Exogenous Silicon Applications Enhance Peach Seedling Response to Flooding-Induced Hypoxia Stress

AbstractPeach trees are highly susceptible to hypoxic conditions during flooding, which causes oxidative damage in plant cells, resulting in death. Silicon (Si) has been reported to improve plants’ performance under abiotic stresses, such as flooding. This study aimed to evaluate the performance of peach rootstock (‘MP-29’) seedlings under hypoxic stress. Seedlings were foliar sprayed with two levels (1000 and 1500 ppm) of silicon dioxide nanoparticles (SiNPs) and silicon dioxide solution (SiSol) to determine their capacity to mitigate oxidative damage. Seedlings treated with SiNPs had significantly higher antioxidant activities (superoxide dismutase, peroxidase, and catalase), and accumulation of compatible solutes (proline and glycine betaine) compared to those treated with SiSol and control seedlings. The rate of lipid peroxidation and generation of reactive oxygen species (ROS) O2and H2O2was higher in flooding stressed seedlings as compared to control seedlings; however, Si applications reduced those differences. SiNPs were more effective than SiSol in lowering the rate of lipid peroxidation and formation of ROS. In addition, Si applications to seedlings under non-hypoxic conditions aided to increase N, P, K, and Zn contents in leaves, compared to hypoxic-stressed and control seedlings, particularly when using 1500 ppm. Micronutrient content (Fe and Mn) was high in flooding-stressed seedlings, but SiNPs limited their concentration to levels lower than those in SiSol treated seedlings. In conclusion, Si applications improved the performance of peach seedlings exposed to flooding conditions. Additionally, SiNPs were more effective than SiSol in improving the adaptative stress response of peach seedlings to flooding stress.