Use of different temporal scales to monitor phenology and its relationship with temporal evolution of normalized difference vegetation index in wheat

Use of Farmer Knowledge in the Delineation of Potential Management Zones in Precision Agriculture: A Case Study in Maize (Zea mays L.)

“…The aNDVI, as proposed by Campos et al [25] and González-Gómez [26], was preferred to map the within-field variability instead of only using indices of a specific date (e.g., just before tasselling) because, according to our experience, the crop development stage in different parts of the plot is not uniform. It can vary according to soil properties, irrigation rates, and other factors.…”

“…After calculating the NDVI for each valid image, and following the criteria proposed by González-Gómez et al [26], we plotted the average NDVI of the field for each date to identify the date of the green-up and the date of grain maturity (Figure 3). Only the B04 (Red 664.5 nm, width 38 nm) and B08 (near infrared NIR 835.1 nm, width 145 nm), with 10-m pixel size, were used to calculate the normalized difference vegetation index (NDVI) according to the Equation (1) [33].…”

“…After calculating the NDVI for each valid image, and following the criteria proposed by González-Gómez et al [26], we plotted the average NDVI of the field for each date to identify the date of the green-up and the date of grain maturity (Figure 3). The green-up corresponds to the beginning of the growing phase or crop development stage [36].…”

“…The green-up corresponds to the beginning of the growing phase or crop development stage [36]. The time series of NDVI allowed for the identification of the green-up moment [26]. Specifically, the green-up does not correspond to any phenological stage.…”

“…For example, Maresma et al [19,24] investigated the correlation of different multispectral vegetation indices with the N status at V12 (12 leaves with visible leaf collar) just before tasselling with a single date image. However, other authors point out that good estimator of biomass and yield can be derived from the use of temporal series of remote-sensing images to characterize dynamics of crop canopy throughout the growing and development cycle [25,26]. From that, the accumulation of vegetation index values (e.g., the normalized difference vegetation index, NDVI) from the beginning of the biomass accumulation to grain maturity could be a good alternative to yield maps to estimate the within-field variability to finally delineate potential zones for different management practices.…”