Tissue biomechanical strength, wear resistance and recovery in C4 turfgrass species: physiological and morphological factors and innovative evaluation techniques.

Turfgrass wear effects are known to be the sum of soil compaction and plant tissue injury. As such, tissue intrinsic resistance to several mechanical factors, including traction stress, is a decisive in determining the wear resistance of a turfgrass species. Wear simulation in the field can suffer from climate, soil and machinery operator error, and is always inclusive of the soil compaction factor that is one of the origins of turfgrass wear effects in the field. Lignin, dry matter, starch, sugars and silica are some of the tissue constituents and characteristics that have been associated with leaf and stem mechanical resistance, while little information is to be found concerning stolons and rhizomes. These organs not only enable C4 turfgrass species lateral growth, soil colonization and injury recovery, but are also key constituents of mature swards. A firsts study consisted in an extensive investigation on the effective leaf, rhizome traction resistance of Cynodon dactylon L. Pers. var. dactylon x C. transvaalensis Burt-Davy cv. Tifway 419 (Cdxt), Zoysia matrella (L.) Merr. Cv. Zeon (Zm) and Paspalum vaginatum Swartz. cv. Salam (Pv), as measured with a FIFA-approved dynamometer, and correlating these results with laboratory investigations on key tissue constituents. Several aspects emerged from the present work that can be summarized as follows: 1. Tensile strength tests on leaf, rhizome and stolon tissues of Cdxt, Zm and Pv can supply useful information regarding these species’ starch, sugars, dry matter, lignin and silica content. 2. Tensile strength was more influenced by tissue constituents than by tissue dimension. 3. The results of tensile strength tests are in accordance with these species’ wear resistance as tested in previous work, with Zm stronger than Cdxt and Pv. 3. In rhizomes and stolons, tissue breakage usually occurs in the area at the intercalary meristem at the apical zone in the immediate proximity of a node. 4. Older tissues have higher tensile strength thanks to their higher lignification. 5. Starch and sugars content found in tissues is in accordance with the species’ previously observed linear growth rate, with Cdxt faster than Pv and Zm. 6. Starch content is generally inversely proportional to lignin content. 7. Stolon TSS content, and glucose in general, is a clear marker of tissue mechanical strength. 8. Lignin is the principle constituent in determining tissue tensile strength, and as such it could be used as a turfgrass wear resistance predictor in the cultivar breeding stages. 9. Silica is a constituent undermining tissue tensile strength. 10. Leaves are the plant organs with the highest silicization and the lowest lignification of tissues. A second study consisted of testing slabs of mature canopies of the same species for wear resistance in laboratory with a Lisport machine, as adopted by FIFA for artificial turf testing. Worn slabs of turfgrass were then allowed to recover in greenhouse to fathom out percent recovery of shoots. The results of these investigations were once again plotted again laboratory investigations on key tissue constituents. Several aspects emerged from this second work that can be summarized as follows: 1. The Lisport machine can be successfully used in an effective and reproducible way to fathom out natural turfgrass wear resistance, devoid of soil compaction effects. 2. Wear resistance for C4 species as observed in the field does not necessarily coincide with the relative tissue intrinsic resistance, but rather with the initial canopy density. 3. C4 species show a wear resistance that is much higher than C3 species. 4. C3 species show a virtually nil recuperative capability (mainly due to the lack of vegetative propagation organs). 5. The species with a very high intrinsic (tissue) wear resistance are also the species with the slowest recuperation potential. This seems to be due to lower levels of starch and TSS available for recovery. 6. Starch was a clear marker of wear resistance (negatively correlated) and recovery (positively correlated). 7. Silica was a marker positively correlated with wear resistance. 8. Lignin was the clearest marker found to be positively correlated with wear resistance. 9. A more severe wear induces a higher percentage of shoot recovery, and this particular aspects deserves further investigation

Generalized Holographic Principle, Gauge Invariance and the Emergence of Gravity a la Wilczek

We show that a generalized version of the holographic principle can be derived from the Hamiltonian description of information flow within a quantum system that maintains a separable state. We then show that this generalized holographic principle entails a general principle of gauge invariance. When this is realized in an ambient Lorentzian space-time, gauge invariance under the Poincare group is immediately achieved. We apply this pathway to retrieve the action of gravity. The latter is cast a la Wilczek through a similar formulation derived by MacDowell and Mansouri, which involves the representation theory of the Lie groups SO(3,2) and SO(4,1).Comment: 26 pages, 1 figur

Warm-season turfgrass species generate sports surfaces with different playability

