Author(s): Jose Toledo Choquehuanca; Jose Huanuqueno Murillo; David Quispe Tito; Malu Galindo Sanchez; Edwin Pino Vargas And Lia Ramos Fernandez

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Keywords: Crop water stress index; Vapor pressure deficit; Hass avocado; Thermal imagery; UAV

Abstract: This research was conducted to assess water stress in Hass avocados by utilizing aerial thermography within the environmental context of La Molina, Lima, Peru. The study concentrated on analyzing the vapor pressure deficit (VPD) and the crop water stress index (CWSI) from January to April 2023, which aligns with the fruit set and growth periods in that region. To collect data, thermal and RGB (red, green, blue) images were taken using an H20T camera affixed to a Matrice 300 RTK unmanned aerial vehicle (UAV) and subsequently processed with Pix4Dmapper Pro software. Concurrently, soil moisture was gauged with a time domain reflectometer (TDR), and incoming solar radiation was captured using a radiometer across nine different surface types: aluminum, dry avocado leaves, green avocado leaves, expanded polystyrene, and various cloths in yellow, black, red, and green colors, along with bare soil. The thermal image data collected by the UAV and the radiometer exhibited a Pearson correlation coefficient of 0.978. The study's analysis indicated a gradual decline in the minimum Tc-Ta thresholds as VPD rose, with an upper temperature limit (UL) set at 8°C. Furthermore, it identified an inverse linear correlation between the CWSI and gravimetric moisture (θ), with Pearson coefficients of 0.849 in January and 0.522 in February and March. The results also showed that avocado plants respond to restricted water availability in the soil by closing their stomata to avoid dehydration.

DOI: https://doi.org/10.64697/978-90-835589-7-4_41WC-P1985-cd

Year: 2025