Enhancement of Salinity Stress Tolerance in Zea mays L. (maize) Seedlings through Seed Priming and Foliar Applications of Calcium Chloride (CaCl2)

Abstract

Salinity stress is a major constraint to crop establishment and productivity, particularly in salt-affected agricultural soils. The present study evaluated whether calcium chloride (CaCl2) applied through seed priming, foliar application or their combined use could improve salinity tolerance in maize (Zea mays L.) seedlings of variety BS-652. The experiment was conducted under laboratory conditions using a completely randomised design with seven treatments and three replications. Salinity stress was imposed with 150 mM NaCl, and seedlings were grown for 30 days before morphological, physiological and biochemical traits were assessed. Salt stress alone reduced plant height, seedling fresh and dry weight, relative water content, chlorophyll content and total protein content, while increasing proline accumulation and malondialdehyde content. These responses indicate impaired growth, osmotic disturbance and membrane injury under salinity. Calcium chloride treatments improved seedling performance under both non-saline and saline conditions. Foliar application generally produced greater improvement than seed priming alone, while the combined seed priming and foliar application treatment showed the strongest response under salinity stress. This combined treatment improved plant height, biomass accumulation, water status, chlorophyll retention and protein content compared with untreated salt-stressed plants. It also enhanced proline accumulation and the activities of catalase and ascorbate peroxidase, while reducing malondialdehyde content. The results indicate that CaCl2 application may support maize seedling tolerance to salinity by improving water balance, membrane stability, osmotic adjustment and antioxidant defence. Among the treatments evaluated, the combined use of seed priming and foliar application was the most effective approach for mitigating 150 mM NaCl-induced stress in maize seedlings.