Monitoring a calcium biofortification workflow in an orchard of Pyrus communis var. Rocha applying precision agriculture technology

Smart farming techniques can be used to maximize food production. This can be achieved by rapid detection of variations in crops and clever use of resources such as water and fertilizers, which might minimize crop stress through direct target practices. In an orchard located in the West region of Portugal (GPS coordinates 39°23’28.997’’N; 9°4’52.483’’W), a Ca biofortification workflow with 7 foliar sprays of CaCl₂ (4 kg.ha^-1 and 8 kg.ha^-1) was used to increase Ca contents in “Rocha” pear trees. During the biofortification process, an Unmanned Aerial Vehicle synchronized by GPS, was used to characterize the orchard regarding it`s morphology (slope) and to monitor trees (NDVI - Normalized Difference Vegetation Index). These data were correlated with Ca content (assessed by X-Ray fluorescence analysis) and photoassimilates synthesis (assessed by leaf gas exchange measurements). The orchard showed no major slopes and after 4 sprays with CaCl₂, NDVI values revealed no major differences between the control and sprayed trees. Accordingly, leaf gas exchange parameters did not reveal negative impacts in the photoassimilates synthesis of the sprayed trees, although in the leaves Ca content significantly increased. The use of precision agriculture techniques in correlation to other analysis to assess plant stress is discussed.