Efficacy of chitosan loaded zinc oxide nanoparticles in alleviating the drastic effects of drought from corn crop

Water stress significantly impedes the normal growth and development of crops. Water scarcity profoundly affects crop growth and productivity, notably impacting vital crops like maize (Zea mays L.). The field of nanotechnology has surfaced as a promising avenue for mitigating the negative consequences of water stress on crucial crops. The objective of this study was to alleviate the negative impacts of drought stress on maize (Z. mays) via the utilization of chitosan-loaded nanoparticles (CSNPs). The CSNPs were synthesized using extracts from Nigella sativa L. and were characterized by employing scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–Vis spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). The optimized CSNPs doses from the screening experiment (ranges between 300 µg/L to 500 mg/L) were applied as a foliar spray to maize plants in a pot experiment, in both typical and drought scenarios. A completely randomized factorial design (CRD) was employed for the experiment. Characterization by SEM analysis showed the existence of CSNPs, displaying an average particle size of 89 nm. Whereas XRD analysis showed a crystalline structure. FTIR analysis unveiled the existence of diverse functional groups that functioned as reducing agents on the surface of synthesized CSNPs. Furthermore, CSNPs significantly mitigated the negative effects of water stress by positively influencing various growth parameters of maize crops. It was noted that there was an increase in plant length by 10.20 %, leaf area by 29.87 %, number of tillers per plant by 5.92 %, ear length by 8.66 %, cob weight by 47.22 %, and number of grains by 462.42 % in comparison to the control. Moreover, the utilization of CSNPs had a profound impact on phytochemical parameters, including osmotic potential increases by 5.61 %, relative water content decreases by 2.24 %, chlorophyll and carotenoid content decreases by 18.14 % and 17.28 % respectively, membrane stability index increases by 9.82 %, sugar content decreases by 6.085, proteins increases by 61.67 %, phenolics increases by 0.42 %, proline decreases by 5.51 %, flavonoids increases by 21.12 %, and malondialdehyde (MDA) content decreases by 21.07 % in drought stress as compared to control. The levels of MDA, a marker of oxidative stress, in maize, decreased significantly in drought conditions by 21.07 % in response to the application of CSNPs. Stress studies revealed that CSNPs increased the functioning of antioxidant enzymes under drought stress, such as catalase (CAT) by 13.71 %, peroxidase (POD) by 27.17 %, and superoxide dismutase (SOD) by 24.66 %, as compared to control suggesting their role as stress mitigators. In conclusion, the study establishes that chitosan-loaded nanoparticles (CSNPs) positively enhance drought tolerance in maize, making them a potential tool for sustainable agriculture under water-limited conditions.