Mitigating Effect of Iron Chlorin e6 to Silage Maize’s Root System Under Saline-Alkali Stress: An Insight into Iron Chlorin e6’s Effect on Morphology, Respiration, and Antioxidant Systems

Silage maize (Zea mays L.) serves as a key source of high-quality roughage for ruminants, yet its production and the development of the silage maize industry in Xinjiang are severely constrained by saline–alkali stress. In this study, root growth phenotypes, root energy metabolism, cell membrane stability, osmotic regulatory substances, and reactive oxygen species (ROS) metabolism were examined to elucidate the mechanisms by which iron chlorin e6 (ICe6) enhances saline–alkali tolerance in maize roots. The results showed that saline–alkali stress significantly suppressed root growth in maize seedlings, leading to increased malondialdehyde (MDA) content and relative conductivity. This suggests that membrane lipid peroxidation has intensified, resulting in increased cell membrane permeability. Meanwhile, ICe6 enhanced antioxidant enzyme (SOD, POD, CAT, and APX) activities, scavenged H2O2 accumulation, reduced MDA content, and stabilized cell membrane integrity, as indicated by reduced ion leakage. Moreover, ICe6 optimized root respiratory pathways, improved root vigor, and ATP synthesis to provide adequate energy for growth, while decreasing free proline accumulation to maintain cellular osmotic balance. These findings demonstrate that ICe6 mitigates saline–alkali stress in silage maize roots through coordinated regulation of energy metabolism, antioxidant defense, and osmotic adjustment.