Mitigation of drought and cadmium stress in wheat (Triticum aestivum) through blue-red LED light and ginger-mediated ZnO nanoparticles

Drought and cadmium stress are among the significant challenges for wheat production, leading to yield losses and quality issues. Therefore, current study was aimed to investigate the effect of ginger ( Zingiber officinale )- mediated green synthesized ZnO nanoparticles (ZnO NP) and Red+Blue LED light on wheat growth and tolerance under drought and cadmium stress. A pots experiment was conducted in a completely randomized design (CRD) with 16 treatments, each with three replicates. Drought and cadmium stresses were applied at 22 days after sowing (DAS) by applying 0.75 mM cadmium and drought stress by maintaining 40% field moisture capacity. The ZnO NPs (1mM) were applied as foliar spray for three consecutive days (30–33 days after sowing at vegetative stage), and plants were exposed to Red+Blue LED light (400–700 nm, photoperiod of 16 h of light and 8 h of dark with a light intensity of 13700 lx with a plant canopy level from a distance of 25 cm with an estimated Photosynthetic Photon Flux Density of ~ 274 µmol m⁻² s⁻¹ for the 7:3 red-blue LED spectrum) from 30 days after sowing until harvest at 52 DAS. This study uniquely combined ginger ( Zingiber officinale )-mediated green-synthesized ZnO NPs with Red+Blue LED light as a scientific approach which was not previously investigated under combined drought and cadmium stress. The ZnO NPs and LED treatments improved physiological parameters including plant height, shoot and root fresh weight, chlorophyll, relative water content compared with normal and stress controls. Additionally, improvement in stress-related parameters were also observed such as : L + D+ZnO NP treatment led to a 35% decrease in malondialdehyde (MDA) contents as compared to drought (D) stress plants. Superoxide dismutase (SOD) activity in the shoot was increased by 29% in response to L + D+Cd + ZnO NPs treatment compared to the untreated control. Peroxidase (POD) activity in the shoot showed a significant increase of 20% in the combined D + Cd+ZnO NPs treatment and 9% increase in L + D+Cd treatment as compared to the untreated control. Catalase (CAT) activity in the shoot increased by 54% and 46% in response to D + Cd+ZnO NPs and L + D treatment, as compared to the control. Polyphenylalanine ammonia lyase (PAL) activity was increased (22%) in D + ZnO NPs as compared to the untreated control. Hydrogen peroxide (H 2 O 2 ) activity showed decreased of 32% in L + D treatment as compared to D. These findings suggest that the utilization of environmentally friendly strategies, such as green-synthesized ZnO NPs and LED light, holds promise for enhancing crop resilience, improving physiological and biochemical performance of wheat under drought and cadmium stress.