Enhancement of maize drought resilience using nano-buckminsterfullerenes and plant growth-promoting rhizobacteria: insights into pigment stability, oxidative stress reduction, and yield

Drought stress severely impairs the biochemical, physiological, and morphological attributes of crop plants, resulting in reduced agricultural productivity and sustainability. The present study evaluated the potential of plant growth-promoting rhizobacteria (PGPR) and nano-buckminsterfullerenes to alleviate drought-induced stress in maize. A greenhouse experiment was conducted in 2024 using a factorial randomized complete block design with five replications. Treatments included three drought stress levels (well-watered, moderate, and severe drought), four foliar application levels of nano-buckminsterfullerenes (0, 5, 25, and 50 mg L⁻¹), and four PGPR treatments (control, Rhizobium, Burkholderia, and combined Rhizobium + Burkholderia). Severe drought stress significantly increased dry matter remobilization from shoots and stems, with stem reserves contributing substantially to grain yield. However, the combined application of PGPR and nano-buckminsterfullerenes under severe drought markedly improved carotenoid content (49.3%), chlorophyll a (31.4%), total chlorophyll (28.7%), leaf area index (40.2%), grain filling duration (19.6%), effective grain filling duration (15.8%), and grain yield (14.3%) compared with untreated controls. Additionally, these treatments reduced cell death rate, hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) levels, while enhancing soluble sugars and protein content. Overall, the results demonstrate that PGPR and nano-buckminsterfullerenes effectively mitigate drought stress and improve maize productivity by enhancing physiological performance and grain filling characteristics.