Non-invasive water status detection in grapevine(Vitis vinifera L.)by thermography

Grapevines are preferentially grown under mild to moderate water stress conditions to achieve the best compromise between wine quality and quantity.Water status detection for advanced irrigation scheduling is frequently done by predawn leaf water potential(ΨPD)or leaf stomata conductance(gL)measurements.However,these measurements are time and labor consuming.Therefore,the use of infrared thermography(IRT)opens up the possibility to study large population of leaves and to give an overview on the stomatal variation and their dynamics.In the present study IRT was used to identify water stress of potted grapevines.In order to define the sensitivity of IRT measurements to water stress,the IRT-based water status information were compared with simultaneously measuredΨPD and gL data.Correlations between IRT-based CWSI data on the one hand and gL andΨPD on the other showed the potential of IRT for water stress detection.However,the CWSI calculation procedure is laborious and the sensitivity of CWSI for water stress detection still needs to be improved.Therefore,further improvements are necessary in order to apply remote IRT-based systems for irrigation scheduling in the field.

Testing method and distribution characteristics of spatial pesticide spraying deposition quality balance for unmanned aerial vehicle

In order to explore the spatial pesticide spraying deposition distribution,the downwash flow field characteristics for unmanned aerial vehicle(UAV)pesticide application with accurate flight height and velocity and the relationship of these two aspects,a novel measurement method was proposed in this paper.A model‘3WQF80-10’single-rotor diesel UAV was tested using this method in wheat field and the effects of flight direction,flight parameters and crosswind on the distribution of spatial spraying deposition quality balance(SSDQB)and the downwash flow field distribution were researched.A cuboid aluminum sampling frame of spatial spraying deposition quality balance(SFSSDQB)with monofilament wires was made for collecting the droplets in four directions,and a set of multi-channel micro-meteorology measurement system(MMMS)was applied for measuring the downwash wind speed in three directions.Besides,BeiDou Navigation Satellite System(BNSS)was used for controlling and recording the working height,velocity and track of this model of single-rotor UAV.The results showed the distribution of the spatial spray deposition and the downwash flow field of UAV could be measured effectively at exact flight height and velocity via this method.When the average wind speed was 0.9 m/s,the average temperature was 31.5℃ and the average relative humidity was 34.1%,and the average distribution ratios of spraying deposition for model‘3WQF80-10’UAV on the upwind part,the top part,the downwind part and the bottom part were 4.4%,2.3%,50.4%and 43.7%,respectively.The flight directions of forward and backward had an impact on droplet deposition distribution and the working effect of flying backwards,with 60%of deposition ratio of the bottom part of the SFSSDQB,was better than flying forward.There was a linear negative correlation between the coefficient of variation(CV)of the bottom part and the flight height and the coefficient of determination was 0.9178,which means that the deposition distribution becomes more uniform with the increase of height.Additionally,there was a linear positive correlation between weighted mean deposition rate and crosswind speed and the coefficient of determination was 0.9684,which shows the deposition distribution gets more concentrated towards the downwind part with the rise of crosswind speed.Therefore,according to the results of tests of downwash airflow speed,it is shown that regardless of the flight direction and height and the crosswind,all these factors influence the droplet deposition distribution via weakening the intensity of the downwash airflow field in the direction perpendicular to the ground.The results can provide valuable information for the research of UAV pesticide application techniques and the establishment of the standard of spraying deposition and drift tests of UAV in crop field.

Design and experiment of variable rate orchard sprayer based on laser scanning sensor

During different growth periods,canopy size and density in orchards are variable,which need application conditions(flow rate and air flow)to be adjusted to match the canopy’s characteristics.In order to improve orchard sprayer’s automatic operating performance,an automatic variable-rate orchard sprayer(VARS)fixed with 40 electromagnetic valves and 8 brushless fans was developed based on the canopy’s spatial dimensions.Each solenoid valve and brushless motor can be individually adjusted in real-time through pulse width modulation(PWM)signals emitted by a control system to adjust each nozzle’s spout and fan rotation speed.A high-precision laser scanning sensor(light detecting and ranging,LIDAR)was adopted as the detector to measure the canopy volume using the variable rate algorithm principle.Field experiments were conducted in an apple orchard,and conventional air blast sprayer(CABS)and directed air-jet sprayer(DAJS)were tested as a comparison.Results showed that on average,46%less spraying solution was applied compared to conventional applications,while penetration rate was similar to DAJS.Normalized deposition in the canopy with variable application was higher than that of conventional applications,indicating that electronic sprayers are more efficient than conventional sprayers.It was also observed that VARS could significantly reduce off-target loss.The field experiment showed that the newly developed variable-rate sprayer can greatly reduce pesticide use and protect the environment for the orchard fruit production,and also provide a reference for design and performance optimization for plant protection machinery.

