Carbon Nanoparticles Enhance Drought Tolerance Through the Improvement of Morphological and Physiological Traits in Maize Hybrids

Drought stress severely limits maize growth and productivity worldwide. In this study, we examined the effects of foliar-applied carbon nanoparticles (CNPs) on morphological and physiological traits in maize plants exposed to drought stress for 25 days. Two maize hybrids, one drought-tolerant (LG 36745 PRO4) and one drought-sensitive (AG 8088 PRO2), were fertilized with 0 or 1.0 mL L−1 of a CNP-based nanofertilizer at the V2 growth stage and exposed to three drought levels: 0 MPa (control), −0.4 MPa (moderate stress), and −0.8 MPa (severe stress). The experiment followed a 2 × 2 × 3 factorial design (hybrid × CNP treatment × drought level) with four replicates. Results indicated that drought stress adversely affected most morphological and physiological traits, particularly in the drought-sensitive hybrid. However, foliar CNP application significantly alleviated the adverse effects of drought in maize plants under moderate and severe stress, primarily by preserving plant water status, enhancing water use efficiency, carboxylation efficiency, photosynthetic rate, and initial growth in challenging environments. These findings will provide the basis for future research on management practices adopted to control drought and ensure the development of modern and sustainable agriculture.