Substrate Physical Characteristics Research Articles

Key Technologies of Plug Tray Seedling Transplanters in Protected Agriculture: A Review

The process of plug tray seedling transplanting is a crucial step in protected agriculture production. Due to issues such as high labor intensity, poor consistency of work quality, and low efficiency, the application of automated transplanting machines has provided a solution to these issues. For the diversity of transplanting operations, various mechanical structures and technological applications have been developed for automated transplanting equipment. Therefore, this paper provides systematic research of current studies on the key transplanter technologies. Firstly, through an analysis of the types of transplanting operations, the technical requirements of automated transplanting equipment for different operation types are elucidated. Subsequently, the key technologies applied in transplanting machines are discussed from the perspectives of substrate physical characteristics, end effectors, integration of multiple end effectors, vision systems, and transplanting path planning. Moreover, an analysis is conducted on the advantages, disadvantages, and application scenarios of different research methods for each key technology. Lastly, the existing problems and technical difficulties of the transplanting machine are summarized, and future research directions are discussed. This analysis provides a valuable reference for further research and development in the field of transplanting machines for plug tray seedlings.

Single-screen Bark Particle Separation Can be Used to Engineer Stratified Substrate Systems

Substrate stratification is an emerging substrate management strategy involving layering multiple substrate materials within a single container to modify physiochemical characteristics of the substrate system. Specifically, stratifying allows growers and researchers to rearrange the air–water balance within a container to modify hydraulic characteristics. Moreover, fertilizer can be incorporated into just the upper strata to reduce leaching. Research to date has shown benefits associated with resource efficiency, production timing, and weed control. With the associated benefits for substrate stratification, interested growers will need pragmatic solutions for onsite trials. Therefore, the objective of this study was to identify a cost-effective solution for growers interested in exploring stratification options. As such, this research was designed to identify a single-screen bark separation to generate fine and coarse bark textures suitable for use as the top and bottom substrate strata. Loblolly pine bark (Pinus taeda) was screened with either a 4.0-mm, 1/4-inch, or 3/8-inch screen, with the particles passing through the screen (unders) separated from retained particles (overs). Stratified substrate systems were engineered with an individual screen wherein the fines were layered atop the coarse particles from the same screen. ‘Natchez’ crepe myrtle (Lagerstroemia indica) liners were planted in either of the three stratified substrate treatments or a nonstratified control. Substrate physical characteristics were assessed for each strata by pre- and postproduction properties to identify changes of substrate. The final growth index of the crop was unaffected by the substrate treatment (P = 0.90); however, stratified substrates did increase dry root weight (P = 0.02), with the smallest screen (4.0 mm) resulting in the greatest root weight. Separation of roots between the two strata indicated the presence of more roots in the upper strata in all substrates. However, the stratified substrates resulted in a greater shift in root location, encouraging increased rooting in the upper strata with fine particles, with the largest screen (3/8 inch) resulting in the greatest differentiation between upper and lower rooting. Each stratified treatment had increase in water-holding capacity in the lower (coarser) strata without changes in the upper strata. Thus, we conclude that single screens can be used to build stratified substrate systems. Moreover, screen aperture size may be used to achieve different outcomes with regard to root growth and development as well as water–air balance. Further research may indicate that screen selection may be used to target specific crop needs.

Basalt rock dust incorporated to substrate favors Monteverdia ilicifolia seedlings initial growth

This study aims to analyze the incorporation of basalt rock dust to a commercial substrate based on pine bark under two light conditions on initial growth of Monteverdia ilicifolia (Mart. Ex Reissek) Biral seedlings. We evaluated four proportions of rock dust: 0% (control), 10%, 20%, and 30% on plants kept unshaded and under 50% shading for 140 days. The unshaded condition associated with basalt rock dust incorporated to substrate presented the higher seedlings growth. Incorporating rock dust in any proportion to the substrate increased stem diameter and biomass, resulting in a greater Dickson quality index (DQI) in unshaded seedlings. The rock dust in a proportion of 10% showed better results in seedlings growth. Moreover, 20% and 30% of rock dust reduced stem diameter, biomass, and DQI, when compared to 10% of rock dust, possibly due to the substrate physical characteristics. We recommend incorporating 10% of rock dust to the pine bark-based substrate for M. ilicifolia seedlings production in an unshaded environment.

