Differential modulation of growth markers and nutrient limitation signaling molecules mediated by zinc oxide nanoparticles in black nightshade (Solanum nigrum L.)

Abstract A pot experiment was conducted to evaluate the effects of zinc oxide nanoparticles (ZnONPs) and bean husk extract (BHE) on black nightshade. Functional groups, morphological characteristics, and elemental compositions of ZnONPs and BHE were characterized. Growth parameters, reactive oxygen species (ROS), and antioxidant activities were also assessed in the plants. The study followed a randomized complete block design with five replications (n = 5). Both ZnONPs and BHE contained alcohol, hydroxyl, silicon-containing, and aliphatic nitro groups. Internal alkyne, imino, and azo groups were identified in ZnONPs, whereas terminal alkyne and isothiocyanate groups were specific to BHE. Zinc (70.56 wt%; 50.45 at%) and silica (50.25 wt%; 20.34 at%) were the dominant elements in ZnONPs and BHE, respectively. Average particle sizes were 5.64 nm for ZnONPs and 9.19 nm for BHE. ZnONPs at 1.0% significantly (p < 0.05) enhanced plant height (62.33 cm) and leaf number (64.67). Malondialdehyde and hydrogen peroxide levels were higher in control plants but decreased with increasing ZnONP concentrations. In conclusion, ZnONPs, particularly at 1.0%, improved growth and reduced oxidative stress markers, indicating their potential as sustainable soil amendments in crop production systems.