András Pitz

Ultraviolet-B (UV-B, 280–315 nm) radiation is an increasingly relevant abiotic stressor under climate-change scenarios, yet crop-specific tolerance mechanisms remain insufficiently understood. We compared maize (Zea mays L.) and grain sorghum (Sorghum bicolor L.) seedlings exposed to eight UV-B durations (1–12 h), applied every second day over 14 days of juvenile growth. Highly sensitive, non-invasive biophoton emission imaging (NightShade^® LB 985), chlorophyll content measurements (SPAD-502), and morphophysiological traits (shoot/root lengths, biomass, root collar diameter) were assessed. Biophoton emission kinetics measured immediately and 24 h after exposure suggested differing temporal defense dynamics: maize showed an early modest increase, a mid-exposure reduction, and a later pronounced peak around 6 h. Sorghum tended to reach a dominant peak earlier (≈3 h) and maintain relatively steady emissions thereafter, potentially reflecting more uniform antioxidant activation. SPAD patterns aligned with these trends: maize retained higher chlorophyll at lower exposures (0–6 h; p < 0.05), whereas sorghum surpassed maize at extreme exposures (10–12 h; p = 0.036). Morphophysiological traits showed no significant treatment effects, though minor low-dose peaks suggested possible ROS-mediated stimulation. These results indicate species-specific UV-B acclimation patterns and demonstrate the utility of biophoton imaging as a rapid screening tool for assessing crop resilience.

Climate change requires the introduction of alternative crops in certain temperate areas due to the warmer and drier growing seasons. Maize, one of the most important crops, is projected to become less tolerant of a drier climate. Therefore, it is necessary to find an alternative species that is less susceptible to environmental stressors. This study compared the germination, growth vigour, and stress tolerance of maize and sorghum grow in six types of soil under three water regimes. The results indicate that sorghum germination is faster and more uniform. The most significant differences in germination rates were found in chernozem (88.9% and 72.2% for sorghum and maize, respectively) and saline solonetz (74.4% and 63.3% for sorghum and maize, respectively). Maize exhibited higher growth vigour only in three cases, i.e., under solonetz–flooding, shifting sand–drought, and brown forest floor–flooding conditions. An ANOVA showed a significant difference between sorghum and maize stress conditions due to soil conditions and water availability (p < 0.0001). Sorghum can be a suitable alternative to maize, but only in areas with hot, dry periods and in areas where the soil is not too prone to waterlogging, regardless of its quality.