Hybrid, Climatic Variability, and Tillage Effects on Maize Grain Quality Under Sprinkler Irrigation in South-Eastern Romania

This study evaluated the effects of hybrid, climatic variability, and tillage systems on maize grain quality and antioxidant composition under sprinkler irrigation in South-Eastern Romania during 2023–2025. Three maize hybrids (P0900, P0937, and P1441) and three tillage systems (conventional, minimum, and no-tillage) were investigated under field conditions. Grain quality was assessed using hectoliter weight, protein, starch, and moisture content, while antioxidant composition was assessed using tocopherols and β-carotene. The hybrid was the main factor influencing grain quality and antioxidant composition. P0900 recorded the highest hectoliter weight (74.13 kg hL−1), P1441 showed the highest protein content (9.14% DM), α-tocopherol concentration (9.18 µg g−1 DW), and β-carotene content (4.41 µg g−1 DW), whereas P0937 exhibited the highest starch content (74.39% DM). A strong inverse relationship between protein and starch accumulation was observed (r = −0.84, p < 0.01). Climatic variability significantly affected grain quality, with protein content increasing by 28.9%, grain moisture by 7.1% and hectoliter weight by 1.9% from 2024 to 2025, whereas starch content decreased by 1.6%. Tillage systems had comparatively minor effects, with reduced soil disturbance increasing protein and moisture content while slightly decreasing starch concentration. These findings highlight the dominant role of hybrid selection in determining maize grain quality and antioxidant composition under irrigated conditions.