Physiological Responses of Maize to Gamma Irradiation Following Experimental Seed Pre-Treatment

Ionizing radiation can impair maize germination, growth, membrane integrity, and chlorophyll-related traits. Zn-containing seed treatments may modify stress responses, but organic-ligand-containing Zn preparations remain poorly characterized under irradiation. We evaluated a recovered imatinib–Zn material (ZnIM) as an experimental seed pre-treatment in maize genotype ‘Zakatala-68’ under a controlled 150 Gy gamma-radiation challenge. Seeds were soaked for 8 h in water or 0.001%, 0.01%, or 0.1% (w/v) ZnIM, rinsed, surface-dried, and irradiated as designated. The concentrations constituted an exploratory ten-fold treatment series. Germination, germination energy, seedling growth, malondialdehyde (MDA), photosynthetic pigments, and photosystem II maximum quantum efficiency (Fv/Fm) were assessed. Irradiation reduced final germination, germination energy, root length, and shoot length by approximately 9%, 10%, 10%, and 13%, respectively; chlorophyll a, total chlorophyll, and Fv/Fm declined by approximately 32%, 30%, and 6%, while first-week MDA increased 2.06-fold. ZnIM responses varied by concentration and trait. Relative to irradiated controls, 0.01% ZnIM significantly improved final germination, germination energy, root length, chlorophyll a, total chlorophyll, and Fv/Fm; 0.1% ZnIM yielded the lowest numerical MDA values in weeks two and three. These laboratory findings represent physiological proof of concept, not evidence of field efficacy, a defined mechanism, or identified active ZnIM-derived species.