Drop Spreading Research Articles

Effect of Tillage and Sowing Technologies Nexus on Winter Wheat Production in Terms of Yield, Energy, and Environment Impact

Crop production is considered one of the most important agricultural areas in the world, supplying humanity with raw food materials. However, intensive farming very often has a detrimental effect on the environment. The aim of this study was to investigate and assess the efficiency of strip tillage and a sowing machine as well as a direct sowing machine in differently prepared soils in terms of yield, energy, and environmental impact. The experiments were performed with winter wheat (Triticum aestivum L.) grown using three different tillage techniques and two sowing machines. The results show that the inputs of diesel fuel, energy, and time are directly affected by the number and complexity of technological operations throughout the production chain. The highest inputs of diesel fuel, working time, and energy consumption were needed using conventional tillage technology with strip tillage and a sowing machine (CT–STS), amounting to 130.2 l ha−1, 6.65 h ha−1, and 18,349 MJ ha−1, respectively. The best yields were obtained using no tillage–direct sowing technology (NT–DS), where were reached 7.54 t ha−1. The lowest environmental impact was achieved in the winter wheat production system using NT–DS, where the CO2 emissions were as high as 15%, lower than those under conventional tillage–direct sowing (CT–DS) and CT–STS. The costs of winter wheat production can be reduced by up to 23.6%. The main conclusion regarding the use of strip tillage and sowing and direct sowing machines in traditional tillage technology is that energy and environmental indicators have deteriorated compared to no tillage, but no significant difference in winter wheat yields has been identified.

Numerical study of drop spread and rebound on heated surfaces with consideration of high pressure

The impact of a drop on a solid surface has been studied for many years. However, most of the previous numerical simulations were focused on the drop impact on a surface at room temperature and standard atmospheric pressure. This paper presents a numerical study of n-heptane and n-decane drops impacting solid surfaces with the consideration of high temperature and high pressure using smoothed particle hydrodynamics (SPH). The SPH method is validated against experiments from our work and literature. This work is focused on two typical drop-impact regimes, namely, spread and rebound. Different drop impact sequences were simulated at the wall temperature in the range of 27–400 °C and the ambient pressure between 1–20 bars. The difference between the inception of film boiling and liquid saturation temperature was found to decrease with elevating ambient pressure. The spread factor and apex height are investigated for the regime of spread. The results indicate that the lower viscosity fluid has a smaller spread factor as compared to the fluid with higher viscosity. The variation of Leidenfrost temperature with ambient pressure for both n-heptane and n-decane droplets is established numerically and compared with the trend observed in the experiment. The simulation outcomes of drop rebound for high boiling point liquid (n-decane) in the film boiling regime at atmospheric pressure show that with the increasing wall temperature, the drop rebound height and vapor layer height increase. Finally, the effect of ambient pressure on drop rebound height and velocity is investigated. The numerical results indicate that the increase in ambient pressure reduces the droplet rebound velocity and rebound height.

Contact line dynamics of a water drop spreading over a textured surface in the electrowetting-on-dielectric configuration.