Drift potential of UAV with adjuvants in aerial applications

The reduction of pesticide aerial spraying drift is still one of the major challenges in modern agriculture.The aim of this study was to evaluate the drift potential of different types of unmanned aerial vehicle(UAV)and adjuvant products for reducing spray drift in aerial applications.Three types of UAV(3WQF120-12 and 3CD-15 fuel oil powered single-rotor UAV and HY-B-15L battery powered single-rotor UAV)were selected in this study with regular application parameters to compare each spray drift,and 3WQF120-12 fuel oil powered UAV was selected to quantify spray drift of 6 adjuvants dissolved in water under field conditions.Solutions were marked with brillant sulfoflavin dye(BSF)at 0.1%.Petri dishes and rotary impactors were used to collect airborne and sediment drift,respectively.Drift deposits were evaluated by spectrophotometry in order to quantify deposits.The results showed that when the flight height was 1.5-2.0 m above the crop at the flight speed of 4-5 m/s and the average wind speed of 1.63-1.73 m/s,3WQF120-12 fuel oil powered UAV had lower drift potential than the other two types;DV0.5 and percentage of droplets with diameter≤75μm had very significant effects on spray drift percentage(p=0.01);the risk of drift in agricultural spraying could be significantly decreased not only by reducing the percentage of fine droplets but also by changing droplet spectra.Compared to water,Silwet DRS-60,ASFA+B,T1602,Break-thru Vibrant,QF-LY and Tmax could reduce by 65%,62%,59%,46%,42%,and 19%spray drift,respectively.when water without adjuvants were sprayed,90%of drift droplets were located within a range of 10.1 m of the target area while with 0.8%Silwet DRS-60 adjuvant in water,the distance was shortened to 6.4 m.

Spray drift characteristics test of unmanned aerial vehicle spray unit under wind tunnel conditions

Since the 2010s,unmanned aerial vehicle(UAV)sprayer was applied more and more widely for low-volume aerial pesticides spraying operations in China.However,droplets from the UAV sprayer have a higher drift risk due to more fine droplets sprayed and a higher flight height than ground sprayers.Study on UAV spray drift has been a new hot spot within the field of pesticide application technology.Most of previous studies used direct field methods for spray drift,but the meteorological conditions in field were unstable and uncontrollable,and drift research under an actual operation state in wind tunnel has not been reported.Therefore,25 treatments of wind tunnel measurements and droplets spectrum tests of 10 models of nozzles were conducted to explore the influence factor on spray drift characteristics of UAV chemicals application in this study.A spray unit with a rotor of UAV was innovatively installed in wind tunnel,and the airstream from the wind tunnel was regarded as the relative moving natural wind to simulate the flight status.The airborne and the sediment spray drift was measured to study the effects of the nozzle type and size(flat fan,hollow cone and air-inclusion nozzles),flight speed,adjuvant(DRS-60,Y-20079,MF and G-611)and meteorological parameters(20°C&40%,20°C&80%,30°C&40%and 30°C&60%).The drift potential(DP)and the drift potential reduction percentage(DPRP)in vertical and horizontal directions were obtained for each test.Both nozzle type and size had an impact on the spray drift potential obviously by affecting the droplet size and the ratio of fine droplets,and the regression linear models between DPRPV/DPRPH and DV50,V75 were established(R2=0.934/0.925).Flight speed also had a significant effect on the spray drift characteristics,and reducing the flight speed could increase the DP effectively.Adding spray adjuvants could affect the DP under experimental meteorological parameters,and the anti-drift performance ranked in the order of DRS-60>MF>Y-20079>G-611.Recommendations were proposed in order to reduce the spray drift for UAV sprayer’s operation.These findings can contribute to provide guidelines and technical support for the wind tunnel spray drift tests of UAV and the field operation regulation of unmanned aerial PPP application.

Fuzzy intelligent control method for improving flight attitude stability of plant protection quadrotor UAV

At present,the attitude control method of plant protection UAV is the classical PID control,but there are some imperfections in the PID control,such as the contradiction between speediness and overshoot,the weak anti-jamming ability and adaptability.The physical parameters of plant protection UAV are time-varying,and the airflow also interferes with it.The control ability of classical PID is limited,and its control parameters are fixed,and its anti-jamming ability and adaptability are not strong.Therefore,a fuzzy adaptive PID controller is proposed in this paper.Fuzzy logic control is used to optimize the control parameters of PID in order to improve the dynamic and static performance and adaptability of attitude control of plant protection UAV.In the process of research,the mathematical model of UAV is established firstly,then the fuzzy adaptive PID is designed,and then the simulation is carried out in Simulink.The simulation results show that the fuzzy adaptive PID controller has better dynamic and static control performance and adaptability than the traditional PID controller.Therefore,the proposed control method has excellent application value in the attitude of plant protection UAV.

