Temporal Dynamics of Crop Health in Maize Cultivars: Insights for Drone-Based Data Interpretation

<p>Monitoring plant vigor through the growing season is crucial for supporting precision agriculture practices and improving crop yield. While remote sensing technologies offer rapid and efficient tools for crop monitoring, challenges persist in accurately interpreting data. We explored the temporal dynamics of leaf biochemical properties in diurnal periods and across phenological stages. Leaf chlorophyll and flavonoid contents, and nitrogen balance index (NBI) were assessed in seven maize cultivars during the growing season. We found significant diurnal variation in chlorophyll content and NBI, with higher values observed in the morning compared with the afternoon. In contrast, no diurnal variation was detected in flavonoid content. Phenology also influenced leaf biochemistry, with distinctions between young and old leaves. For instance, young leaves exhibited higher chlorophyll concentration and NBI and lower flavonoids compared with older leaves, where senescence occurred earlier. Cultivar-specific differences were also observed, with some cultivars showing higher chlorophyll content and NBI, likely influenced by crop maturity duration. These differences in leaf biochemistry did not impact grain yield but rather influenced aboveground biomass. These findings underscore the importance of accounting for diurnal and phenological factors, as well as cultivar-specific differences, when using physiological leaf properties to evaluate crop status and predict yields. We highlight significant differences in biochemical properties between young and old leaves, which introduce biases in remote data collection e.g. via drones or unmanned aerial systems. Since drones predominantly capture data from the upper canopy leaves, this may not adequately reflect the overall plant physiological status. To enhance the accuracy of data and improve precision agriculture practices and yield predictions, combining remote sensing data with ground-level measurements is recommended.</p>