Modeling the electrowetting process of a liquid droplet placed on a hydrophobic surface in an ambient environment has several challenges over and above those of basic spreading [F. Mugele, Soft Matter 5, 3377 (2009)10.1039/b904493k]. At an external voltage below the value that causes contact angle saturation, transient spreading is augmented by contact angle reduction defined by the Young-Lippmann equation. In addition, the macroscopic equilibrium contact angle and, therefore, the spreading rate could be altered by the surface hysteresis. Beyond the saturation point, spreading reveals additional features of higher complexity [Q. Vo and T. Tran, J. Fluid Mech. 925, A19 (2021)10.1017/jfm.2021.677]. These details have been examined from experiments as well as numerical simulation in the present work. Below the saturation point, the contact angle model of Dwivedi etal. [Phys. Rev. Fluids 7, 034002 (2022)10.1103/PhysRevFluids.7.034002] with the correction related to the electric field is seen to be applicable. Beyond saturation, the experimentally determined instantaneous contact angle distribution shows two distinct functionalities with respect to the contact line velocity. The first prevails from the onset of spreading until the spreading factor attains a peak value. The second trend is initiated with the retraction of the contact line. Except for differences in parametric values, the form of the contact angle model remains unchanged. Simulations in the postsaturation regime are shown to match experimental data in terms of the transient spreading factor, drop shapes, and the instantaneous contact angle. The role of the ground wire is found to be important and the three-phase contact line formed on it has been included in simulations. Spreading dynamics of the droplet have also been studied when the ground wire is kept at a distance of 40 μm from the apex of the drop. Simulations as well as experiments, show the propagation of a capillary wave between the ground wire and the three-phase contact line. For spreading over an uncoated polydimethylsiloxane (PDMS) surface, the contact line is trapped at local pinning sites, leading to additional distortions in the instantaneous shapes acquired by the interface.

Design of an Air Suction Wheel-Hole Single Seed Drill for a Wheat Plot Dibbler

Focusing on the problems of the poor filling ability and stability of the mechanical wheat seeder and the complicated structure of the pneumatic seeder, a special air suction wheel-hole single seed drill for remote controlled self-propelled single seed dibbler in wheat plots was designed in this paper. According to the agronomic requirements of precision seeding in wheat plots, the seeding wheel radius was set at 180 mm 16 suction holes. Using the discrete element simulation software EDEM to analyze the seed disturbance effect of different parameter designs, the thickness of seed suction ring was 16 mm, the height of seed suction mouth was 4.5 mm, and the diameter of seed suction cam was 12 mm. Through hydrodynamic simulation, the phase angle of the negative pressure chamber was 280 degrees, positive pressure chamber was 22 degrees, phase angle of the unpressurized interval zone was 20 degrees, thickness of the negative pressure chamber was 24.5 mm, diameter of transition pipe was 17.5 mm and length of the transition pipe was 14.5 mm. Based on the above design parameters, the samples were then processed and benchtop experiments carried out. The results showed that under the best operating parameters, the re-suction index was 0.82%, the leakage index was 6.67%, and the qualified index was 92.41%, which met the design requirements. This study could provide a reference for the design of single-seed dibbling technology in wheat plots.

Direct Inkjet 3D Printing Microwires with Small Feature Size by Freezing, Sublimation, and Evaporation Induced Colloidal Nanoparticles Self‐Assembly Mechanism

AbstractThe feature size (FS) of inkjet printing is limited by nozzle size and drop spreading, which limits the realization of small optoelectronics devices and 3D microstructures. Some methods can realize small FS, but sacrifice advantages of inkjet technology. For instance, dewetting can reduce FS with all the advantages of inkjet technology kept, but is hard to print wires due to Rayleigh–Plateau instability. To solve these problems, in this paper, freezing and sublimation are introduced to direct inkjet printing wire processes. After optimizing the glycerol amount and adding tert‐butyl alcohol (TBA) in water‐based nanoparticle inks, condensed microwires of PS colloidal nanoparticles, graphene oxide (GO) nanosheets, and silver nanowires (AgNws) with small FS can be printed, respectively, by freezing, sublimation, and evaporation induced nanoparticle self‐assembly (FSE‐INS) mechanism. Using printhead with the nozzle size of 21 µm, the minimum feature size is only ≈2 µm for GO nanosheet samples. The FSE‐INS mechanism shows particle‐dimension dependent structure properties, introduces an additional particle manipulation freedom perpendicular to the substrate with sacrificial vertical solid surfaces, and exhibits great potential to realize small and novel devices and 3D structures, without sacrificing the advantages of inkjet technology.

