The citrus industry presents a notorious position in the global economy and whose production of oranges, acid limes and lemons, and tangerines exceeds that of other fruits in Brazil. This production chain requires new technologies and improved methodologies for the success of the activity. Nitrogen (N) and calcium (Ca) influence the synthesis of chlorophyll, tissue growth and plant health (such as the occurrence of postbloom fruit drop, PBF), and consequently, production and quality of citrus orchards. Although ammoniacal fertilizer, such as ammonium nitrate (AN), are used in citrus fertigation, there are differences in the efficiency of fertilizer use, in relation to deleterious effects on plant metabolism and production, when compared to sources, such as calcium nitrate. (CaN), whose orchard responses should be better evaluated in the field. Still, the supply of foliar Ca needs further investigation on the effect of the nutrient on the quality of flower tissue. Among new technologies, remote sensing (RS) can assist plant management in the field. Thus, the research project will evaluate the relationship between soil chemical characteristics, plant nutritional status, growth, and predisposition of citrus to PBF in an orchard fertigated with different sources of nitrogen fertilizer (AN, CaN or AN + CaN, 200 kg ha-1 of N), also applied via foliar (50 kg ha-1 of Ca in the form of CaN). The orchard management responses will be monitored using a RS tool on an unmanned aerial vehicle equipped with RGB, TRI and LIDAR sensors. Exploring the relationship between N and Ca supply x productivity and the ability to use SR monitoring tools will contribute to the insertion of best practices for growing citrus, based on precision agriculture with gains in the efficiency of the input use and sustainability in citrus industry.
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