Evidence of spawning by lake trout Salvelinus namaycush on substrates at the base of large boulders in northern Lake Huron

Identification of lake trout spawning sites has focused on cobble substrates associated with bathymetric relief (e.g., ‘contour’ or ‘slope’ along reefs), but this ‘model’ may be narrow in scope. Previous telemetry work conducted near Drummond Island, USA, Lake Huron, identified egg presence in substrates at the base of large boulders (>1 m diameter); however, the extent of this phenomenon was unknown. Telemetry data paired with multi-beam bathymetry identified a 0.63 km2 area used by lake trout characterized by low bathymetric relief and numerous (~269) large boulders (>1 m diameter) with small-diameter substrates at their bases. Diver surveys revealed egg presence at all 40 boulders surveyed, exclusively associated with clean gravel-cobble (0.6–42 cm) substrates in undercut areas beneath overhanging edges of boulders and in narrow spaces between adjacent boulders. Egg presence was not associated with boulder or substrate physical characteristics which highlighted the possible importance of interstitial currents. Successful incubation in these habitats was inferred by capture of free embryos and post-embryos the following spring using traps and an electrofishing ROV although at lower densities than at popular spawning habitats nearby (1–3 km away). Free embryos and post-embryos were also caught where eggs were not observed the previous fall including unexpectedly on top of boulders which suggested that post-hatch stages may move more than previously thought. Extensive use of boulder-associated habitats for spawning, egg incubation, and early growth suggested this undescribed habitat type may provide an unanticipated contribution to total available lake trout spawning habitat and recruitment in the Great Lakes.

Low levels organic amendments improve fertility and plant cover on non-acid generating gold mine tailings

We tested the use of low quantities of organic amendments (5.3tha−1 papermill sludge and 5.6tha−1 woodchips) and fertilizer in enhancing the cover and survival of vegetation on mine tailings. Plots were subdivided and seeded with a mix of grasses and/or alfalfa and planted with native Picea mariana. The papermill sludge amendment and grass seeding resulted in the highest plant cover and survival of plant P. seedlings. This amendment and the subsequent plant establishment lead to improvements in substrate aggregation and organic content. Other amendment treatments never exceeded 50% cover, and did not improve substrate physical characteristics. The initial pulse of chemical nutrients provided by amendments was relatively short-lived, with all amendment treatments returning to their background levels within one to two growing seasons. This study suggests that certain abandoned tailings dumps can be revegetated with minimal input.

Experimental analysis of green roof substrate detention characteristics

Green roofs may make an important contribution to urban stormwater management. Rainfall-runoff models are required to evaluate green roof responses to specific rainfall inputs. The roof's hydrological response is a function of its configuration, with the substrate - or growing media - providing both retention and detention of rainfall. The objective of the research described here is to quantify the detention effects due to green roof substrates, and to propose a suitable hydrological modelling approach. Laboratory results from experimental detention tests on green roof substrates are presented. It is shown that detention increases with substrate depth and as a result of increasing substrate organic content. Model structures based on reservoir routing are evaluated, and it is found that a one-parameter reservoir routing model coupled with a parameter that describes the delay to start of runoff best fits the observed data. Preliminary findings support the hypothesis that the reservoir routing parameter values can be defined from the substrate's physical characteristics.

