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Abstract

Agrochemicals play a vital role in enhancing crop productivity, yet poor retention and unintended spreading during spraying pose environmental and economic risks. This research addresses these challenges by investigating strategies to improve the effectiveness and stability of agricultural spray formulations through a comprehensive assessment of spray application parameters, polymer solution extensional rheology, the influence of surfactant addition, and the effects of stabilizing agents on storage duration. The findings reveal that nozzle pressure and translation speed jointly influence droplet deposition and retention behavior, with deviations observed at higher nozzle speeds. Beyond application mechanics, molecular characterization highlights the critical role of extensional relaxation time (λₑ), the time required for a polymer solution to recover its original structure after stretching, as a key determinant of spray deposition. This parameter serves as a practical and rapid predictor for assessing formulation performance through extensional rheology tests. The study further demonstrates that ionic surfactants alter the rheological response of polymer solutions, whereas nonionic surfactants primarily act as interfacial agents without significantly affecting relaxation dynamics. Polymer-based solutions exhibit superior leaf retention compared with surfactant-only systems, primarily due to their inherent viscoelastic properties. To improve storage stability, isopropyl alcohol (IPA) and α-tocopherol were identified as effective stabilizers, particularly under refrigerated conditions. Overall, this work establishes a mechanistic link between spray operational factors, extensional rheology, and deposition outcomes. It provides a standardized framework for evaluating spray retention and introduces stabilizing strategies that extend formulation shelf life, contributing to the development of more efficient and sustainable agricultural spray technologies.