Physiological Assessment of Rocha Pear Trees to Agronomic Enrichment with CaCl₂ and Ca(NO₃)₂

The exponential increase of the world`s population is a major concern for the food sector since quantity and quality of food products needs to be ensured for consumers. Thus, in an orchard of pears located in Portugal, a total of seven foliar sprays, using CaCl₂ and Ca(NO₃)₂ were performed. The first two sprays with three different concentrations each (CaCl₂ - 0.4, 0.8 and 1.6 kg.ha^-1; Ca(NO₃)₂ – 0.1, 0.3 and 0.6 kg.ha^-1), the third with CaCl₂ 4 kg.ha^-1 and the remaining four with CaCl₂ 8 kg.ha^-1. During the workflow, normalized difference vegetation index (NDVI) was attained with unmanned aerial vehicle (UAV) and later correlated with photoassimilates synthesis (assessed by a portable open-system infrared gas analyzer) and Ca content in leaves and fruits (assessed by X-Ray fluorescence analysis). Regarding NDVI values, the exclusive use of CaCl₂ presented slightly inferior values, however no major signs of disrupted vegetation were detected. For leaf gas exchange, only minor changes occurred (namely E and iWUE parameters), while calcium content in leaves during the workflow and fruits at harvest increased. In conclusion smart farming techniques can be correlated with in situs analysis to monitor Rocha pear trees and the concentrations used in this study increased Ca content in fruits without reaching toxicity levels.