A Plant Unit Relates to Missing Seeding Detection and Reseeding for Maize Precision Seeding

For the current sowing machine, unavoidable reasons such as clogging of the seed row disc type opener and the seed guide tube, slipping off the ground wheel, and other unavoidable reasons lead to sowing machine leakage. This paper designs a system to detect and compensate for missed sowing of maize precision seeds. The system mainly consists of a missed seeding detection system module, a control system module, a display system module, an actuation system module, a compensation system module, etc. Detection of missed seedings uses a microcontroller as the controller and a fiber optic sensor as the detection element. Through the microcontroller’s input capture and timer timing function, the total number of rows of missed and reseeded seeds is displayed on the LED display and fed back to the replenishment system to realize the alarm of missed seeds and automatic compensation. The results show that: the detection accuracy of missed seeding is more than 96%, and the highest detection accuracy can reach 100%. Less than 4% error occurred in missed seeding compensation (0.3% error in stepper motor speed, 4% error in rotation angle). The replanting rate of replanters is more than 90%; the replanting pass rate is more than 95%. When the tractor driving speed is 3~8 km/h, the sowing qualified rate is more than 90% to meet the sowing and replanting requirements.

Coexistence of solid and liquid phases in shear jammed colloidal drops

Complex fluids exhibit a variety of exotic flow behaviours under high stresses, such as shear thickening and shear jamming. Rheology is a powerful tool to characterise these flow behaviours over the bulk of the fluid. However, this technique is limited in its ability to probe fluid behaviour in a spatially resolved way. Here, we utilise high-speed imaging and the free-surface geometry in drop impact to study the flow of colloidal suspensions. Here, we report observations of coexisting solid and liquid phases due to shear jamming caused by impact. In addition to observing Newtonian-like spreading and bulk shear jamming, we observe the transition between these regimes in the form of localised patches of jammed suspension in the spreading drop. We capture shear jamming as it occurs via a solidification front travelling from the impact point, and show that the speed of this front is set by how far the impact conditions are beyond the shear thickening transition.

Effect of Contact Angle Hysteresis on Evaporation Dynamics of a Sessile Drop on a Heated Surface

Contact angle hysteresis (CAH) is a significant factor affecting the drop motion on solid substrates. A model of CAH is introduced to explore the influence of CAH on the dynamics of a sessile drop on a uniformly heated surface, and a two-dimensional evolution equation of the drop thickness is established using the lubrication approximation and Navier slip boundary conditions. A numerical simulation is performed to examine the dynamic behaviors of an evaporating drop, and the drop profile, contact angle, contact line, and moving speed are investigated. Simulated results indicate that the drop evolution process involves drop spreading, pinning, and depinning of the contact line. In the drop spreading stage, when the hysteresis angle increases, the spreading period is shortened, and the spreading radius and spreading speed are reduced; in contrast, the pinning period is raised, and the mass of the drop is apparently reduced with increasing hysteresis angle. In the depinning stage, the CAH declines the contact angle, and a flatter pattern is evolved, thereby improving the heat transfer performance, promoting drop evaporation, and shortening the depinning time. The presence of CAH can speed up the drying of the drop, and the large hysteresis angle leads to faster evaporation. Regulating the CAH is an effective way to manipulate the motion of the contact line for an evaporating drop.

