## 3 Results  
### Vegetation Dynamics Monitored by Remote Sensing  
The development of winter wheat represented by the average NDVI as recorded by PlanetScope (PS), is shown in Figure 3. The NDVI time series effectively tracks the key phenological stages of the crop, with the SOS, POS, and EOS marked by their respective indicators. The progression of GDD is shown on the \(x\)-axis, corresponding to the timeline of the study. Based on actual observations, the start of the season (SOS) was on 18 November 2022, and the end of the season (EOS) was on 27 June 2023. PlanetScope satellite estimates detected the SOS on 26 November 2022, underestimating the actual date by 8 days, and the EOS on 15 June 2023, overestimating the actual date by 12 days compared to the sowing and harvest, respectively. In the early stages, corresponding to the sowing stage (Z\({}_{0}\)), the crop starts to emerge in early November 2022. At this stage, the accumulated GDD ranged from 0 to 440 GDD, and the NDVI ranged from a minimum of 0.11 to a maximum of 0.54, with a mean value of 0.31 (Table 3). As the crop progresses into the tillering stage (Z\({}_{2.3}\)) between mid-December 2022 and late January 2023, the NDVI steadily increases, indicating additional wheat tillers. Figure 3: Winter wheat temporal dynamics of NDVI and GDD across different phenological stages. During this period, the cumulative GDD ranged from 464 to 884, and the NDVI increased from a minimum of 0.36 to a maximum of 0.69, with a mean value of 0.52. The peak NDVI values occur during the grain development stage (\(Z_{7.1}\)), which extends from the end of March to the end of May 2023. At this time, the crop reaches maximum vegetative growth, with \(GDD_{accum}\) ranging from 1004 to 1911. The NDVI at this stage increases to an average of 0.62, with a maximum of 0.77. Finally, the senescence stage (\(Z_{9.3}\)) occurs from late May to June 2023 and marks the decline in NDVI as the crop matures. During senescence, the \(GDD_{accum}\) ranges from 1928 to 2505, while the NDVI values drop from a maximum of 0.46 to a minimum of 0.19, with a mean value of 0.30. In addition to the NDVI evolution, a comparative analysis between the MicaSense and PlanetScope reflectance values was conducted based on coincident acquisition dates (Supplementary Material: Figures S2 and S3). Figure S2 illustrates notable differences in RGB and NDVI values, with MicaSense providing higher spatial detail but differing NDVI ranges. Scatterplots in Figure S3 quantify these discrepancies, showing low R\({}^{2}\) values for individual acquisition dates, particularly in the blue and green bands (R\({}^{2}\) < 0.25). However, the overall R\({}^{2}\) improves when combining data across all dates, especially in the NIR band (R\({}^{2}\) = 0.70), capturing seasonal variability but not per-date agreement. In the MicaSense images, reflectance values are consistently lower than those from PlanetScope, with significant deviations in March and May. In fact, the scatter plots (Figure S3) further illustrate the weak correlation between MicaSense and PlanetScope reflectance, particularly in the blue and green bands, where Pearson's R\({}^{2}\) values are as low as 0.06 in January and 0.10 in May. Despite this, some bands, such as the red edge and NIR bands, show slightly better correlations, although the overall R\({}^{2}\) values remain below 0.30 across all acquisition dates. These discrepancies can be attributed to several factors, including differences in the relative spectral responses of the sensors and possible variations in the radiometric calibration procedures. Nevertheless, the overall relationship between the two sensors reflectance values is relatively weak. The PlanetScope time series evolution of NDVI for the different treatments is shown in Figure 4. As observed, the NDVI trends differ significantly between the control and the different experimental treatments, especially after the fertilizer application.