Enhancing geranium plants' tolerance against basal stem and root rot pathogens and improving productivity via smart NPK-silica, neem oil, and turmeric nanocomposites

Basal stem rot and root rot pose major challenges, resulting in significant economic losses and negatively impacting both farmers and food supply chains. Enhanced resistance against basal stem and root rot pathogens serves as a safe and effective approach to managing these serious diseases. This study investigated the effectiveness of NPK-neem oil, NPK-silica, and NPK-turmeric nanocomposites encapsulated in nano-chitosan as soil treatments for increasing resistance to geranium against basal stem rot and root rot pathogens, as well as improving plant productivity via regulating NPK release. The synthesized nanocomposites exhibit optimal sizes for agricultural applications, between 172.9 and 184.7 nm, along with excellent colloidal and thermal stability, which are crucial for maintaining particle integrity during soil application and ensuring uniform distribution around plant roots.The treatment of NPK-silica nanocomposite encapsulated in nano-chitosan was the most effective, significantly reducing basal stem rot (78.01 and 84.08%) and root rot disease incidence (77.64 and 86.52%), coinciding with a decrease in disease severity (87.81 and 93.78%) in geranium plants during the two growing seasons, respectively. This treatment enhanced photosynthetic pigments, and improved growth characteristics. It also resulted in increased levels of antioxidant enzymes and total phenolic content, particularly during the first plant cut, as well as improved NPK uptake and soil nutrient availability. In conclusion, the study demonstrated that nano-silica, neem oil, or turmeric encapsulated in nano-chitosan effectively enhance plant disease resistance and serve as an excellent carrier for NPK nutrients, improving fertilizer use efficiency and potentially reducing fertilizer consumption while maintaining environmental quality.