ANALYSIS AND PROSPECTS OF TECHNOLOGICAL AND DESIGN FEATURES OF SOWING MACHINES

To date, sowing is one of the most urgent tasks, therefore, universal sowing equipment is widely in demand, which should ensure a uniform distribution of the number of plants per unit area to create the same conditions for development. It is the sowing machines of this type that will largely solve the problems of timely high-quality sowing with a combination of other technological operations - soil preparation, fertilization, embedding, rolling, etc. At the same time, a significant amount of technical and human resources will be released, sowing dates will be strictly observed. Accordingly, the purpose of the study was to conduct a comparative analysis and prospects for the technological and design features of sowing machines to improve the operational reliability of the mechanism for copying the relief of sowing machines using advanced structural materials. The research was carried out by the method of technological and structural analysis of technologies and machines for sowing machines. In the process of research, methods of comparison and mathematical modeling of technological processes were used. The information base of the research was the works of Ukrainian and foreign scientists on technologies and machines for sowing. On the basis of the comparative analysis and the prospect of technological and design features of sowing machines, it was found that friendly stairs (at least 90%), and, as a result, a high yield depend on the quality of the work of the parallelogram mechanism for copying sowing complexes. The reason for the violation of agricultural requirements for sowing, in particular the depth and uniformity of seed placement, is the low durability of the mechanisms for copying the soil surface. It has been established that the main reason for the low reliability of these mechanisms is the use of "steel-to-steel" tribo-couplers in their mobile joints, which ensure operability with frequent (every 40...50 hours of operation) maintenance (lubrication). It has been revealed that it is promising to introduce polymer-composite materials for structural purposes in the movable mates of the parallelogram copying mechanism, which will change the working conditions and increase the durability of this mechanism as a whole. To solve the problems associated with the development and study of the properties of new or modified PCM in the movable joints of sowing machines, it is necessary to conduct a theoretical justification and experimental feasibility of using polymer parts and their effectiveness. It is necessary to develop a model that describes the dynamics of loads under different operating conditions of the disc coulter. It is also necessary to carry out theoretical calculations that take into account the change in the load on individual nodes of the parallelogram copying mechanism.

Stability Bounds for Micron Scale Ag Conductor Lines Produced by Electrohydrodynamic Inkjet Printing.

Continuous conducting lines of width 5–20 μm have been printed with a Ag nanoparticle ink using drop-on-demand (DOD) electrohydrodynamic (EHD) inkjet printing on Si and PDMS substrates, with advancing contact angles of 11° and 35°, respectively, and a zero receding contact angle. It is only possible to achieve stable parallel sided lines within a limited range of drop spacings, and this limiting range for stable line printing decreases as the contact angle of the ink on the substrate increases. The upper bound drop spacing for stable line formation is determined by a minimum drop overlap required to prevent contact line retraction, and the lower bound is governed by competing flows for drop spreading onto an unwetted substrate and a return flow driven by a Laplace pressure difference between the newly deposited drops and the fluid some distance from the growing tip. The upper and lower bounds are shown to be consistent with those predicted using existing models for the stability of inkjet printed lines produced using piezoelectric droplet generators. A comparison with literature data for EHD printed lines finds that these limiting bounds apply with printed line widths as small as 200 nm using subfemtoliter drop volumes. When a fine grid pattern is printed, local differences in Laplace pressure lead to the line width retracting to the minimum stable width and excess ink being transported to the nodes of the grid. After printing and sintering, the printed tracks have a conductivity of about 15%–20% of bulk Ag on the Si substrate, which correlates with a porosity of about 60%.

