Spreading and evaporation behaviors of adjuvant-amended droplets on different wheat surfaces
DOI:
https://doi.org/10.24425/jppr.2026.7074Abstract
Delivering spray droplets to complex, superhydrophobic wheat (Triticum aestivum L.) structures, particularly heads and stems, remains a major challenge. Because most studies evaluate flat leaves, this research investigated droplet wetted areas and evaporation time across four wheat surfaces (adaxial/abaxial leaves, stem, head) under varying concentrations of modified seed oil (MSO), non-ionic surfactant (NIS), oil surfactant blend (OSB), and crop oil concentrate (COC). All adjuvants significantly increased spreading but reduced evaporation time compared to water. MSO and NIS maximized wetted areas but dried the fastest, whereas COC exhibited the weakest spreading and the slowest evaporation. A strong negative correlation confirmed a severe thermodynamic trade-off: extensive spreading on highly textured heads and stems created critically thin liquid films that accelerated evaporation. Consequently, maximizing spreading which then risks premature pesticide crystallization. Because interactions are strictly dose-dependent and surface-specific, no universal optimal concentration exists. Agronomists must balance target coverage with droplet longevity through precise adjuvant selection and dosing to ensure maximum biological efficacy.
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