Abstract
The effectiveness of phytohormone application is largely limited by their rapid degradation, uneven distribution on the seed surface, and the lack of control over their release during germination. In this study, a multilayer polymer coating based on methylcellulose was developed and investigated for the controlled delivery of the phytohormone fusicoccin (FC) to soybean seeds using a mineral filler (talc) and a polysaccharide filler (potato starch). The physicochemical properties of the coatings, application uniformity, degradation kinetics, and release of the active compound under different temperature and humidity conditions were evaluated. The methylcellulose-talc compositions exhibited higher mechanical stability, lower swelling tendency, and longer degradation time compared with starch-based systems. The release of FC followed first-order kinetics, with a rate constant of 0.025 h⁻¹ and a half-life of 27.8 h. The obtained results confirm the potential of the developed methylcellulose-talc coatings for the prolonged and controlled delivery of phytohormones in seed pre-sowing treatment technologies. In the future, these findings may be used in further studies of polymer coatings under seed germination conditions.