ЭКСПЕРИМЕНТАЛЬНОЕ ИССЛЕДОВАНИЕ ТРАВМИРОВАНИЯ СЕМЯН В СЕЛЬСКОХОЗЯЙСТВЕННЫХ МАШИНАХ

In agricultural machines, seeds are injured, which damages the crop: conditions are created for the development of harmful organisms during storage, field germination decreases. The relevance of the study of seed injury is caused by the need to improve technologies and designs of agricultural machines that reduce or eliminate seed damage. Currently, there are no studies to assess the change in the amount of grain injury over the entire production cycle. The purpose of this work is to establish the regularity of changes in grain injury in agricultural machines by stages of technology. On the basis of a specially developed end-to-end technique, the injury of wheat seeds of different varieties, differing in categories according to GOST R 52325-2005 “Varietal and sowing qualities of seeds of grain and leguminous plants” and their reproductive anatomical parts - endosperm, embryo, tuft, was experimentally investigated. A new concept of “degree of injury” is introduced and a formula for its calculation is proposed, which allows quantifying the amount of injury to grain seeds and their anatomical parts. It was revealed that the greatest injury occurs in combine harvesters, where the degree of injury is 36.1 ...44.2%. It is established that at each stage, regardless of the technology used, the complex of machines and equipment, the number of injured seeds increases: during post-harvest processing, taking into account the separation of part of the injured grains, which cannot be tracked by 0.1 ...3.3%; when removing from storage and final processing of seed material before etching by 5.0... 10.4%; in a etching machine with screw loading and unloading devices by 7.3 %; in a screw-type seed loader by 4.9%; in seeding machines of individual dosing and gravity feeding of seeds into coulters by 2.9...3.2%, and group dosing with pneumatic transport of the sown material by 4.4...4.7%. In the end, when entering the soil, the degree of injury to wheat seeds is in the range of 57.0 ... 61.4%. Of these, with injury to the endosperm – 51.7...58.4%, germ – 1.9...2.2%, tuft – 1.1…1.8%. The lowest values were obtained when using bags for loading sowing machines, instead of a screw loader of seeders.

Drop impact of dairy product solutions at the onset of drying

Vertical impacts of heated dairy product droplets onto stainless steel surfaces have been experimentally studied using high-speed photography. The experiments were carried out under conditions of controlled temperature and humidity within an environmental chamber, and a numerical model was used to simulate the initial heating and evaporation processes. The droplets consisted of non-Newtonian (shear-thinning) solutions of infant formula or whole milk reconstituted at 45 wt % total solids content in water. Data obtained from image analysis were used to determine the effect of air and surface temperatures up to 140 °C on droplets during impact and spreading. The results show that drop spreading following an initial drying treatment depends on the type of drying applied. Droplets spread further with increasing air temperature, whereas it was found that surface temperatures below 120 °C only had a minor effect on droplet spreading. Moreover, the drops spread less with increasing chamber air temperature when they were air-dried at room temperature in an acoustic levitator for two minutes prior to impact. These trends have been analysed by considering the fluid viscosity, which decreases with temperature in bulk samples, but increases within any outer crust of dried liquid. Impacts were recorded for drop diameters in the range 1.5–3 mm at an impact velocity of 2.90 ± 0.03 m/s. This research should assist with understanding spray-drying of dairy products, and will be more broadly applicable to drop impacts involving heat flows and complex, non-Newtonian fluids.

Evaluation of Siddha Diagnostic Methods for Karpavippuruthi with the aid of Conventional Diagnostic Methods

The diagnosis of diseases comprise revealing its causes. In Siddha medical system testimony of causative elements is through the examination of pulse, urine, eyes, study of voice, colour of body, tongue and the status of the digestive system. This system has labored out specific technique of urine exam which incorporates look at of its colour, odor, density, quantity and oil drop spreading pattern. So the study was aimed to decide the sensitivity and specificity of the Siddha diagnostic method for Karpavippuruthi. Applying Siddha system of diagnosis with inclusion and exclusion criteria, clinical study was carried out on persons having the disease Karpavippuruthi. The above stated diagnostic equipment along with wrist circummetric sign had been used for this study. Most patients had the wrist circumference of 8 finger units and a mere range of affected person`s urine, drop of oil took the shape of slowly spread. Similarly, eight fold examinations found out maximum patients had pulse play with Vatha pitham. Bitter taste, pale coloured and coated tongue had been observed in tongue examination. Patient`s urine samples had slight aromatic odor and normal density, normal Enjal and nearly absence of frothy. So it may be concluded that the subsequent Siddha tactics in amalgamation particularly Wrist circummetric sign, oil on urine sign and eight fold examinations differentiate the patients of Karpavippuruthi from the healthy volunteers.

Smartphone-Integrated Label-Free Rapid Screening of Anemia from the Pattern Formed by One Drop of Blood on a Wet Paper Strip.

