Optimization of low-pressure solid cone nozzle parameters for pesticide application on trellised crops in plastic greenhouses

TANG Xiuying; SUN Zhongqing; CHENG Bin; LIU Zhenglin; WANG Pei; ZHANG Yonghua; CHEN Lichang

doi:10.13522/j.cnki.ggps.2025178

Abstract：[Background and Objective]Pesticide spraying operations for trellised crops in plastic greenhouses are constrained by complex canopy structures and limited operational space,leading to uneven pesticide deposition,high drift loss,and reduced control efficacy.Focusing on low-pressure solid cone nozzle,this paper addresses these challenges and proposes a method to optimize its application and operation parameters.[Method]A combination of high-speed imaging and water-sensitive paper was used in the experiment to characterize the droplet morphology;a time-based collection method was employed to measure nozzle flow rate.Multiple regression analysis and analysis of variance(ANOVA)were applied to determine the significance of influencing factors(nozzle orifice diameter and spray pressure)on spray performance.[Result]①Spray angle increased with both nozzle orifice diameter and spray pressure.When the nozzle orifice diameter was 0.5-0.6 mm and the spray pressure was maintained at 0.55-0.75 MPa,the spray angle remained within the optimal range of 60°-80°,facilitating uniform canopy coverage and drift reduction.②Analysis of droplet size parameters(volume median diameter,VMD;Dv10;Dv90;relative span,RS)showed that the interaction between nozzle orifice diameter and spray pressure had a statistically significant effect on VMD.When the nozzle orifice diameter was 0.3-0.6 mm and spray pressure was 0.65-0.85 MPa,VMD values fell within the biologically effective range of 30-150 μm,and RS values were consistently below 1.3,indicating a concentrated and uniform droplet size distribution that favours effective pesticide deposition.③Flow rate tests revealed that when the orifice diameter was 0.5-0.6 mm and spray pressure was 0.65-0.85 MPa,the actual flow rate was highly consistent with the theoretical value;additionally,the effect of nozzle orifice diameter on flow rate was statistically significant.Our results indicated that optimal parameters were nozzle orifice diameter 0.5-0.6 mm and spray pressure 0.65-0.75 MPa.[Conclusion]Our analysis showed that the nozzle configuration with a 0.6 mm orifice diameter and 0.65 MPa spray pressure were optimal for pesticide spraying on trellised crops in plastic greenhouses.