Improvement of spring maize performance through physical and physiological seed enhancements

Temperature extremes adversely affect plant growth and productivity. Early planting is an option to avoid heat stress at the reproductive stage, but maize may then be subjected to chilling stress at stand establishment. An experiment was therefore conducted to alleviate the devastating effect of chilling stress in maize hybrid Pioneer-32F10 through pre-sowing seed treatments: magnetic seed stimulation (150 mT for three minutes), hydropriming (24 hours) and priming with 0.5% ZnSO₄ (24 hours). Treated and untreated seeds were sown at early and optimal times in the field. Chilling stress altered maize seedling performance. All treated seeds gave better results compared with non-treated seeds, but magnetically-treated seeds performed better than primed seeds. Magnetic seed stimulation was more effective in inducing chilling stress tolerance in this maize hybrid primarily by improving stand establishment, phenology, allometry, agronomic traits and yield components. Furthermore, magnetic stimulation also significantly enhanced chlorophyll content, total phenolics, gaseous exchange attributes, seed protein and oil contents, and reduced membrane permeability in contrast to ZnSO₄-priming. In conclusion, magnetic seed stimulation followed by ZnSO₄-priming was an efficient tool for enhancing the performance of spring maize under cool conditions.