Screening of anemic patients poses demanding challenges in extreme point-of-care settings where the gold standard diagnostic technologies are not pragmatic and the alternative point-of-care technologies suffer from compromised accuracy, prohibitive cost, process complexity, or reagent stability issues. As a disruption to this paradigm, here, we report the development of a smartphone-based sensor for rapid screening of anemic patients by exploiting the patterns formed by a spreading drop of blood on a wet paper strip wherein blood attempts to displace a more viscous fluid, on the porous matrix of a paper, leading to "finger-like" projections at the interface. We analyze the topological features of the pattern via smartphone-enabled image analytics and map the same with the relative occupancy of the red blood cells in the blood sample, allowing for label-free screening and classification of blood samples corresponding to moderate to severe anemic conditions. The accuracy of detection is verified by comparing with gold standard reports of hematology analyzer, showing a strong correlation coefficient (R2) of 0.975. This technique is likely to provide a crucial decision-making tool that obviates delicate reagents and skilled technicians for supreme functionality in resource-limited settings.

Biodegradation of Premium Motor Spirit using surfactant-expressing bacteria from mechanic workshops in Malumfashi, Katsina State, Nigeria

Biosurfactant-expressing bacteria have been shown to have potential in many biotechnological applications including the biodegradation of petroleum fractions, such as premium motor spirit (PMS). This study was aimed at investigating the potential use of biosurfactant-expressing bacterial isolates in the biodegradation of premium motor spirit (PMS) at various concentrations (100-100,000ppm). The biosurfactant-expressing bacteria were isolated from mechanic workshop in Malumfashi, Katsina, Nigeria using standard techniques. The isolates identified belonged to the genera Acinetobacter, Bacillus, Micrococcus, Pseudomonas and Stenotrophomonas. These isolates were screened for biosurfactant expression using drop collapse, haemolysis, oil–water behavior assays and emulsification index test. Positives isolates were investigated for PMS degradation by growing the isolates on mineral salt media supplemented with (0.1ml) premium motor spirit (PMS) as sole source of carbon. Although, higher total hydrocarbon degrading bacterial counts were obtained from soils where isolates positive for biosurfactant expression are predominant, there was no statistically significant difference between isolate source using Kruskal-Wallis H test (p = 0.67). The isolates Bacillus velezensis and Stenotrophomonas maltophilia were positive for biosurfactant-production potential using drop-collapse, β-haemolysis, oil spreading, and emulsification index and drop collapse tests with higher tolerance to PMS at concentrations up to 100,000 ppm. Statistical analysis using multiple-comparison analysis of variance (ANOVA) confirmed that the isolates exhibited varying PMS degradation response (p = 0.0066); furthermore, the tolerance of the bacteria to the PMS is dose-dependent (p = 0.00012). Post-hoc analysis using Tukey’s test identified Bacillus velezensis as the most efficient biosurfactant-producing and hydrocarbon degrading isolate (p = 0.0264 and 0.0034); moreover, the threshold concentration for high PMS tolerance was found to be 1000ppm and above (p = 0.0174, 0.0008 and 0.0001).These isolates’ ability to grow on mineral salt media supplemented with PMS as a sole source of carbon presents a veritable avenue for exploitation in biotechnology, towards biosurfactants-mediated bioremediation of hydrocarbon pollutants in oil contaminated soils.

RESEARCH RESULTS OF DESIGN PARAMETER INFLUENCE OF A TORSION-PIN SOWING MACHINE ON DOSING UNIFORMITY OF HARD-RUNNING SEEDS

