Comprehensive Study on the Effects of Peanut Leaf Characteristics and Tank-Mix Adjuvant on Droplet-Spreading Behavior

Abstract

In agricultural production, the application of pesticides via spraying is an effective approach to controlling pests and diseases. However, the pesticide utilization efficiency in peanut fields is generally low, owing to factors such as crop-specific characteristics and the nonoptimal use of adjuvants. To enhance the spreading performance of droplets on the surface of peanut leaves and increasing pesticide utilization efficiency, in this study, the effects of leaf surface characteristics and three different types of tank-mixed adjuvants on the droplet-spreading characteristics of peanut leaves were comprehensively analyzed. The results indicate that structural differences exist between the adaxial and abaxial surfaces of peanut leaves, leading to varying degrees of hydrophobicity. The adaxial surface is covered with a uniform, erect, waxy crystal structure, which increases the surface roughness and consequently enhances hydrophobicity. On the Adaxial of peanut leaves have higher CA and lower SA. While tank-mix adjuvants can improve the wetting and spreading performance of droplets on peanut leaves, the efficacy of the methylated plant oil adjuvant Beidatong (BDT) and the mineral oil adjuvant VELEZIA PRO (VP) is limited. In contrast, organosilicon adjuvant Nongjianfei (NJF) effectively improved the wettability of peanut leaf surfaces. Specifically, the addition of NJF can significantly reduce the surface tension of the spray solution, dissolve the waxy structure on the surface of peanut leaves, and greatly enhance the spreading performance of droplets on those leaves. On the adaxial leaf surface, the contact angle (CA) of the droplet rapidly reached 0°, and the droplet-spreading area (SA) increased by 150 times. On the abaxial leaf surface, the effect of NJF was relatively weaker, where the CA was 16.5° and the SA increased by 3.8 times. Therefore, in peanut field applications, incorporating the tank-mix adjuvant NJF can greatly enhance the spreading and retention of pesticides on peanut leaf surfaces, thereby improving pesticide utilization efficiency.