Desenvolvimento de sistemas poliméricos à base de quitosana, breu e cera de carnaúba com potencial ação nematicida obtidos por ultrassom

Abstract

The damage caused by plant-parasitic nematodes in agriculture represents a global challenge, with significant productivity losses in crops such as soybeans. Conventional control of these pathogens often relies on synthetic chemical nematicides, which, although effective, pose risks to human health and the environment. Given this scenario, the pursuit of sustainable and safe alternatives is urgently needed. This thesis explored the potential of chitosan in combination with bioactive components of natural origin, carnauba wax (Copernicia prunifera) and rosin (Pinus), to develop film-forming systems with potential nematicidal activity. The study innovated by employing ultrasound as a processing method to obtain homogeneous and stable suspensions, demonstrating that this technique not only considerably reduces preparation time (from 24 hours to 20 minutes) but also promotes significant morphological and surface modifications. DSC and FTIR characterizations confirmed that ultrasound processing does not chemically alter the components, preserving their thermal and functional properties. SEM analyses revealed that ultrasound directly influences film topography, and these morphological changes correlated directly with wettability assays, in which ultrasound-processed samples mostly exhibited a reduced contact angle, indicating increased hydrophilicity—a desirable characteristic for seed coating applications. Nematode tests showed that the film containing rosin achieved 50% mortality within 72 h, a value six times higher than the control. Carnauba wax also demonstrated nematicidal effectiveness, albeit to a lesser extent (20% at 72 h), contributing to a multifunctional approach. In summary, this research not only demonstrates the feasibility of using biopolymers and natural compounds as alternatives to traditional nematicides but also establishes well-founded correlations between processing, morphology, wettability, and biological activity. The results pave the way for future studies focused on active release kinetics and tests under real field conditions, contributing to more sustainable and safe agriculture.