Porous Biopolymer Matrices: Advanced Seed Delivery Platforms for Beneficial Microbes to Combat Soilborne Diseases

Amidst the growing challenges posed by soilborne phytopathogens and the dual threats of abiotic and biotic stressors, sustainable solutions are imperative for safeguarding agricultural productivity. Chemical pesticides, though widely used, face limitations due to resistance development, residual toxicity, and overuse. Additionally, traditional filler-based bio formulations, such as wettable powders and suspension concentrates, often compromise spore viability, necessitating innovative alternatives. This study introduces eco-friendly controlled-release carrier-based biopolymers entrapping Trichoderma harzianum (Th4d) spores within cross-linked polymer-1 (CP-1) and polymer-2 (CP-2) matrices. Evaluated for spore viability, root colonization, and disease management, the formulation demonstrated slow and sustained spore release in soil and buffered environments. Notably, it retained spore viability for six months at elevated temperatures of 31 and 40 °C, underscoring its thermal stability and adaptability to warmer climates. Enhanced root colonization, both surface-level and endophytic, was observed, alongside improved agronomic parameters. Seed treatment with the CP-2 + Th4d boosted germination rates to 73.3% in soybean and 96.6% in castor, with seedling vigor indices reaching 1025 and 3536, respectively. Disease incidence was notably reduced, with quantifiable suppression levels, with Macrophomina root rot in soybean decreasing to 23.3% and Fusarium wilt in castor to 20%. These results highlight the potential of this novel formulation as a robust, sustainable alternative to conventional methods, offering a scalable solution to manage plant diseases effectively while addressing the challenges of chemical pesticide use.