A highly sustainable and versatile granulation method of nanodrugs via their electrostatic adsorption onto chitosan microparticles as the granulation substrates

Nanodrugs play important roles in enhancing the sustainability of pharmaceutical manufacturing via their ability to enhance the bioavailability of poorly soluble drugs, resulting in less drug wastage and less mass/energy consumed in their manufacturing. Despite their sustainability enhancement capability, solid dosage form manufacturing of nanodrugs remains lacking from the sustainability perspective. One example is the granulation of nanodrugs prior to tablet preparation, where existing methods (e.g. wet granulation, spray granulation, spray drying) require high energy and time expenses, or are highly intricate often leading to product inconsistencies. Herein we present an alternative nanodrug granulation method via electrostatic adsorption of the nanodrugs onto chitosan microparticles acting as granulation substrates. The method is sustainable involving only mixing of aqueous suspensions of the nanodrugs and substrates under ambient conditions, followed by washing and drying. We investigate the effects of substrate's physical characteristics and nanodrug to substrate ratio on the nanodrug loading in the granules, content uniformity, nanodrug recovery, and granule flowability. Ciprofloxacin and curcumin nanoplexes prepared by drug-polyelectrolyte complexation are used as the model nanodrugs with neutrally, positively, and negatively charged chitosan microparticles as the substrates. Granules having 25% (w/w) nanodrug loading at 50% (w/w) recovery with good flowability have been successfully prepared.

Inducing endoderm differentiation by modulating mechanical properties of soft substrates

Early embryonic stem cell (ESC) differentiation is marked by the formation of three germ layers from which all tissues types arise. Conventionally, ESCs are differentiated by altering their chemical microenvironment. Recently however, it was established that a mechanical microenvironment can also contribute towards cellular phenotype commitment. In this study, we report how the cellular mechanical microenvironment of soft substrates affects the differentiation and phenotypic commitment of ESCs. Mouse ESCs were cultured in a fibrin hydrogel matrix in 2D and 3D cultures. The gelation characteristics of the substrates were modulated by systematically altering the fibrinogen concentration and the fibrinogen-thrombin crosslinking ratio. Analysis of the ESCs cultured on different substrate conditions clearly illustrated the strong influence that substrate physical characteristics assert on cellular behaviours. Specifically, it was found that ESCs had a higher proliferation rate in gels of lower stiffness. Early differentiation events were studied by analyzing the gene and protein expression levels of early germ layer markers. Our results revealed that lower substrate stiffness elicited stronger upregulation of endoderm related genes Sox17, Afp and Hnf4 compared to stiffer substrates. While both 2D and 3D cultures showed a similar response, the effects were much stronger in 3D culture. These results suggest that physical cues can be used to modulate ESC differentiation into clinically relevant tissues such as liver and pancreas.

TAGETES PATULA SEEDLING PRODUCTION

The objective of this project was to propose an alternative for ecological destination of residues discarded in the environment. The selected residue was carbonized rice coat mixed with sand in different proportions in order to obtain substrates with 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 and 0.9 g.cm -3 densities. The substrates were tested in an experiment with Tagetes patula seedlings, and the experimental layout adopted was a complete randomized design with 8 treatments, 6 replications and 30 plants per parcel. At the end of the experiment, the phytotechnical parameters and substrate physical characteristics were evaluated. The data obtained were analyzed through the SAEG software and the analyses performed were analysis of variance and Tukey test. When different densities of substrates were evaluated in Tagetes seedlings cultivation it was observed that the 0.2 and 0.3 g.cm -3 densities presented the best results in most of the evaluated variables. Regarding the phytotechnical characteristics, the experiment presented results that are significantly better for height of seedlings, fresh top weight, dry top weight and root weight and roots volume. As for the physical characteristics, the substrates presented total porosity, space occupied by air, available water and easily available water with adequate levels for substrates. When analyzed as a whole, the data obtained in the phytotechnical and physical characteristics showed that the air volume was the limiting factor for the seedlings development.

