Effects of the soil moisture content and leaf memory effect on pesticide droplet absorption

Abstract

Most pesticide spraying studies focus on increasing droplet deposition on target surfaces, with little consideration of post-deposition pesticide droplet absorption mechanisms. 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 variationsindicated a memory effect, 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. The results are crucial for rational pesticide use, crop spraying optimization, and water savings.