Towards eco-friendly plant growth regulator: A robustly stable and efficient uniconazole emulsion based on onion-like lamellar liquid crystal

Abstract

As a commonly water-based pesticide formulation, conventional Emulsions in Water (EWs) always suffer from demulsification in actual complex environments and burst release due to their thermodynamic instability. The ecotoxicity and phytotoxicity caused by chemosynthetic adjuvants cannot be ignored. To address these issues, herein, using a soybean lecithin-based lamellar liquid crystal emulsion (LCE) as the carrier, we construct a robustly stable and low-toxicity EW with the “onion-like” bionic structure and achieve the efficient delivery of plant growth regulator (PGR) uniconazole (UZ). The hydrophobic UZ is firmly encapsulated within the orderly assembled Oil-in-Liquid Crystal-in-Water (O/LC/W) multilayers. This confinement endows UZ-LCE with robust stability, even while encountering disturbances such as dilution, shaking, and changes in pH, ions, and temperature. Furthermore, UZ-LCE exhibits enhanced wettability and affinity to foliar surfaces, as well as specific sustained-release ability. Owing to these superiorities of UZ-LCE, during two consecutive years of efficacy evaluations in cotton field experiments, UZ-LCEs administered through drip irrigation and foliar spray demonstrate remarkable enhancements in controlling excessive plant growth, increasing chlorophyll content, and boosting flower bud formation, surpassing the effectiveness of conventional EWs. UZ-LCE even outperforms commercial preparations (WP and SC) in balancing vegetative growth and reproductive growth, resulting in an 8.3% increase in yield. This research provides an innovative pesticide formulation with eco-friendly adjuvants, less organic solvent, and synergistic functionalities, which is prospective to be extended to other pesticide EWs and contribute to sustainable agriculture.