The purpose of the study is to increase uniformity of sowing of difficult-to-flow seeds by substantiating the design parameters of the torsion-pin sowing machine. Sowing is crucial technological operation in ensuring high yields of agricultural crops. Concurrently, sowing of legumes is associated with certain difficulties due to increased requirements of these crops to the amount of moisture at initial stage of development. One of the most effective ways to eliminate moisture deficiency is pre-sowing soaking. However, the existing sowing machines are not capable of sowing soaked seed materials with high quality parameters. To solve the problem of sowing difficult-to-flow seeds of legumes, a torsion-pin sowing machine was developed. Laboratory studies of the developed sowing machine were carried out to assess the influence of its design parameters on uniformity of longitudinal distribution of seeds. The results of experimental studies on assessing the quality of seeding of hard-to-flow seeds of legumes with a torsion-pin sowing machine showed that uniformity of longitudinal distribution of seeds increased in case of installing movable pins. Under these circumstances, the highest uniformity of seed sowing, both of sweet clover and sainfoin, amounted respectively to 39...46% and 45...51%, of the variation coefficient in the mass of seeds in one-centimeter cells, the highest uniformity was obtained in case of equipping the sowing machine with four torsion-pin groups with three movable 15 mm high pins.

Contact Line Catch Up by Growing Ice Crystals

The effect of freezing on contact line motion is a scientific challenge in the understanding of the solidification of capillary flows. In this Letter, we experimentally investigate the spreading and freezing of a water droplet on a cold substrate. We demonstrate that solidification stops the spreading because the ice crystals catch up with the advancing contact line. Indeed, we observe the formation and growth of ice crystals along the substrate during the drop spreading, and show that their velocity equals the contact line velocity when the drop stops. Modeling the growth of the crystals, we predict the shape of the crystal front and show that the substrate thermal properties play a major role on the frozen drop radius.

SPH-ASR study of drop impact on a heated surface with consideration of inclined angle and evaporation

This paper studies the problem of drop impact on a heated surface by using a numerical method based on smoothed particle hydrodynamics with adaptive spatial resolution (SPH-ASR). The physical model considers the interaction and heat transfer between the liquid drop, solid wall and ambient gas, and the phase change between liquid and gas phases. The phase change process will change the particle mass and resolution. The SPH-ASR method is able to adaptively adjust the spatial resolution according to the distance to the interface between different phases. A series of numerical simulations were performed to investigate the effects of different factors on drop-wall interaction, including the drop diameter, impact velocity, liquid evaporation, wall temperature, and the inclined angle of wall. The comparison of impact regimes shows good agreement between the numerical and experimental results. The characteristics of drop impact on a heated surface were studied, particularly the drop spreading factor and mass evaporation ratio. The numerical results indicate that the maximum spreading factor and the mass evaporation ratio can be predicted as a function of dimensionless numbers.

Neopestalotiopsis rosae Causing Black Spot on Leaf and Fruit of Pecan (Carya illinoinensis) in China.