Synthetic sports surfaces are increasingly subject to standardization of athlete-surface and ball-surface interactions (playability parameters). Such standardizations have led to an increase in the level of the engineering and predictability of these surfaces, and as such may be beneficial also for natural turf. In warm and temperate climates, many natural turf sports surfaces are established with warm-season (C4) turfgrass species due to their suitability to the environment in such areas. This study was aimed at evaluating the Féderation Internationale de Football Association (FIFA)-standard playing characteristics of different sports turf surfaces obtained from three commonly used C4 turfgrass species: 1) ‘Tifway 419’ hybrid bermudagrass (Cynodon dactylon var. dactylon × C. transvaalensis), 2) ‘Zeon’ manilagrass (Zoysia matrella), and 3) ‘Salam’ seashore paspalum (Paspalum vaginatum) for factors concerning leaf tissue (silica, lignin, water content) and canopy structure (shoot density, leaf architecture, stolon density, etc.). Results showed that surfaces of different C4 turfgrass species generate different playability parameters, with seashore paspalum being a harder faster surface, manilagrass being a softer slower surface, and hybrid bermudagrass showing intermediate characteristics. These playing quality results were associated with certain specific canopy biometrical/morphological parameters such as shoot density, horizontal stem density (HSD), leaf section, and, to a lesser extent, to certain plant tissue compounds (lignin, silica)

Industrial exoskeletons from bench to field: Human-machine interface and user experience in occupational settings and tasks

OBJECTIVE: Work-related musculoskeletal disorders (WRMSDs) are considered nowadays the most serious issue in the Occupational Health and Safety field and industrial exoskeletons appear to be a new approach to addressing this medical burden. A systematic review has been carried out to analyze the real-life data of the application of exoskeletons in work settings considering the subjective responses of workers. METHODS: The review was registered on PROSPERO. The literature search and its report have been performed following the PRISMA guidelines. A comprehensive literature search was performed in PubMed, EMBASE, Web of Science, and Scopus. RESULTS: Twenty-four original studies were included in the literature review; 42% of the papers retrieved included automobilist industry workers, 17% of the studies evaluated the use of exoskeletons in logistic facilities, and 17% of articles involved healthcare. The remaining six papers recruited farmers, plasterers, wasting collectors, construction workers, and other workmen. All the papers selected tested the use of passive exoskeletons, supporting upper arms or back. Usability, perceived comfort, perceived exertion and fatigue, acceptability and intention to use, occupational safety and health, and job performance and productivity were the main topic analyzed. CONCLUSION: Exoskeletons are not a fix-all technology, neither for workers nor for job tasks; they tend to show more of their potential in static activities, while in dynamic tasks, they can obstacle regular job performance. Comfort and easiness of use are the key factors influencing the user's experience. More research is needed to determine the most effective and safe ways to implement exoskeleton use in occupational settings. SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=275728, identifier CRD42021275728

Improving aesthetic and diversity of bermudagrass lawn in its dormancy period

Among warm season grasses, Cynodon dactylon (L.) Pers, commonly called bermudagrass, is one of the species that better tolerates drought stress and is the most widely employed for turf in Italy.When temperatures drop below 0 °C, bermudagrass plants enter dormancy and eventually leaves turn brown. In spring, exit from dormancy occurs when soil temperatures persist for several days with an average above 10 °C. The management of an ornamental turf during dormancy could include the use of other herbaceous species able to enhance aesthetic quality, although no study has so far been carried out on the potential for combined planting of warm season grasses, wildflowers and/or bulbous species. The present study was carried out to (a) evaluate the possibility of integrating into the dormant Cynodon dactylon x C. Transvaalensis cv. Tifway 419 lawn some plants able to enhance the ornamental aspect and biodiversity, (b) attempt to identify the best species, (c) observe phenomena of competition, and (d) define the protocol for cultivation of a lawn composed of hybrid bermudagrass, bulbous, annual and perennial herbaceous plant species.The experiment was carried out on a mature (over 5 years-old) sward of hybrid bermudagrass on which eight bulbous species (geophytes) were planted and eight species of native forbs (wildflowers) were sown. Forbs that could coexist after two years with bermudagrass were B. perennis and G. molle. Concerning the bulbous species C. pulchellus, M. neglectum, G. nivalis and N. minor were suitable to be planted in a Bermuda grass. The presence of these species on a dormant bermudagrass turf improved the aesthetical quality and the diversity of the vegetation; as the studied species are able to attract pollinating insects therefore, support a habitat. Further studies will be required to test the most suitable forbs as a mix in combination with bulbous species

Physiological and morphological factors influencing wear resistance and recovery in C3 and C4 turfgrass species

High turfgrass wear resistance and recovery are the most sought after characteristics in turfgrass species when used for sports turf, but they are also very important in home gardens and public parks. Several wear resistance investigations have been conducted in field conditions in recent years, but these investigations involved the use of machinery and techniques that are not able to segregate the plant wounding and death effects from soil compaction effects that are generally associated with turfgrass wear. The same can be said of wear recovery investigations, with an extensive use of agronomical machinery for field trials. This study focussed on the wear resistance and recovery of mature swards of Cynodon dactylon (L.) Pers. var.dactylonC. transvaalensis Burt-Davy cv. Tifway 419, Zoysia matrella (L.) Merr. cv. Zeon and Paspalum vaginatum Swartz. cv. Salam and a typical sports-type mix of Lolium perenne L. (cvv. Speedster 35% and Greenway 35%) + Poa pratensis L. (cvv. SR2100 15% and Greenknight 15%). The goal of this trial was to evaluate turfgrass wear resistance and recovery devoid of climatic and soil effects and thus, sward growing, wear simulation and recovery were conducted in controlled environment. Furthermore, wear simulation was conducted with FIFA-approved, numerical control machinery (Lisport). Wear resistance and recovery data was plotted against results from laboratory investigations on key tissue constituents. Zoysia matrella proved to be the most wear resistant, but the slowest in recovery, whereas the bermudagrass hybrid showed the exact opposite behaviour. Lignin and carbohydrate concentrations proved to be the two factors most closely correlated with wear resistance and recovery respectively. These two classes of compounds were present in an equilibrium that was species specific, with a frequent mutual exclusion between lignin and starch concentrations that deserves further investigation at the intra-specific level

