Title : Effects of soil moisture and leaf diurnal rhythms on pesticide droplet absorption and utilization efficiency
Abstract:
Leaf pesticide spraying is the predominant method for crop protection, yet its efficiency is often severely limited by poor droplet absorption after deposition, leading to substantial pesticide waste and environmental contamination. While significant research has focused on maximizing droplet deposition on leaf surfaces, the critical post-deposition process of absorption—particularly for hydrophilic systemic pesticides—remains underexplored. The pesticide droplet absorption efficiency of leaves is related to environmental factors and plant growth status during pesticide application. In field environments, irrigation-based soil moisture content regulation is a key plant growth status adjustment method. A theoretical pesticide droplet leaf absorption model was established to study the effects of soil moisture content on droplet absorption. Controlled environment experiments were carried out to investigate the absorption of pesticide droplets, and a chi-square test was used to verify the model reliability. The results showed that pesticide droplet leaf absorption flux first increased and then decreased with increasing soil water content. The diurnal leaf water potential and stomatal conductance variations indicated intrinsic diurnal rhythms, resulting in diurnal variationsin the pesticide droplet leaf absorption flux. Under the same soil water conditions, the absorption flux first increased and then decreased from 8 am to 6 pm (Beijing Time). Effective application of pesticides can be significantly enhanced by controlling soil moisture content and selecting the appropriate spraying time. The best spraying combination improved the application effectiveness nearly threefold overthat of the worst combination. This finding is pivotal for improving pesticide use efficiency, as enhanced absorption directly translates to reduced pesticide runoff and volatilization, thereby mitigating environmental pollution. By elucidating the interplay between soil management and plant physiology, this research provides a practical framework for precision agriculture. It empowers growers to move beyond merely maximizing deposition and towards optimizing the entire absorption process, enabling more effective, economical, and environmentally responsible pesticide applications through informed irrigation and targeted spraying schedules.
