GIS and Remote Sensing

Chlorophyll (Chl) is an important biophysical parameter related to photosynthesis and micronutrient content in plants. The contents of Chl and nitrogen (N) present significant relationships in several crops. N is the main nutrient for the plant growth process and its content varies according to the phenological stage. Remote sensing data can provide specific local information of Chl content as an approximation of the N status of the plant. The goal of this study was to relate the content of Chl in olive-trees to their phenological stages using Sentinel-2A satellite images. TCARI/OSAVI index was used to estimate the leaf Chl content in four olive groves located in the Southwest of Spain. Satellite images from July 2016 to February 2018 were analyzed and TCARI/OSAVI indexes were computed monthly. Results indicated similar variation of the leaf Chl content index along the studied period for the four olive groves. Estimated Chl contents were lower during summer and autumn seasons, coinciding with the highest N consumption stages of the olive-tree (fruit set/early fruit growth and autumm growth). Estimated Chl contents were higher during winter season, coinciding with the nutrient acumulation period of the olive-tree (harvesting and latency stages). Minimum estimated Chl content was recorded in November 2016 and maximum in January 2017. The next step will be to calibrate TCARI/OSAVI values using spectral signatures of the  live-tree leaf reflectances measured in field.