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

Monitoring plant vigor throughout the growing season is crucial for supporting precision agriculture practices and improving crop yield predictions. While remote sensing technologies offer rapid and efficient tools for crop monitoring, challenges persist in accurately interpreting the data. This study explores the temporal dynamics of leaf biochemical properties in diurnal periods (morning and afternoon), phenological stages (vegetative and reproductive), and cultivar-specific differences. Leaf chlorophyll and flavonoid contents, and nitrogen balance index (NBI) were assessed in seven maize cultivars during the growing season, using the portable device Dualex® Scientific meter. The results revealed 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. Phenological stages 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 significantly impact grain yield but rather influenced aboveground biomass (i.e. plant height and ear weight). 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 strongly recommended. • We examine leaf biochemistry dynamics by time, growth stage, and cultivar in maize crop. • Phenological factors affect cultivar and diurnal responses of physiological leaf properties. • Young leaves display higher chlorophyll and NBI, and less flavonoids than old leaves. • Cultivar-specific differences in leaf biochemistry affect aboveground biomass but not grain yield. • Combining remote sensing with ground data can improve accuracy in yield predictions.