Hyaluronic acid and carboxymethyl cellulose are eco-friendly polysaccharides known for their excellent moisture retention properties, making them suitable components of agricultural fertilizers. On the other hand, humic acids exhibit surface-active properties, suggesting their potential to replace synthetic surfactants in agricultural applications. Naturally, the interaction between polysaccharides and humic substances influences their colloidal and chemical behavior. The mutual interactions between humic acids and these polysaccharides were examined at immiscible liquid interfaces and on plant leaf surfaces using radiotracer analysis and tensiometry (pendant drop and sessile drop methods). The results indicate that humic acids achieve optimal adsorption at a hyaluronic acid concentration of 30 g/L, regardless of molecular weight. In contrast, carboxymethyl cellulose reduces the surface activity of humic acids. Additionally, a combined solution of humic acids and hyaluronic acid improves the wetting efficiency of wheat leaves compared to individual solutions. However, humic acids showed minimal impact on the absorption or systemic distribution of hyaluronic acid within the plant.

Zinc is an essential micronutrient in agricultural systems, fulfilling vital roles in both plant physiology and modern fertilizer formulations. Despite its importance, zinc deficiency has emerged as one of the most prevalent micronutrient limitations in global agriculture. Humic acids (HA) can serve as effective transporters of trace elements for crops, including in foliar fertilization. Our investigation addressed two key aspects: (1) the synthesis of HA-stabilized ZnO nanoparticles, and (2) the assessment of nanoparticle efficacy as zinc sources for foliar fertilization. ZnO and HA-coated ZnO nanoparticles were synthesized via a chemical deposition method and characterized by FTIR, XRD, DLS, ELS, UV-Vis spectroscopy, and TEM. The penetration ability of the nanoparticles through plant leaves was investigated using wheat sprouts. After 24 h of saturation, the plants were dried, and their leaves and seedlings were dissolved in nitric acid; the solution was analyzed by ICP-AES. HA-coated ZnO nanoparticles showed competitive performance compared to conventional zinc chelates used in agriculture. Wheat leaf studies confirmed that nanoparticle accumulation and uptake are pH-dependent, with acidic conditions favoring HA-coated ZnO nanoparticles. These findings provide valuable insights for developing advanced zinc-containing formulations for foliar crop fertilization. The demonstrated effectiveness of HA-stabilized ZnO nanoparticles suggests they represent a promising alternative to traditional zinc supplements in agriculture.