PhytoSynthesized Nano-Zinc Formulation for Sustainable Growth and Yield Enhancement in Tomatoes Under Protected Cultivation

Zinc (Zn), an important micronutrient, plays an essential role in plant growth and development. Being the most crucial divalent metallic enzyme, Zn acts as a catalyst in many biochemical processes that regulate growth hormones in plants. Nanoseed priming is an effective agrotechnology that enhances the quality parameters of young seedlings for establishing a good crop stand. In the present study, zinc nanoparticles synthesized from M. oleifera leaf extracts were characterized by UV spectroscopy, XRD, FTIR, FE-SEM, TEM, TGA, DLS, and zeta analysis. The synthesized nanoparticles showed moderate antioxidant, anti-inflammatory, and antimicrobial activities. Phytosynthesized nanoparticles were tested for their efficiency in modulating plant growth and development, where modern nanoscience technology is at the seedling stage. In the present research, tomato seeds were hydropriming carried out with sample solution of 100 mL from a 1 L stock solution for each treatment with ZnONPs at 50 ppm, 100 ppm, 150 ppm, 200 ppm, and 250 ppm, as well as ZnSO4 used as an ionic control at 1.5 g/L. 150 and 200 ppm increased germination percentage. Plant height at seedling stage was enhanced to 22.33 and 19.67 cm at 150 and 250 ppm, respectively. Foliar applications were initiated at 35 DAT, when the plants were at 10–12 true leaves and in the transition phase of tomato plants from the vegetative stage to the flowering stage; 150 ppm induced early flowering, as well as the highest leaf area, TSS content, chlorophyll levels, the number of fruits per cluster, and the number of fruits per plant. Foliar application at 150 ppm enhanced the total and marketable yields to a maximum of 4102.63 and 3984.30 g, respectively. Foliar application at 150 ppm induced the lowest disease severity, at 20.02%, in vivo and in vitro, with the maximum mycelial inhibition of 19.50 mm at 0.15 mg/mL.