Pecan (Carya illinoinensis K. Koch) is very productive and brings good economic returns for mountain dwellers. In recent years, symptoms were observed on both leaves and fruits of pecan in orchards, Fuyang, Anhui Province, and Jiande, Zhejiang Province. On the leaf, spots, rust-colored, long shuttle to irregular shaped, and 1-3 mm in size, firstly appeared between veins. The color of area around the spot gradually changed from green to yellow making a yellow halo. Then, some spots often merged in to a big lesion. On the fruit, symptoms firstly appear as irregular and black spots. The spots gradually spread to most part of the fruit and the core of the fruit turned black at the late stage of pathogenesis. Normally, the leaf infection rate was less than 10%, whereas infection rate of fruit could reach 5-15% which leads to drastic quality reduction and significant yield losses. To isolate the pathogens, fresh infected tissues were cut from samples, disinfected and cultured at 2% water agar at 28 oC till colony could be spotted. Fungal isolates were obtained by mycelia tip transferring. Similar cultural and morphological characters showed on 39 of the total 45 isolates. The mycelia grew rapidly in PDA plates, and colony diameter could reach 8.0 cm after culture at 25 oC in dark for 5 days. Mycelia on surface of the colony were cotton-like and showed obvious growth rings, and turn yellow from the middle on aged cultures. Pycnidia, brown to dark in color, began to form on PDA after 15 days' culture in the dark. Conidia were fusoid, straight to slightly curved, 4-septate, 23.5-26.3×7.6-9.0μm, average 24.9×8.3μm (n=60) in size. The basal cell was hyaline, conic with a truncate base and thin-walled, average 4.4-5.1μm long (n=60). The three median cells were doliiform and brown with darker septa. The apical cell was hyaline, cylindrical, with 2-3 tubular apical appendages arising from the apical crest, unbranched, filiform, average 21.7-29.2 μm(n=60) long. The cultural and morphological characters of the strains matched the previous descriptions of Neopestalotiopsis sp. (Maharachchikumbura et al., 2014). Their 3 partial genes, ITS, β-tubulin (TUB) and translation elongation factor 1-alpha (TEF1-α), were amplified and sequenced with primers (Lee et al., 2006; Maharachchikumbura et al., 2014). These sequences were submitted in GenBank with accession number of MW504791 (ITS), MW633956 (TEF1-α), and MW633958 (TUB2), seperately. The BLAST results against the GenBank database showed more than 99% identity with sequences claimed from Neopestalotiopsis sp. The multilocus phylogenetic analysis of the three genes showed the isolate was closest with N. rosae. The strains were finally identified as N. rosae by morphological and molecular analysis. Pathogenicity testing was performed by spreading 20μl conidia suspension drop (1 × 106 conidia ml-1) on surface of wounded or unwounded leaves and fruits. The pecan variety MaHan was used for inoculation. Wounds were made by scratching with sterile needles, and then a drop of 20μl conidia suspension was spread on the wounded area. For unwounded inoculation, a drop of 20μl conidia suspension was spread without wound procedure. The same amount of water drops were spread on the surface of wounded and unwounded tissues as controls. The plant parts were wrapped with PE films to keep moisture after drop spreading. Ten trees were selected for inoculation, and 10 leaves and fruits were randomly selected separately for wounded and unwounded inoculation and corresponding controls in each tree. The similar symptoms appeared from 3 dpi on leaves and 9 dpi on fruits, and finally showed on more than 90% wounded inoculated leaves or fruits and on less than 50% after unwounded inoculation, while controls remained symptomless. N. rosae was consistently re-isolated from inoculated parts with symptoms, while not from the control. Therefore, N. rosae was confirmed as the pathogen causing black spot on leaf and fruit of pecan (C. illinoinensis). To the best of our knowledge, this is the first report of N. rosae causing black spot disease of pecan (C. illinoinensis). In recent years, both the infection area and severity of this disease grow rapidly, which means the potential of the disease to become a big problem in local orchards.

Paddy straw management practices in Northern India for improved efficiency and techno-economic feasibility

The study deals with the optimization of paddy residue management technologies for the management of paddy straw in combine harvested fields. The study emphasizes paddy straw management under different techniques (Retention, Incorporation and Removal of straw) with the use of different combinations of machinery. The research was conducted at farmer's field Dabra, Hisar, Haryana during 2017–18. The objective of the research was to evaluate techno-economic feasibility of different options of machinery. According to the results of the trials, the M4 (Combine harvester with SMS + Reversible mould board plough + Rotavator + Seed drill) had the greatest fuel consumption of 53.12 l/ha. M2 (Combine harvester with SMS + Spatial till drill) had the lowest fuel consumption of 22.29 l/ha. The lowest cost of operation of 63.32 `/q was found in treatment M2. Highest unit cost operation of 140.52 `/q was found in M9 (Traditional combine + Stubble shaver + Hay rake + Straw baler + Disc harrow (2 pass) + Planker + Seed drill). The benefit-cost ratio was found to be highest in traditional combine (1.99) and lowest in zero-till drill (1.11). Treatment-wise, benefit-ratio ratio was found maximum in treatment M10 (1.80) and minimum in M5 (1.50). According to the findings of study, residue retention technology is found better in comparison to straw incorporation and straw removal.