Effects of UV-C irradiation and Spirulina priming on physiology and sanitary quality in creole maize

Abstract Salinity stress severely limits crop productivity, particularly in maize, necessitating innovative pre-sowing treatments that can enhance seed resilience and performance. This study evaluates the effects of pre-sowing treatments on the germination, physiological quality, salt stress tolerance, and fungal resistance of Zea mays (criollo maize) seeds. Three treatments were evaluated: (1) UV-C irradiation, the treatments applied were using four UV-C light prototypes (prototype irradiator 1 (commercial), prototypes 2, 3 and 4 made in-house at ESIME-Zacatenco) with radiation intensities of (1) 108, (2) 1,222, (3) 141 and (4) 1,515 mW/cm2), (2) UV-C irradiation (1,222 mW/cm2 ) combined with Spirulina-supplemented irrigation, and (3) UV-C irradiation (1,222 mW/cm2) with hydro- and nutripriming using Spirulina. Seeds were tested under both saline and non-saline conditions to simulate stress environments (The saline solution used to induce saline stress on the seeds was prepared with distilled water to which 7.5 g/L of sea salt). The experimental design included multiple evaluation time points and assessed variables such as germination rate, emergence velocity, seedling vigor, and infection by fungal pathogens. Across three experiments, results showed that hydro and nutripriming with 0.5 g/L Spirulina and UV-C exposure for 10 min improved germination up to 98.75%, enhanced the emergence velocity index by 39.35%, and reduced fungal infestation by up to 65% under non-saline conditions. Under saline conditions, the best treatment increased salt stress tolerance index by 86% and reduced germination losses by up to 51% compared to untreated controls. Principal Component Analysis revealed strong correlations between early germination variables (G30–G54), physiological performance, and improved sanitary quality due to treatment. Additionally, color changes in the seed coat due to UV-C irradiation were documented as potential indicators of surface modification. These findings demonstrate that optimized combinations of UV-C irradiation and Spirulina priming offer a viable and eco-friendly strategy for improving maize productivity in salt-affected regions.