Turfgrass spectral reflectance: simulating satellite monitoring of spectral signatures of main C3 and C4 species

In recent years, within the European Union several legislative, monitoring and coordinating actions have been undertaken to encourage sustainable use of resources, reduction in the use of chemicals and improvement of the urban environment. In this respect, two concepts that are strictly related to most of the aspects above are: ‘‘precision agriculture’’ and ‘‘precision conservation’’ and more specifically ‘‘precision turfgrass management.’’ Optical sensing has become a crucial part of precision turfgrass management and spectral reflectance in particular has been an active area of research for many years. However, while turfgrass status evaluation by proximity-sensed spectral reflectance appears to be an established and reliable practice, much more could be achieved in terms of monitoring of large turfgrass areas through remote sensing, and in particular through satellite imagery. This paper reports the results of a trial attempting to evaluate the spectral signatures of several turfgrass species and cultivars, for future use in turfgrass satellite monitoring. Our experimental study focused on 20 turfgrass species/varieties including perennial ryegrasses, tall fescues, kentucky bluegrasses, bermudagrass ecotypes, seeded commercial bermudagrasses, vegetatively propagated bermudagrasses, Zoysia japonica and non-japonica zoysiagrasses. Various biological and agronomical parameters were studied and turfgrass spectral reflectance for all entries was gathered. Vegetation indices were calculated by simulating the available wavelengths deriving from World View 2 satellite imagery. Results showed that within the same species selected vegetation indices are often able to discriminate between different varieties that have been established and maintained with identical agronomical practice

Monitoring turfgrass species and cultivars by spectral reflectance

Like all modern agriculture sectors, turfgrass productionand management is headed towards cost reduction, resourceoptimization and reduction of the environmentalimpact. In recent years the development of newtechnologies has provided new tools for monitoringagricultural crops. In particular, the combined adoptionof geographic information systems, global positioningsystems, multispectral lenses on board satellitesand cartographic techniques allow a large scalemanagement of agricultural resources. This paper reportsthe results of a trial attempting to evaluate thespectral signatures of several turfgrass species\cultivars,for future use in satellite monitoring. This experimentalstudy focused on 20 turfgrass species\cultivars,including perennial ryegrasses, tall fescues, kentuckybluegrasses, bermudagrasses (ecotypes, seededand vegetatively propagated cultivars) and zoysiagrasses.Various agronomical and biological parameterswere studied (quality, colour, dry matter, chlorophyll,carotenoids, nitrogen content) and turfgrass spectralreflectance for all entries was gathered. Results showedthat, within the same species, selected vegetation indicesare often able to discriminate between differentcultivars that have been established and maintainedwith identical agronomical practices. Evaluation ofthe spectral reflectance of plants using field spectroradiometryprovides the possibility to identify differentspecies\ cultivars, especially through the use of hyperspectralproximity and remote sensing

The effect of increasing application rates of nine plant growth regulators on the turf and Stolon characteristics of pot-grown ‘patriot’ hybrid bermudagrass

Vegetatively propagated warm-season turfgrasses are established with methods that rely on large quantities of propagation material and subsequent plant growth support. The precision seeding adopted for some seed propagated crops controls the depth and spacing at which seeds are placed in the soil. Sprigs that are reduced in length could potentially be suitable for existing machinery, and precision planting could enhance the efficiency of use of the propagation material. The aim of the present study was to carry out a preliminary screening on products known to act as plant growth regulators to explore their potential use for controlling stolon development and elongation of ‘Patriot’ hybrid bermudagrass (Cynodon dactylon x C. transvaalensis) grown in pots for propagation purposes. Trinexapac-ethyl (TE), chlormequat chloride (CM), paclobutrazol (PB), propiconazole (PPC), diquat (DQ), flazasulfuron (FS), glyphosate (GP), ethephon (EP), and gibberellic acid (GA) were applied to pot-grown ‘Patriot’ hybrid bermudagrass turf in eight different application rates, ranging for each product from the minimum expected effective rate to a potentially harmful rate. Of the tested treatments, TE applied at 2.0 kg·ha-1 and PB applied at 1.0 kg· ha-1 reduced stolon and internode length without causing a reduction in the stolon number or turf quality. PPC was also effective in reducing stolon length, but the effect on internode length was not statistically significant. Stolon length was unaffected by CM, while DQ and GP induced stolon elongation. FS, EP, and GA affected stolon length without a consistent relation between stolon length and application rate. The chemical suppression of stolon elongation in pot-grown ‘Patriot’ hybrid bermudagrass can contribute to controlling sprig size for use with precision seeding machinery