Effects of No-Tillage Versus Conventional Tillage and Nitrogen Fertilization on Durum Wheat Grain Quality and Intestinal Cell Responses

Background: Conservation agriculture has emerged as a sustainable strategy to improve soil quality while maintaining crop productivity and grain nutritional value. However, limited information is available on how agronomic practices influence the biological activity of durum wheat grain. This study, conducted within the framework of the PFRLab project, investigated the effects of no-tillage (NT) and conventional tillage (CT) under two nitrogen fertilization levels (0 and 180 kg ha−1 N) on durum wheat grain quality and the biological responses of Caco-2 intestinal epithelial cells. Methods: Grain quality was evaluated by determining protein, lutein, and mineral contents. The biological activity of grain extracts was assessed by measuring Caco-2 cell viability using the MTT assay and intracellular oxidative activity using H2DCFDA-derived fluorescence after 3, 24, and 48 h of incubation. Results: Grain protein and lutein contents tended to be higher under nitrogen fertilization, whereas differences between tillage systems were less consistent for the measured compositional traits. In contrast, distinct responses emerged in the cellular assays. NT-derived extracts generally maintained higher Caco-2 cell viability than CT-derived extracts, particularly after 24 and 48 h, while CT-derived extracts generally elicited higher H2DCFDA-derived intracellular fluorescence. Nitrogen fertilization influenced both cellular endpoints, with effects varying according to incubation time and tillage system. Correlation analysis revealed negative but non-significant associations between intracellular fluorescence and cell viability at individual incubation times (r = −0.649 at 3 h, −0.353 at 24 h, and −0.198 at 48 h). Conclusions: The findings of this pilot exploratory study suggest that long-term no-tillage can maintain the measured durum wheat grain-quality traits at levels comparable to conventional tillage under Mediterranean conditions, while agronomic management is also associated with differences in the biological activity of grain extracts. The cellular findings provide complementary information rather than evidence of direct health effects or specific chemical mechanisms. Future studies integrating targeted phytochemical characterization of grain extracts, soil microbial analyses, and complementary cellular approaches may help clarify the relationships between agronomic management, grain composition, and biological activity.