The twist-to-bend compliance of the Rheum rhabarbarum petiole: integrated computations and experiments

Measurement and Analysis of Root Anchorage Effect on Stalk Forces in Lodged Corn Harvesting

The effect of root anchorage on corn stalk is the main cause of difficulties in stalk lifting and ear picking of lodged corn. To quantify the forces on the stalks caused by root anchorage in corn harvesting, a root force measurement system was designed and applied in this study. The bending moment and torsional moment on the upright and lodged corn stalks were measured in corn harvesting with the designed system and the results were compared with the manually measured failure boundaries. The manually measured results showed bending moments to push down the upright stalks, to lift the lodged corn stalks, and to slip the lodged corn stalks were 35.12, 23.33, and 40.36 Nm, respectively, whereas the torsional moments needed to twist off the upright and lodged corn stalks were 4.02 and 3.33 Nm, respectively. The bending moments that the corn header applied to the upright, forward lodged, reverse lodged, and lateral lodged corn stalks were 10.68, 22.24, 16.56, and 20.42 Nm, respectively, whereas the torsional moments on them were 1.32, 1.59, 1.55, and 1.77 Nm, respectively. The bending force was the main factor that broke the root anchorage and influenced the stalk movement of lodged corn in harvesting. By analyzing the bending moment curves on the lodged corn stalks, it was proposed that for the harvesting of corn lodged in the forward, reverse, and lateral direction, the corresponding harvester header improvement suggestions are enlarging the size of pins on the gathering chains, reducing the speed of gathering chains, and lengthening the snouts with a sleeker surface, respectively. This study provides base data for the root anchorage effect on lodged corn and provides references for the improved design of the corn harvester header.

Environmental-biomechanical reciprocity and the evolution of plant material properties

Abiotic-biotic interactions have shaped organic evolution since life first began. Abiotic factors influence growth, survival, and reproductive success, whereas biotic responses to abiotic factors have changed the physical environment (and indeed created new environments). This reciprocity is well illustrated by land plants who begin and end their existence in the same location while growing in size over the course of years or even millennia, during which environment factors change over many orders of magnitude. A biomechanical, ecological, and evolutionary perspective reveals that plants are (i) composed of materials (cells and tissues) that function as cellular solids (i.e. materials composed of one or more solid and fluid phases); (ii) that have evolved greater rigidity (as a consequence of chemical and structural changes in their solid phases); (iii) allowing for increases in body size and (iv) permitting acclimation to more physiologically and ecologically diverse and challenging habitats; which (v) have profoundly altered biotic as well as abiotic environmental factors (e.g. the creation of soils, carbon sequestration, and water cycles). A critical component of this evolutionary innovation is the extent to which mechanical perturbations have shaped plant form and function and how form and function have shaped ecological dynamics over the course of evolution.

Wonderful Natural Drugs with Surprising Nutritional Values, Rheum Species, Gifts of the Nature

Abstract:

Nutrition therapy on the basis of traditional medicinal plants and herbs is common in many Asian countries, especially Iran and China. Rheum species, especially rhubarbs, belong to plant medicines recognized in 2500 BC. An online search of the literature was carried out at Pubmed/Medline, Scopus, and Google scholar, covering all years until April 2021. The following key terms were used, usually in combinations: Rheum species, rhubarb, natural products, pharmaceutical benefits, anthraquinones and anthranone. After performing the literature search, the bibliographies of all articles were checked for cross-references that were not found in the search databases. Articles were selected if they reported any biological effects, ethnomedicinal uses, phytochemical compounds and botanical description of Rheum species. The most important components of rhubarb are anthraquinones, anthranone, stilbenes, tannins and butyrophenones. Anthraquinones consist of rhein, emodin, aloe-emodin and chrysophanl, and anthranone includes sennosides and rheinosides. The most important health benefits of rhubarb are antioxidant and anticancer activities, antimicrobial activity, wound healing action, hepatoprotective and anti-diabetic effects, and nephroprotective effect, as well as anti-inflammatory, analgesic and antibacterial activities. Integration of both traditional pharmaceutical science and modern medicines may promote sustainability, lead to organic life and promote the cultivation of medicinal plants.

A Superellipse with Deformation and Its Application in Describing the Cross-Sectional Shapes of a Square Bamboo

Many cross-sectional shapes of plants have been found to approximate a superellipse rather than an ellipse. Square bamboos, belonging to the genus Chimonobambusa (Poaceae), are a group of plants with round-edged square-like culm cross sections. The initial application of superellipses to model these culm cross sections has focused on Chimonobambusa quadrangularis (Franceschi) Makino. However, there is a need for large scale empirical data to confirm this hypothesis. In this study, approximately 750 cross sections from 30 culms of C. utilis were scanned to obtain cross-sectional boundary coordinates. A superellipse exhibits a centrosymmetry, but in nature the cross sections of culms usually deviate from a standard circle, ellipse, or superellipse because of the influences of the environment and terrain, resulting in different bending and torsion forces during growth. Thus, more natural cross-sectional shapes appear to have the form of a deformed superellipse. The superellipse equation with a deformation parameter (SEDP) was used to fit boundary data. We find that the cross-sectional shapes (including outer and inner rings) of C. utilis can be well described by SEDP. The adjusted root-mean-square error of SEDP is smaller than that of the superellipse equation without a deformation parameter. A major finding is that the cross-sectional shapes can be divided into two types of superellipse curves: hyperellipses and hypoellipses, even for cross sections from the same culm. There are two proportional relationships between ring area and the product of ring length and width for both the outer and inner rings. The proportionality coefficients are significantly different, as a consequence of the two different superellipse types (i.e., hyperellipses and hypoellipses). The difference in the proportionality coefficients between hyperellipses and hypoellipses for outer rings is greater than that for inner rings. This work informs our understanding and quantifying of the longitudinal deformation of plant stems for future studies to assess the influences of the environment on stem development. This work is also informative for understanding the deviation of natural shapes from a strict rotational symmetry.