Effects of ZnO-NPs Treatments on Fruit Characteristics of Capsicum

To evaluate the effects of zinc oxide nanoparticles (ZnO-NPs) treatments: applied via seed treatment and foliar spray; on post-harvest quality attributes of capsicum fruits, including texture score, specific gravity, maximum penetration and shearing force, cuticle thickness, moisture content, shelf life, and capsaicin content. A two-year pot experiment using a completely randomized design with seven treatments (control, three seed treatment concentrations, and three foliar spray concentrations of ZnO-NPs) and three replications; was conducted in net-house conditions at Department of Soil Science and Water Management, Dr. Yashwant Singh Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh, India. Capsicum seeds were soaked (T2, T4, T6) in ZnO-NPs suspensions (50, 100, 150 mg/L) for 24 hours before sowing (seed treatment); and sprayed (T3, T5, T7) with corresponding suspensions 15 days post-transplanting (foliar). T1 was taken as control (without application of ZnO-NPs). After harvest, uniform fruits were assessed for various fruit characteristics. The results revealed an increment in texture score (8.08), specific gravity (0.84), penetration force (11.98 N), shearing force (80.70 N), cuticle thickness (38.9 µm), moisture content (93.7%), shelf life (6.9 days), and capsaicin (0.21%) content, under treatment comprising seed treatment of capsicum with 50 mg/L ZnO-NPs. With increased concentrations or foliar application, most attributes decreased; however, at 150 mg/L foliar spray, performance frequently returned to control levels. A low-dose ZnO-NP seed treatment (50-100 mg/L) significantly improved the pungency, post-harvest quality, and mechanical integrity of capsicum fruits. Based on the results, which highlight the significance of dosage and application technique, capsicum fruit quality can be considerably improved by targeted early-stage root uptake of ZnO-NPs.