Design and test of target-oriented profile modeling of unmanned aerial vehicle spraying

Unmanned aerial vehicles(UAVs)are a new frontier in specialized plant protection equipment,which will increasingly be utilized in modern sustainable agricultural applications.The use of UAVs retrofitted with new structures for spraying allows precision pesticide applications on fruit canopies,which have positive effects on pesticide reduction,along with fruit quality and production improvement.In this work,a precision toward-target device(BUAV)was established through profiling of fruit branch modeling,along with a quality analysis of the coverage in a pear orchard compared to a conventional multi-rotor UAV(CUAV).Coverage under different canopy sections and on both sides of leaves was evaluated using Polyvinyl Chloride card samplers.The results indicate that coverage of the BUAV was 0.98%and 1.41%on the abaxial of the lower leaves interior of the canopy,which was 2.38 and 3.14 times higher than that of the CUAV.The BUAV tended to increase coverage in the course-parallel direction,while both the course-parallel and vertical directions increased the deposition coverage on the abaxial side of the interior canopy leaves by 1.8 times and 2.1 times compared to the CUAV,respectively.Simultaneously,the BUAV increased the proportion of droplets deposited on the canopy and reduced ground loss.The BUAV can improve the distribution of the wind field within the canopy effectively and improve the droplet deposition on the reverse side of the interior bore blade.

Effects of xanthan gum on atomization and deposition characteristics in water and Silwet 408 aqueous solution

In order to investigate the effects of viscosity on spray formation and utilization of pesticide,different concentrations of xanthan gum(XG)were added into water and 0.1%Silwet 408 aqueous solution.Droplet size,relative span(RS),fan angle,length of breakup and maximum retention(Rm)were measured with the LU120-02 nozzle spraying under the pressure of 0.3 MPa.The dynamic spreading of the different solutions on maize leaves was tested using a 5μL micro-injector.The results showed:VMD,RS,length of breakup and Rm went up as the increasing of XG concentration in the range of 0-0.5%with the same solution,while the fan angle of nozzle and spreading area on maize leaf showed the opposite tendency.Silwet 408 could reduce the surface tension of liquid,which could alter the dominant mode of spray formation and lead to earlier sheet breakup,especially in low viscosity solutions.Under the same concentration of XG the addition of Silwet 408 could reduce the RS of drop size spectrum but has no effect on VMD or fan angle.In water solution,there was no difference with different concentrations of XG in the spreading time on maize leaf.Besides,in the 0.1%Silwet 408 aqueous solution,the spraying time and area were several-fold of that in water with same XG concentration.Moreover,with the same XG concentration,the smaller surface tension liquid indicated lower Rm,and the difference was magnified as the concentration increases.This work has demonstrated that initial spray characteristics such as droplet size and RS,fan angle,length of breakup,Rm and spreading area can vary depending on the viscosity of spray liquids.Therefore,by transforming the viscosity of the spray liquid to adjust the droplet spectrum to reduce drift,increasing the Rm and spreading area to improve liquid utilization and reduce the usage of pesticides.

Dynamic evaporation of droplet with adjuvants under different environment conditions

Pesticide droplet is evaporating during the falling from the nozzle to the target.This dynamic evaporation is influenced by ambient temperature,relative humidity(RH),adjuvant type and concentration.In the evaporation process,the droplet size at different height is affected by the droplet evaporation.Based on this,this study determined the droplet dynamic evaporation by collecting the droplets from different height via silicone oil method with a certain temperature and RH.Eight adjuvants were chosen,including three organo-silicon,three vegetable oil and two non-ionic,with five concentrations.All droplets were generated by a droplet generator.The results showed that the type of adjuvant,ambient temperature and RH had no significant influence on droplet size generated by droplet generator.All the adjuvants in this experiment cannot reduce dynamic evaporation;Concentration of adjuvant made a difference in dynamic evaporation.This could be because of the property of adjuvant.Organo-silicon adjuvants have a negative correlation with water vapor pressure,it showed less dynamic evaporation at high temperature and RH.Vegetable oil and non-ionic adjuvant,they are the same as the controlled blank that the dynamic evaporation reduces with decreasing temperature and increasing RH.