), indicating that high LAI improved SMS. In conjunction with the cellulosic composition, root tensile strength of the species studied was highly correlated with the alpha-cellulose content (r = 0.9) and showed that high alpha-cellulose content of roots improved mechanical properties of plants to provide reinforcement in the soil. The highroot tensile strength, root cellulosic composition and VH-type root of L. leucocephala make the species special for growing as a soil reinforcing plant. In conclusion, L. leucocephala properties revealed that it possessed excellent hydro-mechanical properties and root architecture and can be planted on slopes for soil reinforcement.

Interactive effects of mechanical stress, sand burial and defoliation on growth and mechanical properties in Cynanchum komarovii

In drylands, wind, sand burial and grazing are three important factors affecting growth and mechanical properties of plants, but their interactive effects have not yet been investigated. Plants of the semi-shrub Cynanchum komarovii, common in semi-arid parts of NE Asia, were subjected to brushing, burial and defoliation. We measured biomass allocation and relative increment rates of dry mass (RGR(m)), height (RGR(h)) and basal diameter (RGR(d)). We also measured the stem mechanical properties, Young's modulus (E), second moment of area (I), flexural stiffness (EI) and breaking stress (σ(b)), and scaled these traits to the whole-plant level to determine the maximum lateral force (F(lateral)) and the buckling safety factor (BSF). Brushing increased RGR(m); neither burial nor defoliation independently affected RGR(m), but together they reduced it. Among buried plants, brushing positively affected stem rigidity and strength through increasing RGR(d), E, I and EI, and at whole plant level this resulted in a larger BSF and F(lateral). However, among unburied plants this pattern was not observed. Our results thus show that effects of mechanical stress and grazing on plants can be strongly modified by burial, and these interactions should be taken into account when considering adaptive significance of plant mechanical traits in drylands.

Simulation Design of Bionic Blade on Wind Turbine

After millions of years of competition and the natural evolution of species, the biological nature (plant leaves) has formed a number of natural and rational structure. This form of the structure and organisms inherit environmental stress exist some connection. This paper as a study of plant leaves, using numerical simulation methods to explore the structure and mechanical properties of plant leaves the relationship between: Collection of fresh plant leaves, leaf through the AutoCAD software to obtain the coordinates of the point cloud, created in the ANSYS finite element model of a simplified blade, applied uniformly distributed wind load calculations to solve; and optimal blade vibration modal analysis program.

Leaf biomechanics as a potential tool to predict feeding preferences of the geometric tortoise Psammobates geometricus

Food and non food plant characteristics were studied for the geometric tortoise, Psammobates geometricus, to test the hypothesis that feeding preferences in tortoises may be influenced by the mechanical properties of plant leaves. Twelve focal feeding observations made between 8 October and 31 October 2002 were synthesized with literature reports to develop species lists of food and non food grasses and geophytes in renosterveld habitat. Failure load and tensile strength were determined in the field for leaves of food and non food plants that were spatially available to the tortoises and present in relative abundance during the course of the study. Leaves of geophyte food plants were fleshy and succulent with a low failure load and tensile strength. Leaves of food plant grasses had significantly higher failure loads and tensile strengths compared to leaves of food plant geophytes. In non food plants there was no signifi cant difference in failure load between grasses and geophytes, but tensile strength was signifi cantly higher in the grasses. Non food plant grasses and geophytes overall had significantly higher failure load and tensile strength values than did food plants. Two non food plants that overlapped in mechanical strength to the food plants either have toxic/unpalatable chemicals in high amounts or are recent invasive species to the renosterveld. Thus, these studies support the hypothesis that leaf biomechanical properties may be an important factor in determining the diet of the geometric tortoise and perhaps tortoises in general.

Time-dependent aspects of the mechanical properties of plant and vegetative tissues

Based on a single regular cell structural model, the effects of loading rate on the compressive behaviour of plant and vegetative tissues have been qualitatively investigated. The cell walls were treated as a polymeric composite material with microfibrils embedded in the highly structured cell wall matrix. The rubber elasticity, the turgor permeability and the loading rate were taken into account to qualitatively predict the tissue stiffness, cell wall stress, turgor pressure, cell debonding force, and the percentage of weight loss of the cell fluid. The predicted results are consistant with the related experimental phenomena.