In the present investigation, nanoscale zinc oxide particulates (ZnO-nanoparticulates) were prepared using a modified oxalate decomposition method. Prepared ZnO-nanoparticulates (mean size = 25 nm) were characterized using techniques such as transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and zeta potential analyzer. Different concentrations (50, 100, 200, 400, 600, 800, 1000, 1500, and 2000 ppm) of ZnO-nanoparticulates were examined to reveal their effects on maize crop on overall growth and translocation of zinc along with bulk ZnSO4 and control. Highest germination percentage (80%) and seedling vigor index (1923.20) were observed at 1500 ppm of ZnO-nanoparticulates. The yield was 42% more compared to control and 15% higher compared to 2000 ppm of ZnSO4. Higher accumulation of zinc (35.96 ppm) in grains was recorded with application of 100 ppm followed by 400 ppm (31.05 ppm) of ZnO-nanoparticulates. These results indicate that ZnO-nanoparticulates have significant effects on growth, yield, and zinc content of maize grains, which is an important feature in terms of human health.

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Evidence-based synergistic effects of nanoscale materials (size of <100 nm in at least one dimension) were scantly documented in agriculture at field scale. Herein, we report for the first time on effects of nanoscale zinc oxide (n-ZnO), calcium oxide (n-CaO), and magnesium oxide (n-MgO) on growth and productivity of sweet sorghum [Sorghum bicolor (L.) Moench]. A modified sol-gel method was used to prepare nanoscale materials under study. Characterization was performed using transmission and scanning electron microscopies, X-ray diffraction, and dynamic light scattering. Average sizes (25, 53.7, and 53.5 nm) and ζ potentials (-10.9, -28.2, and -16.2 mV) of n-ZnO, n-CaO, and n-MgO were measured, respectively. The significant grain yield (17.8 and 14.2%), cane yield (7.2 and 8.0%), juice yield (10 and 12%), and higher sucrose yield (21.8 and 20.9%) were recorded with the application of nanoscale materials in the years 2014 and 2015, respectively. Nutrient uptake was significant with foliar application of nanoscale nutrients.

In recent years, foliar applications of nanoparticles are increasingly being employed in agricultural fields as fertilizers to enhance crop yields. However, limited studies are available on the foliar uptake of nanoscale nutrients and their interaction with plants. In this study, we reported the effects of foliar spray with varied concentrations of nanoscale silica (N-SiO2) and bulk tetraethyl orthosilicate (TEOS at 2000 ppm) on the growth and yield of groundnut. Nanosilica was prepared by a sol–gel method and characterized by transmission electron microscopy, dynamic light scattering, and X-ray diffraction. The size and zeta potential of N-SiO2 were found to be 28.7 nm and 32 mV, respectively. The plant height, number of branches, total dry weight, SPAD chlorophyll meter reading, photosynthetic rate, water use efficiency, number of nodules, and ascorbic acid content were increased significantly with the N-SiO2 foliar application at 400 ppm over control. The number of filled pods increased significantly by 38.78 and 58.60% with N-SiO2 at 400 ppm application over TEOS and control, respectively. The pod yield per plant in N-SiO2 at 400 ppm increased by 25.52 and 31.7% higher over TEOS and control, respectively. Antioxidant enzyme activities enhanced significantly in N-SiO2 at 200 and 400 ppm over control, indicating a stimulatory effect on the plant growth. In addition, confocal microscopy revealed that fluorescein isothiocyanate (FITC)-N-SiO2 entered through stomata and then transported to vascular bundles via apoplastic movement. Our study for the first time demonstrated that N-SiO2 can significantly modulate multiple complex traits in groundnut through an eco-friendly and sustainable approach.

Application of nanoscale materials in agriculture for various reasons, including plant nutrition, has been an interesting multidisciplinary research component. Among the plant nutrients, silica plays an important role as a quasi-essential nutrient besides enhancing resistance against disease and pests in the plant system. In the present investigation, we report the effects of foliar spray (field experiment) of varied concentrations (250, 500, and 750 ppm) of nanoscale silica (NSiO2) and osic acid (350, 700, and 1050 ppm) on structural and biochemical processes and yield in chilli (Capsicum annuum L.). NSiO2 was prepared using the sol–gel method and characterized by UV–vis spectroscopy, dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The DLS analysis revealed the size (26.2 nm) and ζ-potential (−43.6 mV) of NSiO2. Significant increases in plant height, chlorophyll content, carotenoids, lycopene, and superoxide dismutase enzymatic activities were recorded with particulate NSiO2 foliar application at 750 ppm. Further, we are the first to report that foliar application of particulate NSiO2 led to the formation of a silicic acid layer on epidermal cells in chilli. Hence, foliar application of particulate nanoscale silica increases the flexural rigidity of epidermal cells, the chlorophyll content, carotenoids, lycopene content, and yield in chilli.