Efficacy of Plant Defence Activators for Disease Reduction and Growth Promotion in Bell Pepper (Capsicum annuum L.) in Sub-Temperate, Semi-Humid Climate Conditions

Bell pepper production is often constrained by diseases such as Cercospora leaf spot, anthracnose, bacterial spot, Phytophthora rot, and viral infections. This study evaluates the efficacy of plant defence activators, including salicylic acid (SA), jasmonic acid (JA), β-aminobutyric acid (BABA), and potassium nitrate (KNO₃), as eco-friendly strategies for disease management. For this, bell pepper seeds were subjected to seed priming with these activators at various concentrations for 4–10 h before sowing. The effects of these treatments on seed quality and mycoflora incidence were assessed to optimize priming protocols for enhanced plant resistance. Seed priming with 75 ppm SA for 8 h increased germination up to 85%, boosted seed vigor index-length (SVI-I) from 856.88 to 1,078.44, and seed vigor index-mass (SVI-II) from 161.25 to 234.39. KNO₃ priming at 1.5% for 10 h enhanced germination up to 87%, SVI-I from 856.88 to 1,108.38, and SVI-II from 161.25 to 229.03, while reducing seed-borne fungal incidence from over 22% in untreated seeds to as low as 2–3%. BABA showed an optimal effect at moderate concentrations, while higher MeJA doses had inhibitory impacts on early seedling growth. These results demonstrate that seed priming treatments can significantly enhance seed quality, vigor, and disease resistance in bell pepper, offering a sustainable and effective alternative to chemical methods.