Impact of Substrate Physical Characteristics on Grow Out of Freshwater Prawn, Macrobrachium rosenbergii, in Ponds and Pond Microcosm Tanks

Abstract Two independent trials were conducted to evaluate the effects of different physical characteristics of substrate materials on growth and survival of freshwater prawn. In Trial 1, juvenile prawns (0.4 ± 0.2 g) were stocked at 123 prawns/m2 of tank bottom into twenty‐one 18,000‐L fiberglass tanks managed as pond microcosms. Six substrate materials were chosen to allow comparisons of surface area, mesh size, color, and texture. A control treatment received no added substrate. There were three replicate tanks per treatment. Substrates were positioned vertically at a rate sufficient to increase the bottom surface area by 100%. Prawns were fed a 32% protein sinking diet according to a feed chart. After 110 d, there was no significant difference (P > 0.05) in survival among treatments, averaging 72.6% overall. Prawns in the control treatment (no substrate) had significantly lower (P ≤ 0.05) average weights (9.5 g), lower production (1342 kg/ha), and higher feed conversion ratio (FCR; 2.5) than those in substrate treatments, which were not significantly different (P > 0.05) and averaged 13.4 g, 2404 kg/ha, and 1.3, respectively. For Trial 2, the least expensive substrate material from Trial 1 (lightweight polyethylene bird netting) was compared with the substrate most commonly used in commercial production (heavyweight orange polyethylene safety fencing) under practical pond conditions. Juvenile prawns (0.8 ± 0.3 g) were stocked at 61,600/ha into six 0.04‐ha earthen ponds. Each was randomly assigned one of the two substrate materials, and there were three replications per treatment. After 101 d, there were no significant differences (P > 0.05) between treatments in terms of survival (91%), average weight (34 g), total production (2150 kg/ha), or FCR (3.1). In these studies, physical characteristics of the substrate materials had little impact. The lightweight netting represents a 68% cost savings compared to the currently recommended substrate material.

Matched calorimetric loads for high power millimeter-wave gyrotrons

High power gyrotron testing at long pulses is a necessary step in the development of mm-wave systems for fusion research. For this purpose a compact calorimetric load is being developed, with low overall reflectivity (<5%) and aiming at 1 MW-CW capabilities, after the good performances of the loads (0.5 MW, 0.5 s per pulse) installed on the 140 GHz ECRH plant of the FTU Tokamak in Frascati. Tests at the same frequency but at higher power (0.7 MW, 1 s) and longer pulses (up to 2 s at 0.5 MW) on the ASDEX-Upgrade ECRH plant showed, after repeated exposures, damages on the absorbing layer, recognized as thermal effects due to the local enhancement of incident power: the effects visible near the entrance port are explained studying the superposition (with interference) of waves reflected inside the sphere. Samples of degraded and non-degraded coating have been analyzed with various techniques, revealing changes of the substrate's physical characteristics. Measurements of absorber temperature during and after the pulse, performed with an infrared detector looking directly into the load, allowed estimates of the peak temperature and thermal properties of the coating in the real working conditions. Improvements on power deposition, geometry and cooling are proposed, to be integrated in a new load design.

Pine Bark Physical Characteristics Influence Pour-through Nitrogen Concentrations

Pine bark (PB), either unamended or amended with sand (S) at 9 PB: 1 S or 5 PB:1 S (v/v), was fertilized with solutions of 100,200, or 300 mg N/liter solution and tested for N concentration using the pour-through method (PT). PB, 9 PB: 1 S, and 5 PB: 1 S had porosities of 84%, 75%, and 66%, respectively. PT NO3-N concentrations, obtained via PT, of the 5 PB:1 S substrate were 43%,28%, and 15% higher than PB NO3-N values for the 100,200, and 300 mg·liter-1 treatments, respectively. Differences in N concentration obtained with PT can be attributed to substrate physical characteristics. Based on the results, data for PT should be interpreted with regard to substrate porosity.

Effects of Substrate Physical Characteristics and Orientation on Oviposition by Eoreuma loftini1 (Lepidoptera: Pyralidae)

The effects of substrate physical characteristics and orientation on oviposition by Eoreuma loftini (Dyar) were investigated in the laboratory. Dead sugarcane leaves were strongly preferred over live, green leaves for oviposition. Vertically oriented dead leaves were preferred over horizontally oriented dead leaves. Females oviposited more eggs on rough surfaces than on smooth surfaces. More eggs were laid in leaf crevices and folds than on exposed leaf surfaces. Substrate composition, texture, orientation, and exposure affected egg mass size.