Botanical synthesis of silver nanoparticles (AgNPs) and its antifungal effect against Alternaria porri causing purple blotch of onion: An in vitro and natural epiphytic study

Tulsi (Ocimum sanctum) leaf extract was used to manufacture stable silver nanoparticles. The synthesized AgNPs were characterized by EDX (Energy dispersive X-ray Spectrometry), TEM, and DLR to confirm the size of particles which varied widely within 100 nm and pure. In-vitro analysis was carried out to find the best concentration of AgNPs against Alternaria porri, which showed various levels of inhibition. Maximum inhibition percentage was recorded at 150ppm (91.71%) followed by 125 (91.24%) and 100ppm (87.56%). Similarly, AgNPs was also evaluated against Alternaria porri in natural epiphytic condition. From the result of the field experiment, it has been observed that AgNPs were capable enough to manage the purple blotch disease. The maximum inhibition percentage of purple blotch disease was observed at 100ppm (80.93%), followed by 75ppm (77.17%) under field conditions.