Document Type : Novel Research Articles
Authors
1
Botany and Microbiology,Faculty of Science,Assiut,Egypt
2
Botany and Microbiology,Faculty of science, Assiut University,
3
Botany and Microbiology department,Faculty of Science,Assiut university
4
Botany and Microbiology,Faculty of Science,Assiut university
10.21608/aunj.2025.367384.1124
Abstract
The effect of foliar spraying by micrometer-sized TiO2 particles (TiO2-Bulk) and TiO2-nanoparticles (TiO2-NPs) at different concentrations (50, 150, 300, and 600 ppm) on Lupinus albus subjected to different levels of water availability (25%, 50%, 75%, and 100% of field capacity) were examined. Under drought stress circumstances, all potential associations between plant enzymatic activities (CAT, APX and GPX), proline and membrane damage monitors (H2O2 concentration, lipid peroxidation and membrane injury index) were evaluated. Significant relationships between both types of TiO2 and enzymatic activities were found, especially in the roots of Lupinus. All enzyme activities were elevated by decreasing water availability, indicating to increasing the efficiency of antioxidant defense mechanisms. These activities were diminished in some enzymes by foliar spraying by bulk or nano-TiO2, specially at low concentrations, suggesting possible roles of TiO2 in increasing the capability of plants in attenuating ROS-induced oxidative damage. Lipid peroxidation was positively correlated with H2O2 concentration that increased by water-stress in the plant organs. The unique grouping of treatments based on the type and concentration of TiO2 and on the water-stress level was further highlighted by Cluster Analysis to reflect the interdependent impact of both factors on plant responses. Treatments with bulk or nano-TiO2 particles showed a propensity to strengthen antioxidant defense mechanisms in Lupinus albus under moderate water-stress. The protective properties of these particles seemed to be lessened under extreme water-stress (25% FC), indicating that both kinds of TiO2 particles may worsen oxidative stress in the plant under severe water-deficit especially under higher concentration.
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